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   3373105篇
  免费   239692篇
  国内免费   8427篇
耳鼻咽喉   45390篇
儿科学   110930篇
妇产科学   94131篇
基础医学   479316篇
口腔科学   93850篇
临床医学   310867篇
内科学   658479篇
皮肤病学   78958篇
神经病学   276061篇
特种医学   128691篇
外国民族医学   964篇
外科学   496077篇
综合类   69058篇
现状与发展   7篇
一般理论   1447篇
预防医学   266042篇
眼科学   75946篇
药学   246078篇
  12篇
中国医学   6467篇
肿瘤学   182453篇
  2019年   26442篇
  2018年   36783篇
  2017年   28347篇
  2016年   32427篇
  2015年   36834篇
  2014年   50736篇
  2013年   76930篇
  2012年   102354篇
  2011年   108577篇
  2010年   64994篇
  2009年   62498篇
  2008年   101956篇
  2007年   108465篇
  2006年   109675篇
  2005年   105778篇
  2004年   101820篇
  2003年   98133篇
  2002年   94834篇
  2001年   156301篇
  2000年   159954篇
  1999年   135111篇
  1998年   39157篇
  1997年   34973篇
  1996年   35428篇
  1995年   34084篇
  1994年   31425篇
  1993年   29478篇
  1992年   106250篇
  1991年   103130篇
  1990年   99917篇
  1989年   96444篇
  1988年   88943篇
  1987年   87165篇
  1986年   82169篇
  1985年   78306篇
  1984年   58899篇
  1983年   50245篇
  1982年   29963篇
  1981年   26933篇
  1979年   53029篇
  1978年   37963篇
  1977年   32210篇
  1976年   29792篇
  1975年   31903篇
  1974年   38015篇
  1973年   36667篇
  1972年   34517篇
  1971年   32091篇
  1970年   29860篇
  1969年   28505篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
54.
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   
55.
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   
56.
57.
58.
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   
59.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  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