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   2592436篇
  免费   185748篇
  国内免费   7581篇
耳鼻咽喉   34331篇
儿科学   85411篇
妇产科学   71723篇
基础医学   364357篇
口腔科学   69720篇
临床医学   235176篇
内科学   516520篇
皮肤病学   62560篇
神经病学   214117篇
特种医学   99995篇
外国民族医学   736篇
外科学   386933篇
综合类   50454篇
现状与发展   5篇
一般理论   973篇
预防医学   196757篇
眼科学   56782篇
药学   188307篇
  9篇
中国医学   5339篇
肿瘤学   145560篇
  2021年   20272篇
  2019年   20866篇
  2018年   29546篇
  2017年   22796篇
  2016年   26425篇
  2015年   29679篇
  2014年   40679篇
  2013年   60718篇
  2012年   80610篇
  2011年   84898篇
  2010年   51197篇
  2009年   49306篇
  2008年   79283篇
  2007年   84065篇
  2006年   85789篇
  2005年   81933篇
  2004年   78892篇
  2003年   76238篇
  2002年   73501篇
  2001年   128450篇
  2000年   131367篇
  1999年   110531篇
  1998年   31283篇
  1997年   27930篇
  1996年   28244篇
  1995年   27392篇
  1994年   25076篇
  1993年   23429篇
  1992年   85188篇
  1991年   81589篇
  1990年   78798篇
  1989年   76080篇
  1988年   69491篇
  1987年   68011篇
  1986年   63559篇
  1985年   60529篇
  1984年   44960篇
  1983年   37955篇
  1982年   22467篇
  1981年   19990篇
  1979年   38964篇
  1978年   27449篇
  1977年   23267篇
  1976年   21502篇
  1975年   22816篇
  1974年   26796篇
  1973年   25377篇
  1972年   23755篇
  1971年   21965篇
  1970年   20187篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
51.
Imaging     
  相似文献   
52.
53.
54.
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