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   1209551篇
  免费   78897篇
  国内免费   1660篇
耳鼻咽喉   17325篇
儿科学   39665篇
妇产科学   31882篇
基础医学   172529篇
口腔科学   33531篇
临床医学   105457篇
内科学   227584篇
皮肤病学   28346篇
神经病学   94294篇
特种医学   49897篇
外国民族医学   224篇
外科学   185596篇
综合类   22735篇
现状与发展   1篇
一般理论   311篇
预防医学   81297篇
眼科学   28017篇
药学   96104篇
  7篇
中国医学   2979篇
肿瘤学   72327篇
  2019年   8952篇
  2018年   13808篇
  2017年   10974篇
  2016年   12959篇
  2015年   14454篇
  2014年   18606篇
  2013年   26969篇
  2012年   37938篇
  2011年   39451篇
  2010年   23112篇
  2009年   21189篇
  2008年   36831篇
  2007年   39776篇
  2006年   40351篇
  2005年   39070篇
  2004年   37356篇
  2003年   35942篇
  2002年   34732篇
  2001年   64453篇
  2000年   65714篇
  1999年   54624篇
  1998年   13097篇
  1997年   11416篇
  1996年   11104篇
  1995年   10924篇
  1994年   9917篇
  1993年   9372篇
  1992年   39494篇
  1991年   37920篇
  1990年   37339篇
  1989年   35792篇
  1988年   32175篇
  1987年   31332篇
  1986年   29423篇
  1985年   27607篇
  1984年   20087篇
  1983年   16831篇
  1982年   9334篇
  1979年   17975篇
  1978年   12120篇
  1977年   10789篇
  1976年   9387篇
  1975年   10796篇
  1974年   12428篇
  1973年   12003篇
  1972年   11500篇
  1971年   10807篇
  1970年   9893篇
  1969年   9536篇
  1968年   8513篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
Patients admitted to intensive care after cardiac arrest are at risk of circulatory shock and early mortality due to cardiovascular failure. The aim of this study was to evaluate the ability of the veno-arterial pCO2 difference (∆pCO2; central venous CO2 – arterial CO2) and lactate to predict early mortality in postcardiac arrest patients. This was a pre-planned prospective observational sub-study of the target temperature management 2 trial. The sub-study patients were included at five Swedish sites. Repeated measurements of ∆pCO2 and lactate were conducted at 4, 8, 12, 16, 24, 48, and 72 h after randomization. We assessed the association between each marker and 96-h mortality and their prognostic value for 96-h mortality. One hundred sixty-three patients were included in the analysis. Mortality at 96 h was 17%. During the initial 24 h, there was no difference in ∆pCO2 levels between 96-h survivors and non-survivors. ∆pCO2 measured at 4 h was associated with an increased risk of death within 96 h (adjusted odds ratio: 1.15; 95% confidence interval [CI]: 1.02–1.29; p = .018). Lactate levels were associated with poor outcome over multiple measurements. The area under the receiving operating curve to predict death within 96 h was 0.59 (95% CI: 0.48–0.74) and 0.82 (95% CI: 0.72–0.92) for ∆pCO2 and lactate, respectively. Our results do not support the use of ∆pCO2 to identify patients with early mortality in the postresuscitation phase. In contrast, non-survivors demonstrated higher lactate levels in the initial phase and lactate identified patients with early mortality with moderate accuracy.  相似文献   
6.
7.
8.
Bulletin of Experimental Biology and Medicine - Fast neutron therapy, which previously has demonstrated effective results, but along with a large number of complications, can again be considered a...  相似文献   
9.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Heavy metal concentrations in surface soils of Reserved Forests (RFs) have a significant impact on...  相似文献   
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