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   4314053篇
  免费   363870篇
  国内免费   15930篇
耳鼻咽喉   62379篇
儿科学   134237篇
妇产科学   114432篇
基础医学   659632篇
口腔科学   120263篇
临床医学   392071篇
内科学   775644篇
皮肤病学   106028篇
神经病学   367820篇
特种医学   175205篇
外国民族医学   912篇
外科学   660623篇
综合类   126960篇
一般理论   2647篇
预防医学   360759篇
眼科学   102825篇
药学   309823篇
  19篇
中国医学   12324篇
肿瘤学   209250篇
  2021年   49285篇
  2020年   37008篇
  2019年   60405篇
  2018年   75280篇
  2017年   56823篇
  2016年   63706篇
  2015年   78490篇
  2014年   113897篇
  2013年   180190篇
  2012年   127467篇
  2011年   130566篇
  2010年   127690篇
  2009年   129843篇
  2008年   114887篇
  2007年   121531篇
  2006年   130210篇
  2005年   125131篇
  2004年   125108篇
  2003年   115015篇
  2002年   104980篇
  2001年   155162篇
  2000年   150803篇
  1999年   138370篇
  1998年   65914篇
  1997年   62249篇
  1996年   60009篇
  1995年   61212篇
  1994年   55379篇
  1993年   51322篇
  1992年   103783篇
  1991年   99498篇
  1990年   94460篇
  1989年   92025篇
  1988年   85534篇
  1987年   84057篇
  1986年   79754篇
  1985年   78118篇
  1984年   65895篇
  1983年   58669篇
  1982年   47803篇
  1981年   44530篇
  1980年   41807篇
  1979年   57722篇
  1978年   46857篇
  1977年   41312篇
  1976年   38437篇
  1975年   37652篇
  1974年   42349篇
  1973年   40518篇
  1972年   38091篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
The International Journal of Cardiovascular Imaging - Global longitudinal strain (GLS) has proven to be a powerful prognostic marker in various patient populations, but the prognostic value of...  相似文献   
4.
Numerous studies showed that postural balance improves through light touch on a stable surface highlighting the importance of haptic information, seemingly downplaying the mechanical contributions of the support. The present study examined the mechanical effects of canes for assisting balance in healthy individuals challenged by standing on a beam. Sixteen participants supported themselves with two canes, one in each hand, and applied minimal, preferred, or maximum force onto the canes. They positioned the canes in the frontal plane or in a tripod configuration. Statistical analysis used a linear mixed model to evaluate the effects on the center of pressure and the center of mass. The canes significantly reduced the variability of the center of pressure and the center of mass to the same level as when standing on the ground. Increasing the exerted force beyond the preferred level yielded no further benefits, although in the preferred force condition, participants exploited the altered mechanics by resting their arms on the canes. The tripod configuration allowed for larger variability of the center of pressure in the task-irrelevant anterior–posterior dimension. High forces had a destabilizing effect on the canes: the displacement of the hand on the cane handle increased with the force. Given this static instability, these results show that using canes can provide not only mechanical benefits but also challenges. From a control perspective, effort can be reduced by resting the arms on the canes and by channeling noise in the task-irrelevant dimensions. However, larger forces exerted onto the canes can also have destabilizing effects and the instability of the canes needs to be counteracted, possibly by arm and shoulder stiffness. Insights into the variety of mechanical effects is important for the design of canes and the instructions of how to use them.  相似文献   
5.
In the last decade, the development of new radiopharmaceuticals for the imaging and therapy of prostate cancer has been a highly active and important area of research, especially focusing on the prostate-specific membrane antigen (PSMA), an antigen which is upregulated in prostate, as well as in other tumor cells. A large variety of PSMA ligands have been radiolabeled, to date. Among the various derivatives, PSMA-617 resulted to be one of the most interesting in terms of interaction with the antigen and clinical properties, and its lutetium-177 labeled version has recently been approved by regulatory agencies for therapeutic purposes. For this reasons, the radiolabeling with fluorine-18 of a PSMA-617 derivative might be of interest. Beside other methodologies to radiolabel macromolecules with fluorine-18, the “click-chemistry” approach resulted to be very useful, and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is considered one of most efficient and reliable. This paper proposes the synthesis of a suitable precursor for the radiolabeling with fluorine-18 of a new PSMA-617 derivative. The whole radiosynthetic procedure has been fully automated, and the final product, which proved to be stable in plasma, has been obtained with radiochemical yield and purity suitable for subsequent preclinical studies.  相似文献   
6.
7.
8.
9.
10.
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