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   1415943篇
  免费   113505篇
  国内免费   3351篇
耳鼻咽喉   18416篇
儿科学   46754篇
妇产科学   41176篇
基础医学   201419篇
口腔科学   37850篇
临床医学   126401篇
内科学   285428篇
皮肤病学   33458篇
神经病学   117369篇
特种医学   53966篇
外国民族医学   464篇
外科学   211191篇
综合类   32769篇
现状与发展   3篇
一般理论   488篇
预防医学   110489篇
眼科学   31545篇
药学   98781篇
  1篇
中国医学   3368篇
肿瘤学   81463篇
  2021年   11001篇
  2019年   11840篇
  2018年   16717篇
  2017年   12773篇
  2016年   14355篇
  2015年   16117篇
  2014年   22714篇
  2013年   33625篇
  2012年   45695篇
  2011年   48274篇
  2010年   28345篇
  2009年   27224篇
  2008年   44604篇
  2007年   47121篇
  2006年   47675篇
  2005年   46102篇
  2004年   43965篇
  2003年   41907篇
  2002年   40361篇
  2001年   73153篇
  2000年   74676篇
  1999年   61667篇
  1998年   17027篇
  1997年   15483篇
  1996年   15612篇
  1995年   14813篇
  1994年   13421篇
  1993年   12599篇
  1992年   45889篇
  1991年   43534篇
  1990年   41525篇
  1989年   39593篇
  1988年   36212篇
  1987年   35395篇
  1986年   32882篇
  1985年   31304篇
  1984年   23845篇
  1983年   20036篇
  1982年   12215篇
  1981年   10784篇
  1979年   20715篇
  1978年   14586篇
  1977年   12097篇
  1976年   11374篇
  1975年   11628篇
  1974年   13998篇
  1973年   13540篇
  1972年   12639篇
  1971年   11477篇
  1970年   10924篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
22.
23.
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   
24.
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   
25.
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   
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