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   2641377篇
  免费   203459篇
  国内免费   4999篇
耳鼻咽喉   37869篇
儿科学   84072篇
妇产科学   76257篇
基础医学   372281篇
口腔科学   79685篇
临床医学   230026篇
内科学   513392篇
皮肤病学   58499篇
神经病学   213171篇
特种医学   105797篇
外国民族医学   879篇
外科学   404754篇
综合类   64522篇
现状与发展   9篇
一般理论   925篇
预防医学   196676篇
眼科学   62237篇
药学   199916篇
  6篇
中国医学   5395篇
肿瘤学   143467篇
  2018年   24232篇
  2015年   24396篇
  2014年   33874篇
  2013年   51916篇
  2012年   69068篇
  2011年   72994篇
  2010年   43370篇
  2009年   41493篇
  2008年   70068篇
  2007年   74952篇
  2006年   75910篇
  2005年   73810篇
  2004年   72256篇
  2003年   69671篇
  2002年   68457篇
  2001年   122515篇
  2000年   126248篇
  1999年   107552篇
  1998年   29372篇
  1997年   26704篇
  1996年   26198篇
  1995年   25201篇
  1994年   23671篇
  1993年   22201篇
  1992年   86721篇
  1991年   84095篇
  1990年   82316篇
  1989年   80219篇
  1988年   74668篇
  1987年   73534篇
  1986年   70193篇
  1985年   67363篇
  1984年   50486篇
  1983年   43345篇
  1982年   25746篇
  1981年   23274篇
  1980年   21799篇
  1979年   48350篇
  1978年   34100篇
  1977年   29118篇
  1976年   26864篇
  1975年   29352篇
  1974年   35522篇
  1973年   34255篇
  1972年   32089篇
  1971年   30167篇
  1970年   28180篇
  1969年   26751篇
  1968年   24886篇
  1967年   22403篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
91.
92.
93.
To evaluate the changes in alveolar contour after guided bone regeneration (GBR) with two different combinations of biomaterials in dehiscence defects arou  相似文献   
94.
95.
96.
97.
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   
98.
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   
99.
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   
100.
Reactive lymphoid infiltrates of the skin composed predominantly of gamma‐delta (γδ) T cells are not well described in the literature. Herein we report a case of an otherwise healthy 4‐year‐old male who presented with a waxing and waning papular rash characterized by small, discrete crusted papules spread across his trunk, face and extremities. Clinical evaluation revealed no evidence of systemic disease. Microscopic examination revealed a dermal, perivascular infiltrate of highly atypical lymphocytes with a γδ T cell phenotype, worrisome for primary cutaneous γδ T cell lymphoma. The clinical course, however, was that of a reactive condition and prompted consideration of a diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP). In many ways, this case defies current classification schemes and seems to expand the spectrum of reactive γδ T cell infiltrates of the skin.  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