摘要篇首：Chinese Medical Journal (CMJ) and its electronic version are published monthly by the Chinese Medical Association and distributed worldwide. Manuscripts are welcome from any part of the world and should be sent to the Editorial Office, Chinese Medical Journal, Chinese Medical Association, 42 Dongsi Xidajie, Beijing 100710, China.Manuscripts. Manuscripts are received with the understanding that they have not previously been published in English and are not under simultaneous consideration for another publication and electronic medium. A complete report following presentation or publication of preliminary findings elsewhere (e.g., in an abstract) can be considered. A covering letter and an introduction letter from author's institution are needed. For multicenter clinical trial, at least one person's name must accompany a group name-e.g., Zhu Wenling, for the Collaborative Study Group on Thrombolysis with China-made Recombinant Streptokinase. All persons who meet the criteria for authorship as stated in the Uniform Requirements for Manuscripts Submitted to Biomedical Journals are listed as authors who must make substantial contributions to: ① conception and design, or analysis and interpretation of data; ② the drafting of the article or critical revision for important intellectual content; and ③ the final approval of the version to be published. All three conditions must all be met.