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   3430387篇
  免费   241391篇
  国内免费   9375篇
耳鼻咽喉   48379篇
儿科学   111459篇
妇产科学   97265篇
基础医学   481771篇
口腔科学   97186篇
临床医学   308497篇
内科学   669739篇
皮肤病学   81693篇
神经病学   279970篇
特种医学   132670篇
外国民族医学   1122篇
外科学   516414篇
综合类   72787篇
现状与发展   11篇
一般理论   1301篇
预防医学   256872篇
眼科学   79096篇
药学   252471篇
  12篇
中国医学   7127篇
肿瘤学   185311篇
  2018年   35987篇
  2017年   27945篇
  2016年   32156篇
  2015年   36209篇
  2014年   50077篇
  2013年   75582篇
  2012年   99754篇
  2011年   105654篇
  2010年   63744篇
  2009年   61119篇
  2008年   99335篇
  2007年   106305篇
  2006年   107854篇
  2005年   103741篇
  2004年   100199篇
  2003年   97060篇
  2002年   93951篇
  2001年   160872篇
  2000年   164938篇
  1999年   139514篇
  1998年   40151篇
  1997年   35817篇
  1996年   35460篇
  1995年   34215篇
  1994年   31557篇
  1993年   29592篇
  1992年   109073篇
  1991年   105318篇
  1990年   102331篇
  1989年   99256篇
  1988年   91553篇
  1987年   89806篇
  1986年   84829篇
  1985年   81075篇
  1984年   60764篇
  1983年   51624篇
  1982年   30927篇
  1981年   27709篇
  1979年   55252篇
  1978年   39255篇
  1977年   33841篇
  1976年   31034篇
  1975年   34024篇
  1974年   40105篇
  1973年   38498篇
  1972年   36376篇
  1971年   33948篇
  1970年   31661篇
  1969年   30542篇
  1968年   28342篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
76.
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   
77.
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   
78.
79.
80.
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