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   1338422篇
  免费   98169篇
  国内免费   2232篇
耳鼻咽喉   19188篇
儿科学   44120篇
妇产科学   38923篇
基础医学   194108篇
口腔科学   36738篇
临床医学   114429篇
内科学   264365篇
皮肤病学   27464篇
神经病学   105458篇
特种医学   52167篇
外国民族医学   371篇
外科学   208393篇
综合类   27278篇
现状与发展   1篇
一般理论   391篇
预防医学   97885篇
眼科学   30357篇
药学   101816篇
  1篇
中国医学   2601篇
肿瘤学   72769篇
  2018年   13424篇
  2016年   11245篇
  2015年   12891篇
  2014年   18002篇
  2013年   27189篇
  2012年   37827篇
  2011年   40441篇
  2010年   23649篇
  2009年   22187篇
  2008年   38953篇
  2007年   42087篇
  2006年   42572篇
  2005年   41865篇
  2004年   40207篇
  2003年   38881篇
  2002年   38199篇
  2001年   58579篇
  2000年   60014篇
  1999年   51244篇
  1998年   14903篇
  1997年   13404篇
  1996年   13598篇
  1995年   12799篇
  1994年   12201篇
  1993年   11247篇
  1992年   41302篇
  1991年   40670篇
  1990年   40148篇
  1989年   38952篇
  1988年   36362篇
  1987年   35583篇
  1986年   33961篇
  1985年   32469篇
  1984年   24318篇
  1983年   21161篇
  1982年   12858篇
  1981年   11385篇
  1980年   10605篇
  1979年   22817篇
  1978年   16138篇
  1977年   13970篇
  1976年   13164篇
  1975年   14403篇
  1974年   16849篇
  1973年   16239篇
  1972年   15448篇
  1971年   14335篇
  1970年   13295篇
  1969年   12805篇
  1968年   12049篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
62.
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   
63.
64.
65.
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   
66.
67.
68.

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   
69.
70.
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