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   1644645篇
  免费   111357篇
  国内免费   2574篇
耳鼻咽喉   22744篇
儿科学   53482篇
妇产科学   43218篇
基础医学   243027篇
口腔科学   46206篇
临床医学   148112篇
内科学   309449篇
皮肤病学   37485篇
神经病学   121738篇
特种医学   63314篇
外国民族医学   276篇
外科学   246854篇
综合类   33925篇
现状与发展   3篇
一般理论   404篇
预防医学   118011篇
眼科学   38394篇
药学   129475篇
  10篇
中国医学   4719篇
肿瘤学   97730篇
  2019年   12295篇
  2018年   17734篇
  2017年   13861篇
  2016年   15579篇
  2015年   17369篇
  2014年   23709篇
  2013年   35073篇
  2012年   47466篇
  2011年   50088篇
  2010年   29450篇
  2009年   27712篇
  2008年   46289篇
  2007年   49675篇
  2006年   50539篇
  2005年   47681篇
  2004年   46030篇
  2003年   44096篇
  2002年   42662篇
  2001年   86444篇
  2000年   88347篇
  1999年   73432篇
  1998年   18778篇
  1997年   16330篇
  1996年   16517篇
  1995年   15631篇
  1994年   14187篇
  1993年   13366篇
  1992年   55337篇
  1991年   54063篇
  1990年   52998篇
  1989年   51424篇
  1988年   46525篇
  1987年   45273篇
  1986年   42868篇
  1985年   40213篇
  1984年   29374篇
  1983年   24849篇
  1982年   13763篇
  1979年   26569篇
  1978年   18249篇
  1977年   15951篇
  1976年   14404篇
  1975年   16282篇
  1974年   18972篇
  1973年   18293篇
  1972年   17383篇
  1971年   16273篇
  1970年   15234篇
  1969年   14450篇
  1968年   12973篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
102.
103.
104.
105.
Four clinical trials of porcine islet transplantation have been reported, and there are verbal reports that clinical trials on much larger scales are continuing in centers in China and Russia. The four reported trials are briefly reviewed and, in the light of the present status of experimental islet xenotransplantation, consideration is given to whether such trials are currently justified. The Ethics Committee of the International Xenotransplantation Association has (1) emphasized the need for encouraging studies in non-human primates before clinical trials should be undertaken, (2) mandatory monitoring for the transfer of porcine microorganisms, and (3) careful regulation and oversight by recognized bodies. Other aspects of the topic, such as the need for informed consent, are briefly discussed. We conclude that, at the present time, more data documenting convincing efficacy, focused on clinically applicable immunosuppressive regimens, are needed to justify the initiation of closely monitored clinical trials. A clinical trial may then be justified even though the potential risk to the patients, and possibly for society, will not be zero.  相似文献   
106.
107.
OBJECTIVE: To determine whether under-reporting of rheumatic fever occurs at hospital, municipal, provincial and national levels of the South African health system. BACKGROUND: Information on the incidence of rheumatic fever (RF) and the prevalence of rheumatic heart disease (RHD) is required for the prevention of valvular heart disease in developing countries. In South Africa, RF was made a notifiable condition in 1989. It has recently been suggested that the reporting of RF cases may be incomplete, possibly because of underreporting by health care professionals and deficient administration of the disease notification system in South Africa. METHOD AND RESULTS: We assessed whether underreporting of RF cases occurs by comparing the numbers of RF cases reported per year at hospital, municipal, provincial and national levels from 1990 to 2004. There was a fall in the number of RF cases reported per year at national and provincial level over the 15 years of observation. A detailed analysis of the number of RF cases reported at hospital, municipal and provincial level for a 5-year period showed that more cases were diagnosed in one hospital (serving a smaller population) than were captured at municipal and provincial level (serving a larger population), suggesting underreporting by health care professionals. There were discrepancies in the number of cases reported at municipal, provincial and national level, suggesting poor administration of the notification system. CONCLUSION: There appears to be underreporting of RF cases by health care professionals, and poor administration of the RF notification system. Health care professionals need to be educated about the statutory requirement to notify all RF cases in South Africa. An effective national disease notification system is required.  相似文献   
108.
109.
110.
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