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   2587413篇
  免费   185309篇
  国内免费   7573篇
耳鼻咽喉   34274篇
儿科学   85203篇
妇产科学   71568篇
基础医学   363606篇
口腔科学   69663篇
临床医学   234505篇
内科学   515664篇
皮肤病学   62451篇
神经病学   213484篇
特种医学   99879篇
外国民族医学   736篇
外科学   386429篇
综合类   50403篇
现状与发展   5篇
一般理论   968篇
预防医学   196172篇
眼科学   56713篇
药学   187990篇
  9篇
中国医学   5336篇
肿瘤学   145237篇
  2021年   19980篇
  2019年   20625篇
  2018年   29295篇
  2017年   22595篇
  2016年   26226篇
  2015年   29509篇
  2014年   40447篇
  2013年   60425篇
  2012年   80226篇
  2011年   84488篇
  2010年   51006篇
  2009年   49148篇
  2008年   79020篇
  2007年   83834篇
  2006年   85565篇
  2005年   81730篇
  2004年   78725篇
  2003年   76040篇
  2002年   73333篇
  2001年   128410篇
  2000年   131334篇
  1999年   110501篇
  1998年   31254篇
  1997年   27920篇
  1996年   28217篇
  1995年   27384篇
  1994年   25067篇
  1993年   23419篇
  1992年   85160篇
  1991年   81563篇
  1990年   78783篇
  1989年   76059篇
  1988年   69468篇
  1987年   67996篇
  1986年   63543篇
  1985年   60510篇
  1984年   44940篇
  1983年   37944篇
  1982年   22456篇
  1981年   19984篇
  1979年   38959篇
  1978年   27440篇
  1977年   23253篇
  1976年   21496篇
  1975年   22813篇
  1974年   26787篇
  1973年   25371篇
  1972年   23751篇
  1971年   21958篇
  1970年   20183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