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   4675753篇
  免费   334224篇
  国内免费   10346篇
耳鼻咽喉   66095篇
儿科学   153233篇
妇产科学   128097篇
基础医学   663434篇
口腔科学   134186篇
临床医学   433303篇
内科学   892755篇
皮肤病学   105943篇
神经病学   379126篇
特种医学   177842篇
外国民族医学   1375篇
外科学   697240篇
综合类   104207篇
现状与发展   16篇
一般理论   1968篇
预防医学   375268篇
眼科学   109877篇
药学   344747篇
  18篇
中国医学   9007篇
肿瘤学   242586篇
  2018年   51177篇
  2017年   38738篇
  2016年   44404篇
  2015年   50045篇
  2014年   70198篇
  2013年   107249篇
  2012年   143093篇
  2011年   152275篇
  2010年   92015篇
  2009年   87037篇
  2008年   142137篇
  2007年   151535篇
  2006年   153317篇
  2005年   148255篇
  2004年   142762篇
  2003年   137507篇
  2002年   132920篇
  2001年   207791篇
  2000年   213679篇
  1999年   180941篇
  1998年   54746篇
  1997年   48044篇
  1996年   48036篇
  1995年   46246篇
  1994年   42727篇
  1993年   40162篇
  1992年   143504篇
  1991年   139860篇
  1990年   136191篇
  1989年   131788篇
  1988年   121759篇
  1987年   119709篇
  1986年   113137篇
  1985年   108648篇
  1984年   81681篇
  1983年   69717篇
  1982年   41780篇
  1981年   37618篇
  1979年   75394篇
  1978年   53809篇
  1977年   45627篇
  1976年   42817篇
  1975年   46044篇
  1974年   55244篇
  1973年   52864篇
  1972年   49896篇
  1971年   46762篇
  1970年   43249篇
  1969年   41302篇
  1968年   37997篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
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   
96.
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   
97.
98.
99.
100.
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