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   3268449篇
  免费   279827篇
  国内免费   13418篇
耳鼻咽喉   45094篇
儿科学   102280篇
妇产科学   84087篇
基础医学   521880篇
口腔科学   89551篇
临床医学   294301篇
内科学   566242篇
皮肤病学   90791篇
神经病学   277122篇
特种医学   131486篇
外国民族医学   225篇
外科学   511985篇
综合类   100038篇
现状与发展   23篇
一般理论   2187篇
预防医学   266952篇
眼科学   75721篇
药学   232683篇
  22篇
中国医学   9629篇
肿瘤学   159395篇
  2021年   49466篇
  2020年   35270篇
  2019年   58256篇
  2018年   71250篇
  2017年   53986篇
  2016年   59780篇
  2015年   74029篇
  2014年   108437篇
  2013年   173710篇
  2012年   89313篇
  2011年   88638篇
  2010年   116276篇
  2009年   120909篇
  2008年   75340篇
  2007年   77878篇
  2006年   88963篇
  2005年   84102篇
  2004年   85752篇
  2003年   76434篇
  2002年   66037篇
  2001年   106854篇
  2000年   99329篇
  1999年   96917篇
  1998年   59429篇
  1997年   57181篇
  1996年   54856篇
  1995年   55735篇
  1994年   49739篇
  1993年   46470篇
  1992年   67942篇
  1991年   64580篇
  1990年   61543篇
  1989年   60662篇
  1988年   55571篇
  1987年   54078篇
  1986年   51288篇
  1985年   51022篇
  1984年   46557篇
  1983年   42413篇
  1982年   40418篇
  1981年   38012篇
  1980年   35924篇
  1979年   37436篇
  1978年   33117篇
  1977年   30996篇
  1976年   27843篇
  1975年   26783篇
  1974年   27063篇
  1973年   26077篇
  1972年   24556篇
排序方式: 共有10000条查询结果,搜索用时 15 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