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   1864456篇
  免费   141475篇
  国内免费   3213篇
耳鼻咽喉   25687篇
儿科学   62234篇
妇产科学   53471篇
基础医学   262859篇
口腔科学   55858篇
临床医学   160132篇
内科学   367456篇
皮肤病学   41501篇
神经病学   147784篇
特种医学   75887篇
外国民族医学   567篇
外科学   281108篇
综合类   41210篇
现状与发展   3篇
一般理论   580篇
预防医学   147211篇
眼科学   42620篇
药学   139529篇
  4篇
中国医学   3563篇
肿瘤学   99880篇
  2018年   22159篇
  2017年   17639篇
  2016年   17971篇
  2015年   21645篇
  2014年   27155篇
  2013年   38594篇
  2012年   58728篇
  2011年   57136篇
  2010年   32351篇
  2009年   31406篇
  2008年   51343篇
  2007年   54575篇
  2006年   55033篇
  2005年   61023篇
  2004年   61006篇
  2003年   54565篇
  2002年   49074篇
  2001年   81371篇
  2000年   82584篇
  1999年   72741篇
  1998年   18539篇
  1997年   16795篇
  1996年   16810篇
  1995年   16507篇
  1994年   15453篇
  1992年   61395篇
  1991年   59915篇
  1990年   58908篇
  1989年   56745篇
  1988年   52778篇
  1987年   51978篇
  1986年   49515篇
  1985年   47432篇
  1984年   35189篇
  1983年   30150篇
  1982年   17027篇
  1981年   15158篇
  1979年   33872篇
  1978年   23174篇
  1977年   19359篇
  1976年   18138篇
  1975年   19849篇
  1974年   24342篇
  1973年   23260篇
  1972年   21434篇
  1971年   20383篇
  1970年   18754篇
  1969年   17646篇
  1968年   16107篇
  1967年   14728篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Lithium is a widely prescribed drug used for the treatment of bipolar affective illness. Previous reports on its effects on sperm motility and male fertility are conflicting. The effect of lithium on human sperm motility was examined in vitro using the modified transmembrane migration method. This technique takes account of the dilution of lithium that occurs during the incubation. Lithium inhibits human sperm motility in vitro in concentrations comparable with those reported to be achieved in semen after oral administration.  相似文献   
992.
The myopathies that can manifest themselves within the lower extremity are reported here and can serve as a guideline for clinicians in the early diagnosis of these disabling conditions. The classification of these disease entities based on signs and symptoms is significant if correlated with the age of the patient at the time of onset, the evolution and course, and the type of familial inheritance. This article can also aid the practitioner in assessing and planning the course of treatment for a particular patient.  相似文献   
993.
A study has been carried out on the possible pharmaceutical use of spanish talcs following the normalized assays of the main european pharmacopoeia and other quantitative methods. Only the talc nr3, not processed, meets all the assays of pharmacopoeia. The samples 2 and 4 (crushed) exceed the highest tolerated content in chlorides. The talc 1 (also crushed) only meets the loss on drying. The measures of some of these assays by using quantitative methods lead to more correct results and even sometimes in opposition with those obtained by pharmacopoeia methods. The particle size estimated by shifting and sedimentation shows that the crushed talcs are silty, whereas the only talc not processed is sandy. Considering the medium sizes estimated by scanning microscopy, it can be said that the pulverization of the talcs 1, 2 and 4 is characteristic of a micronization.  相似文献   
994.
In open chest dogs myocardial ischemia was induced by formation of an occlusive thrombus in the left anterior circumflex artery (LCX). Reperfusion of the LCX was achieved by infusion of the fibrin specific recombinant single-chain urokinase-type plasminogen activator (r-scu-PA). The myocardial salvage by r-scu-PA alone and in combination with the epoprostenol (prostacyclin) analog taprostene (CG 4203) was compared. There were four experimental groups: group 1 (n = 4) did not receive any treatment after LCX thrombosis; in group 2 (n = 9) at 100 min after LCX thrombosis r-scu-PA (20 micrograms.kg-1.min-1 i.v. for 30 min) was infused; in groups 3 and 4 treatment with taprostene started concomitantly with r-scu-PA infusion. The taprostene infusions lasted for 120 min and the doses were 0.1 microgram.kg-1.min-1 in group 3 (n = 6) and 0.215 microgram.kg-1.min-1 in group 4 (n = 6). Time to r-scu-PA-induced recanalisation ranged from 18-22 min with no significant difference between groups 2-4. Percent of left ventricle at risk did not differ between the groups. Infarct size as percent of the risk zone was 48.3 +/- 7.7 in group 1, 25.3 +/- 3.7 in group 2, 21.3 +/- 6.5 in group 3 and 17.1 +/- 3.5 in group 4 (p less than 0.05 groups 2-4 vs group 1). Incidence of ectopic beats increased after r-scu-PA-induced reperfusion in groups 2-4, but was significantly reduced by taprostene.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
996.
997.
998.
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   
999.
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   
1000.
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