Use indexing or not to search PubMed
Search PubMed efficiently

PubMed is the freely accessible interface to the Medline medical bibliographic database and other sources. It contains over 37 million references to date, with articles published since 1920. Searching is now easy, as the search engine itself explores the thesaurus and translates the query.

However, depending on whether you have too few or too many results, there are certain features you need to know about in order to make the most of this resource.