AIDSinfo HIV/AIDS information from the U.S. Dept. of Health and Human Services
Astrophysics Data System Abstract Service (1975+) The NASA Astrophysics Data System Abstract Service provides a powerful search engine for each of its four bibliographic databases: Astronomy and Astrophysics，Instrumentation，Physics and Geophysics，ArXiv Preprints
Atomic Spectra Databases This database contains critically evaluated NIST data for radiative transitions and energy levels in atoms and atomic ions
ATSDR Toxicological Profiles The Agency for Toxic Substances and Disease Registry (ATSDR) produces Toxicological Profiles for hazardous substances
Cancer Literature The database contains references to cancer literature published from the 1960s to the present and is updated with more than 8,000 records every month
