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   1751500篇
  免费   140042篇
  国内免费   6710篇
耳鼻咽喉   22639篇
儿科学   56880篇
妇产科学   47378篇
基础医学   252313篇
口腔科学   48644篇
临床医学   157108篇
内科学   351201篇
皮肤病学   41732篇
神经病学   139311篇
特种医学   70256篇
外国民族医学   330篇
外科学   271860篇
综合类   38367篇
现状与发展   2篇
一般理论   516篇
预防医学   139169篇
眼科学   38263篇
药学   126933篇
  5篇
中国医学   3089篇
肿瘤学   92256篇
  2018年   17182篇
  2016年   15933篇
  2015年   17762篇
  2014年   24679篇
  2013年   37344篇
  2012年   46412篇
  2011年   50398篇
  2010年   31073篇
  2009年   30069篇
  2008年   47328篇
  2007年   50556篇
  2006年   51776篇
  2005年   49919篇
  2004年   47972篇
  2003年   46567篇
  2002年   44599篇
  2001年   84351篇
  2000年   87027篇
  1999年   72384篇
  1998年   21018篇
  1997年   18680篇
  1996年   19877篇
  1995年   19747篇
  1994年   18333篇
  1993年   17343篇
  1992年   59376篇
  1991年   58720篇
  1990年   57008篇
  1989年   54594篇
  1988年   50445篇
  1987年   49691篇
  1986年   46830篇
  1985年   45139篇
  1984年   34178篇
  1983年   28889篇
  1982年   17517篇
  1981年   15878篇
  1980年   14896篇
  1979年   31322篇
  1978年   22734篇
  1977年   19200篇
  1976年   17882篇
  1975年   19162篇
  1974年   22600篇
  1973年   21495篇
  1972年   20224篇
  1971年   18850篇
  1970年   17287篇
  1969年   16296篇
  1968年   15231篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Computed tomography of the brain in the Smith-Lemli-Opitz syndrome   总被引:1,自引:0,他引:1  
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.  相似文献   
993.
994.
995.
996.
The effects of nonprotein energy source (ie, glucose only vs glucose and lipid) on nitrogen retention and total-body protein turnover were studied in 20 parenterally fed newborn infants. All infants received approximately 3 g amino acids and 80-90 kcal.kg body wt.d. Total-body protein synthesis was estimated by using three constant-infusion, end-product methods: enrichment of urinary urea and ammonia in response to a [15N]glycine label and exhaled carbon dioxide enrichment in response to a [1-13C]leucine label. No differences were seen in nitrogen retention between the two energy sources. The estimate of total-body protein turnover obtained from the 13C label was similar to that obtained with the [15N]urea label. No differences in turnover rates were observed between the two diet groups. Use of the glucose-plus-lipid fuel system enhanced energy storage and the reutilization of amino acid for protein synthesis.  相似文献   
997.
The authors present 50 cases of cervical spondylotic myelopathy treated by anterior or posterior approach. To assess the severity of the pre- and postoperative neurological symptoms, they define an original ten-point classification scale taking into account gait and urinary disturbance, ability to manipulate objects and pain. With C2-C7 laminectomy, 60% of the patients are improved, essentially for walk. A few cases only (14%) are upgraded for upper limbs function. The authors conclude that this surgical treatment should be applied only when there is a multi-level narrowed canal and predominant lower limbs deficits. The efficacy of the anterior approach depends on complete removal of osteophytes. In cases with complete osteophytectomy, this surgical treatment can improve both the upper and lower limbs function and 77.8% good results are obtained. In a few cases it may be necessary to use both approach successively. Discriminant analysis applied to 12 factors shows that pre-operative scores of upper and lower limbs and sagittal diameter of spinal canal are the most important factors for neurological prognosis.  相似文献   
998.
A series of C(3)-cyclopropyl cephems and carbacephems has been prepared by palladium catalyzed addition of diazomethane to the corresponding C(3)-vinyl derivatives. The phenylglycyl cyclopropyl cephem derivatives exhibit better Gram-positive activity than cephalexin or cefaclor, while the aminothiazole oxime cyclopropyl cephem derivatives were not as active as the corresponding C(3)-vinyl cephems.  相似文献   
999.
The clinical profile of tropical spastic paraparesis (TSP), described in scattered tropical and subtropical territories over the past 30 years, has been more clearly defined since the discovery of its direct association with human T lymphotropic virus type 1 (HTLV-1). A chronic disease of adults, commoner in women, it usually presents as a progressive spastic paraparesis with sphincter disturbance, sometimes with backache and lower limb sensory disorder. Most cases are chair-bound within 10 years. Histology reveals a chronic lymphocytic meningomyelopathy, predominantly in the spinal cord, together with long tract demyelination and hyalinoid thickening of the media and adventitia of small blood vessels. Geographical areas of high prevalence of TSP are known in the Caribbean, South America, South Africa, southern Japan, the Seychelles and probably in India, and it is sparsely endemic elsewhere. The virus appears to exist within lymphocytes for long periods. Vertical transmission occurs postnatally, and sexual and transfusion infection are also recognized, but much remains to be clarified regarding its pathogenesis and epidemiology.  相似文献   
1000.
The hepatotropic effect of nonsteroidal anti-inflammatory drugs (NSAID) such as indomethacin, voltaren, piroxicam, phenylbutazon, mefenamic acid was studied. It was found that according to their level of the pharmacological protection of the liver against tetrachlormethan these agents may be arranged in the following sequence: mefenamic acid, phenylbutazon, voltaren, piroxicam. The hepatoprotective effect of NSAID correlates with the antioxidant properties and fails to correlate with the antioxidant ones. The hepatotoxic effect of NSAID was determined by their ability to suppress synthesis of prostaglandins.  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