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   2741427篇
  免费   213915篇
  国内免费   4691篇
耳鼻咽喉   39486篇
儿科学   85006篇
妇产科学   72433篇
基础医学   396834篇
口腔科学   78641篇
临床医学   248737篇
内科学   529507篇
皮肤病学   56554篇
神经病学   224074篇
特种医学   108566篇
外国民族医学   936篇
外科学   415023篇
综合类   62267篇
现状与发展   1篇
一般理论   1070篇
预防医学   219927篇
眼科学   64625篇
药学   206955篇
  4篇
中国医学   5035篇
肿瘤学   144352篇
  2018年   27376篇
  2016年   23249篇
  2015年   26167篇
  2014年   37559篇
  2013年   57240篇
  2012年   77391篇
  2011年   82192篇
  2010年   48282篇
  2009年   46119篇
  2008年   78048篇
  2007年   83188篇
  2006年   84164篇
  2005年   81908篇
  2004年   79076篇
  2003年   76140篇
  2002年   75451篇
  2001年   126877篇
  2000年   131567篇
  1999年   110734篇
  1998年   31462篇
  1997年   28479篇
  1996年   28653篇
  1995年   27505篇
  1994年   25799篇
  1993年   24182篇
  1992年   89572篇
  1991年   87538篇
  1990年   84975篇
  1989年   82052篇
  1988年   76264篇
  1987年   75092篇
  1986年   71157篇
  1985年   67849篇
  1984年   51197篇
  1983年   43742篇
  1982年   26186篇
  1981年   23360篇
  1980年   21973篇
  1979年   48476篇
  1978年   34275篇
  1977年   28818篇
  1976年   27258篇
  1975年   29120篇
  1974年   35862篇
  1973年   33843篇
  1972年   31988篇
  1971年   29715篇
  1970年   27906篇
  1969年   26053篇
  1968年   23851篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
47.
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   
48.
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   
49.
50.
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   
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