An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Yan-Ling Z, Chang-Quan H, Li Y, Bi-Rong D.Yan-Ling Z, et al. Among authors: chang quan h.Age (Dordr). 2014 Feb;36(1):427-34. doi: 10.1007/s11357-013-9547-6. Epub 2013 Jun 12.Age (Dordr). 2014.PMID: 23756707Free PMC article.