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   3717492篇
  免费   310713篇
  国内免费   14437篇
耳鼻咽喉   50639篇
儿科学   119099篇
妇产科学   97940篇
基础医学   581182篇
口腔科学   101632篇
临床医学   335838篇
内科学   656723篇
皮肤病学   98613篇
神经病学   312043篇
特种医学   146616篇
外国民族医学   262篇
外科学   577031篇
综合类   113362篇
一般理论   2388篇
预防医学   304608篇
眼科学   88414篇
药学   259812篇
  21篇
中国医学   11012篇
肿瘤学   185407篇
  2021年   47043篇
  2020年   35771篇
  2019年   58755篇
  2018年   72782篇
  2017年   54923篇
  2016年   60596篇
  2015年   74743篇
  2014年   109161篇
  2013年   174870篇
  2012年   105779篇
  2011年   107879篇
  2010年   121235篇
  2009年   123717篇
  2008年   93509篇
  2007年   98173篇
  2006年   107523篇
  2005年   102145篇
  2004年   103771篇
  2003年   93459篇
  2002年   82560篇
  2001年   135427篇
  2000年   128562篇
  1999年   119626篇
  1998年   62803篇
  1997年   59447篇
  1996年   57092篇
  1995年   57982篇
  1994年   52084篇
  1993年   48429篇
  1992年   84651篇
  1991年   80897篇
  1990年   76525篇
  1989年   74936篇
  1988年   68779篇
  1987年   67038篇
  1986年   63365篇
  1985年   62610篇
  1984年   54579篇
  1983年   49163篇
  1982年   43181篇
  1981年   40561篇
  1980年   37996篇
  1979年   44506篇
  1978年   37912篇
  1977年   34490篇
  1976年   31591篇
  1975年   30479篇
  1974年   32252篇
  1973年   30991篇
  1972年   28946篇
排序方式: 共有10000条查询结果,搜索用时 109 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