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   1361359篇
  免费   117670篇
  国内免费   8809篇
耳鼻咽喉   17067篇
儿科学   43285篇
妇产科学   36886篇
基础医学   186180篇
口腔科学   36793篇
临床医学   124468篇
内科学   280686篇
皮肤病学   32198篇
神经病学   111590篇
特种医学   56729篇
外国民族医学   298篇
外科学   212840篇
综合类   37817篇
现状与发展   13篇
一般理论   414篇
预防医学   107861篇
眼科学   29076篇
药学   96770篇
  30篇
中国医学   4007篇
肿瘤学   72830篇
  2018年   14588篇
  2017年   11791篇
  2016年   13776篇
  2015年   15829篇
  2014年   21829篇
  2013年   31365篇
  2012年   38795篇
  2011年   41554篇
  2010年   25960篇
  2009年   25173篇
  2008年   37890篇
  2007年   40385篇
  2006年   41519篇
  2005年   40145篇
  2004年   37744篇
  2003年   36766篇
  2002年   34599篇
  2001年   66647篇
  2000年   68478篇
  1999年   57114篇
  1998年   16547篇
  1997年   14833篇
  1996年   15701篇
  1995年   16561篇
  1994年   15392篇
  1993年   14270篇
  1992年   47284篇
  1991年   45956篇
  1990年   44129篇
  1989年   41946篇
  1988年   38867篇
  1987年   38158篇
  1986年   35922篇
  1985年   34686篇
  1984年   26358篇
  1983年   22078篇
  1982年   13835篇
  1981年   12419篇
  1980年   11672篇
  1979年   23513篇
  1978年   17020篇
  1977年   14336篇
  1976年   13139篇
  1975年   13694篇
  1974年   16067篇
  1973年   15379篇
  1972年   14167篇
  1971年   13023篇
  1970年   11863篇
  1969年   11092篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
21.
22.
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   
23.

Physical activity brings significant health benefits to middle-aged adults, although the research to date has been focused on late adulthood. This study aims to examine how ageing affects the self-reported and accelerometer-derived measures of physical activity levels in middle-aged adults. We employed the data recorded in the UK Biobank and analysed the physical activity levels of 2,998 participants (1381 men and 1617 women), based on self-completion questionnaire and accelerometry measurement of physical activity. We also assessed the musculoskeletal health of the participants using the dual-energy X-ray absorptiometry (DXA) measurements provided by the UK Biobank. Participants were categorised into three groups according to their age: group I younger middle-aged (40 to 49 years), group II older middle-aged (50 to 59 years), and group III oldest middle-aged (60 to 69 years). Self-reported physical activity level increased with age and was the highest in group III, followed by group II and I (P?<?0.05). On the contrary, physical activity measured by accelerometry decreased significantly with age from group I to III (P?<?0.05), and the same pertained to the measurements of musculoskeletal health (P?<?0.05). It was also shown that middle-aged adults mostly engaged in low and moderate intensity activities. The opposing trends of the self-reported and measured physical activity levels may suggest that middle-aged adults over-report their activity level as they age. They should be aware of the difference between their perceived and actual physical activity levels, and objective measures would be useful to prevent the decline in musculoskeletal health.

  相似文献   
24.
综述信息化技术在静脉血栓栓塞症护理领域中风险预测、警报接收与上报、抗凝防治管理、医护人员相关继续医学教育、患者疾病预后管理的应用现状,总结其应用阻碍因素,旨在为我国静脉血栓栓塞症护理信息化建设提供参考。  相似文献   
25.
26.
27.
28.
Journal of Behavioral Medicine - Evidence supports the use of graphic warnings to educate the public about the health harms of smoking and suggests warnings eliciting negative emotional responses...  相似文献   
29.
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass.  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