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   2326356篇
  免费   187094篇
  国内免费   4480篇
耳鼻咽喉   31848篇
儿科学   78658篇
妇产科学   66628篇
基础医学   333826篇
口腔科学   68625篇
临床医学   208477篇
内科学   448954篇
皮肤病学   51454篇
神经病学   187706篇
特种医学   92100篇
外国民族医学   753篇
外科学   352508篇
综合类   57698篇
现状与发展   3篇
一般理论   893篇
预防医学   182176篇
眼科学   54026篇
药学   173517篇
  5篇
中国医学   4320篇
肿瘤学   123755篇
  2018年   22917篇
  2016年   20135篇
  2015年   23043篇
  2014年   31714篇
  2013年   48599篇
  2012年   64994篇
  2011年   68802篇
  2010年   40952篇
  2009年   38877篇
  2008年   65413篇
  2007年   69087篇
  2006年   70209篇
  2005年   67914篇
  2004年   66652篇
  2003年   63781篇
  2002年   62154篇
  2001年   107711篇
  2000年   111102篇
  1999年   93538篇
  1998年   24739篇
  1997年   22458篇
  1996年   22139篇
  1995年   22942篇
  1994年   21539篇
  1993年   20253篇
  1992年   77156篇
  1991年   75323篇
  1990年   74026篇
  1989年   71369篇
  1988年   65836篇
  1987年   65468篇
  1986年   61787篇
  1985年   59782篇
  1984年   44910篇
  1983年   38423篇
  1982年   22748篇
  1981年   20410篇
  1980年   19093篇
  1979年   42514篇
  1978年   29935篇
  1977年   25260篇
  1976年   23792篇
  1975年   25022篇
  1974年   30645篇
  1973年   29546篇
  1972年   27128篇
  1971年   25564篇
  1970年   23537篇
  1969年   22037篇
  1968年   20241篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
2.
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   
3.
4.
5.
6.
7.
8.
9.
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   
10.
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   
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