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   103592篇
  免费   43006篇
  国内免费   68篇
耳鼻咽喉   1753篇
儿科学   5265篇
妇产科学   1390篇
基础医学   18772篇
口腔科学   5475篇
临床医学   17285篇
内科学   27292篇
皮肤病学   7765篇
神经病学   15718篇
特种医学   2659篇
外科学   16008篇
综合类   422篇
一般理论   85篇
预防医学   8057篇
眼科学   1547篇
药学   7045篇
中国医学   1033篇
肿瘤学   9095篇
  2023年   195篇
  2022年   258篇
  2021年   1711篇
  2020年   5385篇
  2019年   11349篇
  2018年   10670篇
  2017年   11846篇
  2016年   12573篇
  2015年   12510篇
  2014年   12564篇
  2013年   13570篇
  2012年   5963篇
  2011年   5910篇
  2010年   9873篇
  2009年   6162篇
  2008年   3844篇
  2007年   2832篇
  2006年   2872篇
  2005年   2557篇
  2004年   2436篇
  2003年   2365篇
  2002年   2376篇
  2001年   1009篇
  2000年   891篇
  1999年   499篇
  1998年   440篇
  1997年   305篇
  1996年   304篇
  1995年   278篇
  1994年   256篇
  1993年   239篇
  1992年   169篇
  1991年   134篇
  1990年   136篇
  1989年   140篇
  1988年   126篇
  1987年   107篇
  1986年   128篇
  1985年   158篇
  1984年   136篇
  1983年   140篇
  1982年   156篇
  1981年   151篇
  1980年   152篇
  1979年   70篇
  1978年   67篇
  1977年   70篇
  1976年   69篇
  1975年   61篇
  1974年   52篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
31.
32.
33.
34.
35.
Ganoderma sinensis has been used widely in Oriental countries for the prevention and treatment of various diseases including cancer. Previous studies have shown that the lipid extract from Ganoderma exhibits direct cytotoxicity against tumor cells. Here, it is reported that the lipid extract from germinating G. sinensis spores, at lower concentrations that have no direct tumoricidal activity, induce potent antitumor immune responses in human monocytes/macrophages. Upon stimulation with the lipid extract, monocytes/macrophages exhibited markedly increased production of proinflammatory cytokines and surface expression of costimulatory molecules. Conditioned medium from stimulated cells effectively suppressed the growth of tumor cells. Apparently, the lipid extract triggered macrophage activation via a mechanism different from that associated with LPS. Moreover, it was observed that the lipid extract could partially re‐establish the antitumor activity of the immunosuppressive tumor‐associated macrophages. These results indicated that in addition to its direct tumoricidal activity, the lipid extract from G. sinensis spores could exert antitumor activity by stimulating the activation of human monocytes/macrophages. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
36.
37.
38.
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma.  相似文献   
39.
Abstract: We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor–enzyme complex, Ki, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z‐Arg‐Leu‐His‐Agly‐Ile‐Val‐OMe ( 7 ) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7 . We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K.  相似文献   
40.
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