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   4220734篇
  免费   297526篇
  国内免费   9316篇
耳鼻咽喉   58950篇
儿科学   138679篇
妇产科学   116237篇
基础医学   604217篇
口腔科学   119013篇
临床医学   388033篇
内科学   808923篇
皮肤病学   97790篇
神经病学   340687篇
特种医学   159012篇
外国民族医学   1177篇
外科学   630132篇
综合类   87738篇
现状与发展   15篇
一般理论   1678篇
预防医学   332167篇
眼科学   99476篇
药学   311943篇
  16篇
中国医学   8207篇
肿瘤学   223486篇
  2018年   46183篇
  2017年   35000篇
  2016年   40244篇
  2015年   45268篇
  2014年   63335篇
  2013年   96227篇
  2012年   129437篇
  2011年   137728篇
  2010年   82849篇
  2009年   78677篇
  2008年   129059篇
  2007年   137342篇
  2006年   139292篇
  2005年   134421篇
  2004年   129464篇
  2003年   124606篇
  2002年   120632篇
  2001年   190261篇
  2000年   195561篇
  1999年   165344篇
  1998年   49237篇
  1997年   43172篇
  1996年   43372篇
  1995年   41628篇
  1994年   38270篇
  1993年   36035篇
  1992年   130116篇
  1991年   126517篇
  1990年   123285篇
  1989年   119681篇
  1988年   110147篇
  1987年   108151篇
  1986年   101804篇
  1985年   97740篇
  1984年   73138篇
  1983年   62321篇
  1982年   37089篇
  1981年   33485篇
  1979年   67093篇
  1978年   47816篇
  1977年   40483篇
  1976年   38041篇
  1975年   40963篇
  1974年   49025篇
  1973年   46719篇
  1972年   44084篇
  1971年   41528篇
  1970年   38393篇
  1969年   36812篇
  1968年   33933篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
84.
85.
86.
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   
87.
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   
88.
89.
90.
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