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   4166007篇
  免费   287862篇
  国内免费   9620篇
耳鼻咽喉   58109篇
儿科学   137053篇
妇产科学   114978篇
基础医学   591901篇
口腔科学   116868篇
临床医学   381322篇
内科学   802806篇
皮肤病学   96825篇
神经病学   335576篇
特种医学   158825篇
外国民族医学   1219篇
外科学   620776篇
综合类   84777篇
现状与发展   15篇
一般理论   1620篇
预防医学   328161篇
眼科学   96917篇
药学   306409篇
  17篇
中国医学   8243篇
肿瘤学   221072篇
  2021年   33502篇
  2019年   33976篇
  2018年   49103篇
  2017年   37802篇
  2016年   42164篇
  2015年   48202篇
  2014年   65796篇
  2013年   97251篇
  2012年   134566篇
  2011年   139114篇
  2010年   83208篇
  2009年   79963篇
  2008年   127726篇
  2007年   136048篇
  2006年   137900篇
  2005年   139063篇
  2004年   135367篇
  2003年   127245篇
  2002年   119578篇
  2001年   184735篇
  2000年   188819篇
  1999年   160865篇
  1998年   47643篇
  1997年   41797篇
  1996年   41868篇
  1995年   40271篇
  1994年   36987篇
  1993年   34744篇
  1992年   127018篇
  1991年   123462篇
  1990年   120314篇
  1989年   116628篇
  1988年   107455篇
  1987年   105322篇
  1986年   99291篇
  1985年   94931篇
  1984年   70882篇
  1983年   60367篇
  1982年   35687篇
  1979年   64792篇
  1978年   45888篇
  1977年   38694篇
  1976年   36303篇
  1975年   39194篇
  1974年   46910篇
  1973年   44621篇
  1972年   42112篇
  1971年   39675篇
  1970年   36534篇
  1969年   35130篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
135.
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   
136.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
137.
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   
138.
139.
140.
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