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   190929篇
  免费   2107篇
  国内免费   32篇
耳鼻咽喉   1282篇
儿科学   7346篇
妇产科学   3430篇
基础医学   18332篇
口腔科学   1714篇
临床医学   14605篇
内科学   33713篇
皮肤病学   835篇
神经病学   18051篇
特种医学   9234篇
外科学   30342篇
综合类   2537篇
一般理论   15篇
预防医学   20207篇
眼科学   3083篇
药学   10319篇
中国医学   637篇
肿瘤学   17386篇
  2023年   137篇
  2022年   234篇
  2021年   564篇
  2020年   348篇
  2019年   535篇
  2018年   22366篇
  2017年   17687篇
  2016年   19866篇
  2015年   1319篇
  2014年   1371篇
  2013年   1640篇
  2012年   8113篇
  2011年   22254篇
  2010年   19384篇
  2009年   12079篇
  2008年   20451篇
  2007年   22695篇
  2006年   1520篇
  2005年   3039篇
  2004年   4154篇
  2003年   5093篇
  2002年   3139篇
  2001年   396篇
  2000年   527篇
  1999年   303篇
  1998年   351篇
  1997年   301篇
  1996年   169篇
  1995年   187篇
  1994年   168篇
  1993年   122篇
  1992年   139篇
  1991年   206篇
  1990年   215篇
  1989年   166篇
  1988年   127篇
  1987年   109篇
  1986年   110篇
  1985年   121篇
  1984年   86篇
  1983年   79篇
  1982年   76篇
  1981年   55篇
  1980年   96篇
  1979年   53篇
  1974年   55篇
  1970年   49篇
  1969年   50篇
  1938年   60篇
  1932年   56篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
The specific characteristics of genetic data lead to ethical-legal conflicts in the framework of genetic diagnosis. Several international organisations, including UNESCO and the Council of Europe, have enacted rules referring to the use of genetic information. This paper discusses possible legal and ethical criteria that could be used in genetic testing.  相似文献   
23.
24.

Introduction  

This paper presents the results of a study on the psychometric properties of an authorized Spanish version of the McMaster Family Assessment Device, a self-report measure of family functioning.  相似文献   
25.
BackgroundHuman studies on exercise, cognition, and apolipoprotein E (APOE) genotype show that ε4 carriers may benefit from regular physical activity.MethodsWe examined voluntary wheel-running, memory, and hippocampal plasticity in APOE ε3 and APOE ε4 transgenic mice at 10–12 months of age.ResultsSedentary ε4 mice exhibited deficits in cognition on the radial-arm water maze (RAWM), a task dependent on the hippocampus. Six weeks of wheel-running in ε4 mice resulted in improvements on the RAWM to the level of ε3 mice. Hippocampal brain-derived neurotrophic factor (BDNF) levels were similar in ε3 and ε4 mice, and after exercise BDNF was similarly increased in both ε3 and ε4 mice. In sedentary ε4 mice, tyrosine kinase B (Trk B) receptors were reduced by 50%. Exercise restored Trk B in ε4 mice to the level of ε3 mice, and in ε4 mice, exercise dramatically increased synaptophysin, a marker of synaptic function.ConclusionsOur results support the hypothesis that exercise can improve cognitive function, particularly in ε4 carriers.  相似文献   
26.
FDA’S Perspectives on Cardiovascular Devices   总被引:1,自引:0,他引:1  
The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug & Cosmetic Act, §903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 ). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA’s review of extensive preclinical bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular device in a U.S. clinical trial.  相似文献   
27.
28.
29.

Introduction  

Although ependymoma is the third most common pediatric brain tumor, we know little about the genetic/epigenetic basis of its initiation, maintenance, or progression. This is due in part to the heterogeneity of the disease, as well as the small sample size of the cohorts analyzed in most studies.  相似文献   
30.
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