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   2286篇
  免费   133篇
  国内免费   10篇
耳鼻咽喉   8篇
儿科学   81篇
妇产科学   56篇
基础医学   253篇
口腔科学   36篇
临床医学   214篇
内科学   461篇
皮肤病学   22篇
神经病学   204篇
特种医学   194篇
外科学   322篇
综合类   32篇
预防医学   132篇
眼科学   73篇
药学   127篇
中国医学   7篇
肿瘤学   207篇
  2023年   19篇
  2022年   40篇
  2021年   53篇
  2020年   23篇
  2019年   34篇
  2018年   50篇
  2017年   29篇
  2016年   46篇
  2015年   49篇
  2014年   48篇
  2013年   93篇
  2012年   105篇
  2011年   114篇
  2010年   83篇
  2009年   94篇
  2008年   89篇
  2007年   105篇
  2006年   108篇
  2005年   104篇
  2004年   88篇
  2003年   82篇
  2002年   68篇
  2001年   57篇
  2000年   60篇
  1999年   61篇
  1998年   43篇
  1997年   41篇
  1996年   45篇
  1995年   39篇
  1994年   37篇
  1993年   27篇
  1992年   36篇
  1991年   40篇
  1990年   35篇
  1989年   50篇
  1988年   43篇
  1987年   36篇
  1986年   25篇
  1985年   31篇
  1984年   25篇
  1983年   18篇
  1982年   13篇
  1981年   13篇
  1980年   15篇
  1979年   18篇
  1978年   12篇
  1977年   16篇
  1976年   10篇
  1975年   13篇
  1973年   10篇
排序方式: 共有2429条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Adult patients with Niemann-Pick disease type C (NPC) usually develop cognitive impairment progressing to dementia, whose pathophysiology remains still unclear. Noteworthy parallels exist in cognitive impairment and cellular pathology of NPC and Alzheimer’s disease (AD). In particular, alterations of cholinergic system, which represent one of the pathological hallmarks and contribute to cognitive deterioration in AD, have recently been demonstrated in a human brain autopsy and in an experimental model of NPC. This finding raised the issue that central cholinergic circuits dysfunction may contribute to pathophysiology of cognitive impairment in NPC as well, and prompted us to evaluate the cholinergic functional involvement in NPC patients by applying a neurophysiologic technique, named short-latency afferent inhibition (SAI). We describe clinical, biochemical, molecular and neuropsychological features, and SAI findings in three patients affected by NPC. Diagnosis of NPC was assessed by molecular analysis of the NPC1 gene in all patients. In two of them, biochemical analysis of intracellular accumulation of unesterified cholesterol was also performed. The main clinical features were cerebellar ataxia, vertical supranuclear gaze palsy and a variable degree of cognitive impairment ranging from only memory impairment to severe dementia. Electrophysiological evaluation revealed a reduced SAI in all three patients. Our SAI findings provide evidence of cholinergic dysfunction in patients with the adult form of NPC, supporting that cholinergic alterations may play a role in cognitive impairment in NPC, and strengthening the similarities between NPC and AD.  相似文献   
75.
Retinal stem cell culture has become a powerful research tool, but it requires reliable methods to obtain high‐quality images of living and fixed cells. This study describes a procedure for using phase contrast microscopy to obtain three‐dimensional (3‐D) images for the study of living cells by photographing a living cell in a culture dish from bottom to top, as well as a procedure to increase the quality of scanning electron micrographs and laser confocal images. The procedure may also be used to photograph clusters of neural stem cells, and retinal explants with vigorous axonal growth. In the case of scanning electron microscopy and laser confocal images, a Gaussian procedure is applied to the original images. The methodology allows for the creation of anaglyphs and video reconstructions, and provides high‐quality images for characterizing living cells or tissues, fixed cells or tissues, or organs observed with scanning electron and laser confocal microscopy. Its greatest advantage is that it is easy to obtain good results without expensive equipment. The procedure is fast, precise, simple, and offers a strategic tool for obtaining 3‐D reconstructions of cells and axons suitable for easily determining the orientation and polarity of a specimen. It also enables video reconstructions to be created, even of specimens parallel to the plastic base of a tissue culture dish, It is also helpful for studying the distribution and organization of living cells in a culture, as it provides the same powerful information as optical tomography, which most confocal microscopes cannot do on sterile living cells. Anat Rec, 297:770–780, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
76.
77.
A 9-year-old boy was found to have ruptured sinus of Valsalva aneurysm (RSVA) and aortic coarctation. Following relief of aortic coarctation by balloon angioplasty, transcatheter coil occlusion of the RSVA was performed successfully under transesophageal echocardiographic and fluoroscopic monitoring; bioptome-assisted delivery of 0.052" Gianturco coil was undertaken via a 7 Fr sheath stabilized by an 0.035" guidewire passing through the RSVA and the sheath. This report details the technique of occlusion.  相似文献   
78.
79.
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