The Lancet
http://download.thelancet.com/flatcontentassets/authors/lancet-information-for-authors.pdf
Nature Medicine
http://www.nature.com/nm/authors/index.html
BMJ
http://bmjopen.bmj.com/site/about/guidelines.xhtml
JAMA
http://jama.ama-assn.org/site/misc/ifora.xhtml
The New England Journal of Medicine (NEJM)
http://www.nejm.org/page/author-center/manuscript-submission