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   4703348篇
  免费   370391篇
  国内免费   14373篇
耳鼻咽喉   66402篇
儿科学   150607篇
妇产科学   125769篇
基础医学   709784篇
口腔科学   130665篇
临床医学   429584篇
内科学   846741篇
皮肤病学   116911篇
神经病学   384059篇
特种医学   185342篇
外国民族医学   690篇
外科学   721113篇
综合类   132240篇
现状与发展   23篇
一般理论   2696篇
预防医学   386305篇
眼科学   112673篇
药学   339204篇
  26篇
中国医学   12456篇
肿瘤学   234822篇
  2021年   50261篇
  2019年   58863篇
  2018年   75194篇
  2017年   57277篇
  2016年   63672篇
  2015年   76168篇
  2014年   110762篇
  2013年   176184篇
  2012年   135386篇
  2011年   143468篇
  2010年   129955篇
  2009年   129771篇
  2008年   129050篇
  2007年   138720篇
  2006年   146229篇
  2005年   141063篇
  2004年   140865篇
  2003年   130622篇
  2002年   119473篇
  2001年   182815篇
  2000年   178851篇
  1999年   160477篇
  1998年   67941篇
  1997年   62940篇
  1996年   61108篇
  1995年   61736篇
  1994年   55804篇
  1993年   51760篇
  1992年   117828篇
  1991年   114117篇
  1990年   110334篇
  1989年   107355篇
  1988年   98615篇
  1987年   96807篇
  1986年   91318篇
  1985年   89126篇
  1984年   72674篇
  1983年   64327篇
  1982年   49254篇
  1981年   45744篇
  1980年   42974篇
  1979年   63577篇
  1978年   50285篇
  1977年   44404篇
  1976年   41069篇
  1975年   42240篇
  1974年   46723篇
  1973年   44898篇
  1972年   42319篇
  1971年   39440篇
排序方式: 共有10000条查询结果,搜索用时 218 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