Duplicate publication

Duplicate publication is publication of a paper that overlaps substantially with one already published,without clear,visible reference to the previous publication.Prior publication may include release of information in the public domain.

Readers of medical journals deserve to be able to trust that what they are reading is original unless there is a clear statement that the author and editor are intentionally republishing an article （which might be considered for historic or landmark papers,for example）.The bases of this position are international copyright laws,ethical conduct,and cost-effective use of resources.Duplicate publication of original research is particularly problematic because it can result in inadvertent double-counting of data or inappropriate weighting of the results of a single study,which distorts the available evidence.

When authors submit a manuscript reporting work that has already been reported in large part in a published article or is contained in or closely related to another paper that has been submitted or accepted for publication elsewhere,the letter of submission should clearly say so and the authors should provide copies of the related material to help the editor decide how to handle the submission.

This recommendation does not prevent a journal from considering a complete report that follows publication of a preliminary report,such as a letter to the editor,a preprint or an abstract or poster displayed at a scientific meeting.It also does not prevent journals from considering a paper that has been presented at a scientific meeting but was not published in full,or that is being considered for publication in proceedings or similar format.Press reports of scheduled meetings are not usually regarded as breaches of this rule,but they may be if additional data tables or figures enrich such reports.Authors should also consider how dissemination of their findings outside of scientific presentations at meetings may diminish the priority journal editors assign to their work.

重复发表指发表与已发表论文内容雷同的文章，而不清晰和明确地守用之前已发表的论文。

医学期刊的读者理当相信他们所阅读的是原创作品，除非有明确的说明指出作者和编辑特意再次发表某篇论文（例如可能被视为历史性或里程碑式的文章）。这一立场是基于国际版权法、道德操守以及资源利用的成本效益。原创性研究的重复发表特别成问题，因为这会造成对单个研究的数据无意识地双倍计数或不恰当地夸大该研究结果的分量，从而歪曲现有的证据。

如果作者的投稿所报告的研究，大部分在某篇已经发表的论文中报告过，或包含在已向他处投稿或已被接受将在他处发表的另一篇文章中，或与这样一篇文章密切相关，则应在投稿信中如实说明；而且，作者应该提供相关材料的复印件，以便于编辑决定如何处理作者的投稿。

若已发表过初步报告，如致编辑的信、预印本、学术会议摘要或壁报等，此推荐规范不阻止期刊考虑发表其完整的报告。此推荐规范也不阻止期刊考虑发表在科学会议上报告过但尚未全文发表的文章，或拟安排在会议论文集中以摘要的形式发表的论文。对会期已定的学术会议的新闻报道通常并不被视为违反这一规则，但若附加图表数据扩充这种报道则另当别论。作者还应明白，以会议学术报告之外的方式传播其研究结果可能有损编辑在期刊上发表其研究工作的优先权。