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   2591143篇
  免费   185369篇
  国内免费   7568篇
耳鼻咽喉   34353篇
儿科学   85273篇
妇产科学   71598篇
基础医学   363884篇
口腔科学   69749篇
临床医学   234979篇
内科学   516488篇
皮肤病学   62527篇
神经病学   213974篇
特种医学   99957篇
外国民族医学   736篇
外科学   386692篇
综合类   50414篇
现状与发展   5篇
一般理论   968篇
预防医学   196405篇
眼科学   56773篇
药学   188252篇
  57篇
中国医学   5338篇
肿瘤学   145658篇
  2021年   20476篇
  2019年   20679篇
  2018年   29337篇
  2017年   22625篇
  2016年   26262篇
  2015年   29559篇
  2014年   40500篇
  2013年   60495篇
  2012年   80328篇
  2011年   84572篇
  2010年   51056篇
  2009年   49187篇
  2008年   79098篇
  2007年   83892篇
  2006年   85616篇
  2005年   81771篇
  2004年   78766篇
  2003年   76085篇
  2002年   73367篇
  2001年   128421篇
  2000年   131340篇
  1999年   110511篇
  1998年   31259篇
  1997年   27927篇
  1996年   28224篇
  1995年   27388篇
  1994年   25073篇
  1993年   23426篇
  1992年   85163篇
  1991年   81572篇
  1990年   78788篇
  1989年   76063篇
  1988年   69472篇
  1987年   67999篇
  1986年   63545篇
  1985年   60514篇
  1984年   44942篇
  1983年   37947篇
  1982年   22460篇
  1981年   19987篇
  1979年   38960篇
  1978年   27439篇
  1977年   23252篇
  1976年   21495篇
  1975年   22814篇
  1974年   26786篇
  1973年   25370篇
  1972年   23751篇
  1971年   21957篇
  1970年   20185篇
排序方式: 共有10000条查询结果,搜索用时 15 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