Biological and Chemical Sciences

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Provides in-depth information on 112 known chemical elements. Basic information, more geared for high school students but useful for non-majors.

PubChem provides information on the biological activity of small molecules. It consists of three databases, comprising over 69 million substances, 27 million unique structures, and 434,000 bioassays.

The Macromolecular Modeling Database, along with several tools that allow comparison with known protein sequences and prediction of interaction sites, among other computationally-intensive tasks. A good resource for chemistry, biochemistry, and bioinformatics.