Science
http://www.sciencemag.org/site/feature/contribinfo/faq/
“WHAT ABOUT MANUSCRIPTS THAT HAVE BEEN POSTED ONLINE BEFORE SUBMISSION?
We do not consider manuscripts that have been previously published elsewhere. Posting of a paper on the Internet may be considered prior publication that could compromise the originality of the Sciencesubmission, although we do allow posting on not-for-profit preprint servers in many cases. Please contact the editors for advice about specific cases. We provide a free electronic reprint service to authors that allows visitors to the authors’ web site free access to the published version of the Sciencepaper on Science Online immediately after publication.”
Nature
http://www.nature.com/authors/policies/confidentiality.html
“More details about the Nature journals’ pre-publicity policy:
Nature journal authors must not discuss contributions with the media (including other scientific journals) until the publication date; advertising the contents of any contribution to the media may lead to rejection. The only exception is in the week before publication, during which contributions may be discussed with the media if authors and their representatives (institutions, funders) clearly indicate to journalists that their contents must not be publicized until the journal’s press embargo has elapsed. Authors will be informed of embargo dates and timings after acceptance for publication of their articles.
Presentation and discussion of material submitted to a Nature journal at scientific meetings is encouraged, but authors must indicate that their work is subject to press embargo and decline to discuss it with members of the media. Authors are free to publish abstracts in conference proceedings and to distribute preprints of submitted or ‘in press’ papers to professional colleagues, but not to the media.
Occasionally, journalists and editors hear about work at talks given at scientific meetings and mention this work in meeting reports or editorials in their journals. In these cases, a Nature journal will assess the extent to which authors have solicited this interest or cooperated with journalists. If, in the judgement of the editors, the journal’s embargo policy has been broken, the submitted paper may be rejected, even if it is technically ‘in press’.
Contributions being prepared for or submitted to a Nature journal can be posted on recognized preprint servers (such as ArXiv or Nature Precedings), and on collaborative websites such as wikis or the author’s blog. The website and URL must be identified to the editor in the cover letter accompanying submission of the paper, and the content of the paper must not be advertised to the media by virtue of being on the website or preprint server. Material in a contribution submitted to a Nature journal may also have been published as part of a PhD or other academic thesis.
Taxonomic descriptions. Authors of papers that contain taxonomy (that is, the formal nomenclature and description of a newly discovered species) should be aware that it is possible for third parties to exploit the prior publication of nomenclature at any time between online posting of a preprint and the print publication date in a journal, by publishing the name in print and asserting priority according to the rules of the Code of Zoological Nomenclature. Nature Publishing Group takes no responsibility for such assertions of priority in the case of manuscripts it publishes if the content of those manuscripts have previously appeared in the public domain as online preprints or other form of online posting.”
