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   1495990篇
  免费   112416篇
  国内免费   3025篇
耳鼻咽喉   21276篇
儿科学   46023篇
妇产科学   40628篇
基础医学   223900篇
口腔科学   43676篇
临床医学   133045篇
内科学   282862篇
皮肤病学   31635篇
神经病学   113821篇
特种医学   58151篇
外国民族医学   242篇
外科学   229198篇
综合类   37702篇
现状与发展   3篇
一般理论   409篇
预防医学   113397篇
眼科学   35536篇
药学   113572篇
  3篇
中国医学   3797篇
肿瘤学   82555篇
  2018年   14415篇
  2016年   12660篇
  2015年   14450篇
  2014年   20247篇
  2013年   30600篇
  2012年   40941篇
  2011年   43062篇
  2010年   25348篇
  2009年   23827篇
  2008年   40506篇
  2007年   44033篇
  2006年   44164篇
  2005年   42510篇
  2004年   41678篇
  2003年   39911篇
  2002年   38599篇
  2001年   67640篇
  2000年   69002篇
  1999年   57721篇
  1998年   16317篇
  1997年   14480篇
  1996年   14616篇
  1995年   13850篇
  1994年   13095篇
  1992年   47127篇
  1991年   46485篇
  1990年   45568篇
  1989年   44503篇
  1988年   41160篇
  1987年   40162篇
  1986年   38238篇
  1985年   36653篇
  1984年   27768篇
  1983年   23680篇
  1982年   14140篇
  1981年   12856篇
  1980年   12190篇
  1979年   27043篇
  1978年   19397篇
  1977年   16394篇
  1976年   15352篇
  1975年   16749篇
  1974年   20352篇
  1973年   19463篇
  1972年   18444篇
  1971年   17156篇
  1970年   16428篇
  1969年   15650篇
  1968年   14221篇
  1967年   12996篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
81.
82.
One of our patients had trouble maintaining therapeutic and safe levels of theophylline, even though we were careful in planning and monitoring her drug regimen. This case report shows how we were able to use principles of pharmacokinetics to distinguish among plausible explanations for her experience. We discovered that she was not taking the drug consistently as prescribed and that supervised administration resolved apparent contradictions between doses and serum levels. We believe that physicians can use the same information and methods that we used to get better and safer results from theophylline therapy.  相似文献   
83.
Herpes zoster probably occurs more often than generally thought. Since it produces a radicular distribution of pain, it should be included in the differential diagnosis of radiculopathy. A case is presented in which evaluating the radicular low back pain before the characteristic rash appears was misleading. Careful history-taking concerning the exact nature of the pain and sensory changes is needed to differentiate between zoster and radiculopathy, if no rash is evident.  相似文献   
84.
Chorioretinal folds have been reported as a result of many intraocular and extraocular inflammatory processes or tumors. Visual loss is usually secondary to a combination of the underlying process and chorioretinal folds involving the macula. We report a patient who developed decreased vision, metamorphopsia, chorioretinal folds, and a lamellar macular hole secondary to global compression by a bone fragment. The chorioretinal folds regressed and his vision stabilized following surgical decompression. Chorioretinal folds and lamellar macular hold formation are previously unrecognized complications of reconstructive craniofacial surgery.  相似文献   
85.
In the isolated perfused rat pancreas, D,L-difluoromethylornithine, tested at a concentration of 3 mmol/L, failed to affect the release of glucagon and insulin caused, over 15 min stimulation, by either L-arginine or L-ornithine (2.0, 5.0 or 10.0 mmol/L) in the presence of either 3.3 or 5.6 mmol/L D-glucose. The inhibition of ornithine decarboxylase also failed to affect the release of glucagon provoked by either L-leucine (2 or 3 mmol/L) or L-glutamine (2 mmol/L) and the secretion of insulin stimulated by a rise in glucose concentration from 5.6 to 10.6 mmol/L. These data are interpreted to suggest that the rapid generation of polyamines from either L-arginine or L-ornithine does not play any significant role in the immediate glucagonotropic and insulinotropic action of these cationic amino acids.  相似文献   
86.
Eighty-nine cases of chronic bronchitis were matched against167 asymptomatic controls from the glass bangle industry ofFirozabad. Factors of age, social status, smoking habit andduration of exposure were studied. Duration of exposure wasfound to be a factor contributing significantly to the causationof disease. Requests for reprints should be addressed to: Dr B. N. Gupta, Division of Epidemilogy, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, Lucknow P.O. Box 80, 226001, India  相似文献   
87.
88.
The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.  相似文献   
89.
90.
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