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   1493498篇
  免费   113835篇
  国内免费   2867篇
耳鼻咽喉   20814篇
儿科学   50093篇
妇产科学   39042篇
基础医学   209247篇
口腔科学   37821篇
临床医学   133613篇
内科学   303179篇
皮肤病学   30954篇
神经病学   122677篇
特种医学   60777篇
外国民族医学   673篇
外科学   229924篇
综合类   29459篇
现状与发展   2篇
一般理论   608篇
预防医学   111237篇
眼科学   33028篇
药学   108994篇
  4篇
中国医学   2718篇
肿瘤学   85336篇
  2021年   12686篇
  2019年   13525篇
  2018年   18510篇
  2017年   13918篇
  2016年   15234篇
  2015年   17476篇
  2014年   24573篇
  2013年   36400篇
  2012年   51441篇
  2011年   54228篇
  2010年   31906篇
  2009年   30299篇
  2008年   51047篇
  2007年   54384篇
  2006年   54287篇
  2005年   53017篇
  2004年   51378篇
  2003年   49048篇
  2002年   47839篇
  2001年   66022篇
  2000年   68079篇
  1999年   58440篇
  1998年   17676篇
  1997年   15809篇
  1996年   16012篇
  1995年   15121篇
  1994年   14204篇
  1993年   13222篇
  1992年   45671篇
  1991年   44529篇
  1990年   43121篇
  1989年   41005篇
  1988年   37711篇
  1987年   37004篇
  1986年   34440篇
  1985年   33097篇
  1984年   25123篇
  1983年   21164篇
  1982年   12794篇
  1981年   11657篇
  1979年   21928篇
  1978年   15384篇
  1977年   13016篇
  1976年   12157篇
  1975年   12988篇
  1974年   15022篇
  1973年   14456篇
  1972年   13186篇
  1971年   11950篇
  1970年   11226篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
71.
72.
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures.  相似文献   
73.
74.
75.
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   
76.
77.
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   
78.
79.
80.
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