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   2588402篇
  免费   184583篇
  国内免费   7571篇
耳鼻咽喉   34273篇
儿科学   85219篇
妇产科学   71580篇
基础医学   363635篇
口腔科学   69668篇
临床医学   234595篇
内科学   515611篇
皮肤病学   62464篇
神经病学   213468篇
特种医学   99883篇
外国民族医学   736篇
外科学   386481篇
综合类   50405篇
现状与发展   5篇
一般理论   970篇
预防医学   196278篇
眼科学   56693篇
药学   188017篇
  8篇
中国医学   5331篇
肿瘤学   145236篇
  2021年   19992篇
  2019年   20631篇
  2018年   29294篇
  2017年   22605篇
  2016年   26229篇
  2015年   29512篇
  2014年   40453篇
  2013年   60435篇
  2012年   80247篇
  2011年   84518篇
  2010年   51021篇
  2009年   49157篇
  2008年   79036篇
  2007年   83866篇
  2006年   85592篇
  2005年   81744篇
  2004年   78752篇
  2003年   76069篇
  2002年   73343篇
  2001年   128426篇
  2000年   131345篇
  1999年   110510篇
  1998年   31260篇
  1997年   27922篇
  1996年   28218篇
  1995年   27387篇
  1994年   25071篇
  1993年   23423篇
  1992年   85172篇
  1991年   81570篇
  1990年   78791篇
  1989年   76062篇
  1988年   69475篇
  1987年   68008篇
  1986年   63551篇
  1985年   60518篇
  1984年   44949篇
  1983年   37950篇
  1982年   22462篇
  1981年   19989篇
  1979年   38966篇
  1978年   27444篇
  1977年   23257篇
  1976年   21501篇
  1975年   22814篇
  1974年   26791篇
  1973年   25379篇
  1972年   23752篇
  1971年   21957篇
  1970年   20190篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
ABSTRACT

Purpose

To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR).  相似文献   
52.
53.
54.
55.
56.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  相似文献   
57.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  相似文献   
58.
59.
In the 6th Basic Plan for Long-Term Electricity Supply and Demand (6th BPE) for Korea, for the first time, the environmental costs of air pollution caused by oxides of sulfur (SOx), oxides of nitrogen (NOx), and particulate matters (PM) from power plants were estimated and included. However, several deficiencies in evaluating the environmental costs were found. In this study, (1) the validity of the environmental costs used in the 6th BPE was assessed, (2) a systematic approach was suggested and used to improve the environmental costs estimation, and (3) the sensitivity of the cost of generating electricity to the environmental costs by fuel type with the proposed approach was discussed. We found that the applied environmental costs used in the 6th BPE did not fully include the demographic characteristics of Korea. By applying more realistic parameter values, it was found that the newly estimated environmental cost was about 23 times higher than the cost estimated in the original 6th BPE for coal-fired power plants and about 1.5 times higher for liquefied natural gas (LNG)-fired power plants, suggesting that LNG-fired power plants are more economical if using more realistic environmental costs. Thus, it is critical to check the validity of parameter values when calculating environmental costs.  相似文献   
60.
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