首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17198篇
  免费   1363篇
  国内免费   40篇
耳鼻咽喉   396篇
儿科学   392篇
妇产科学   243篇
基础医学   2240篇
口腔科学   549篇
临床医学   1658篇
内科学   3527篇
皮肤病学   213篇
神经病学   1855篇
特种医学   610篇
外科学   2339篇
综合类   269篇
一般理论   12篇
预防医学   1474篇
眼科学   343篇
药学   1214篇
  1篇
中国医学   9篇
肿瘤学   1257篇
  2023年   95篇
  2022年   153篇
  2021年   285篇
  2020年   215篇
  2019年   240篇
  2018年   312篇
  2017年   248篇
  2016年   256篇
  2015年   259篇
  2014年   409篇
  2013年   690篇
  2012年   924篇
  2011年   988篇
  2010年   587篇
  2009年   577篇
  2008年   1010篇
  2007年   1051篇
  2006年   1089篇
  2005年   1036篇
  2004年   1022篇
  2003年   1027篇
  2002年   1012篇
  2001年   221篇
  2000年   181篇
  1999年   187篇
  1998年   227篇
  1997年   207篇
  1996年   215篇
  1995年   176篇
  1994年   158篇
  1993年   125篇
  1992年   164篇
  1991年   165篇
  1990年   152篇
  1989年   134篇
  1988年   144篇
  1987年   147篇
  1986年   146篇
  1985年   160篇
  1984年   167篇
  1983年   166篇
  1982年   190篇
  1981年   160篇
  1980年   168篇
  1979年   116篇
  1978年   139篇
  1977年   121篇
  1976年   130篇
  1974年   89篇
  1972年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Samples taken from an activated sludge reactor used for the biodegradation of metal cutting fluids were studied for the presence of plasmid-containing bacteria. Twenty different bacterial isolates contained one or more plasmids. After numerous transfers of the isolates through LB broth, 55% of the plasmids were spontaneously lost as evidenced by agarose gel electrophoresis. Eighty percent of the isolates were resistant to one or more antibiotics, 65% resistant to two or more antibiotics, 40% resistant to three or more, 20% resistant to four or more and 5% resistant to five antibiotics. The isolates were also tested for their sensitivity to several common metals. This study has demonstrated that activated sludge is a natural reservoir for plasmid-containing bacteria involved in biodegradation of wastes.  相似文献   
54.
55.
56.
57.
A pilot study was conducted of the biological characteristics of the leukemia cells of newly diagnosed patients with poor prognosis acute myelogenous leukemia (AML). This study included measurements of the pretherapy proliferative rate of the leukemia cells in vivo, assessment of differentiation in vivo during remission induction therapy, and the level of expression of the fms, myc, and IL1β genes in pretherapy leukemia cells. Short cell cycle times were characteristic of the best prognostic category and were associated with a rapid reduction in marrow leukemia cells in cytosine arabinoside (araC)-sensitive patients. Expression of c-fms was associated with rapid reduction in marrow leukemia cells during araC therapy and with a successful treatment outcome. Expression of the IL1β gene was associated with short remissions. These studies suggest that when compared to newly diagnosed standard prognosis AML, the leukemia of poor prognosis patients is more likely to exhibit long cell cycle times, low levels of fms expression, and is less likely to be associated with myeloid differentiation during remission induction therapy. © 1993 Wiley-Liss, Inc.  相似文献   
58.
Surgical rejuvenation of the upper face involves the correction of excess and lax forehead, eyelid, and periorbital skin. Improving the appearance by correcting the effects of aging involves a combination of blepharoplasty and open coronal foreheadplasty. Many surgeons and several reports question the safety of both procedures being performed concomitantly. The difficulty arises in precisely balancing the skin excision from the frontal forehead and upper eyelid areas. Over-resection of skin may result in incomplete closure of the eyelid and dry-eye syndrome, while an inadequate resection may produce a poor aesthetic result. There is no large series that documents the safety and effectiveness of these two procedures being performed concomitantly. Furthermore, with the recent and rapid development of complex multiplanar endoscopic facial rejuvenation techniques, the basic open forehead-plasty has become increasingly overlooked as a legitimate, efficacious technique for rejuvenation of the upper face. The technique utilized in this series is presented in detail. The consistently excellent results obtained satisfy the aesthetic goals of patients as well as the goals of surgeons, and suggest a renewed interest in the technique based upon its simplicity and easily reproducible results.  相似文献   
59.
60.
The papers which follow are revised and expanded versions of presentations made at the Conference on Improving Florida's Services for the Mentally Ill: The Role of Psychiatry, held in Tallahassee, Florida on October 7–8, 1986, and organized by the Florida Mental Health Institute, University of South Florida. The conference was sponsored by the Florida Department of Health and Rehabilitative Services through the Committee on Public Psychiatry. The authors and their organizational affiliations are listed below  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号