PubChem provides information on the biological activities of small molecules. PubChem is organized as three linked databases within the NCBI's Entrez information retrieval system. These are PubChem Substance, PubChem Compound, and PubChem BioAssay. PubChem also provides a fast chemical structure similarity search tool.
A free archive of biomedical and life sciences journal literature at the
U.S. National Institutes of Health's National Library of Medicine. PMC serves as a digital counterpart to the National Library of Medicine's extensive print journal collection. (Journals currently available in the archive)