PubMed is a search engine that allows querying the MEDLINE database which is the most important publications related to biomedical research. It is a resource offered by the National Library of Medicine US
The search engine has indexed more than 24 million citations for biomedical literature, magazines life sciences, and online books. It allows direct access to open access publishing abstracts or in default of such articles when they are published in journals of payment. PUBMED search over 4800 journals published in the United States and in more than 70 countries worldwide, including publications from 1966 to the present.