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   1027814篇
  免费   75170篇
  国内免费   2439篇
耳鼻咽喉   15090篇
儿科学   29013篇
妇产科学   28240篇
基础医学   144842篇
口腔科学   28768篇
临床医学   91133篇
内科学   198706篇
皮肤病学   19624篇
神经病学   86064篇
特种医学   40831篇
外国民族医学   184篇
外科学   159436篇
综合类   26696篇
现状与发展   4篇
一般理论   456篇
预防医学   78886篇
眼科学   24881篇
药学   75052篇
  24篇
中国医学   1774篇
肿瘤学   55719篇
  2018年   10358篇
  2016年   9145篇
  2015年   10737篇
  2014年   15669篇
  2013年   23780篇
  2012年   32758篇
  2011年   34635篇
  2010年   19910篇
  2009年   18668篇
  2008年   32757篇
  2007年   35376篇
  2006年   34827篇
  2005年   34813篇
  2004年   33806篇
  2003年   32489篇
  2002年   31255篇
  2001年   37233篇
  2000年   37561篇
  1999年   32352篇
  1998年   11263篇
  1997年   10300篇
  1996年   9961篇
  1995年   9400篇
  1994年   8970篇
  1993年   8405篇
  1992年   27623篇
  1991年   26992篇
  1990年   26390篇
  1989年   25431篇
  1988年   23987篇
  1987年   23562篇
  1986年   22537篇
  1985年   21945篇
  1984年   17448篇
  1983年   15050篇
  1982年   10288篇
  1981年   9522篇
  1980年   8919篇
  1979年   17442篇
  1978年   12900篇
  1977年   10890篇
  1976年   9952篇
  1975年   10664篇
  1974年   13189篇
  1973年   12576篇
  1972年   11899篇
  1971年   10945篇
  1970年   10426篇
  1969年   10101篇
  1968年   9033篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
73.
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   
74.
75.
Data on 232 members of a single pedigree, descended from two pairs of original parents, were made available to the participants of Genetic Analysis Workshop 8 (GAW8). In addition to information concerning age and sex, measurements for 10 quantitative traits and genotypes at 22 polymorphic marker loci were also provided for a subset of 193 of these family members. © 1993 Wiley-Liss, Inc.  相似文献   
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