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   1275407篇
  免费   94239篇
  国内免费   1987篇
耳鼻咽喉   18185篇
儿科学   42261篇
妇产科学   37841篇
基础医学   187052篇
口腔科学   35382篇
临床医学   108078篇
内科学   251459篇
皮肤病学   26550篇
神经病学   99290篇
特种医学   50006篇
外国民族医学   366篇
外科学   197787篇
综合类   26509篇
现状与发展   1篇
一般理论   300篇
预防医学   92488篇
眼科学   29029篇
药学   97770篇
  1篇
中国医学   2497篇
肿瘤学   68781篇
  2018年   11830篇
  2015年   11640篇
  2014年   16027篇
  2013年   24375篇
  2012年   33586篇
  2011年   36009篇
  2010年   21241篇
  2009年   20047篇
  2008年   35015篇
  2007年   37994篇
  2006年   38547篇
  2005年   37871篇
  2004年   36435篇
  2003年   35426篇
  2002年   34982篇
  2001年   58118篇
  2000年   59608篇
  1999年   50711篇
  1998年   14242篇
  1997年   12817篇
  1996年   13088篇
  1995年   12352篇
  1994年   11766篇
  1993年   10870篇
  1992年   41001篇
  1991年   40368篇
  1990年   39898篇
  1989年   38721篇
  1988年   36121篇
  1987年   35361篇
  1986年   33730篇
  1985年   32145篇
  1984年   23925篇
  1983年   20822篇
  1982年   12380篇
  1981年   10929篇
  1980年   10208篇
  1979年   22641篇
  1978年   15881篇
  1977年   13731篇
  1976年   12975篇
  1975年   14202篇
  1974年   16687篇
  1973年   16082篇
  1972年   15320篇
  1971年   14229篇
  1970年   13218篇
  1969年   12731篇
  1968年   11978篇
  1967年   10479篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
51.
52.
53.
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   
54.
55.
56.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
57.

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   
58.
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