Pubmed introduction and tutorial


This page is condensed from the NCBI Pubmed Tutorial Pages . You may find the full tutorial quite useful.

Whenyou enter search terms on the main Pubmed search page,  the pubmed server processes your request to attempt to identify what type of search you are attempting: are you looking up an author name, journal title, subject area, or phrase from the atricle abstract?  It accomplishes this by filtering your search terms through successive lists to identify the types of terms you provide and use them effectively.
Automatic Term Mapping

Pubmed compares your search terms against several lists of search terms to determine what you are looking for. It checks four lists in order  and stops loooking once it finds a match:


  1. MeSH Translation Table  
  2. Journals Translation Table  
  3. Phrase List  
  4. Author Index  

The MeSH Translation Table contains:

The Journals Translation Table contains:

Since MESH terms are searched before Journal Titles, If you want to look up a Journal whose name is also a MESH term, like  RNA or Cell, the search will stop with the MESH term and the search for your journal will not be done.

The Phrase List contains several hundred thousand phrases generated from:

These are frequently used phrases that are not aprt of the MeSH translation table

The Author Index if a word has one or two letters after it.

If the term is not found, PubMed will then search the individual words in All Fields.

Author Searching

The format for author searching is last name plus initials. 
PubMed will automatically truncate the author's name to account for varying initials.

Truncation

You can truncate a word with the asterisk (*) wildcard This will causes Pubmed to return all matches that begin with the truncated string of text. (e.g. enzym* will match enzyme, enzymes, enzymology, enzymatic, etc.) Truncation also turns off Automatic Term Mapping, so the results will be different than nontruncated searches.

Stopwords

PubMed also refers to a list of commonly found words that are referred to as "stopwords ." these are very common words which would match almost every citation and so they are skipped.

the list of stopwords is from PubMed's Help Page.

Stopwords

a did it perhaps these
about do its quite they
again does itself rather this
all done just really those
almost due kg regarding through
also during km seem thus
although each made seen to
always either mainly several upon
among enough make should use
an especially may show used
and etc mg showed using
another for might shown various
any found ml shows very
are from mm significantly was
as further most since we
at had mostly so were
be has must sum what
because have nearly such when
been having neither than which
before here no that while
being how nor the with
between however obtained their within
both i of theirs without
but if often them would
by in on then
can into our there
could is overall therefore
You can use Boolean operators (AND, OR, NOT) to direct your search. These must be entered in UPPERCASE. Operators are processed left-to-right unless you use parentheses to specify the order.

Once you click the "Go" button. your search is performed and the first 20 hits are displayed in a Summary format:

You can easily scan this first page of citations and see how many of them are really related to what you were trying to find. Though only the first 20 citations are displayed by default (in reverse chronological order) you can see how many total articles matched your search. If you got a surprisingly small or large number of hits, or if there seem to be a high percentage of extraneous hits. You might want to click on the "Details" button in th upper gray box.

Details Button

Clicking Details displays: