ChemIDplus (abbreviation for Chemical Identification ) is a free database of the national medical library of the USA ( United States National Library of Medicine , NLM), which contains information on the nomenclature and structural formulas of chemical compounds from the various databases of the "Library of Medicine" summarizes. The ChemIDplus database contains over 400,000 entries, of which more than 320,000 have a structural formula. You can search for names, synonyms, CAS numbers , molecular formulas , chemical-physical and toxicological properties. A structure search with a substructure search is also available. The search results contain information on names, synonyms, identification codes, chemico-physical and toxicological properties, as well as links to other NIH databases.