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   1595300篇
  免费   133474篇
  国内免费   2535篇
耳鼻咽喉   21676篇
儿科学   52942篇
妇产科学   46371篇
基础医学   226502篇
口腔科学   47240篇
临床医学   140606篇
内科学   312750篇
皮肤病学   34064篇
神经病学   129674篇
特种医学   64780篇
外国民族医学   474篇
外科学   243660篇
综合类   39773篇
一般理论   555篇
预防医学   122751篇
眼科学   36412篇
药学   121241篇
  2篇
中国医学   2879篇
肿瘤学   86957篇
  2018年   14931篇
  2016年   12981篇
  2015年   15162篇
  2014年   20879篇
  2013年   31688篇
  2012年   42974篇
  2011年   45203篇
  2010年   26541篇
  2009年   25478篇
  2008年   43239篇
  2007年   45475篇
  2006年   46262篇
  2005年   44878篇
  2004年   44221篇
  2003年   42295篇
  2002年   41392篇
  2001年   75630篇
  2000年   78184篇
  1999年   66037篇
  1998年   16739篇
  1997年   15361篇
  1996年   15314篇
  1995年   15981篇
  1994年   15027篇
  1993年   14170篇
  1992年   55402篇
  1991年   53801篇
  1990年   52569篇
  1989年   50828篇
  1988年   47213篇
  1987年   46562篇
  1986年   44284篇
  1985年   42850篇
  1984年   32011篇
  1983年   27542篇
  1982年   16106篇
  1981年   14398篇
  1980年   13505篇
  1979年   30431篇
  1978年   21036篇
  1977年   17705篇
  1976年   16667篇
  1975年   17524篇
  1974年   21464篇
  1973年   20653篇
  1972年   18857篇
  1971年   17764篇
  1970年   16285篇
  1969年   15259篇
  1968年   13943篇
排序方式: 共有10000条查询结果,搜索用时 15 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