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   2512150篇
  免费   194477篇
  国内免费   10114篇
耳鼻咽喉   32154篇
儿科学   81118篇
妇产科学   67294篇
基础医学   355031篇
口腔科学   68711篇
临床医学   237448篇
内科学   498665篇
皮肤病学   55208篇
神经病学   209958篇
特种医学   97549篇
外国民族医学   635篇
外科学   370660篇
综合类   56847篇
现状与发展   3篇
一般理论   934篇
预防医学   209330篇
眼科学   54560篇
药学   180067篇
  54篇
中国医学   5145篇
肿瘤学   135370篇
  2021年   20716篇
  2019年   20946篇
  2018年   29154篇
  2017年   22498篇
  2016年   25727篇
  2015年   29057篇
  2014年   40405篇
  2013年   61155篇
  2012年   79920篇
  2011年   85455篇
  2010年   51356篇
  2009年   48878篇
  2008年   78619篇
  2007年   83369篇
  2006年   84485篇
  2005年   81949篇
  2004年   77824篇
  2003年   74672篇
  2002年   71580篇
  2001年   110895篇
  2000年   113757篇
  1999年   95934篇
  1998年   29590篇
  1997年   26475篇
  1996年   26904篇
  1995年   26385篇
  1994年   24693篇
  1993年   23132篇
  1992年   78116篇
  1991年   76181篇
  1990年   73478篇
  1989年   69793篇
  1988年   64853篇
  1987年   63557篇
  1986年   60385篇
  1985年   58068篇
  1984年   44425篇
  1983年   37467篇
  1982年   23518篇
  1981年   21049篇
  1979年   40076篇
  1978年   29150篇
  1977年   24203篇
  1976年   23048篇
  1975年   23741篇
  1974年   28437篇
  1973年   27461篇
  1972年   25379篇
  1971年   23438篇
  1970年   21577篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Imaging     
  相似文献   
55.
56.
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   
57.
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   
58.
59.
60.
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