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   4072966篇
  免费   300935篇
  国内免费   10209篇
耳鼻咽喉   57474篇
儿科学   130350篇
妇产科学   111136篇
基础医学   568513篇
口腔科学   116942篇
临床医学   375187篇
内科学   789291篇
皮肤病学   91243篇
神经病学   338102篇
特种医学   158548篇
外国民族医学   1438篇
外科学   610039篇
综合类   91180篇
现状与发展   6篇
一般理论   1721篇
预防医学   325284篇
眼科学   94715篇
药学   301265篇
  11篇
中国医学   7981篇
肿瘤学   213684篇
  2018年   43664篇
  2017年   33591篇
  2016年   38165篇
  2015年   43069篇
  2014年   60641篇
  2013年   92058篇
  2012年   122348篇
  2011年   129824篇
  2010年   77855篇
  2009年   74430篇
  2008年   121848篇
  2007年   129426篇
  2006年   131173篇
  2005年   126819篇
  2004年   122223篇
  2003年   117821篇
  2002年   114670篇
  2001年   187049篇
  2000年   192539篇
  1999年   163295篇
  1998年   48485篇
  1997年   43267篇
  1996年   42905篇
  1995年   41621篇
  1994年   38639篇
  1993年   36153篇
  1992年   129759篇
  1991年   125529篇
  1990年   121334篇
  1989年   117244篇
  1988年   108365篇
  1987年   106753篇
  1986年   100821篇
  1985年   96582篇
  1984年   72639篇
  1983年   62034篇
  1982年   37357篇
  1981年   33618篇
  1979年   66753篇
  1978年   47234篇
  1977年   40023篇
  1976年   37495篇
  1975年   39595篇
  1974年   47990篇
  1973年   45813篇
  1972年   43108篇
  1971年   39925篇
  1970年   37308篇
  1969年   35275篇
  1968年   32453篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
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   
95.
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   
96.
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   
97.
98.
99.
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   
100.
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