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   1411911篇
  免费   113576篇
  国内免费   3334篇
耳鼻咽喉   18370篇
儿科学   46596篇
妇产科学   41091篇
基础医学   200876篇
口腔科学   37727篇
临床医学   126088篇
内科学   284623篇
皮肤病学   33422篇
神经病学   117002篇
特种医学   53913篇
外国民族医学   464篇
外科学   210655篇
综合类   32755篇
现状与发展   3篇
一般理论   487篇
预防医学   110045篇
眼科学   31506篇
药学   98610篇
  1篇
中国医学   3355篇
肿瘤学   81232篇
  2021年   10871篇
  2019年   11680篇
  2018年   16606篇
  2017年   12694篇
  2016年   14280篇
  2015年   16031篇
  2014年   22599篇
  2013年   33422篇
  2012年   45464篇
  2011年   48005篇
  2010年   28207篇
  2009年   27098篇
  2008年   44399篇
  2007年   46881篇
  2006年   47443篇
  2005年   45894篇
  2004年   43814篇
  2003年   41742篇
  2002年   40236篇
  2001年   73042篇
  2000年   74560篇
  1999年   61585篇
  1998年   16998篇
  1997年   15440篇
  1996年   15593篇
  1995年   14802篇
  1994年   13400篇
  1993年   12591篇
  1992年   45856篇
  1991年   43493篇
  1990年   41505篇
  1989年   39564篇
  1988年   36203篇
  1987年   35366篇
  1986年   32872篇
  1985年   31288篇
  1984年   23835篇
  1983年   20029篇
  1982年   12210篇
  1981年   10788篇
  1979年   20703篇
  1978年   14581篇
  1977年   12085篇
  1976年   11371篇
  1975年   11623篇
  1974年   13994篇
  1973年   13537篇
  1972年   12643篇
  1971年   11478篇
  1970年   10918篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Background : The clinical course of chronic hepatitis B is variable. Patients with hepatic decompensation, bridging necrosis or an alpha-fetoprotein level greater than 100 ng/mL during an exacerbation of hepatitis have a high risk of developing cirrhosis. This study was conducted to evaluate the effect of colchicine in the prevention of cirrhosis in such patients.
Methods : Patients with risk factor(s) were randomized to receive either colchicine 5 mg/week or no specific treatment, the end point being development of cirrhosis.
Results : After a follow up period of 4 years, the treatment group had a marked reduction in exacerbations of acute hepatitis (32% vs. 63%/patient/year, P <0.005). Seven out of 38 patients in the treatment group and 10 out of 27 patients in the control group developed cirrhosis. The calculated cumulative incidence of cirrhosis by the end of first, second, third and fourth years in the treatment group was 8.7, 18.6, 32 and 32%, respectively. The corresponding figures in the control group were 30, 35.5, 46.3 and 73.2%, respectively, with a P -value of 0.057.
Conclusions : The results suggest that colchicine may prevent cirrhosis in chronic hepatitis B patients with risk factor(s), possibly by suppressing exacerbations of hepatitis through an anti-inflammatory effect.  相似文献   
102.
103.
104.
105.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.  相似文献   
106.
107.
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   
108.
A rotating contact lens holder for the three-mirror Goldmann lens permits circular examination of the fundus or chamber angle without having to change the position of the fingers on the edge of the lens. The contact lens holder consists of an outer polygonal ring hold by the thumber and index finger. An inner rotating ring holds the contact lens. Continuous rotation of the contact lens is performed with the free middle Finger. This device permits circular examination of the retina without interruption of fixation. The instrument improves not only the speed but also the reliability of the examination.  相似文献   
109.
Six patients who injured their wrists had radiographs documenting a dorsal, 5- to 10-mm oblong fragment of bone immediately proximal to the base of the fourth and/or fifth metacarpal bones. The fragment was seen on the pronation oblique and/or lateral projections, but not on the posteroanterior projection. The radiographic appearance of the fragment was remarkably similar in all cases. In the one patient in which it was performed, pluridirectional tomography demonstrated that the fragment originated from the dorsal surface of the hamate. Five of the six patients also had associated posterior dislocation of the fourth and/or fifth metacarpals. We conclude that this fragment represents a coronal fracture through the body of the hamate resulting from posterior dislocation or subluxation of the fourth and/or fifth metacarpal.  相似文献   
110.
A case is presented which demonstrates the potential utility of the extracranial-intracranial bypass procedure for the treatment of vasospasm after subarachnoid hemorrhage. Extracranial-intracranial bypass surgery offers another alternative to the treatment of patients with vasospasm who have failed aggressive medical management.  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