PubChem: Integrated Platform of Small Molecules and Biological Activities. PubChem is an open repository for experimental data identifying the biological activities of small molecules. PubChem contents include more than: 1000 bioassays, 28 million bioassay test outcomes, 40 million substance contributed descriptions, and 19 million unique compound structures contributed from over 70 depositing organizations. PubChem provides a significant, publicly accessible platform for mining the biological information of small molecules.