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   2158篇
  免费   143篇
  国内免费   21篇
耳鼻咽喉   12篇
儿科学   49篇
妇产科学   106篇
基础医学   240篇
口腔科学   34篇
临床医学   251篇
内科学   548篇
皮肤病学   16篇
神经病学   241篇
特种医学   182篇
外科学   230篇
综合类   37篇
一般理论   1篇
预防医学   123篇
眼科学   35篇
药学   116篇
中国医学   1篇
肿瘤学   100篇
  2023年   11篇
  2022年   10篇
  2021年   39篇
  2020年   20篇
  2019年   30篇
  2018年   31篇
  2017年   22篇
  2016年   17篇
  2015年   26篇
  2014年   58篇
  2013年   84篇
  2012年   84篇
  2011年   125篇
  2010年   73篇
  2009年   87篇
  2008年   98篇
  2007年   75篇
  2006年   85篇
  2005年   89篇
  2004年   62篇
  2003年   63篇
  2002年   77篇
  2001年   61篇
  2000年   72篇
  1999年   58篇
  1998年   52篇
  1997年   53篇
  1996年   51篇
  1995年   45篇
  1994年   31篇
  1993年   33篇
  1992年   40篇
  1991年   45篇
  1990年   49篇
  1989年   52篇
  1988年   58篇
  1987年   37篇
  1986年   26篇
  1985年   28篇
  1984年   32篇
  1983年   22篇
  1982年   29篇
  1981年   18篇
  1980年   26篇
  1979年   13篇
  1978年   21篇
  1977年   21篇
  1976年   11篇
  1970年   8篇
  1969年   9篇
排序方式: 共有2322条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
Histories of childhood trauma have been reported previously in bulimic subjects but no study to date has assessed how these experiences may affect response to fluoxetine. Thirty outpatient subjects in a placebo-controlled trial of 60 mg of fluoxetine for the treatment of bulimia nervosa completed the Dissociative Experiences Scale and a self-report instrument assessing trauma. Response to treatment was measured with the Hamilton Depression Scale-17 (HAMD-17), the CGI, the PGI, and the change in number of binges per day. Subjects taking fluoxetine with histories of physical abuse showed a significantly greater drop in HAMD-17 scores than those without such histories. No relationship between a reported history of abuse and the response of binging to fluoxetine was found. A history of abuse does not appear to predict the response of hinging to fluoxetine but may predict a greater response of nonspecific symptoms like depression. © 1994 by John Wiley & Sons, Inc.  相似文献   
96.
97.
Glial cells have a major role in protecting neurons against various forms of stress. Especially, astrocytes mediate the bulk of glutamate clearance in the brain via specific membrane transporters (GLAST and GLT1), thereby preventing the occurrence of excitotoxic events. Although glutamate-mediated mechanisms are thought to contribute to nigral dopaminergic neuron degeneration in Parkinson's disease, detailed information on the organization of glia in the substantia nigra is still lacking. The present study was performed to provide quantitative information on the organization of astroglia and on the relationships between astrocytes and excitatory synapses in the rat substantia nigra. Using immunolabeling of GLT1 and confocal imaging, we found that the substantia nigra was filled with a dense meshwork of immunoreactive astrocyte processes. Stereological analysis performed on electron microscope images revealed that the density of immunoreactive astrocyte plasma membranes was substantial, close to 1 μm2/μm3, in the substantia nigra neuropil, both in the pars compacta and the pars reticulata. Excitatory synapses had on average two thirds of their perimeters free from glia, a disposition that may favor transmitter spillover. The density of glutamatergic synapses, as quantified on confocal images by the simultaneous detection of bassoon and of vesicular glutamate transporter 1 or 2, was very low (0.01 and 0.025 per μm3 in the reticulata and compacta subdivisions, respectively). Thus the ratio of GLT1-expressing glial membrane surface to glutamatergic synapses was very high (40–100 μm2), suggesting an efficient regulation of extracellular glutamate concentrations.  相似文献   
98.
99.
The process of reendothelialization was studied in a deendothelialized 3 cm segment of the canine descending thoracic aorta from which peripheral endothelial cell ingrowth had been prevented by impervious prosthetic graft sleeves. Three preparations were studied: (1) removal of only the endothelial cells, accomplished by flow surface drying and balloon catheter denudation, (2) removal of the superficial portion of the nonvasal media, accomplished by endarterectomy to a depth of 200 to 300 micron, and (3) removal of the entire inner (nonvasal) media, accomplished by endarterectomy to a depth of 500 to 600 micron to reach the outer (vasal) media. A total of 44 specimens were studied after implantation periods of 7, 14, 28, and 56 days. In all cases endothelial cell ingrowth from the host aorta into the test specimen was prevented by the impervious graft sleeves. In the deep endarterectomy group there were scattered areas of reendothelialization at 1 week, extensive reendothelialization at 2 weeks, almost complete reendothelialization at 4 weeks, and confluence by 8 weeks. However, in the superficial endarterectomy group scanning electron microscopy showed scattered areas of factor VIII/von Willebrand factor (FVIII/vWF)-negative, endothelial-like cells at 4 weeks, whereas at 8 weeks most of the surface was covered by endothelial cells identified by FVIII/vWF. In those specimens subjected to balloon catheter removal of endothelial cells only, reendothelialization was not seen, even at 8 weeks.  相似文献   
100.
Of 394 carotid endarterectomies performed during a 10-year period, 36 (9%) included Dacron patch graft angioplasties. Patch graft angioplasties were used selectively in patients because they had undergone previous carotid endarterectomy or had small-caliber vessels. There were no postoperative infections, occlusions, emboli, stroke, or pseudoaneurysms. In addition, no clinically detectable recurrent stenoses developed in this high-risk group of patients. Twenty-four of the 27 patients available for follow-up were screened for asymptomatic stenoses with spectral analysis and B-mode imaging; there was no sign of hemodynamically significant recurrent stenosis in this group. These encouraging results support the continued selective use of Dacron patch graft angioplasty in carotid surgery.  相似文献   
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