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   2489312篇
  免费   208659篇
  国内免费   10689篇
耳鼻咽喉   35341篇
儿科学   74553篇
妇产科学   65533篇
基础医学   346742篇
口腔科学   69943篇
临床医学   230489篇
内科学   486320篇
皮肤病学   49363篇
神经病学   206403篇
特种医学   99758篇
外国民族医学   926篇
外科学   372398篇
综合类   75184篇
现状与发展   21篇
一般理论   994篇
预防医学   199444篇
眼科学   58703篇
药学   190059篇
  118篇
中国医学   10786篇
肿瘤学   135582篇
  2021年   21384篇
  2019年   20688篇
  2018年   27907篇
  2017年   22271篇
  2016年   23689篇
  2015年   28251篇
  2014年   39866篇
  2013年   57366篇
  2012年   78277篇
  2011年   82543篇
  2010年   49650篇
  2009年   46731篇
  2008年   76101篇
  2007年   80362篇
  2006年   80871篇
  2005年   78325篇
  2004年   73788篇
  2003年   71102篇
  2002年   69622篇
  2001年   114715篇
  2000年   118574篇
  1999年   100332篇
  1998年   29027篇
  1997年   26630篇
  1996年   26344篇
  1995年   25455篇
  1994年   23967篇
  1993年   21988篇
  1992年   79976篇
  1991年   76927篇
  1990年   74034篇
  1989年   71229篇
  1988年   66178篇
  1987年   65076篇
  1986年   61561篇
  1985年   58578篇
  1984年   44337篇
  1983年   37765篇
  1982年   22946篇
  1979年   41388篇
  1978年   29051篇
  1977年   24404篇
  1976年   22870篇
  1975年   23989篇
  1974年   29692篇
  1973年   28085篇
  1972年   26279篇
  1971年   24184篇
  1970年   22778篇
  1969年   21113篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
Porocarcinoma is an unusual, locally aggressive and potentially fatal neoplasm. Several cutaneous malignancies have been described in association with porocarcinoma, including squamous cell carcinoma, basal cell carcinoma and tricholemmal carcinoma. Previous reports have indicated that the occurrence of malignant tumours in combination with porocarcinoma is extremely rare, in particular with regard to Bowen disease (BD). We report an uncommon case of porocarcinoma occurring synchronously in a single BD lesion in a 63‐year‐old woman with multiple BD lesions. The clinical and histological findings confirmed this diagnosis.  相似文献   
106.
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   
107.
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   
108.
109.
110.
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