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ChemIDplus Fact Sheet

ChemIDplus is a free, web search system that provides access to the structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases. ChemIDplus also has structure searching and direct links to resources at NLM, federal agencies, U.S. states, and scientific sites. The database contains more than 400,000 chemical records, of which over 300,000 include chemical structures.

ChemIDplus has two versions. ChemIDplus Lite offers simplified Name and RN searching without the need for plugins or applets. ChemIDplus Advanced provides search capabilities beyond ChemIDplus Lite including chemical structure, toxicity, physical property, molecular formula, classification code, and locator code searching.

Advanced Search Features

The structure drawing and display program Marvin JS, from ChemAxon Ltd., is provided as the default for using ChemIDplus Advanced. The structures displayed as answers use standard web browser graphics (.png). Marvin also allows input from programs such as Biovia Draw.  

Links to further information for a substance are grouped by National Library of Medicine Locators (resources from the National Library of Medicine), Internet Locators (Federal, state or scientific sites providing chemical information) and Superlist Locators (regulatory sites). Ease of navigation from the Locator results page to these sites and vice versa is a characteristic feature of ChemIDplus.

For advanced searchers, there are five structure queries: Substructure Search, Similarity Search, Exact Structure Search, Flex Search, and Flexplus Search. ChemIDplus makes structure searching easier by providing two options that eliminate the need to draw the structure queries. The Transfer Structure option pastes a structure retrieved from a previous query into the Structure Input Box while the Structure Similarity Search option starts an immediate search for similar structures.

Enhanced structure display is also available in ChemIDplus Advanced. Under Basic Information, the Structure button displays the chemical structure, 3D representations, and structure descriptors. Structure descriptors include InChI™ (International Chemical Identifier), InChIKey, and SMILES™ (Simplified Molecular Input Line Entry System) notations which are downloadable. InChiKeys may be used as input to internet search engines to find a structure in other systems.  The Enlarge Structure feature increases the image size of the structure and allows the user to manipulate the display of the atoms and bonds within the chemical structure.

Further Information

For information on NLM services, contact:

Customer Service
National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
Telephone: 1-888-FINDNLM (1-888-346-3656)