PubMed

PubMed Help
Last updated:  September 3, 2004

• PubMed Searches
•     Author 
•     Journal  Titles
•     Automatic Term Mapping
•     Truncation
•     Phrase Searches
•     Additional Search Rules
•         Boolean and Syntax & Search Field Qualification
•     Subsets
•     Cookies
• Creating a Web Link  
• Features Bar - Limits  Preview/Index  History  Clipboard  Details
• Documents
•     Display
•     Sort
•     Send to:  Text  File  Clipboard E-mail Order
•     Import Citations into a Reference Management Program
•     Print
• Links
•     Related Articles - Computation Algorithm
•     Books
•     LinkOut (full-text)
•     NCBI Databases
• Cubby - Registration  Stored Searches  LinkOut Preferences  Document Delivery Services
• Other Services
•     Text Version
•     E-Utilities
•     Journals Database
•     MeSH Database
•     Single Citation Matcher
•     Batch Citation Matcher
•     Clinical Queries
• Customer Support and Training Publications
• References
•     Search Field Descriptions and Tags
•     MeSH Subheadings & Families of MeSH Subheading Explosions
•     NLM Author Indexing Policy
•     Publication Types
•     Stopwords
•     MEDLINE Display Format
•     Grant Abbreviations and Institute Acronyms
•     PubMed Character Conversions

 

PubMed Searches

PubMed was developed by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine (NLM). The Overview contains additional information. The black menu bar includes links to PubMed and the other NCBI databases.

PubMed searching is easy: just enter search terms in the query box and press the Enter key or click Go.  The Features bar directly beneath the query box provides access to additional search options. The PubMed query box and Features bar are available from every screen, so you don't need to return to the homepage to enter a new search.

You may enter one or more terms (e.g., vitamin c common cold) in the query box and PubMed automatically combines (ANDs) significant terms together using automatic term mapping. The terms are searched in various fields of the citation. Your search may include Boolean operators.

Once you click Go, PubMed will display your search results.  The query box displays your search terms as you entered them.

You can modify your current search by adding or eliminating terms in the query box or in Details.  If you applied Limits, the check box next to Limits will be marked and a listing of your limit selections will be displayed.  To turn off the existing limits, click on the check box to remove the check before running your next search.
 

Author

To search by an author's name, enter the name in the format of last name plus initials (no punctuation), e.g., smith ja, jones k.  PubMed automatically truncates the author's name to account for varying initials and designations such as Jr. or 2nd.  A name entered using this format will search in the author field.   If only the author's last name is entered, PubMed searches the name in All Fields, except when the author name is found in the MeSH (National Library of Medicine's Medical Subject Headings) Translation table (e.g., Yang will search as Yin-Yang [MeSH] or Yang [Text Word].) To search for an author in the author field when only the last name is available, qualify the author name with the author search field tag [au], e.g., yang [au].

Note:

• Use double quotes around the author's name with the author search field tag [au] to turn off the automatic truncation, e.g., "smith j" [au].
• Use the [au] search tag if the author name is also a subject term, e.g., moran a [au].  The unqualified phrase, moran a, will search as "moran A"[Substance Name] OR moran a[Text Word].

Journal Titles

Note:

• If a journal is also a MeSH term (e.g., Gene Therapy, Science, or Cell), PubMed will search the unqualified term as MeSH. Qualify the journal title with the Journal Title search field tag, [ta], to search for the journal, e.g., gene therapy[ta].
• Qualify single word journal titles using the Journal Title search field tag, e.g., scanning [ta], because PubMed will search unqualified single journal titles as MeSH terms (if applicable) or as All Fields.
• Searching with the full journal title or MEDLINE abbreviation is recommended for complete retrieval of indexed items; the ISSN number is not guaranteed to be on older citations.
• If a journal title or title abbreviation includes a special character (e.g., parentheses, brackets, &), enter the title or abbreviation without the special characters.  For example: to search, j hand surg [am], enter  j hand surg am.

• Single Citation Matcher
• Batch Citation Matcher

Automatic Term Mapping

1. MeSH Translation Table
The MeSH Translation Table contains MeSH Terms, the See-Reference mappings (also known as entry terms) for MeSH terms, MeSH Subheadings, Publication Types, Pharmacologic Action terms, terms derived from the Unified Medical Language System (UMLS) that have equivalent synonyms or lexical variants in English, and the Supplementary Concept (Substance) Names and their synonyms. If a match is found in this translation table, the term will be searched as MeSH (which includes the MeSH term and any specific terms indented under that term in the MeSH hierarchy), and as a Text Word. For example, if you enter vitamin h in the query box, PubMed will translate this search to: ("Biotin"[MeSH Terms] OR vitamin h[Text Word]). Vitamin H is an entry term for the MeSH term, Biotin.

If you enter a MeSH Term that is also a Pharmacologic Action Term PubMed will search the term as [MeSH Terms], [Pharmacologic Action], OR [Text Word].

Note:

Click on Details to verify how your terms are translated. If you want to report a translation that does not seem accurate for your search topic, please e-mail the information to custserv@nlm.nih.gov

3. Author Index
If the phrase is not found in the above tables and is not a single term, PubMed checks the Author Index for a match.

If no match is found?
PubMed breaks apart the phrase and repeats the above automatic term mapping process until a match is found. If there is no match, the individual terms will be combined (ANDed) together and searched in All Fields.

See also:

•       Truncation
•       Phrase Searching (forcing PubMed to search for a phrase)

Truncation (finding all terms that begin with a given text string)

Wildcard search for term* used only the first 600 variations. Lengthen the root word to search for all endings.

Note:

Truncation turns off automatic term mapping and the automatic explosion of a MeSH term. For example, heart attack* will not map to the MeSH term, Myocardial Infarction, or include any of the more specific terms, e.g., Myocardial Stunning; Shock, Cardiogenic.

Phrase Searches (specifying a phrase in a search)

Note:

• If your search phrase is not in the index of searchable terms, double quotes or a search tag are ignored and the phrase is processed using automatic term mapping. The phrase may actually appear in the citation and abstract data, yet not be in the index of searchable terms. Send suggestions of phrases to add to this index to: custserv@nlm.nih.gov.
• When you enclose a phrase in double quotes, PubMed will not perform automatic term mapping which includes explosion of MeSH terms. For example, "health planning" will include citations that are indexed to the MeSH term, Health Planning, but will not include the more specific terms, e.g., Health Care Rationing, Health Care Reform, Health Plan Implementation, etc., that are included with the automatic MeSH mapping.

•  Limits
• Additional Search Commands

Additional Search Rules

• Boolean and Syntax
• Possessive Names
• Search Field Qualification
• Dates and Date Ranging
• Subsets

• Boolean operators must be used when combining qualified search terms.
• If Boolean operators are not entered, PubMed assumes the AND operator between concepts, e.g., vitamin c common cold is translated as vitamin c AND common cold.
• PubMed processes all Boolean connectors in a left-to-right sequence. You can change the order that PubMed processes a search statement by enclosing individual concepts in parentheses. The terms inside the set of parentheses will be processed as a unit and then incorporated into the overall strategy, e.g., common cold AND (vitamin c OR zinc).
• If PubMed finds a phrase within a search string that uses unqualified terms, it will automatically search the terms as a phrase rather than combining the individual words. For example, if you enter air bladder fistula in the PubMed query box, PubMed will search "air bladder" as a phrase. If you do not want this automatic phrase parsing, enter each term separated by the Boolean operator AND, e.g., air AND bladder AND fistula. Click Details to see how PubMed translated your search.
• Follow PubMed's search and syntax rules to enter search terms, specify the search field to be searched, and the Boolean operators in your search statement:

      search term [tag] BOOLEAN OPERATOR search term [tag]

Examples of Boolean Search Statements:

      Find citations on DNA that were authored by Dr. Crick in 1993.

            dna [mh] AND crick [au] AND 1993 [dp]

      Find articles that deal with the effects of heat or humidity on multiple sclerosis, where
      these words appear in all fields in the citation.

            (heat OR humidity) AND multiple sclerosis

      Find English language review articles that discuss the treatment of asthma in preschool children.

            asthma/therapy [mh] AND review [pt] AND child, preschool [mh] AND
               english [la]

        Find citations about arthritis excluding the Publication Type Letter.

            arthritis NOT letter [pt]

Possessive Names as Part of Terms
If you are searching for a term named for an individual, be sure to include the full name of the term, e.g., crohn's disease or coon's technique.  The possessive form is not required, i.e., crohn disease, can be used.  For Text Word searching, use the non-possessive form of the term with the [tw] search tag, e.g., hodgkin[tw].

Search Field Qualification
Terms can be qualified using PubMed's Search Field tags.

• Add the search tag after the term, e.g., aromatherapy [mh].
• Search field tags must be enclosed in square brackets,  [mh].
• Case does not matter nor does spacing, e.g., crabs [mh] = Crabs[mh].

To enter a date range, insert a colon (:) between each date, e.g., 1993:1995 [edat] or 1997/01:1997/06 [edat].

Note:

Date range searching for citations that include both a print and electronic date of publication will only be retrieved by the print date of publication therefore date searches for a full year should be entered as 2000[dp] rather than 2000:2000[dp].

PubMed's Date Fields:

Date of Publication [DP]
Entrez Date [EDAT]  The date the citation first entered PubMed.
MeSH Date [MHDA]  The date the citation was indexed with MeSH terms.

Date ranging is also available from the `Limits screen.
 

Subsets

PubMed subsets provide an easy way to limit retrieval to particular citations.  There are four types of PubMed subsets: Subject, Citation Status, Journal/Citation, and PubMed Central.  The PubMed Limits screen has a Subsets pull-down menu from which many of these subsets can be selected.  Alternatively, any subset can be incorporated into a search as explained below.

Subject Subset 

Citations to articles on specialized topics.  The following subject subsets are available:  AIDS, Bioethics, Cancer, Complementary Medicine, History of Medicine, Space Life Sciences, Systematic Reviews, and Toxicology.  Each uses its own specialized search strategy to aid in the retrieval of citations on these topics.  Subject subsets (except Systematic Reviews) may be selected from the Subsets pull-down menu in Limits.  Systematic Reviews can be searched from the Clinical Queries screen.   Alternatively, each subject subset can be searched using the respective search value of aids, bioethics, cancer, cam, history, space, systematic, or tox and the [SB] search tag.

Example: asthma AND cam [sb]

Note:  Do not confuse the subject subsets for AIDS, Bioethics, Cancer, History of Medicine, and Space Life Sciences with the Journal/Citation Subsets for the same topics, i.e., jsubsetx, jsubsete, jsubsetq, and jsubsets.

Citation Status Subsets 

Citations include one of the following status tags next to the PMID to indicate the stage of processing:

• PubMed - as supplied by publisher  This tag displays on citations recently added to PubMed via electronic submission from a publisher, and are soon to proceed to the next stage, PubMed - in process (see below). This tag is also on citations received before late 2003 if they are from journals not indexed for MEDLINE, or from a journal that was accepted for MEDLINE after the citations' publication date. These citations have not been reviewed for accurate bibliographic data.
• PubMed - in process  This tag indicates the citations will be reviewed for accurate bibliographic data and indexed, i.e., the articles will be reviewed and MeSH vocabulary will be assigned (if the subject of the article is within the scope of MEDLINE).
• PubMed - indexed for MEDLINE  This tag displays on citations that have been indexed with MeSH Terms, Publication Types, Substance Names, etc., and have been reviewed for accurate bibliographic data.
• PubMed  This tag identifies citations have been reviewed for accurate bibliographic data but will not receive MEDLINE indexing, either because the articles are out of scope or because they are from issues of MEDLINE journals published prior to the date the journal was selected for indexing.
• PubMed - OLDMEDLINE for Pre1966  This tag identifies citations in the OLDMEDLINE subset.

Journal/Citation Subsets

Citations of articles from specialized journals or of articles on specialized topics in other journals.  Values used for searching are listed below, followed by an explanation. Some subsets are closed and no longer being assigned to current data.

 

AIM	Abridged Index Medicus is a list created 20 years ago of 120 core clinical English language journals.  Corresponds to "Core clinical journals" subset in Limits.
D	dentistry journals
E	citations from bioethics journals or selected bioethics citations from other journals
H	health administration journals, non-Index Medicus
IM	Index Medicus journals
K	consumer health journals, non-Index Medicus
N	nursing journals
Q	history of medicine journals and selected citations from other journals
S	citations from space life sciences journals and selected space life sciences citations from other journals
T	health technology assessment journals, non-Index Medicus
X	AIDS/HIV journals (selected citations from other journals 1980-2000)

To search for a Journal/Citation subset use jsubset?,  where ? stands for the subset value, listed above, e.g.,  neoplasms AND jsubsete. The Journal/Citation subset does not use a search tag.

PubMed Central 

Citations with links to full-text in PubMed Central (PMC). This subset may be selected from the Subsets menu in Limits or it may be searched as:  pubmed pmc local[sb], e.g.,  protein p53 AND pubmed pmc local[sb]  PMC has  relaxed the requirement that full-text be viewable free at PMC and instead provides a link to the journal's Web site to view the free full-text article. To include all PMC citations in a PubMed search, use the following subset value: pubmed pmc[sb].

Citations with Abstracts 

To search for citations with abstracts, use the value 'hasabstract', e.g., neoplasms AND hasabstract

Note:

• The 'hasabstract' value does not use a search field tag.
• Limiting to only items with abstracts is also available from the Limits screen.

Ahead of Print Citations
Publishers may submit citations for articles that appear on the Web in advance of the journal issue's release. Following publication of the completed issue, the date an article was published electronically is retained on these citations, e.g.

Search for the citations with 'pubstatusaheadofprint', e.g., pubstatusaheadofprint AND gene

 

Cookies

What is a "cookie"?
A "cookie" is information sent by a Web site server (e.g., PubMed) to your computer. In the case of PubMed, it is information about your interactions that may be needed later to perform a function. Cookies allow PubMed to provide more interactive features such as Preview/Index, Clipboard, History, and the Cubby. Cookies placed by PubMed are removed from your computer after a set time period. If you are interested, there are many Web sites that provide information about cookies. 

How can I tell if my system accepts cookies?
Cookie-dependent features of PubMed include Preview/Index, History, Clipboard, and the Cubby. To use these features, your system must be able to accept cookies. If you still have problems using cookie-dependent features of PubMed even after enabling cookies, possible reasons may include:

• Cookies are blocked by your provider or institution. Check with your Internet provider and/or the system administrator at your institution to see if cookies can be accepted. Even if you have them enabled in your Web browser, if they are blocked by your provider or institution (e.g., by a firewall, proxy server, etc.), cookie-dependent features of PubMed won't work.
• Your computer's date and time settings are incorrect. Check your computer's time settings to ensure that they are correct.

Enabling Cookies
Given the number of possible combinations of computer platforms, operating systems, and Web browser versions, we are unable to provide instructions for enabling cookies on your computer. Consult your browser's Help for information on enabling cookies.
 

Features Bar

Limits

Click Limits from the Features bar to limit your search to specific age group, gender, or human or animal studies. Limits also allows you to restrict your search to articles published in a specific language and to specific types of articles, such as review articles.  You can limit by either Entrez or Publication Date. You may also limit your retrieval to a specific subset of citations within PubMed, such as AIDS-related citations or nursing journals.

Note:

If you select a limit and either run a search or move to another screen, a check will appear in a box next to Limits on the Features bar to indicate that limits have been selected.  If you then run a search, the limits in effect will appear in the yellow bar above the Display button.  To turn off the limits before you run your next search, click on the box to remove the check.

Field Selection
You may limit your search terms to a specific search field. All Fields is the default for searching. To select a specific field, click the All Fields pull-down menu and select a search field.

See also:

•   Search Field Qualification

Only Items with Abstracts
You may limit your retrieval to only citations that contain an abstract by using the check box next to  only items with abstracts.  Most citations in PubMed to articles published prior to 1975 do not include abstracts.

Publication Types

All citations in PubMed are for journal articles. However, you may limit your retrieval based on the type of material the article represents (e.g., Clinical Trials or Review articles). The Publication Types pull-down menu contains a list of frequently searched publication types.  If you do not make a selection, PubMed will not restrict to any particular publication type.  The available selections are:

• Clinical Trial
• Editorial
• Letter
• Meta-Analysis
• Practice Guideline
• Randomized Controlled Trial
• Review

If you use the Publication Types pull-down menu to select a search field, your retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher citations" will be excluded because they have not yet completed the indexing process and will not include a Publication Type.

• Complete list of Publication Types

To select a language, click on the Languages pull-down menu and select one of the following languages:

• English
• French
• German
• Italian
• Japanese
• Russian
• Spanish

• All Infant: birth-23 months
• All Child: 0-18 years
• All Adult:19+ years
• Newborn: birth-1 month
• Infant: 1-23 months
• Preschool Child: 2-5 years
• Child: 6-12 years
• Adolescent: 13-18 years
• Adult: 19-44 years
• Middle Aged: 45-64 years
• Middle Aged + Aged: 45+ years
• Aged: 65+ years
• 80 and over: 80+ years

If you use the Ages pull-down menu to select a search field, your retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations are will be excluded because they have not yet completed the indexing process and do not carry these data.

Note:

If you use the Gender pull-down menu to select a search field, your retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations are will be excluded because they have not yet completed the indexing process and do not carry these data.

Note:

If you use the Human or Animal pull-down menu to select a search field, your retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations are will be excluded because they have not yet completed the indexing process and do not carry these data.

• AIDS
• Bioethics
• Cancer
• Complementary Medicine
• Core clinical journals
• Dental journals
• History of Medicine
• MEDLINE
• Nursing journals
• OLDMEDLINE
• PubMed Central
• Space Life Sciences
• Toxicology

When PubMed displays your search results, the citations are displayed in descending Entrez Date order, i.e., last in, first out. If you do not specify a date range, PubMed searches for citations to articles back to 1966.

• Use the Entrez Date pull-down menu to limit your search back in time from 30 days to 10 years.
• The Publication Date pull-down menu toggles between Publication Date and Entrez Date. Use the From and To boxes to specify a range of dates.  Enter the dates in the format of YYYY/MM/DD; the month and day are optional, e.g., 1999/03/06, or 1999/07, or 2000.

Preview/Index

• view and select terms from the Index of searchable terms to develop searches
• preview the number of search results before displaying the citations
• refine searches by adding one or more terms one at a time
• add terms to a strategy from specific search fields

To search for terms from specific search fields, select a search field from the All Fields pull-down menu and enter a term in the text box.  Click AND, OR, or NOT to add the term to the query box with the appropriate search field tag, or click Preview to see the number of results under "Most Recent Queries.".

The available Boolean operators are:

     Intersection (AND) - only those citations that contain selected terms.
     Union (OR) - citations that contain at least one of the selected terms.
     Difference (NOT) - exclude citations with the selected term.

You can also use the Index to select from a list of terms within a search field. Select a search field from the All Fields pull-down menu, enter a term in the box, and click Index. PubMed displays an alphabetic list of terms in the Index for the selected search field.  The number of citations in PubMed that contain the term appears in parentheses to the right of the term. You can scroll up or down the list, or click Up or Down to move along in the Index.

Highlight a term by clicking on it.  Then click the appropriate operator, AND, OR, NOT. The selected term will be added to the query box.  To OR together multiple terms from an Index display and then add (or AND) them to your search, click on each term while holding down the Ctrl key (PC) or the Command key (Mac).  When all of the terms you want are highlighted, click the connector AND to add the terms (ORed together) to the query.

You may then continue to add additional terms from other search fields. Once your strategy is complete, click Preview to see the number of results, or click Go to display the citations.

For example, to see the MeSH Terms beginning with chickenpox:

1. Select MeSH Terms from the All Fields pull-down menu.
2. Enter the term, chickenpox, in the text box, and click Index.
3. Scroll down in the Index box, highlight the MeSH/Subheading combination term "chickenpox/complications," and click AND.
4. The selection "chickenpox/complications"[MeSH Terms] will be added to the query box.

Note:

• Preview/Index displays the last three queries from History.  Use History to review up to the last 100 queries.
• PubMed automatically truncates on the author's name to account for varying initials, e.g., smith j will retrieve smith ja, smith jb, smith j jr, etc. 
• PubMed processes all Boolean operators left to right. To change this order, enclose search terms to be processed first in parentheses, e.g., common cold AND (vitamin c OR zinc). You may edit (e.g., add parentheses) in any query box.  PubMed will automatically OR (and add parentheses) for multiple terms selected from the Index.
• Preview uses cookies to keep a history of your searches.  For you to use this feature, your Web browser must be set to accept cookies.

History

Click on the linked search statement number to open the options menu that includes Boolean operators to AND, OR or NOT your search to the query box, delete the search from History, re-run the search or display the search details.

You can also combine searches or add additional terms to an existing search by using the pound sign (#) before the search number, e.g., #2 AND #6, or  #3 AND (drug therapy OR diet therapy).  Once you have entered a revised search in the query box, click Go to view the search results. Click Clear History to remove all searches from the History screen and the Preview/Index screen.

Note:

• The maximum number of searches in History is 100.  Once the maximum number is reached, PubMed will remove the oldest search and add the most current search.
• History will be lost after eight hours of inactivity on PubMed or any of the other Entrez databases. The Clear History button in History will also clear the Preview/Index history information.
• PubMed will move a search statement number to the top of the History if the new search is the same as a previous search.
• A separate Search History will be kept for each of the Entrez databases, although the search statement numbers will be assigned sequentially for all databases.
• PubMed uses cookies to keep a history of your searches.  For you to use this feature, your Web browser must be set to accept cookies.
• Citations in the Clipboard are represented by the search number #0, which may be used in Boolean search statements. For example, to limit the citations you have collected in the Clipboard to English language citations, use the following search: #0 AND english [la].  This does not change or replace the Clipboard contents.
• History search numbers may not be continuous because some numbers are assigned to intermediate processes, such as displaying a citation in another format.

Clipboard

Save from the Clipboard
Citations are initially displayed in the summary format in the order they were added. Use Sort to change the order. You can select all or individual citations to display or save in one of the citation display formats. To save citations choose File from the Send to pull-down menu and then click the Send to button.

Note:

Your results may be on more than one page. PubMed will retain your selections from all pages of your results.  To mark specific citations to save, click on the check box to the left of each citation and continue to page through your results. Select File from the Send to menu to save all the selected citations to a file.

• Printing

Delete Citations from the Clipboard
To mark citations for deletion in the Clipboard, click on the check box to the left of the citation and select Clip Remove from the Send to menu, click Send to. To empty your entire Clipboard, do not mark any of the citations; select Clip Remove from the Send to menu, and click Send to.
 

Details

Details lets you view your search as it was translated using PubMed's automatic term mapping and search rules and syntax.  Also, from Details, you can save a search query or edit the search query and resubmit it. Details may contain error messages and notes. If your last action was displaying related article citations or selected items in another format, Details will indicate this rather than the last query.

Edit Your Search
The PubMed Query box shows the actual search and syntax used to run the search. Beneath this box, the Result number hyperlink displays the total number of citations for the search. To return to the current search results screen, click this link or use the "Back" function of your Web browser. The Translations area details how each term was translated using PubMed's search rules and syntax, and the User Query area shows the search terms as you entered them in the query box.

To edit the search in the PubMed Query box, click in the box to add or delete terms and then click Search.

Save a Search
From Details, use the URL button to display the current search as a URL and then bookmark the URL for future use.

To save a search:

1. From Details click the URL button. PubMed will display the search results screen with your search embedded in the URL.
2. Next, use your Web browser's bookmark function to save the URL as a bookmark.  After saving the bookmark, you may want to use your Web browser's edit functions to rename the bookmark.
3. You may also save your searches using the Cubby.

Searches that were created using a search statement number in History  (e.g., #1 OR #2 AND human[mh]) can not be saved using the URL feature because search statements are lost when History expires.

Documents

Display

You can use the Limits page Entrez Date pull-down menu to limit your retrieval to a pre-selected range of dates or use the Entrez Date search field tag to specify a single date or date range. The Entrez Date is only displayed on the MEDLINE display format.

PubMed citations are initially displayed in a summary format. Documents can be viewed in one of six other formats: Summary (default), Brief, Abstract, Citation, MEDLINE, ASN.1, and XML. You can choose to display other formats by:

• Individual Citation - click on the author hyperlink to display the Abstract format for that citation. From this view, you may select another format using the Display pull-down menu, then click Display.
• All Citations -select a display format from the Display pull-down menu and then click Display to view a different display or database Links for all citations on the page.
• Selected Citations - click on the boxes to the left of each author to select specific citations and then select a format or database Links from the Display pull-down menu and click Display.

Display Formats
Your citations can be displayed in any of the following formats.  See Search Field Descriptions for an explanation of the fields.

Summary - this format may include: Authors, Corporate Authors, Title, Journal source, Review Publication Type,  language if the article is not in English, "No abstract available" notation,  PMID, Comment/Correction links, and citation status. Summary also displays icon links next to each citation to indicate whether or not the citation includes an abstract, or when the full article is available free in PubMed Central or elsewhere.
 

		No Abstract		Abstract
		Full-text article available free in PubMed Central.
		Free full-text article available

Brief - authors, first 30 characters of the Title, and PMID.

Abstract - this format may include: Journal source, Comment/Correction links, Title, language if article is not in English, Authors, Corporate Author, Author Affiliation, Abstract (if present), Publication Types (except for the Journal Article publication type), Personal Name as Subject, PMID, and citation status.

Citation - this format may include: Journal Source, Comment/Correction links, Title, language if article is not in English, Authors, Corporate Author, Author Affiliation, Abstract (if present), Publication Types (except for the Journal Article publication type), MeSH Terms, Personal Name as Subject, Chemical Substances, Secondary Source databank accession numbers, Grant numbers, PMID, and citation status.

MEDLINE - two-character tagged field format for the complete record.  Use this format to download records into reference management programs.

ASN.1 -  ASN.1 (Abstract Syntax Notation One) is an international standard used to achieve inter-operability between platforms, including computer-to-computer, pager-to-computer, and many other possible combinations.

XML - EXtensible Markup Language tagged format is a standard maintained by the World Wide Web Consortium (W3C). The XML standard defines a syntax used to create markup languages to specify information structures.  PubMed XML output conforms to several DTDs. A document describing the MEDLINE XML data element descriptions is available.

UI List - use this format with either the Send to File or Text selections to list only PMIDs.

PubMed displays your search results in batches;  the default is 20 citations per page. The Show pull-down menu allows you to change the number of citations displayed on a single page from 5 up to a maximum of 500 items. To do this:

• From the Summary Page, click on the Show pull-down menu, and select a number.  To have all of the citations displayed on a single page, select a number higher than the total number of your search results.
• Click the Display button. PubMed will redisplay your citations according to your selection.

Sort

Send to

Text
You may display citations as plain text without the sidebar menu and toolbars by selecting Text from the Send to pull-down menu. To display citations in a different format, choose the desired format from the display pull-down menu, select Text and click Send to.  To return to your results in PubMed, use your browser's back button.

File
The PubMed File function creates a text file of your PubMed citations on your computer. You can save entire search results or selected citations. If you don't select specific citations before selecting File and clicking on the Send to button, you will create a file on your computer that will contain the entire search results. A confirmation box displays for  more than 10,000 items.

When you save a file, your browser will prompt you where this file should be placed on your computer and also give you the opportunity to rename the file. You can also use Send to File to save citations collected from multiple searches when using the Clipboard feature.

Save Entire Search Results

1. The default for the Send to File feature is to save the entire retrieval, up to 10,000 items, unless you specifically select citations. For example, if you use the Send to File selection on a screen displaying 1-20 items of 2,356, your saved file will contain all 2,356 citations.
2. Use the Display pull-down menu to select a format.
3. Click Send to File, and your items will be saved in this format as plain text.

Save Selected Citations from a Single Search

1. Click in the check boxes next to each citation you want to save.
2. You can move to other pages within the search results to make more selections.
3. Use the Display pull-down menu to select a format.
4. Click Send to File, and your selected items will be saved in the display format as plain text.

Note:

• Saving a large retrieval may take several minutes.
• To save citations in HTML format, use the Save as... function of your browser. Change the file extension to html. You will only save the citations displayed on the screen, so you may want to use the Show function and Send to Text to adjust your display as needed.

Import Citations into a Reference Management Program

• To import search results into a reference management program, change the display format to MEDLINE, select File from the Send to pull-down menu, then click Send to. This format includes the field tags needed for these programs.
• Consider changing the .fcgi extension to .txt if you want to open the file in a text editor, word processing, or reference management program.

Clipboard
The Clipboard is used to temporarily collect citations for later action. To place an item in the Clipboard, click on the check box to the left of the citation, select Clipboard from the Send to pull-down menu, and then click the Send to button. Once you have added a citation to the Clipboard, the record number color will change to green.

Note:

• If you select Clipboard from the Send to menu without selecting citations using the check box, PubMed will add all (up to 500 citations) of your search results to the Clipboard.
• The Clipboard will be lost after eight hours of inactivity on PubMed or any of the other Entrez databases.
• PubMed uses cookies to add your selections to the Clipboard.  For you to use this feature, your Web browser must be set to accept cookies.
• Citations in the Clipboard are represented by the search number #0, which may be used in Boolean search statements. For example, to limit the citations you have collected in the Clipboard to English language articles, use the following search: #0 AND english [la]. This does not affect or replace the Clipboard contents.

E-mail
To e-mail your results click on specific citations or choose E-mail and then click Send to. You may e-mail up to 500 items. Options available include: Format, Sort, HTML or Text. In addition, you may enter a message that will be included with the PubMed search results in the e-mail message. The e-mail page reflects settings from the results page and can be modified.

After clicking the Mail button the system returns you to your results page and displays a message confirming that the e-mail message was sent. Your PubMed results will be sent from the NCBI automatic mail server, Sent by Entrez [nobody@ncbi.nlm.nih.gov] with a "Subject" of PubMed Search Results. Do not reply to this message. This is not a functioning customer service e-mail address.

Note:

If you choose HTML, your PubMed e-mail message displays as a PubMed results page and includes hyperlinks to Related Articles, LinkOut, and other PubMed features. The recipient’s e-mail program must be set for HTML view in order to properly view in HTML format.

Order
Order is an option on the Send to menu that allows you to order the full-text copy of an article from a library in your area using the Order Documents feature of PubMed.

Note:

Before using this program, you must establish an agreement with a Loansome Doc participating library. Local fees may apply. For information on the medical libraries in your area (or country) that can provide the Loansome Doc service, click on Order Documents from the PubMed sidebar menu, then Registration from the Loansome Doc Ordering System screen.

Once you have registered with Loansome Doc, you can order citations by clicking on the check box to the left of each citation. When you have finished marking your selections (you may move to other pages within your results), select Order from the Send to pull-down menu and click the Send to button. You may also use the Clipboard to collect items from multiple searches before ordering.

Note:

For some journals, the full-text of articles is available via a PubMed link to the publisher's Web site. Publisher links for the full-text of the article are displayed on the Abstract or Citation display. You may also choose LinkOut from the Links pull-down menu to the right of each citation.   LinkOut is a PubMed feature that links to outside sources for the full-text of the article, e.g., a publisher's Web site, as well as to other resources such as biological databases and sequencing centers. User registration, a subscription fee, or some other type of fee may be required to access the full-text of articles in some journals.

Print

Note:

• You may also want to display your citations using Send to Text to eliminate the sidebar menu and toolbars before printing your results.
• You may want to print selected items from one or more searches together. You can do this by collecting them in PubMed's Clipboard.

Links

Related Articles

If you select Related Articles from the Display pull-down menu without selecting specific citations, PubMed will retrieve the related articles for citations displayed on the page. Use the ELink utility to retrieve related articles for large sets of citations.

Limits are NOT in effect when you use a Related Articles link. After linking on Related Articles, although the box next to Limits may be checked, there is no yellow bar displaying the Limits in effect.

You can, however, refine the list of Related Articles using PubMed's History feature. In History, you will see that the Related Articles retrieval is represented as "Link to PubMed from (PMID of document)". Use this Search number in a search.  For example:

#3 AND english[la]
#14 AND 1999:2003[dp]

Keep in mind that the list you get with a Related Articles link is displayed in ranked order from most to least relevant.  Refining the list removes the ranked order and may remove citations that are most relevant.

Cited in PMC - citations for articles cited by a full-text article in PubMed Central.

Cited in Books - citations for articles cited in the bibliography of an online Book.

 

Books

In collaboration with book publishers, NCBI is adapting books for the Web and linking them to PubMed to provide background so that users can explore unfamiliar concepts found in search results. The Books link displays a facsimile of the abstract, in which some phrases are hypertext links. These phrases correspond to terms that are also found in the books available at NCBI. Clicking on hypertext links you to a list of book pages in which the phrase is found. You can also search the Books database. Select Books from the Search pull-down menu, enter a search in the query box, and click Go.

 

LinkOut

LinkOut allows publishers, aggregators, libraries, biological databases, sequence centers, and other Web resources to display links to their sites on items from the Entrez databases. These links can take you to the provider's site to obtain the full-text of articles or related resources, e.g., consumer health information. There may be a charge to access the text or information. The current list of LinkOut providers is available.

A publisher's icon link may display on the Abstract and Citation display formats if they have electronically provided their citation data to PubMed.  Links are only available for publishers that are participating in LinkOut; publishers are responsible for providing working links.  Links to other providers appear on the LinkOut display format.  To see the LinkOut format for a retrieved item, change the Display format to LinkOut, or choose LinkOut from the Links pull-down menu.

The LinkOut format displays links (if available) by broad categories (e.g., Literature) and then by subject categories, selected by the LinkOut provider. Full-text provider links also include the form of the article available (e.g., full-text PDF). Links with an asterisk indicate that the LinkOut provider requires a subscription, membership, or fee for access. LinkOut subsets include:

free full text[sb]  - Citations that include a link to a free full-text article.
full text[sb] - Citations that include a link to a full-text article.

Use the Cubby to customize your LinkOut preferences to display only links of interest to you.

Broken Links
Links are supplied to us by the providers; corrections and changes to links are made by the providers and are their responsibility. You or your librarian can send reports of problem links or questions about electronic journal subscriptions directly to the provider. You can usually find a contact link at the provider's Web site. Contact the Help Desk if you need assistance finding this information.
 

NCBI Databases

Links to other resources or NCBI databases are available from the Links pull-down menu to the right of each citation and from the Display pull-down menu.  PubMed will process only the first 500 items with links when using the Display pull-down menu without making selections.  The following links are available:

Protein - amino acid (protein) sequences
Nucleotide - DNA sequences (GenBank)
Structure - three-dimensional macromolecular structures
Genome - complete genome assemblies
Books - BookShelf online books
Domains - Conserved Domain Database (CDD)
Gene - genes defined by sequence or in the NCBI Map Viewer
GEO - Gene Expression Omnibus
HomoloGene - automated detection of homologs among eukaryotic gene sets
Journals - journals in Entrez
PMC - PubMed Central
OMIM - Online Mendelian Inheritance in Man - catalog of human genes and genetic disorders
Taxonomy - organisms in Protein or Nucleotide
PopSet - population study data sets
3D Domains - domains from Entrez Structure
UniSTS - a unified, non-redundant view of sequence tagged sites (STS)
SNP - single nucleotide polymorphisms
UniGene - non-redundant gene oriented clusters
NCBI Web Site - NCBI Web site search

The Links pull-down menu uses JavaScript, which may cause problems for some browsers. To change the way the Links feature displays, include one of the following parameters in PubMed's URL, ( e.g., http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?linkbar=plain), listed below:

linkbar=plain   Displays links as separate selections. Does not use JavaScript.
linkbar=jsmenu3  Default menu.
linkbar=popup   Opens a small window with link selections.
linkbar=menu   Links display as a pull-down menu.

Cubby

Registration

Provide (make up) the following information, then click Register:

• User Name (3-10 alpha-numeric characters)
• Password (6-8 alpha-numeric characters)
• Mother's Maiden Name, or Pet's Name (in the event you forget your password.)
• Record this information for your future reference, because we cannot access this for you.
• Registration information such as User Name and Password are case sensitive.

Forgot Your Password?
If you've forgotten your password, click "Help! I Forgot My Password". In the Password Forgotten box, enter your User Name and click on Lookup. Enter either your Mother's Maiden Name or your Pet's Name on the next screen. Once this has been verified, the Cubby will assign you a new Password. Make a note of this, as you will need it to Login to the Cubby and if you want to change your password to something you can easily remember.

Changing Your Password
Select Change Password from the Cubby Resources menu sidebar and enter your old password and new password, then click Change.

Log Out
Click Log Out from the Cubby sidebar to Log Out. Your Login will remain active for 12 hours, unless you Log Out.
 

Stored Searches

Click on Cubby on the sidebar to store a search, see a list of your stored searches, update, or delete a stored search.

How to Store a Search

1. Run or Preview your search. You can store a search using terms and limits necessary for your topic.
2. Click Cubby on the sidebar. Last Search displays the last search query, including limits, if used. If your last search is not displayed, your system may not be set to accept cookies.
3. Edit the name of the search. Above the Store in Cubby button, there is a box where you can edit the name of the search to something manageable yet meaningful.  Examples, Headaches in Preschool Children, Dr. Murphy's Arthritis Update.
4. Click on Store in Cubby.

• Links to Related Articles cannot be stored as a Cubby Stored Search.
• History numbers (e.g., #3) cannot be used in Cubby Stored Searches.
• Dates and date ranges are not recommended for Stored Searches.
• Stored searches are numbered and listed in descending order according to the date and time they were originally stored.
• The maximum number of stored searches is 100 per User Name.
• Any term from a field other than title or abstract, on an in process or publisher supplied record, may cause the retrieval of a citation a second time.  For example, when a term appears only in the [ad] field.
• Stored Searches cannot be edited.

Update a Stored Search
It is easy to check for new items since your last update.

1. Select the stored search(es) you want to update by clicking the check box(es) next to the Cubby Search Name.  To select all searches, click the "Select/Deselect All" check box.
2. Click "What's New for Selected". The Cubby displays the list of searches you selected along with an additional column indicating the number of new items retrieved since the last time you checked. If there are no new items, the Cubby displays "0 new".
3. Click # new to link to the new items. Clicking on this link displays the new items and updates the stored search in the Cubby with the new Date and Time. If you do not click # new, the search date and time are not updated.

1. Query AND T₁ : T₂ [MHDA]
2. Query [TIAB] AND 1900/00/00 : T₁ [EDAT]
3. #1 NOT #2

Query = stored search.
T₁ = the date and time the search was last updated.
T₂ = today's date and time.
1900/00/00 = the date that will include all citations. (Note: PubMed includes citations back to the early 1960s.)
[MHDA] = the search tag for the MeSH date. This field reflects the date MeSH terms were added to the citation. (Note: until MeSH terms are added, the MHDA value is the same as the EDAT.)
[EDAT] = the search tag for the Entrez date field. This field reflects the date the citation was added to PubMed.
[TIAB] = the search tag for words in the Title and Abstract fields.

Example: The stored search is dna repair. The search was last updated on 2000/07/01 at 9:30 a.m. Today's date and time is 2000/08/01 at 11:00 a.m.

1. dna repair[MeSH Terms] OR dna repair[Text Word] AND "2000/07/01  9:30" : "2000/08/01 11:00" [MHDA]
2. dna repair[TIAB] AND "1900/00/00" : "2000/07/01 9:30" [EDAT]
3. #1 NOT #2

Strategies that include the Search Field Tags AU, PS, IP, TA, LA, PG, TI, TIAB, or VI use the strategy:  Query AND T₁ : T₂ [EDAT]

Strategies that include the Search Field Tags AD, FILTER, SB, RN, MAJR, MESH, PT, SI, SH, NM, or TW, or Tags from both lists, use the strategy:  Query AND T₁ : T₂ [MHDA]

Delete Stored Search
Select the stored search(es) you want to delete by clicking the check box next to the Cubby Search Name. Next, click Delete Selected Searches. You can select and delete multiple searches at a time.
 

LinkOut Preferences

Login, or Register for Cubby.

LinkOut is a service that provides links from items retrieved from Entrez databases to information providers. In PubMed, the link to the citation provider displays with the abstract and citation format of an item. All other links to providers from a retrieved item display on the LinkOut display page. Use Cubby LinkOut Preferences to customize which links display. Whenever you login to the Cubby, PubMed will display LinkOut providers according to your specifications.

Set your Preferences
You can change how provider links are displayed by adding an icon or hiding a link from LinkOut.

Add Icon: Links to providers' Web sites can display on the fuller display formats (e.g., Abstract, GenBank) as icons. The Add Icon option controls which provider icons are displayed. The default is for only the citation provider and PubMed Central icons to be display with these formats.

Hide from LinkOut: This controls which provider links are displayed on the LinkOut display format. The default is for all the provider links to display on the LinkOut display format for each citation.

• Click the Add Icon check box for a category if you want icons for all the providers in that category to show up on the fuller display formats.
• Click the Hide from LinkOut check box if you want to remove the links from all the providers in that category on the LinkOut display format.
• Clicking on a box that has a check in it removes the check and deselects that option.
• Click Update LinkOut Preferences to save any changes.

All LinkOut Providers
This page lists all of the LinkOut providers in alphabetical order.

• Click the Add Icon check box if you want an icon for that provider to show up on the fuller display formats.
• Click the Hide from LinkOut check box if you want to remove the link for that provider on the LinkOut display format.
• Clicking on a box that has a check in it removes the check and deselects that option.
• Click Update LinkOut Preferences to save any changes.
• Click View to display new LinkOut providers since the last time you checked by clicking the View button.

General LinkOut Notes

• Your LinkOut preferences are in effect only when you are logged into the Cubby. Your Login will remain active for 12 hours.
• When you select preferences from a list, this will not be reflected in other provider lists. For example, if you chose to hide all Library LinkOut providers, there will not be a check in the Hide check box for all the libraries on the All Providers list.
• The category and individual providers are in separate sections on the page. If you make changes, be sure to click Update LinkOut Preferences for that section.
• You may not hide the citation provider or PubMed Central icons from the Abstract and Citation display formats.

Document Delivery Services

• The PubMed Order selection defaults to NLM's document delivery provider, Loansome Doc.
• Document Delivery Services provide alternative delivery services for the Order selection.
• To change the PubMed document delivery provider for your Order selection, select from the services provided, and click the Update button.
• Your Document Delivery preference is in effect only when you are logged into the Cubby.

Outside Tool allows institutions to register a tool with NCBI to supplement LinkOut by providing a linking service from all PubMed citations back to that institution.  When the outside tool parameter is set an icon displays on the Abstract and Citation format. The URL behind the icon is the base URL provided by the institution and the PMID of the displayed citation. Please send questions about this service to linkout@ncbi.nlm.nih.gov.

User Preferences

To store an e-mail address:

1. Log into the Cubby and click the sidebar selection, User Preferences.
2. Enter a default address in the E-mail address box and click Update.
3. When logged into Cubby, the stored e-mail address will display on the options page when you select E-mail from the Send to menu on a search results or Clipboard screen.
4. You may replace the stored address with a different address before e-mailing search results. The most recent e-mail address used will be retained on the options page for the search session (until replaced or until eight hours of inactivity have passed).
   

Other Services

Text Version

Journals Database

The Journals database can be searched using the journal title, the variant title as it appears in the NLM catalog, the MEDLINE abbreviation, the ISO (International Organization for Standardization) abbreviation - or words from these fields, the NLM ID (ID number for the NLM Catalog), and the print or electronic ISSNs (International Standard Serial Numbers).  The database also includes the journals in several other Entrez databases.

Suggestions
In addition to the search results, this database provides suggestions. The suggestions are based on an algorithm that compares letter combinations and scores the relatedness of phrases included in a user's journal query. Click on a journal under Suggestions to go directly to a specific journal record; a new set of suggestions will display based on the selected journal.  Suggestions are generated from an index (multi) that is a combination of three indices from this database, i.e., journal title, MEDLINE abbreviation, and ISO (International Organization for Standardization) abbreviation. This may result in a journal being repeated in the list of suggestions.

Note:

• Click the journal title from the Summary display or choose Full from the Display pull-down menu to view additional information about the journal.
• To limit journal searches to PubMed journals, use the Only PubMed journals selection in Limits or include the database journal subset (e.g., journals pubmed[sb], journals nucleotide[sb], etc.) in your search.
• Unqualified journal terms are  searched in all fields. The following qualifiers are available to limit your search to a specific field: [ISO Abbr], [ISSN], [MEDLINE Abbr], [NLM ID], and [Title].
• Click the NLM ID to link to journal information in NLM's online catalog, LOCATORplus.
• If a journal includes parentheses or brackets, e.g., J Hand Surg [Am], enter the abbreviation or title without the special characters, j hand surg am.
• Search results are displayed in alphabetical order except when a user's query exactly matches a journal title, that title will display first.

Search Box
The Journals database provides a Search Box that can be used to build a PubMed search. From any display format:

1. Select a journal.
2. Select Search Box with OR from the Send to pull-down menu.
3. Click the Send to button and the journal appears in the Search Box.
4. To add additional journals to this strategy continue searching the database and add journals to the Search Box using the Send to Search Box feature.
5. When you have completed your search click the Search PubMed button.

Links
The Journals database Links menu includes the following links:

• Entrez databases -  retrieves records for that journal in the selected Entrez database.
• Single Citation Matcher - enters the journal in the Single Citation Matcher fill-in-the-blank form.

Other journal resources include:

• The list of PubMed journals with links to full-text
• A list of all journals that are included in PubMed by FTP in the GNU Zip, Uncompressed, UNIX Compress, or PKZIP format
• The List of Serials Indexed for Online Users
• The List of Journals Indexed in Index Medicus

MeSH Database

Use the MeSH database to find MeSH terms including Subheadings, Publication Types and Pharmacological Actions - and build a PubMed search. The MeSH database can be searched by MeSH term, MeSH Entry Term, Subheading, Publication Type, or words within a MeSH Scope Note. Subheadings and Publication Types are included in the MeSH term searches.

MeSH database tutorials:

• Searching with the MeSH Database

• Combining MeSH Terms

• Applying Subheadings and other features of the MeSH Database

Suggestions
The database displays MeSH or Entry term suggestions based on an algorithm that compares letter combinations in words. You can use the MeSH term/Entry Term suggestion link to go directly to a record. A new set of suggestions will be displayed based on the selected term.

Note:

• Search results are displayed in relevance-ranked order except when a user's query exactly matches a MeSH term, that term will display first.
• Click the MeSH term from the Summary display or choose Full from the Display pull-down menu to view additional information.
• Terms without search tags are searched using the subject portion of the Automatic Term Mapping feature.

Links
The MeSH database Links menu includes the following links:

• PubMed - retrieves citations for the MeSH term in PubMed.
• Clinical Queries - enters the MeSH term in the Clinical Queries query box.
• NLM MeSH Browser - links to the NLM MeSH Browser for more information about the MeSH term.

Search Box
The MeSH database provides a Search Box that can be used to build a PubMed search. From any display format:

1. Select a MeSH term, including specifications if using the Full display, e.g., Subheadings.
2. Use the Send to pull-down menu to select one of the following:
          Search Box with AND
          Search Box with OR
          Search Box with NOT
3. Click the Send to button and your term with specifications appears in the Search Box.
4. To add additional terms to this strategy, continue searching the database and add terms to the Search Box using the Send to Search Box feature.
5. When you have completed your search click the Search PubMed button.

Citation Matcher

• The Single Citation Matcher is a fill-in-the-blank form that allows you to enter partial journal citation information to locate a single citation, or citations from a particular volume or issue of a journal. If you cannot find citations for a journal, a particular journal issue, or are unable to locate a citation for a specific article, please report this to the NLM Help Desk.

• The Batch Citation Matcher allows you to retrieve the PubMed IDs for many articles all at once. This feature requires that you enter the bibliographic information (journal, volume, page, etc.) in a specific format.

• A list of all journals that are included in the PubMed database is available by FTP in the GNU Zip, Uncompressed, UNIX Compress, or PKZIP format.

Clinical Queries

Clinical Queries using Research Methodology Filters  
This specialized search query with built-in search research methodology filters is intended for clinicians. Four study categories or filters are provided: therapy, diagnosis, etiology, and prognosis. Two emphasis categories or filters are provided: sensitive search (broad) - includes relevant articles but probably some less relevant and specific search (narrow) - more precise articles, with less retrieval. See the filter table for details.

Systematic Reviews
This feature is provided to help health professionals locate systematic reviews and similar articles.  It combines your search term(s) with citations identified as systematic reviews, meta-analyses, reviews of clinical trials, evidence-based medicine, consensus development conferences, and guidelines.  Citations from journals specializing in clinical review studies are also included.  The resulting retrieval can be further refined using PubMed's Limits e.g., English language.  (Note: outside of the Clinical Queries screen, this subset can be combined directly with other search terms using AND systematic [sb].  For example, lyme disease AND systematic [sb].)  Systematic Reviews uses a customized search strategy. A list of related sources on this topic is provided.

 

For More Assistance

Customer Support
If you need more assistance, please click on Write to Help Desk or send an e-mail to custserv@nlm.nih.gov.  You may also contact the NLM Customer service desk at 1-888-346-3656 (1-888)- FINDNLM.  Hours of operation are:
Monday - Friday from 8:30 a.m.-8:45 p.m. and Saturday from 9:00 a.m.-5:00 p.m. Eastern Time.

NLM Publications on PubMed
        Tutorial
        NLM PubMed Training Manuals
        NLM Technical Bulletin

References

Search Field Descriptions and Tags

• Affiliation [AD] May include the institutional affiliation and address (including e-mail address) of the first author of the article as it appears in the journal. This field can be used to search for work done at specific institutions (e.g., cleveland [ad] AND clinic [ad]). 
• All Fields [ALL] Includes all searchable PubMed fields. However, only terms where there is no match found in one of the Translation tables or Indexes via the Automatic Term Mapping process will be searched in All Fields. PubMed ignores stopwords from search queries.
• Author [AU]  Various limits on the number of authors included in the MEDLINE citation have existed over the years (see NLM policy on author names). The format to search for this field is: last name followed by a space and up to the first two initials followed by a space and a suffix abbreviation, if applicable, all without periods or a comma after the last name (e.g., fauci as or o'brien jc jr). Initials and suffixes may be omitted when searching. PubMed automatically truncates on an author's name to account for varying initials, e.g., o'brien j [au] will retrieve o'brien ja, o'brien jb, o'brien jc jr, as well as o'brien j. To turn off this automatic truncation, enclose the author's name in double quotes and qualify with [au] in brackets, e.g., "o'brien j" [au] to retrieve just o'brien j. Full names display in the FAU field on the MEDLINE display format. The FAU field is not searchable.
• Comment Correction Type The data in these fields are citations to other associated journal publications, e.g., comments or errata. Often these link to the respective citation. Comments/Corrections data can be retrieved as follows:

• Corporate Author [CN] Identifies the corporate authorship of an article. Corporate names display exactly as they appear in the journal. Note: Citations indexed pre-2000 and some citations indexed in 2000-2001 retain corporate authors at the end of the title field. For comprehensive searches, consider including terms and/or words searched in the title field [ti].
• EC/RN Number [RN] Number assigned by the Enzyme Commission (EC) to designate a particular enzyme or by the Chemical Abstracts Service (CAS) for Registry Numbers, e.g., 1-5-20-4[rn]
• Entrez Date [EDAT] Date the citation was added to the PubMed database. The Entrez Date is set to the Publication Date on citations before September 1997, when this field was first added to PubMed. Citations are  displayed in Entrez Date order which is last in, first out. Dates or date ranges must be entered using the format YYYY/MM/DD [edat], e.g., 1998/04/06 [edat] . The month and day are optional (e.g., 1998 [edat] or 1998/03 [edat]). To enter a date range, insert a colon (:) between each date (e.g., 1996:1997 [edat] or 1998/01:1998/04 [edat]).

Note:

The Entrez Date is not changed to reflect the date a publisher supplied record is elevated to in process or when an in process record is elevated to indexed for MEDLINE. Therefore, use caution when your strategy includes MeSH terms and a date or date range using the search field tag, [edat].

• Filter [FILTER] [SB] Technical tags used by LinkOut, filters include:

loall[sb] - Citations with LinkOut links in PubMed.
free full text[sb]  - Citations that include a link to a free full-text article.
full text[sb] - Citations that include a link to a full-text article.

Use Preview/Index to browse the LinkOut index. Select Filter from the All Fields pull-down menu, enter 'loprov' in the query box, click Index. PubMed displays an alphabetic list of the LinkOut providers. The 'losubj' and 'loattr' entries are links indexed by Subject Types and Attributes. The  'loftext' entries include a link to the online full-text of a journal citation.

• Grant Number [GR] Research grant numbers, contract numbers, or both that designate financial support by any agency of the US PHS (Public Health Service). The three pieces of the grant number (LM05545 - number, LM - acronym, and NLM - institute mnemonic) are each individually searchable using the [gr] tag.
• Issue [IP] The number of the journal issue in which the article was published.
• Investigator [IR] Names of the NASA-funded principal investigator(s) who conducted the research. Search names following the Author field format, e.g., soller b [ir]
• Journal Title [TA] The journal title abbreviation, full journal title, or ISSN number (e.g., J Biol Chem, Journal of Biological Chemistry, 0021-9258). The Journals database is available from the PubMed homepage sidebar to look up the full name, abbreviation, and ISSN number of a journal. If a journal title contains special characters, e.g., parentheses, brackets, enter the name without these characters, e.g., enter J Hand Surg [Am] as J Hand Surg Am.
• Language [LA] The language in which the article was published. Note that many non-English articles have English language abstracts. You can either enter the language or enter just the first three characters of most languages, e.g., chi [la] retrieves the same as chinese [la]. The most notable exception is jpn [la] for Japanese.
•  MeSH Date [MHDA]  The date the citation was indexed with MeSH Terms and elevated to MEDLINE for citations with an Entrez Date after March 4, 2000.  The MeSH Date is initially set to the Entrez Date when the citation is added to PubMed. If the MeSH Date and Entrez Date on a citation are the same, and the Entrez Date is after March 4, 2000, the citation has not yet been indexed.  Dates or date ranges must be entered using the format YYYY/MM/DD [mhda], e.g. 2000/03/15 [mhda] . The month and day are optional (e.g., 2000 [mhda] or 2000/03 [mhda]). To enter a date range, insert a colon (:) between each date (e.g., 1999:2000 [mhda] or 2000/03:2000/04 [mhda]).
• MeSH Major Topic [MAJR] A MeSH term that is one of the main topics discussed in the article denoted by an asterisk on the MeSH term or MeSH/Subheading combination, e.g., Cytokines/physiology* See MeSH Terms.
• MeSH Subheadings [SH] MeSH Subheadings are used with MeSH terms to help describe more completely a particular aspect of a subject. For example, the drug therapy of asthma is displayed as asthma/drug therapy, see MeSH/Subheading Combinations. The MeSH Subheading field allows users to "free float" Subheadings, e.g., hypertension [mh] AND toxicity [sh]. MeSH Subheadings automatically include the more specific Subheading terms under the term in a search. To turn off this automatic feature, use the search syntax [sh:noexp], e.g., therapy [sh:noexp].  In addition, you can enter the MEDLINE two letter MeSH Subheading abbreviations rather than spelling out the Subheading, e.g., dh [sh] = diet therapy [sh].
• MeSH Terms [MH] NLM's Medical Subject Headings controlled vocabulary of biomedical terms that is used to describe the subject of each journal article in MEDLINE. MeSH contains more than 22,000 terms and is updated annually to reflect changes in medicine and medical terminology. MeSH terms are arranged hierarchically by subject categories with more specific terms arranged beneath broader terms. PubMed allows you to view this hierarchy and select terms for searching in the MeSH Database.

Skilled subject analysts examine journal articles and assign to each the most specific MeSH terms applicable - typically ten to twelve. Applying the MeSH vocabulary ensures that articles are uniformly indexed by subject, whatever the author's words.

Notes on MeSH Terms and Major MeSH Topic search fields:

• To search the term only as a MeSH term, it must be qualified using the search field tags, e.g., [mh] for MeSH Terms or [majr] for MeSH Major Topic. A qualified term is checked against the MeSH Translation table and mapped to the appropriate MeSH term. Some concepts may map to two or more MeSH terms.  To turn off this mapping, enclose the MeSH term in double quotes and qualify with [mh], e.g., "cold" [mh].
• MeSH terms are arranged hierarchically by subject categories with more specific terms arranged beneath broader terms. MeSH terms in PubMed automatically include the more specific MeSH terms in a search.
• MeSH/Subheading Combinations:  To directly attach MeSH Subheadings, use the format MeSH Term/Subheading, e.g., neoplasms/diet therapy. You may also use the MEDLINE two letter MeSH Subheading abbreviations, e.g., neoplasms/dt. The [mh] tag is not required, however [majr] may be used, e.g., plants/genetics[majr]. Only one Subheading may be directly attached to a MeSH term.  For a MeSH/Subheading combination, PubMed always includes the more specific terms arranged beneath broader terms for the MeSH term and also includes the more specific terms arranged beneath broader Subheadings. The broader Subheading or one of its indention's will be directly attached to the MeSH term or one of its indention's. For example, hypertension/therapy also retrieves hypertension/diet therapy; hypertension/drug therapy; hypertension, malignant/therapy; hypertension, malignant/drug therapy, and so on, as well as hypertension/therapy.
• To turn off the automatic inclusion of the more specific terms, use the syntax [field:noexp], e.g., hypertension [mh:noexp], or hypertension [majr:noexp], or hypertension/therapy [mh:noexp]. The latter example turns off the more specific terms in both parts, searching for only the one Subheading therapy attached directly to only the one MeSH term hypertension.

• If parentheses are embedded in a MeSH term, replace the parentheses with a space and qualify with [mh] e.g., enter the MeSH term Benzo(a)pyrene as benzo a pyrene [mh].

• MeSH terms can be selected for searching in the MeSH database and from Preview/Index.

• NLM Unique ID [JID] The alpha-numeric identifier for the cited journal that was assigned by NLM's Integrated Library System LOCATORplus, e.g., 0375267 [jid].
• Other Term [OT] Mostly non-MeSH subject terms (keywords), including NASA Space Flight Mission, assigned by an organization other than NLM. The Other Term data may be marked with an asterisk to indicate a major concept, however asterisks are for display only. You cannot search Other Terms with a major concept tag. The OT field is searchable with the Text Word [tw] and Other Term [ot] search tags.
• Owner Acronym that identifies the organization that supplied the citation data. Search using owner + the owner acronym, e.g. ownernasa.
• Pagination [PG] Enter only the first page number that the article appears on. The citation will display the full pagination of the article but this field is searchable using only the first page number. See Single Citation Matcher.
• Personal Name as Subject [PS] Use this search field tag to limit retrieval to where the name is the subject of the article, e.g., varmus h [ps]. Search names following the Author field format, e.g., varmus h[ps].
• Pharmacologic Action MeSH Terms [PA]  Substances known to have a particular pharmacologic action. Each pharmacologic action term index is created with the drug/substance terms known to have that affect. This includes both MeSH terms and terms for Supplementary Concept Records.
• Place of Publication [PL] Indicates the cited journal's country of publication. Geographic Place of Publication regions are not searchable. In order to retrieve records for all countries in a region (e.g., North America) it is necessary to OR together the countries of interest. Note: This field is not included in All Fields or Text Word retrieval.
• Publication Date [DP] The date that the article was published. Dates or date ranges must be searched using the format YYYY/MM/DD [dp], e.g. 1998/03/06 [dp] . The month and day are optional (e.g., 1998 [dp] or 1998/03 [dp]). To enter a date range, insert a colon (:) between each date (e.g., 1996:1998 [dp] or 1998/01:1998/04 [dp]).

Note:

Journals vary in the way the publication date appears on an issue. Some journals include just the year, whereas others include the year plus month or year plus month plus day. And, some journals use the year and season (e.g., Winter 1997). The publication date in the citation is recorded as it appears in the journal.

• Publication Type [PT] Describes the type of material the article represents (e.g., Review, Clinical Trial, Retracted Publication, Letter); see full listing, e.g., review[pt].
• Secondary Source ID [SI] The SI field identifies secondary source databanks and accession numbers of molecular sequences discussed in MEDLINE articles.  The field is composed of the source followed by a slash followed by an accession number and can be searched with one or both components, e.g., genbank [si], AF001892 [si], genbank/AF001892 [si].

The SI field and the Entrez sequence database links are not related. The PubMed links to these databases are created from the reference field of the GenBank or GenPept flatfile. These references include citations that discuss the specific sequence presented in these flatfiles.

•  Subset [SB] Method of restricting retrieval by Subject Subsets and Citation Status Subsets. Searchable with [SB]. Other Subsets are available for searching that do not use this search tag. See also Limits and LinkOut.
• Substance Name [NM] The name of a chemical discussed in the article. Synonyms to the Supplementary Concept Substance Name will automatically map when qualified with [nm]. This field was implemented in mid-1980. Many chemical names are searchable as MeSH terms before that date.
• Text Words [TW] Includes all words and numbers in the title, abstract, other abstract, MeSH terms, MeSH Subheadings, chemical substance names, personal name as subject, MEDLINE Secondary Source, and Other Terms typically non-MeSH subject terms (keywords), including NASA Space Flight Mission, assigned by an organization other than NLM.
• Title [TI] Words and numbers included in the title of a citation.
• Title/Abstract [TIAB] Words and numbers included in the title, abstract, and other abstract of a citation.
• Unique Identifier [UID]  PubMed Unique Identifier PMID. To search for the PMID type in the number with or without the search field tag [uid]. You can search for several ID numbers by entering each number in the query box separated by a space (e.g., 95091318 97465762); PubMed will OR the terms together.

To search in combination with other terms, you must enter the search field tag, e.g., smith [au] AND (10403340 [uid] OR vaccines [mh]).

• Volume [VI] The number of the journal volume in which an article is published. See Single Citation Matcher.
   

MeSH Subheadings

 

Families of MeSH Subheading Explosions

adverse effects	etiology	physiology
poisoning	chemically induced	genetics
toxicity	complications	growth and development
analysis	secondary	immunology
blood	congenital	metabolism
cerebrospinal fluid	embryology	biosynthesis
isolation and purification	genetics	blood
urine	immunology	cerebrospinal fluid
anatomy and histology	microbiology	deficiency
blood supply	virology	enzymology
cytology	parasitology	pharmacokinetics
pathology	transmission	urine
ultrastructure	metabolism	physiopathology
embryology	biosynthesis	secretion
abnormalities	blood
innervation	cerebrospinal fluid	statistics and numerical data
chemistry	deficiency	epidemiology
agonists	enzymology	ethnology
analogs and derivatives	pharmacokinetics	mortality
antagonists and inhibitors	urine	supply and distribution
chemical synthesis	microbiology	utilization
complications	virology
secondary	organization and admin	surgery
	economics	transplantation
cytology	legislation and juris
pathology	manpower	therapeutic use
ultrastructure	standards	admin and dosage
	supply and distribution	adverse effects
diagnosis	trends	contraindications
pathology	utilization	poisoning
radiography	pharmacology
radionuclide imaging	admin and dosage	therapy
ultrasonography	adverse effects	diet therapy
	poisoning	drug therapy
embryology	toxicity	nursing
abnormalities	agonists	prevention and control
	antagonists and inhib	radiotherapy
epidemiology	contraindications	rehabilitation
ethnology	diagnostic use	surgery
mortality	pharmacokinetics	transplantation

 

NLM Author Indexing Policy

NLM's author indexing policy was and is as follows:

• 1966 - 1984: MEDLINE did not limit the number of authors.
• 1984 - 1995: The NLM limited the number of authors to 10, with "et al" as the eleventh occurrence.
• 1996 - 1999: The NLM increased the limit from 10 to 25. If there were more than 25 authors, the first 24 were listed, the last author was used as the 25th, and the twenty-sixth and beyond became "et al.".
• 2000 - Present: MEDLINE does not limit the number of authors.

Until 1990, only five transliterated (Japanese and Cyrillic) authors were included on each citation.  Since 1990, the first ten transliterated authors have been entered.  Chinese ideograms for co-authors are not transliterated at all if the journal lists only a single transliterated name in the table of contents.

Publication Types

Stopwords

MEDLINE Display Format

Not all fields are searchable in PubMed. Information on searching with tags is available at Search Field Descriptions and Tags.
 

Grant Abbreviation and Institute Acronyms found in the ID Field in MEDLINE

NATIONAL INSTITUTES OF HEALTH (NIH)

HEALTH RESOURCES AND SERVICES ADMINISTRATION (HRSA)

FOOD AND DRUG ADMINISTRATION (FDA)

CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC)

ALCOHOL, DRUG ABUSE, AND MENTAL HEALTH ADMINISTRATION (ADAMHA)

See codes under Substance Abuse and Mental Health Services Administration and codes AA, DA and MH under National Institutes of Health.

OFFICE OF THE ASSISTANT SECRETARY OF HEALTH (OASH)

SUBSTANCE ABUSE AND MENTAL HEALTH SERVICES ADMINISTRATION (SAMHSA)

AGENCY FOR HEALTH CARE POLICY AND RESEARCH (AHCPR)

Source: Information Systems Branch, Division of Research Grants, National Institutes of Health: July 1993