The PubMed database has more than 23 million citations for biomedical articles from MEDLINE and life science journals. Citations may include links to full-text articles from PubMed Central or publsiher websites in the fields of medical, nursing, dentistry, verterinary, and preclinical sciences. PubMed is a free resource that was developed and is maintained by the National Center for Biotechnology Information (NCBI), the U.S. National Library of Medicine (NLM) and is located at the the National Institutes of Health (NIH).
PubMed is structured on Medical Subject Headings, better known as MeSH, that provide a consistent manner of searching for matching concepts.
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.
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]|
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.
Bound phrases: Putting quotes (" ") around terms will force PubMed to search your terms as an exact phrase.
Examples: "baby boomers", "right to die," "soft drinks"
Important Note: Using quotes (" ") around terms turns off automatic term mapping and explosion of MeSH terms. In other words, to include mapping to MeSH and automatic explosion, do not use quotes (" ").
The following are ways you can retrieve articles in PubMed that employ the study designs discussed this guide.