Science Directories

Government Science Portal
Science.gov is a gateway to government science information provided by U.S. Government science agencies, including research and development results.
http://www.science.gov/

Science and Technology Web Site Resources
web site locates thousands of U.S. Government science and technology resources on the web that let you tap into government expertise, services, facilities, and know-how.
http://www.scitechresources.gov/