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   2580298篇
  免费   208712篇
  国内免费   7692篇
耳鼻咽喉   34510篇
儿科学   84894篇
妇产科学   72187篇
基础医学   360493篇
口腔科学   74612篇
临床医学   231363篇
内科学   512907篇
皮肤病学   58508篇
神经病学   211426篇
特种医学   104339篇
外国民族医学   720篇
外科学   396023篇
综合类   63513篇
现状与发展   5篇
一般理论   916篇
预防医学   205465篇
眼科学   57440篇
药学   187931篇
  8篇
中国医学   4587篇
肿瘤学   134855篇
  2018年   25049篇
  2016年   22801篇
  2015年   26015篇
  2014年   36165篇
  2013年   54758篇
  2012年   70236篇
  2011年   74776篇
  2010年   45567篇
  2009年   43942篇
  2008年   70839篇
  2007年   75154篇
  2006年   76656篇
  2005年   74327篇
  2004年   72213篇
  2003年   69696篇
  2002年   67188篇
  2001年   120191篇
  2000年   123894篇
  1999年   104358篇
  1998年   30403篇
  1997年   27479篇
  1996年   28113篇
  1995年   27837篇
  1994年   26149篇
  1993年   24575篇
  1992年   86985篇
  1991年   84753篇
  1990年   82077篇
  1989年   78986篇
  1988年   73481篇
  1987年   72363篇
  1986年   68545篇
  1985年   66268篇
  1984年   50228篇
  1983年   42798篇
  1982年   26067篇
  1981年   23422篇
  1980年   22070篇
  1979年   46898篇
  1978年   33313篇
  1977年   28188篇
  1976年   26224篇
  1975年   27652篇
  1974年   33305篇
  1973年   32012篇
  1972年   29485篇
  1971年   27577篇
  1970年   25309篇
  1969年   23773篇
  1968年   21864篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
We report two patients with severe hypoglycorrhachia after a subarachnoid hemorrhage. They had no obvious meningeal infection, and they spontaneously recovered within a few weeks. Such cases have previously been reported in neonates, but exceptionally in adults. Contrary to detailed cases from the literature, our patients recovered without antibiotics, and hypoglycorrhachia was very severe.  相似文献   
993.
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   
994.
Intracranial venous thrombosis has been described in newborns, but there have been no reports of intractable neonatal seizures due to this condition. We report cortical venous sinus thrombosis in two term neonates who presented with seizures in the first 24 hours of life. The diagnosis was made by cranial computed tomography and was confirmed by cerebral angiography. Both patients improved clinically after the intracranial venous thrombosis resolved. These patients demonstrate that intracranial venous thrombosis should be considered in the differential diagnosis of neonatal seizures.  相似文献   
995.
996.
We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries.  相似文献   
997.
998.
999.
1000.
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   
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