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   74114篇
  免费   6741篇
  国内免费   157篇
耳鼻咽喉   675篇
儿科学   2720篇
妇产科学   2466篇
基础医学   8918篇
口腔科学   882篇
临床医学   11378篇
内科学   13604篇
皮肤病学   1169篇
神经病学   7174篇
特种医学   1727篇
外科学   8341篇
综合类   787篇
现状与发展   1篇
一般理论   98篇
预防医学   9556篇
眼科学   1295篇
药学   4905篇
中国医学   86篇
肿瘤学   5230篇
  2023年   757篇
  2022年   961篇
  2021年   2178篇
  2020年   1403篇
  2019年   2190篇
  2018年   2439篇
  2017年   1918篇
  2016年   2117篇
  2015年   2169篇
  2014年   3102篇
  2013年   4146篇
  2012年   5719篇
  2011年   5743篇
  2010年   3243篇
  2009年   2896篇
  2008年   4700篇
  2007年   4697篇
  2006年   4369篇
  2005年   4128篇
  2004年   3715篇
  2003年   3253篇
  2002年   2962篇
  2001年   774篇
  2000年   675篇
  1999年   756篇
  1998年   672篇
  1997年   546篇
  1996年   517篇
  1995年   488篇
  1994年   408篇
  1993年   365篇
  1992年   484篇
  1991年   406篇
  1990年   437篇
  1989年   420篇
  1988年   336篇
  1987年   332篇
  1986年   352篇
  1985年   335篇
  1984年   307篇
  1983年   300篇
  1982年   219篇
  1981年   234篇
  1980年   187篇
  1979年   236篇
  1978年   219篇
  1976年   173篇
  1975年   159篇
  1974年   153篇
  1973年   164篇
排序方式: 共有10000条查询结果,搜索用时 592 毫秒
111.
Exposure to trauma and stress has been linked with poor health, while forgiveness appears to be positively associated with health outcomes. The current study investigates whether traits such as forgiveness and ruminative tendencies predict levels of trauma and stress experienced by New York City residents on the 1‐year anniversary of the September 11th terrorist attack. Seventy‐one students and staff members (57 females, 14 males) of a graduate school in New York City were administered the Impact of Events Scale, the Perceived Stress Scale, and questionnaires designed for the purpose of this study to measure ruminative tendencies and forgiveness on September 11, 2002. Rumination predicted levels of trauma (p < 0.05) and perceived stress (p < 0.01). Lower levels of forgiveness predicted perceived stress (p < 0.05), but not trauma. Rumination mediated the relationship between forgiveness and perceived stress. These findings suggest that individuals with higher levels of rumination have an elevated risk of experiencing trauma and stress‐related symptoms following a traumatic event. Forgiveness is associated with lower levels of stress, but not trauma, perhaps because trauma is an extreme form of stress. Forgiveness appears to serve as a buffer against stress more so in individuals with low levels of rumination than in individuals with high levels of rumination. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
112.
113.
114.
115.
116.
Monoclonal antibodies against human and bovine 2′:3′-cyclic nucleotide 3′-phosphodiesterase (CNPase) were generated by fusing FOX-NY myeloma cells with spleen cells from RBF/Dn mice previously immunized with the purified brain antigens. The enzyme isolated from bovine brain was quite basic, with an isoelectric point of 9.71 and both the bovine and human enzymes consisted of a closely spaced doublet at approximately 44 and 46 kDa on SDS-PAGE. Six monoclonals were identified as strongly recognizing the enzyme on both ELISA plates and on immunoblots of whole brain protein. Four monoclonals very weakly cross-reacted with guinea pig myelin basic protein. In contrast with two previous reports, some of our monoclonal antibodies did immunostain 2 or 3 protein bands in peripheral nerve, two bands closely corresponding to those immunostained in central nervous system (CNS) myelin, the Wolfgram protein fraction and in acetone powders of whole brain. Each of the 6 monoclonals reacting strongly on immunoblots recognized the enzyme in from 2 to 5 of the species examined (human, bovine, rat, mouse and rabbit). In addition, all 6 monoclonals that immunostained the enzyme in whole brain, myelin and Wolfgram protein immunoblots recognized both CNP1 (44 kDa) and CNP2 (46 kDa). The two closely spaced protein bands observed on SDS-PAGE and previously stained on immunoblots of CNS CNPase using polyvalent rabbit anti-bovine CNPase antisera, and now different monoclonal antibodies, appear to be immunologically related and to contain highly conserved sequences.  相似文献   
117.
118.
119.
Supercritical fluids are a unique class of nonaqueous media in which biocatalytic reactions can occur. The physical properties of supercritical fluids, which include gas-like diffusivities and liquid-like densities, can be predictably controlled with changing pressure. This paper describes how adjustment of pressure, with the subsequent predictable changes of the dielectric constant and Hildebrand solubility parameter for fluoroform, ethane, sulfur hexafluoride, and propane, can be used to manipulate the activity of lipase in the transesterification of methylmethacrylate with 2-ethyl-1-hexanol. Of particular interest is that the dielectric constant of supercritical fluoroform can be tuned from approximately 1 to 8, merely by increasing pressure from 850 to 4000 psi (from 5.9 to 28 MPa). The possibility now exists to predictably alter both the selectivity and the activity of a biocatalyst merely by changing pressure.  相似文献   
120.
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