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   1584075篇
  免费   129715篇
  国内免费   14957篇
耳鼻咽喉   19937篇
儿科学   48357篇
妇产科学   43256篇
基础医学   220969篇
口腔科学   40779篇
临床医学   149094篇
内科学   309304篇
皮肤病学   35414篇
神经病学   125725篇
特种医学   59972篇
外国民族医学   561篇
外科学   227755篇
综合类   61945篇
现状与发展   42篇
一般理论   505篇
预防医学   121846篇
眼科学   36074篇
药学   117385篇
  190篇
中国医学   14205篇
肿瘤学   95432篇
  2022年   11839篇
  2021年   20430篇
  2020年   14084篇
  2019年   17803篇
  2018年   22965篇
  2017年   18568篇
  2016年   19769篇
  2015年   24490篇
  2014年   32833篇
  2013年   42796篇
  2012年   59030篇
  2011年   62777篇
  2010年   37654篇
  2009年   34330篇
  2008年   53928篇
  2007年   55964篇
  2006年   56146篇
  2005年   54402篇
  2004年   49127篇
  2003年   46548篇
  2002年   44197篇
  2001年   75924篇
  2000年   77638篇
  1999年   64899篇
  1998年   19158篇
  1997年   17642篇
  1996年   17267篇
  1995年   16443篇
  1994年   14849篇
  1993年   13433篇
  1992年   46879篇
  1991年   44391篇
  1990年   42221篇
  1989年   40227篇
  1988年   36785篇
  1987年   35817篇
  1986年   33244篇
  1985年   31593篇
  1984年   23960篇
  1983年   20147篇
  1982年   12270篇
  1979年   20781篇
  1978年   14605篇
  1977年   12117篇
  1976年   11396篇
  1975年   11640篇
  1974年   14019篇
  1973年   13555篇
  1972年   12645篇
  1971年   11482篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
22.
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   
23.
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   
24.
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   
25.
26.
27.
28.
29.
30.
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