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   1301753篇
  免费   96908篇
  国内免费   3734篇
耳鼻咽喉   18571篇
儿科学   42552篇
妇产科学   37960篇
基础医学   189526篇
口腔科学   36241篇
临床医学   111428篇
内科学   254488篇
皮肤病学   26695篇
神经病学   100139篇
特种医学   51001篇
外国民族医学   372篇
外科学   200161篇
综合类   32892篇
现状与发展   8篇
一般理论   301篇
预防医学   94863篇
眼科学   29694篇
药学   100568篇
  36篇
中国医学   4536篇
肿瘤学   70363篇
  2018年   12536篇
  2016年   10733篇
  2015年   12818篇
  2014年   17545篇
  2013年   26021篇
  2012年   35930篇
  2011年   38482篇
  2010年   23129篇
  2009年   21784篇
  2008年   36922篇
  2007年   39916篇
  2006年   40211篇
  2005年   39321篇
  2004年   37406篇
  2003年   36390篇
  2002年   35748篇
  2001年   58762篇
  2000年   60091篇
  1999年   51011篇
  1998年   14425篇
  1997年   12974篇
  1996年   13187篇
  1995年   12449篇
  1994年   11844篇
  1993年   10900篇
  1992年   41018篇
  1991年   40395篇
  1990年   39912篇
  1989年   38737篇
  1988年   36138篇
  1987年   35373篇
  1986年   33744篇
  1985年   32152篇
  1984年   23932篇
  1983年   20825篇
  1982年   12383篇
  1981年   10935篇
  1979年   22659篇
  1978年   15884篇
  1977年   13733篇
  1976年   12983篇
  1975年   14212篇
  1974年   16692篇
  1973年   16083篇
  1972年   15331篇
  1971年   14238篇
  1970年   13217篇
  1969年   12734篇
  1968年   11987篇
  1967年   10486篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis.  相似文献   
53.
54.
55.
The aim of the present study was to evaluate the antimicrobial activity of two synbiotic combinations, Lactobacillus fermentum with short-chain fructooligosaccharides (FOS-LF) and Bifidobacterium longum with isomaltooligosaccharides (IMO-BL), against enterohaemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli O86. Antimicrobial activity was determined (1) by co-culturing the synbiotics and pathogens in batch cultures, and (2) with the three-stage continuous culture system (gut model), inoculated with faecal slurry from an elderly donor. In the co-culture experiments, IMO-BL was significantly inhibitory to both E. coli strains, while FOS-LF was slightly inhibitory or not inhibitory. Factors other than acid production appeared to play a role in the inhibition. In the gut models, both synbiotics effectively inhibited E. coli O157 in the first vessel, but not in vessels 2 and 3. E. coli O86 was not significantly inhibited.  相似文献   
56.
57.
58.

Background

Arterial vascular anomalies in patients undergoing kidney transplantation (KT) are correlated with a higher incidence of early surgical complications, potentially causing graft loss. Arterial reconstruction allows patients to overcome these surgical challenges, thus minimizing the risk of poor outcomes. The aim of the present study is to retrospectively investigate the safety and effectiveness of the multiple arterial reconstruction technique with a Teflon patch in case of an unavailable aortic patch: to do so, surgical complications, graft function, and patient survival were evaluated.

Methods

During the period January 2009 to August 2016, 202 adult deceased-donor KTs were performed at our center. Group A (n = 27; reconstruction of multiple arteries) and Group B (n = 175; control group) were compared.

Results

No differences were observed between the 2 groups in terms of early postoperative course, with no vascular complication observed in Group A. No vascular patch infections were reported, nor longer cold ischemia time rates. Similarly, long-term survival rates were similar between the 2 groups.

Conclusions

The Teflon-patch arterial reconstruction technique appears to be safe and effective, with an acceptable balance of benefits and potential risks of using a prosthetic material. Studies based on larger series are needed to further validate this approach.  相似文献   
59.
60.
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