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   1336339篇
  免费   114602篇
  国内免费   6364篇
耳鼻咽喉   16705篇
儿科学   43005篇
妇产科学   36554篇
基础医学   183627篇
口腔科学   36272篇
临床医学   120684篇
内科学   278507篇
皮肤病学   31886篇
神经病学   110494篇
特种医学   55533篇
外国民族医学   274篇
外科学   210336篇
综合类   31528篇
现状与发展   2篇
一般理论   414篇
预防医学   106626篇
眼科学   28085篇
药学   93703篇
  5篇
中国医学   2227篇
肿瘤学   70838篇
  2018年   13373篇
  2017年   10630篇
  2016年   12795篇
  2015年   14297篇
  2014年   19945篇
  2013年   29731篇
  2012年   36231篇
  2011年   38882篇
  2010年   24369篇
  2009年   23901篇
  2008年   36360篇
  2007年   38772篇
  2006年   39897篇
  2005年   38489篇
  2004年   36724篇
  2003年   35819篇
  2002年   33833篇
  2001年   66055篇
  2000年   67917篇
  1999年   56587篇
  1998年   16723篇
  1997年   15017篇
  1996年   16016篇
  1995年   16232篇
  1994年   15098篇
  1993年   14153篇
  1992年   47098篇
  1991年   45747篇
  1990年   43971篇
  1989年   41816篇
  1988年   38758篇
  1987年   38081篇
  1986年   35859篇
  1985年   34635篇
  1984年   26358篇
  1983年   22108篇
  1982年   13847篇
  1981年   12447篇
  1980年   11718篇
  1979年   23544篇
  1978年   17072篇
  1977年   14385篇
  1976年   13182篇
  1975年   13722篇
  1974年   16093篇
  1973年   15396篇
  1972年   14173篇
  1971年   13036篇
  1970年   11880篇
  1969年   11101篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.  相似文献   
15.
16.
Maternal and Child Health Journal - Early life exposures can have an impact on a child’s developmental trajectory and children born late preterm (34–36 weeks gestational age)...  相似文献   
17.
18.
19.
Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake () and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in . Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.  相似文献   
20.
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