真傻一直弄不很清楚。尽管英语很蹩脚，还是向PNAS（The Proceedings of the National Academy of Sciences of the United States of America）去email打听。
感谢PNAS好心的回复！现贴在下面。
发件人： PNAS <PNAS@nas.edu> 主 题： RE: Inquire, ZL Yang 日 期： Thu, 24 Mar 2011 10:21:50 -0400
Dr. Yang,
Thank you for your email to PNAS. All published manuscripts are made available online at no charge after 6 months following publication. The surcharge of 1,275 is for those authors who want to make their manuscript available online immediately at the time of publication.
Regarding your other question, although PNAS cannot prevent authors from making their papers available online prior to submission, it is strongly advised to not do so. Although PNAS policy only explicitly states that papers may not be submitted to other journals at the same time as PNAS, it is suggested that you do not make the information public prior to official publication. If you do choose to make a manuscript publicly available prior to submission to PNAS, this should be disclosed with the submission.
Kind Regards,
Mitch Sipus
PNAS Editorial Office
Sent: Wednesday, March 23, 2011 9:41 PM To: PNAS Subject: Inquire, ZL Yang
Dear Editor,
If a paper (draft) has been published in a Website, such as the arXiv (www.arxiv.org/) or the Sciencepaper Online (http://www.paper.edu.cn/en), can thispaper be submitted to PNAS again?
I found some authors first published their papers in the arXiv, then submitted papers to some JOURNALS, such as Physical Review Letters. I wonder if they were no trouble.
Besides, "Authors of research articles may pay a surcharge of $1,275 to make their paper freely available through PNAS open access option." If the $1,275 can not be paid, can the paper be published in the traditional papery PNAS only?
Thank you! Best regards,
Zheng-Ling YANG
PhD, associate professor, Tianjin University, Tianjin, China
