PubChem is an open archive for the biological activities of substances. PubChem is a part of the National Center for Biotechnology Information (NCBI), a division of the U.S. National Library of Medicine.
PubChem contains the chemical structures of small organic molecules and information on their biological activities. PubChem includes substance information, compound structures, and bioactivity data in three primary databases, PCSubstance, PCCompound, and PCBioAssay, respectively. PubChem is integrated with Entrez, NCBI's primary search engine, and also provides compound neighboring, sub/superstructure, similarity structure, bioactivity data, and other searching features.