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   1003308篇
  免费   80092篇
  国内免费   2402篇
耳鼻咽喉   14447篇
儿科学   28138篇
妇产科学   27427篇
基础医学   142768篇
口腔科学   28591篇
临床医学   89358篇
内科学   194471篇
皮肤病学   20013篇
神经病学   82983篇
特种医学   41400篇
外国民族医学   185篇
外科学   158213篇
综合类   26306篇
现状与发展   2篇
一般理论   367篇
预防医学   77462篇
眼科学   23535篇
药学   73709篇
中国医学   1803篇
肿瘤学   54624篇
  2018年   10561篇
  2017年   8320篇
  2016年   9373篇
  2015年   10939篇
  2014年   15688篇
  2013年   22928篇
  2012年   31897篇
  2011年   33641篇
  2010年   19553篇
  2009年   18512篇
  2008年   31281篇
  2007年   33733篇
  2006年   33549篇
  2005年   33231篇
  2004年   31999篇
  2003年   30535篇
  2002年   29308篇
  2001年   37736篇
  2000年   38089篇
  1999年   32749篇
  1998年   10962篇
  1997年   9944篇
  1996年   9665篇
  1995年   9104篇
  1994年   8702篇
  1992年   27771篇
  1991年   27103篇
  1990年   26482篇
  1989年   25484篇
  1988年   23962篇
  1987年   23619篇
  1986年   22489篇
  1985年   21824篇
  1984年   17154篇
  1983年   14664篇
  1982年   9670篇
  1981年   8914篇
  1979年   17281篇
  1978年   12647篇
  1977年   10637篇
  1976年   9764篇
  1975年   10505篇
  1974年   13069篇
  1973年   12505篇
  1972年   11861篇
  1971年   10946篇
  1970年   10476篇
  1969年   10108篇
  1968年   9093篇
  1967年   8388篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
74.
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   
75.
76.
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   
77.
78.
79.
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   
80.
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