Use the MeSH Browser, an online vocabulary look-up aid, to build searches in PubMed.
For instance, if you want to search cancer of the jaw, finding the MeSH term will help you narrow down your results. The actual MeSH term is "Jaw Neoplasms" and it is further subdivided into additional catagories. Your term may fall under MULTIPLE categories, as in the example below.
You can also use additional subheadings or quantifiers to group together those citations about a particular aspect of a subject.
Check off the terms you want to search and send them to the PubMed search builder. Click Search PubMed to complete the search.
Then use Limits to refine your search even further.
MeSH (Medical Subject Headings) is the National Library of Medicine's controlled vocabulary thesaurus, used for indexing articles for the MEDLINE®/PubMED® database. Each article citation is associated with a set of MeSH terms that describe the content of the citation. If you can search using MeSH entry terms instead of keyword searching you can focus your search and find more relevant citations. Be sure to look for the "Year Introduced" on a MeSH entry and expand your search to include years not within this time period.