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   2751977篇
  免费   192683篇
  国内免费   7884篇
耳鼻咽喉   36356篇
儿科学   89803篇
妇产科学   75151篇
基础医学   386946篇
口腔科学   73786篇
临床医学   248514篇
内科学   550353篇
皮肤病学   66734篇
神经病学   228520篇
特种医学   104512篇
外国民族医学   810篇
外科学   407218篇
综合类   51099篇
现状与发展   5篇
一般理论   1014篇
预防医学   211609篇
眼科学   59923篇
药学   199548篇
  8篇
中国医学   5824篇
肿瘤学   154811篇
  2021年   22621篇
  2019年   23592篇
  2018年   34865篇
  2017年   26240篇
  2016年   29837篇
  2015年   33564篇
  2014年   44694篇
  2013年   67129篇
  2012年   92387篇
  2011年   96781篇
  2010年   56974篇
  2009年   53552篇
  2008年   89432篇
  2007年   95034篇
  2006年   95719篇
  2005年   91870篇
  2004年   88100篇
  2003年   84674篇
  2002年   81445篇
  2001年   131047篇
  2000年   134060篇
  1999年   112955篇
  1998年   31756篇
  1997年   28370篇
  1996年   28630篇
  1995年   27766篇
  1994年   25413篇
  1993年   23739篇
  1992年   86789篇
  1991年   83036篇
  1990年   80179篇
  1989年   77356篇
  1988年   70751篇
  1987年   69152篇
  1986年   64609篇
  1985年   61546篇
  1984年   45773篇
  1983年   38655篇
  1982年   22897篇
  1981年   20315篇
  1979年   39703篇
  1978年   27975篇
  1977年   23773篇
  1976年   21899篇
  1975年   23327篇
  1974年   27441篇
  1973年   26036篇
  1972年   24373篇
  1971年   22544篇
  1970年   20783篇
排序方式: 共有10000条查询结果,搜索用时 853 毫秒
61.
Imaging     
  相似文献   
62.
63.
64.
65.
66.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
67.
ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)  相似文献   
68.
69.
70.
BACKGROUND: Three dimensional skin equivalents are widely used in dermatopharmacological and toxicological studies and as autologous transplants in wound healing. In pharmacology, there is tremendous need for monitoring the response of engineered skin equivalents to external treatment. Transplantation of skin equivalents for wound healing requires careful verification of their quality prior to transplantation. Optical coherence tomography (OCT) is a non-contact, non-destructive imaging technique for living tissues offering the potential to fulfill these needs. This work presents an analysis of OCT for high-resolution monitoring of skin equivalents at different stages during the culture process. METHODS: We developed a high-resolution OCT imaging setup based on a commercially available OCT system. A broadband femtosecond laser light source replaces the original superluminescence diode. Tomograms of living skin equivalents were recorded with an axial resolution of 3 mum and correlated with histology and immunofluorescence images. Comparison with standard low-resolution OCT is presented to emphasize the advantages of high-resolution OCT for this application. RESULTS: OCT is particularly able to distinguish between different layers of skin equivalents including stratum corneum, epidermal and dermal layer as well as the basement membrane zone. The high-resolution OCT scans correlate closely with two key benchmarks, histology and immunofluorescence imaging. CONCLUSIONS: This study clearly demonstrates the benefits of high-resolution OCT for identifying living tissue structure and morphology. Compared with the current gold standard histology, OCT offers non-destructive tissue imaging, enabling high-resolution evaluation of living tissue morphology and structure as it evolves.  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