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Medline Database: PubMed version

In aspects of social science and humanities relating to medicine, Medline includes only items from medical journals; for other material, search in appropriate social science and humanities indexes. Popular literature on medical topics is not included; search in general periodical indexes.

About PreMedline

The PreMedline database provides basic citation information and abstracts before the full records are prepared and added to Medline. New records are added to PreMedline daily. After MeSH terms, publication types, GenBank accession numbers, and other indexing data added, the completed records transferred weekly to Medline.

For more details about PubMed, see the Database producer's information

For alternative ways of searching Medline, see our Medline Comparisons

How To Access

The PubMed database can be accessed through the Web, and is available to the general public.

if you are reading this on the Web, you can connect directly PubMed Otherwise, connect through the Biology Library Home Page at www.princeton.edu/~biolib/, or by pointing your browser to: http://www.ncbi.nlm.nih.gov/PubMed/. You will be connected directly to the basic PubMed search page.

OTHER VERSIONS:
Medline is publicly available on the Web direct from the National Library of Medicine with two different search interfaces:
PubMed.
The PubMed version is recommended for quick general searching, and the Internet Grateful Med version is recommended for the simple entry of complex logical search queries.

Medline is also available using the Silver Platter search software for both Windows and the Web. The Silver Platter versions, though not as rapid, offer somewhat greater flexibility. The version on Windows, in particular, has the most customizable output facilities. The Silver Platter version of the Medline database can be accessed either in the libraries using the Library network on Microsoft Windows, or outside the libraries through the Web (outside access to this version is limited to Princeton University users). See the instructions for the Web version.

Basic Searching

To search PubMed without worrying about fancy features, just enter a search into the text box, following the on-screen instructions. This is the Basic Search mode. (All of the Advanced Search capabilities are still available in Basic mode, they are just hidden.)

• TO LOOK FOR A SUBJECT/TITLE KEYWORD,
  Enter the term or terms that you wish to search on, separating terms by spaces, and press the Return key or the Search button. This takes you immediately to the Document Summary Page, where you can see the results.
  You can enter a word, e.g., chromatin
  or a fixed phrase, e.g., dna synthesis
  or a logical expression, e.g.,
  chromatin OR dna,
  or: rna AND structure, or: tuberculosis AND (aids OR hiv)
  To enter a TRUNCATED word or phrase, use the asterisk ( * )
  e.g., chromos* , or: genetic transf*
  The system searches the title, abstract, and indexing terms, but not the article text.
  Warning! The connecting words: AND OR NOT must be entered in CAPITALS.
  You may enter other search terms in lower case or CAPITALS --the system does not distinguish.
  
  
• TO LOOK FOR AN AUTHOR enter the name in the box on the Basic Search screen in one of the following forms:
  1. If you know the middle initial, enter: cox ec OR cox e
  2. If you do not know the middle initial, enter: cox e*
  Always use either two initials or one initial and the * sign, since some articles use the first initial only, and others use both initials. Initials may be omitted altogether when searching if this will not be ambiguous.
  
  
• TO LOOK FOR AN JOURNAL TITLE
  Journal titles may be entered in full, as valid Medline abbreviations, or as ISSN numbers. For details, see this section in Advanced Search.
  
  
• TRUNCATION
  Placing an asterisk at the end of a search term causes PubMed to search for all terms that begin with that word; for instance bacter* finds all terms that begin with the letters bacter, e.g. bacteria, bacterium, bacteriophage, etc. For details, see this section in Advanced Search.
  
  
• PHRASE SEARCHING
  PubMed does its best to find logical groupings in your input. For instance, if you enter:
  Lipman DJ Genomics PubMed recognizes that Lipman DJ is the name of an author and converts your search into: Lipman DJ AND Genomics.
  
  Most phrases can be searched simply by entering the two adjacent words, e.g. bacterial proteines For details, see this section in Advanced Search.

SEEING RESULTS

• TO DISPLAY RECORDS
  To see the documents that satisfy your query, press the Retrieve button. This produces a listing, called the Document Summary Page containing each document's title, author, publication year, and bibliographic reference.

  If many documents are retrieved, a box will appear indicating the maximum number that will be displayed at a time (you can change this number.) The articles that will be displayed first are the more recent ones in the database. To see the next group of records, use the next page button at the bottom of the display screen.
  Once you have determined which documents in the list are of interest, you can view the full records individually or as a group.
  
  

• TO VIEW FULL RECORDS
  To view the full record for a single document in PubMed, select the link under the author's name at the top of the document. This will show you the document in default Citation format.
  To view several full records at once, choose the documents by selecting their checkboxes.
  Pick the type of report from the pull down menu at the top of the screen and click Display.
  To view all of the documents on the page as full records, there is no need to select any of them individually; just select the report type and click Display
  
  The formats available include:
  • Citation report - Journal Citation, Title, Authors, Address or Affiliation, Abstract, MeSH terms, chemical substances, Medline and PubMed unique identifiers.
  • Abstract report - Journal Citation, Title, Authors, Address or Affiliation, and Abstract.
  • Medline report - Traditional two-character tagged field Medline format for the full record. Use this format to download records into bibliographic management software packages.
• TO PRINT RECORDS
  The records will print the way they are displayed.
  To print, first, click anywhere in the records area of the page, and then use the print...button on your browser.
  
• TO DOWNLOAD RECORDS
  You can download results to your disk from the Web browser. Click the Save button on the at the bottom of the record display screen and select from the choices listed.
  Another way is to select the material you want with the mouse, and then copy and paste it into a word processor.
  
• To E-MAIL RECORDS
  You can E-mail results to your mailbox from the Web browser. Click send page from the File menu.
• TO ENTER ANOTHER SEARCH
  Click on the reset button at the top of the documents summary page, click on the PubMed box at the far right top of the page header, or use the Back button on your browser.
  
• SAVING SEARCHES
  There is no way to save searches on this version.
  
• TO QUIT
  Just quit the Web browser.

Finding References

ADVANCED PubMed SEARCH

• ENTERING SEARCH TERMS
  
  Enter one or more search terms, separating terms by spaces, just as in Basic search mode. However, also specify Search fields and Search mode, using the drop-down list boxes. Then press the Search button.
  
  Enter author names as in Basic search mode for author names.
  
  Boolean search statements can be entered directly in the search box, using the logic operators:

  AND

  OR

  NOT

  
  Be sure to enter these in CAPITALS as shown. See Boolean Expressions below for more information.
  
• TRUNCATION
  
  Placing an asterisk at the end of a search term causes PubMed to search for all terms that begin with that word; for instance bacter* finds all terms that begin with the letters bacter, e.g. bacteria, bacterium, bacteriophage, etc.
  Phrases that have a space in the word that occurs after the asterisk will NOT be included; for instance, infection* will include "infections", but not "infection control".
  Note! If the use of an * character gives too many terms to process efficiently (more than a hundred or so), PubMed will not perform the search and will so inform you.
  Only the asterisk, not the question mark or pound sign, work for truncation in this system.
  
• PHRASE SEARCHING
  
  PubMed does its best to find logical groupings in your input. For instance, if you enter Lipman DJ Genomics (without quotes), PubMed recognizes that Lipman DJ is the name of an author and converts your search into: Lipman DJ AND Genomics
  
  PubMed might fail to find a phrase that you think is vital to a search. For instance, if you enter: brca 1 PubMed will not recognize that this is all one item and will search for "brca" and "1" separately, but the latter is a numeral and is not included in the index for title and abstract fields. You can circumvent this by putting quotes (") around the phrase that PubMed is failing to recognize, e.g.: "brca 1"
  
  PubMed does not actually perform adjacency searching, but employs a list of recognized phrases against which search terms are matched. If your search phrase is not on that list, then the individual terms are ANDed together. Using quotes forces PubMed to check a second, larger dictionary to identify the phrase and to specify that the search be performed ONLY if the phrase is recognized. Individual search terms are not ANDed in this case. (These searches can take a relatively long time to complete.)
  
  Important! It is usually best to use quotes only when PubMed has failed to find anything because of a failure to group words properly. Forcing PubMed to group words will result in "No Documents Found" if the phrase was not indexed as a group.
  
  
• JOURNAL NAMES
  Search in the Journal Name field for the name of the journal where the item was published. Journal names can be searched in several ways.
  1. Journal names are stored in a standard abbreviated form; for instance, the Journal of Biological Chemistry is stored as J Biol Chem.
     If you are not sure how the name is abbreviated, use List Terms mode to browse the journal titles.
     
  2. You may also enter the complete journal name, e.g. Journal of biological chemistry
  3. You may also enter the ISSN number in this field.
  A built-in Journal Browser is available to look up the full name, abbreviation, and ISSN number.
  
  
• LOOKING FOR AN INSTITUTIONAL NAME
  
  Look for distinctive words from the name as individual words connected by the operator and.
  e.g., princeton AND molecular
  Search in the affiliation field, and use full words from the name, not abbreviations.
  Only one address is given, usually the address of the author to whom correspondence should be addressed, as specified by the article.

Searches in this version of Medline can be limited by Year, language, and publication type.

• TO LIMIT BY PUBLICATION YEAR.
  there are two methods:
  Use the Publication date selection box at the first Basic screen before you begin your search. This limitation will continue until you change it.
  Alternatively, select a year from the years field
  TO LIMIT BY LANGUAGE.
  In the Advanced search page, using the list terms mode, search in the Language field,
  then combine the result with your other search terms
  Be aware that many of the articles in other languages have English abstracts.
  
  

  TO LIMIT BY PUBLICATION TYPE.

  Medline classifies the indexed items according to publication type. Some available terms are:
  

  Bibliography Editorial Letter Multicenter-Study Review

  Clinical-Trial Journal-article Meta-analysis News Technical-report

  
  In the advanced search page, using the list terms mode, search in the Publication type field, then combine the result with your search terms
  
  

  SPECIAL NAMES: ORGANISMS and GENES
  To look for ORGANISMS, use both scientific and common names; include likely synonyms
  chimpanzee* OR pan , or: mus OR mouse or mice
  Use GENE NAMES and standard ABBREVIATIONS whenever applicable:
  myc, or: atpase , or: 3t3
  
  

  NUMBERS AND SPECIAL CHARACTERS
  NUMBERS.
  Search for numbers surrounded by quotation marks, e.g., "14".
  
  SPECIAL CHARACTERS.
  Greek letters and other special characters are usually spelled out.
  e.g., beta radiation, or: lambda bacteriophage
  
  HYPHENATED WORDS.
  Words written with a hyphen should be searched for as two adjacent words.
  Enter compound words using both the one-word and two-word forms, e.g.,
  alpha3 OR alpha 3 <
  
  SPELLING
  Words in titles and abstracts are spelled as in the original. It is therefore necessary to allow for spelling variations, including especially British spelling.

subheadings:

MeSH terms often have an additional term, called a subheading, which further defines how the MeSH term relates to the article. This subheading is appended to the MeSH term, e.g. pneumonia/diagnosis. Searching on the MeSH term (here, pneumonia) retrieves all of the articles that use that MeSH term, whether they have subheadings or not. Use the subheading terms if you require more specificity. It is usually best to use the List Terms Mode to find the appropriate subheadings.

explosions:

MeSH terms searched for using explicitly the MeSH or MeSH Major Topic fields are automatically "exploded" by PubMed; that is, all terms which are logical subsets of the term entered are included. For instance, vision disorders includes blindness. MeSH terms found using the "All fields" search, however, are NOT exploded.

Title Words [TI, TITL] includes only those words found in the title of a record.

Volume [VI, VOL] is the number of the journal volume in which this article is published..

Medline ID [UI, MUID] is the Medline unique identifier of a given citation.

PubMedID [PMID] is the PubMed unique identifier of a given citation.

SEARCH MODES

AUTOMATIC MODE
In Automatic mode, the term or terms that you enter are immediately added to your search. If you enter more than one word, PubMed looks for a phrase with the terms entered. If no phrase is found the terms will be ANDed for your query results. If PubMed groups or fails to group the words you entered properly, you can place one or more words in quotes (") to force PubMed to group them as you wish.
Automatic mode is the default mode.

LIST TERMS MODE
This mode corresponds to an Index. In List Terms mode, when you enter a term, PubMed displays the list of available terms for that field, starting at the first term which begins with the characters that you entered. You can then select one or more terms to add to your search. For example, to see the text terms beginning with "pneum", you would enter pneum in the term box, select the Text Terms field and the List Terms mode, then press Search. The List Terms mode thus allows you to browse through the terms in any given field. This can be very useful if you are not sure how something is spelled. Use this mode only with a single word or phrase, not a logicval expression.

CHOOSING A TERM IN LIST TERMS MODE
When a term is entered in the term box using List Terms mode and the Search button pressed, a list of the terms that begin with the characters entered in the term box will be presented, giving the available terms for the field selected, and specifying the number of articles that the term appears in.

To pick one or more of the terms in the list of available terms, highlight them and press Select; the terms will then be added to your search. If you picked more than one term you will retrieve articles that contain any of the terms.

If the term that you want to select is not in the scrolling list of terms, you can scroll up or down further by selecting Scroll List Up/Down from the list, then pressing Select. If you want to look at another list of terms altogether, reenter the new term in the term box as before and press Search.

CHOSEN LIST OF TERMS
As you enter or select terms, the terms will be added to the search and also placed into a list at the bottom of your screen; this is called the Chosen List. For example, if you had entered the term "pneumonia", and then entered cytomegalo*, the Chosen List would show the terms chosen and the number of documents retrieved for each term.

PubMed automatically calculates the intersection of the terms you enter and displays the resulting search statement at the top of the screen. The terms included in the search are highlighted in the Chosen List.
If the number of documents found is appropriate, press the Retrieve button to see the items.

MODIFYING SEARCHES
To modify the search, select and/or deselect terms in the chosen list until the terms you wish to include in the search are highlighted, then press the Search button. The system will then create a new search statement based upon only the highlighted terms, combined as you have selected. Here is what each of the search types do:

• Intersection (AND): only those records that contain all of the terms specified are returned by the search. This is abbreviated to '&' in the search statement.
• Union (OR): those records that contain any of the terms specified are returned. This is abbreviated to '|' in the search statement.
• Difference (BUTNOT): those records that contain the uppermost term but not any of the lower terms are returned. This is abbreviated to '-' in the search statement.

• term is the term string that you wish to search on. All of the terms that begin with a given string can be searched on by appending an * to the end of the string.
  For example, baker*[auth] would find all of the author names that begin with 'baker'.
• field is the PubMed field designation; see the fields list, above.
• operator is any of:

  AND (for intersection)

  OR (for union)

  NOT (for difference)

1. Find the records in the Journal of Biological Chemistry that contain the term "p21" in their text :
   J Biol Chem [TA] AND p21 [TW]
2. Find the records that contain the word "dna", and an author with the last name "Crick" that were published during 1993.
   dna AND Crick [AU] AND 1993 [DP]
3. Find the records that have the term 'AZT' in any field, but are not derived from animal studies:
   AZT [ALL] NOT animal [MH]
4. Find articles dealing with the effects of heat or humidity on multiple sclerosis, where these words appear anywhere in the record:
   (heat OR humidity) AND multiple sclerosis

• neighbors in the same database,
• links to other databases, and
• links to outside journals

At Princeton, many of these links do not work as desired, for some of the following reasons:

• Only a few publishers provide their full text without extra charge or special registration procedure.
• For those publishers to which the library has paid the extra charge, the necessary login often works only from the library full text journal links, not the links here.
• For some publishers, the library has not yet negotiated this payment, either because the charges are excessive or because the publisher requires extra payment for a large number of journals all together, and we do not want most of them.
• In some cases, the publisher refuses to give the library permission at all, and will only give access to individual subscribers.

• Category: therapy diagnosis etiology prognosis
• Emphasis: sensitivity specificity
• Enter subject search (do not repeat any of the words above):

MeSH Browser (thesaurus)
A "MeSH Browser" is now available on the PubMed starting page. This Browser displays MeSH descriptors in a hierarchical structure and lets users select terms for searching. In addition, users can attach subheadings directly and limit terms to a Main Concept. If a non-MeSH term is entered, the MeSH Browser will check against the MeSH Mappings and display the associated MeSH term.

Citation Matcher
A "Citation Matcher" is available from the PubMed starting page. This is a fill-in-the-blank form that allows users to enter journal citation information to locate a specific single article, issue's content, or entire journal's content.

PubMed JOURNAL DATABASE BROWSER

The PubMed Journal Browser allows you to look up journal names, Medline abbreviations, or ISSN numbers for journals that are included in the PubMed system.

Enter the journal name, Medline abbreviation, or ISSN that you wish to look up. If you do not know the whole name, enter the words that you do know. You may use the symbol '*' to stand for any characters, or '?' to stand for a single character. For example: engl* would match England, English, etc. Case is unimportant.

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