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   2506574篇
  免费   180350篇
  国内免费   4668篇
耳鼻咽喉   36955篇
儿科学   80919篇
妇产科学   70239篇
基础医学   354030篇
口腔科学   72348篇
临床医学   212390篇
内科学   496977篇
皮肤病学   56562篇
神经病学   198407篇
特种医学   98312篇
外国民族医学   1057篇
外科学   382141篇
综合类   54267篇
现状与发展   7篇
一般理论   783篇
预防医学   188296篇
眼科学   58639篇
药学   188646篇
  6篇
中国医学   5522篇
肿瘤学   135089篇
  2018年   26532篇
  2017年   20034篇
  2016年   21770篇
  2015年   24589篇
  2014年   33627篇
  2013年   51383篇
  2012年   71250篇
  2011年   75498篇
  2010年   44130篇
  2009年   41288篇
  2008年   71056篇
  2007年   76875篇
  2006年   77069篇
  2005年   74844篇
  2004年   72780篇
  2003年   70331篇
  2002年   68915篇
  2001年   117109篇
  2000年   121375篇
  1999年   102708篇
  1998年   27475篇
  1997年   24750篇
  1996年   24575篇
  1995年   23239篇
  1994年   21819篇
  1993年   20329篇
  1992年   79880篇
  1991年   77647篇
  1990年   75811篇
  1989年   73206篇
  1988年   67896篇
  1987年   66842篇
  1986年   63240篇
  1985年   60311篇
  1984年   45224篇
  1983年   38250篇
  1982年   22486篇
  1981年   20469篇
  1979年   42294篇
  1978年   29712篇
  1977年   25628篇
  1976年   23555篇
  1975年   26355篇
  1974年   31121篇
  1973年   30158篇
  1972年   28511篇
  1971年   26350篇
  1970年   24954篇
  1969年   23596篇
  1968年   21962篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
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   
104.
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   
105.
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   
106.
107.
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   
108.
109.
110.
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