PubMed is the National Library of Medicine's online database for searching MEDLINE and additional biomedical and life sciences literature. It is one of the most up to date, comprehensive and powerful databases for finding scholarly literature in biomedicine.
To start, try doing a simple search of PubMed as shown below:
To take advantage of PubMed's excellent indexing, try doing a more advanced search using Medical Subject Headings, or MeSH terms. Watch this tutorial to learn more.