science.gov

www.science.gov

From the site, “Science.gov searches over 42 databases and over 2000 selected websites from 14 federal agencies, offering 200 million pages of authoritative U.S. government science information including research and development results. Science.gov is governed by the interagency Science.gov Alliance“.
Searches can be done by keyword or topic. A link to ‘science in the news’ is also provided.