Searching with MeSH (Medical Subject Headings) will give you more relevant search results. Use PubMed's MeSH Database to find MeSH terms by selecting MeSH from the dropdown menu next to the PubMed search box.
Once you have selected MeSH, enter your keyword(s) into the search box and click Search. Select a term by checking a box next to a term name.
Clicking the hyperlinked MeSH term will give you a more complete description of the term, including subheadings and options to limit your search.
Once your selections have been made, use the Add to search builder dropdown menu to build your search with the AND option. When your search is ready, send it to PubMed by clicking the Search PubMed button.
For more information, see Searching PubMed with MESH, from the National Networks of Libraries of Medicine.