An official website of the United States government
Here's how you know
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
As a library, NLM provides access to scientific literature. Inclusion in an NLM database does not imply endorsement of, or agreement with,
the contents by NLM or the National Institutes of Health.
Learn more:
PMC Disclaimer
|
PMC Copyright Notice
Department of Chemistry, Massachusetts Institute of Technology.
‡
Department of Chemistry, Yale University.
*
This research has been supported by the National Science Foundation under grants GP 7034X and GP 6672, and by a grant from the Petroleum Research Fund administered by the American Chemical Society.