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   950444篇
  免费   75948篇
  国内免费   2233篇
耳鼻咽喉   13812篇
儿科学   26843篇
妇产科学   26671篇
基础医学   135162篇
口腔科学   27042篇
临床医学   84871篇
内科学   182069篇
皮肤病学   18202篇
神经病学   79068篇
特种医学   38588篇
外国民族医学   174篇
外科学   150204篇
综合类   25579篇
现状与发展   2篇
一般理论   390篇
预防医学   74369篇
眼科学   22359篇
药学   70395篇
中国医学   1684篇
肿瘤学   51141篇
  2018年   9587篇
  2016年   8283篇
  2015年   9747篇
  2014年   14110篇
  2013年   20941篇
  2012年   29291篇
  2011年   30886篇
  2010年   17856篇
  2009年   16674篇
  2008年   28861篇
  2007年   31172篇
  2006年   30738篇
  2005年   30104篇
  2004年   29559篇
  2003年   28150篇
  2002年   26918篇
  2001年   36575篇
  2000年   36959篇
  1999年   31661篇
  1998年   10319篇
  1997年   9350篇
  1996年   9123篇
  1995年   8608篇
  1994年   8241篇
  1992年   27046篇
  1991年   26457篇
  1990年   25901篇
  1989年   24930篇
  1988年   23467篇
  1987年   23132篇
  1986年   21958篇
  1985年   21336篇
  1984年   16646篇
  1983年   14224篇
  1982年   9152篇
  1981年   8464篇
  1980年   7866篇
  1979年   16835篇
  1978年   12239篇
  1977年   10277篇
  1976年   9395篇
  1975年   10208篇
  1974年   12704篇
  1973年   12205篇
  1972年   11580篇
  1971年   10716篇
  1970年   10244篇
  1969年   9940篇
  1968年   8929篇
  1967年   8245篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
An ultrasound contrast agent which survives transit through the pulmonary circulation after injection into a peripheral vein can also be used for the demonstration of flow characteristics in the peripheral organs. Such a substance (SH U 508 A, Schering AG, Berlin) was tested in the Gynecological Department of the University of Marburg for its suitability for enhancing color-coded Doppler signals in mammary diagnosis in a group of ten women with breast tumors. The observations made are compared with the histologically confirmed diagnoses. The very distinct enhancement of the color-coded Doppler signals allows reliable demonstration of the vascularization characteristics, not only of the malignant, but also of all benign solid tumors examined. Color signals were even recorded from normal mammary tissue, which means that the demonstration of perfusion can no longer be used on its own as a diagnostic criterion. Observation of the characteristics of the blood supply to a tumor might, on the other hand, be an advantage, not only in respect of tumor typing, but also as regards the prognosis of a tumor. In this connection, the registration of the arrival, retention and wash-out phases specific to a contrast agent appears to furnish particularly interesting information about the growth dynamics of a tumor.  相似文献   
63.
64.
SUMMARY. Samples from 1828 donations were screened for anti-HBc at seven sites in the UK using kits supplied by 10 manufacturers. Only 10 (0.55%) donations were considered to have true anti-HBc reactivity and these were detected by all 10 kits. Additional markers of HBV infection were found in nine of these 10 donations. Additional reactives were found by all kits, the number ranging from 1 to 43.
In the four more specific kits, the 10 true reactives were clearly distinguished from the 'false reactives' by the strength of the reaction. It is concluded that the reliance on a single ELISA test for anti-HBc diagnosis is unwise. The use of a second test known to be more specific than the screening ELISA is recommended.  相似文献   
65.
66.
PCP and related compounds inhibit 3H-mazindol binding to the cocaine receptor on dopamine transporters. The relative potencies of these compounds are such that some of the behavioral effects of PCP could be related to its action at the cocaine receptor; however, the affinity of PCP at the cocaine site (Ki = 1.59 microM) is less than its affinity at its own receptor (Ki about 0.12 microM). More data will be needed to conclusively implicate the cocaine receptor in the action of PCP.  相似文献   
67.
68.
69.
Treatment versus no treatment in chronic open angle glaucoma   总被引:1,自引:0,他引:1  
In a controlled randomized study 15 patients (20 eyes) with chronic open angle glaucoma and visual field defects were followed by greater than 1 year, 12 of them were followed for 3 years. Half of the group were untreated controls, the other half treated with pressure reducing medical therapy. At least 5 consecutive computerized visual fields were recorded (COMPETER) on each eye, and the linear regression coefficient was calculated. With the reservation for uncontrolled compliance no significant difference in the line of favourable effect of pressure reduction could be spotted, in spite of an average pressure reduction in the treated group of 4 mmHg. More important than this result, which is open to criticism for the smallness of the material, uncontrolled compliance etc, is the lesson that a randomized experiment with treated and non-treated glaucoma cases carried out in accordance with the Helsingfors convention is hardly feasible.  相似文献   
70.
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