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   3251587篇
  免费   278975篇
  国内免费   13288篇
耳鼻咽喉   44856篇
儿科学   102097篇
妇产科学   83999篇
基础医学   519547篇
口腔科学   89098篇
临床医学   293205篇
内科学   561793篇
皮肤病学   90486篇
神经病学   275703篇
特种医学   130890篇
外国民族医学   225篇
外科学   509249篇
综合类   100057篇
现状与发展   23篇
一般理论   2188篇
预防医学   266580篇
眼科学   75499篇
药学   231361篇
  22篇
中国医学   9610篇
肿瘤学   157362篇
  2021年   49104篇
  2020年   35120篇
  2019年   57972篇
  2018年   70942篇
  2017年   53724篇
  2016年   59499篇
  2015年   73687篇
  2014年   108007篇
  2013年   173150篇
  2012年   88631篇
  2011年   87870篇
  2010年   115811篇
  2009年   120506篇
  2008年   74623篇
  2007年   77116篇
  2006年   88171篇
  2005年   83110篇
  2004年   84860篇
  2003年   75555篇
  2002年   65135篇
  2001年   106410篇
  2000年   98837篇
  1999年   96449篇
  1998年   59209篇
  1997年   57009篇
  1996年   54693篇
  1995年   55594篇
  1994年   49587篇
  1993年   46337篇
  1992年   67608篇
  1991年   64275篇
  1990年   61252篇
  1989年   60349篇
  1988年   55275篇
  1987年   53826篇
  1986年   51019篇
  1985年   50769篇
  1984年   46355篇
  1983年   42270篇
  1982年   40327篇
  1981年   37934篇
  1980年   35853篇
  1979年   37317篇
  1978年   33027篇
  1977年   30908篇
  1976年   27767篇
  1975年   26721篇
  1974年   26980篇
  1973年   25990篇
  1972年   24483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