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   3627010篇
  免费   257114篇
  国内免费   9490篇
耳鼻咽喉   48880篇
儿科学   120273篇
妇产科学   99773篇
基础医学   509691篇
口腔科学   102402篇
临床医学   332592篇
内科学   706918篇
皮肤病学   85468篇
神经病学   293654篇
特种医学   137434篇
外国民族医学   941篇
外科学   541365篇
综合类   78073篇
现状与发展   8篇
一般理论   1407篇
预防医学   278200篇
眼科学   83976篇
药学   264838篇
  12篇
中国医学   8001篇
肿瘤学   199708篇
  2019年   28807篇
  2018年   41015篇
  2017年   31247篇
  2016年   35574篇
  2015年   40295篇
  2014年   55763篇
  2013年   83382篇
  2012年   112392篇
  2011年   118942篇
  2010年   71234篇
  2009年   67596篇
  2008年   110733篇
  2007年   117929篇
  2006年   119471篇
  2005年   114595篇
  2004年   110332篇
  2003年   106121篇
  2002年   102462篇
  2001年   175961篇
  2000年   180122篇
  1999年   151525篇
  1998年   43101篇
  1997年   37994篇
  1996年   38083篇
  1995年   36933篇
  1994年   33747篇
  1993年   31640篇
  1992年   117255篇
  1991年   113115篇
  1990年   109499篇
  1989年   105827篇
  1988年   96763篇
  1987年   94744篇
  1986年   88989篇
  1985年   84952篇
  1984年   63351篇
  1983年   53790篇
  1982年   31548篇
  1981年   28118篇
  1979年   56028篇
  1978年   39348篇
  1977年   33464篇
  1976年   31206篇
  1975年   33025篇
  1974年   39405篇
  1973年   37677篇
  1972年   35190篇
  1971年   32674篇
  1970年   30177篇
  1969年   28848篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
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   
75.
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   
76.
77.
78.
79.
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   
80.
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