Truncation is represented by the asterisk (*), sometimes referred to as a "wildcard" in some instances.
Example: pharm* retrieves documents with the word pharmacology, as well as the pharmacy, pharmaceutical, etc.
Important Note: Truncation turns off automatic term mapping and explosion of MeSH terms. In other words, to include mapping to MeSH and automatic explosion, do not truncate.
When the (*) asterisk is placed within a word, it serves as a Wildcard to search for muliple spellings of a word.
Example: sul*ur retrieves sulphur and sulfur
Expands and retrieves any or all of the search terms [Example: heart attack OR myocardial infarction]
|AND||Narrows and retrieves records with only both search terms [Example: blood pressure AND stroke]|
|NOT||Excludes designated second term, only retrieves records for first [Example: health reform NOT health policy]|
|JOINING||Narrows, and tells PubMed you want articles with EITHER of two terms AND another [Example: (smoking OR nicotine) AND cancer]|
Proximity operator that searches for words near each other no matter the order [Example: Prozac n3 heart disease - finds 'Prozac' near or within 3 words of 'heart disease']
|w||Proximity operator that searchers for terms in same order as entered [Example: blood pressure w2 stroke - finds 'blood pressure' within 2 words before 'stroke']|
|Searches for an exact phrase [Example: "ball cancer"]|
MeSH? What's that?
Medical Subject Headings (MeSH) is the NLM's controlled vocabulary for indexing vocabulary. Using MeSH can help you specify results by doing a subject search than judges content rather than text. MeSH terminiology provides a consistent way to retrieve information in the case that many different terminologies may represent the same concepts.
Review MeSH terms and read scope notes before selecting them for searches if you are unfamiliar with the term to understand tree structure. It's also important to look for the "Year Introduced" on a MeSH entry in the case that you would like to expand your search to include years beyond the given time period.
To start using MeSH, you can use the MeSH Browser to look up MeSH terms and build a search in PubMed.
For a brief walkthrough, let's say we want to search through the most recent citations for articles on "breast cancer". We start by searching for the term in the MeSH browser:
In the results, you will see that that the first mapped term, Breast Neoplasms, is at the top of the list because it most matches the concept that we are searching. Selecting or clicking on Breast Neoplasms will bring you to Subheadings, as well as give you a list of other revelant Entry Terms:
Check off the terms that you want to search, and send them to the PubMed Search Builder by clicking "Add to search builder". When you have included all the terms that you want, click "Search PubMed".
The Query constructed will then be saved in the PubMed Advanced Search Builder's History for you to search at another time should you like.