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   3254690篇
  免费   279114篇
  国内免费   13267篇
耳鼻咽喉   44842篇
儿科学   102193篇
妇产科学   84114篇
基础医学   519936篇
口腔科学   89036篇
临床医学   294330篇
内科学   562088篇
皮肤病学   90472篇
神经病学   276096篇
特种医学   130936篇
外国民族医学   225篇
外科学   509098篇
综合类   100008篇
现状与发展   23篇
一般理论   2192篇
预防医学   267320篇
眼科学   75445篇
药学   231463篇
  22篇
中国医学   9580篇
肿瘤学   157652篇
  2021年   49331篇
  2020年   35085篇
  2019年   57958篇
  2018年   70900篇
  2017年   53741篇
  2016年   59454篇
  2015年   73650篇
  2014年   107941篇
  2013年   173150篇
  2012年   88784篇
  2011年   88071篇
  2010年   115818篇
  2009年   120520篇
  2008年   74879篇
  2007年   77482篇
  2006年   88520篇
  2005年   83593篇
  2004年   85432篇
  2003年   76049篇
  2002年   65544篇
  2001年   106389篇
  2000年   98808篇
  1999年   96445篇
  1998年   59225篇
  1997年   57033篇
  1996年   54699篇
  1995年   55599篇
  1994年   49599篇
  1993年   46338篇
  1992年   67610篇
  1991年   64260篇
  1990年   61245篇
  1989年   60334篇
  1988年   55265篇
  1987年   53817篇
  1986年   51021篇
  1985年   50765篇
  1984年   46360篇
  1983年   42271篇
  1982年   40332篇
  1981年   37934篇
  1980年   35860篇
  1979年   37313篇
  1978年   33027篇
  1977年   30903篇
  1976年   27768篇
  1975年   26722篇
  1974年   26976篇
  1973年   25987篇
  1972年   24478篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
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   
4.
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   
5.
6.
7.
8.
9.
10.
Aristodemou  E.  Retzepi  M.  Calciolari  E.  Donos  N. 《Clinical oral investigations》2022,26(8):5223-5235
Clinical Oral Investigations - To evaluate the effect of membrane occlusiveness and experimental diabetes on early and late healing following guided bone regeneration. A total of 30 Wistar rats...  相似文献   
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