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   1991906篇
  免费   157657篇
  国内免费   3009篇
耳鼻咽喉   27370篇
儿科学   66180篇
妇产科学   56595篇
基础医学   292854篇
口腔科学   58918篇
临床医学   175626篇
内科学   381569篇
皮肤病学   43597篇
神经病学   156380篇
特种医学   78908篇
外国民族医学   529篇
外科学   303627篇
综合类   46058篇
现状与发展   3篇
一般理论   647篇
预防医学   153979篇
眼科学   46190篇
药学   152624篇
  2篇
中国医学   3656篇
肿瘤学   107260篇
  2018年   18438篇
  2015年   18417篇
  2014年   25369篇
  2013年   38834篇
  2012年   52438篇
  2011年   56041篇
  2010年   32929篇
  2009年   31402篇
  2008年   53694篇
  2007年   56822篇
  2006年   57799篇
  2005年   55862篇
  2004年   55148篇
  2003年   52553篇
  2002年   51599篇
  2001年   93050篇
  2000年   96354篇
  1999年   80983篇
  1998年   20676篇
  1997年   18648篇
  1996年   18803篇
  1995年   19320篇
  1994年   18165篇
  1993年   17214篇
  1992年   66886篇
  1991年   66199篇
  1990年   65119篇
  1989年   62929篇
  1988年   58449篇
  1987年   57643篇
  1986年   54732篇
  1985年   52966篇
  1984年   39417篇
  1983年   33869篇
  1982年   19546篇
  1981年   17654篇
  1980年   16556篇
  1979年   37835篇
  1978年   26489篇
  1977年   22317篇
  1976年   21206篇
  1975年   22812篇
  1974年   27779篇
  1973年   26554篇
  1972年   24702篇
  1971年   23363篇
  1970年   21515篇
  1969年   20290篇
  1968年   18696篇
  1967年   16936篇
排序方式: 共有10000条查询结果,搜索用时 547 毫秒
1.
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   
2.
3.
4.
5.
6.
7.
Kinase alterations are increasingly recognised as oncogenic drivers in mesenchymal tumours. Infantile fibrosarcoma and the related renal tumour, congenital mesoblastic nephroma, were among the first solid tumours shown to harbour recurrent tyrosine kinase fusions, with the canonical ETV6::NTRK3 fusion identified more than 20 years ago. Although targeted testing has long been used in diagnosis, the advent of more robust sequencing techniques has driven the discovery of kinase alterations in an array of mesenchymal tumours. As our ability to identify these genetic alterations has improved, as has our recognition and understanding of the tumours that harbour these alterations. Specifically, this study will focus upon mesenchymal tumours harbouring NTRK or other kinase alterations, including tumours with an infantile fibrosarcoma-like appearance, spindle cell tumours resembling lipofibromatosis or peripheral nerve sheath tumours and those occurring in adults with a fibrosarcoma-like appearance. As publications describing the histology of these tumours increase so, too, do the variety kinase alterations reported, now including NTRK1/2/3, RET, MET, RAF1, BRAF, ALK, EGFR and ABL1 fusions or alterations. To date, these tumours appear locally aggressive and rarely metastatic, without a clear link between traditional features used in histological grading (e.g. mitotic activity, necrosis) and outcome. However, most of these tumours are amenable to new targeted therapies, making their recognition of both diagnostic and therapeutic import. The goal of this study is to review the clinicopathological features of tumours with NTRK and other tyrosine kinase alterations, discuss the most common differential diagnoses and provide recommendations for molecular confirmation with associated treatment implications.  相似文献   
8.
Bulletin of Experimental Biology and Medicine - We studied the effect of microalgae of various systematic groups added to the ration on the biochemical parameters of blood serum and liver and...  相似文献   
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