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   4284篇
  免费   126篇
  国内免费   28篇
  4438篇
  2023年   10篇
  2022年   45篇
  2021年   66篇
  2020年   17篇
  2019年   9篇
  2018年   26篇
  2017年   25篇
  2016年   300篇
  2015年   1069篇
  2014年   1369篇
  2013年   146篇
  2012年   224篇
  2011年   166篇
  2010年   100篇
  2009年   66篇
  2008年   87篇
  2007年   64篇
  2006年   50篇
  2005年   84篇
  2004年   89篇
  2003年   53篇
  2002年   52篇
  2001年   49篇
  2000年   28篇
  1999年   19篇
  1998年   16篇
  1997年   13篇
  1996年   6篇
  1995年   5篇
  1994年   8篇
  1993年   21篇
  1992年   14篇
  1991年   9篇
  1990年   12篇
  1989年   16篇
  1988年   7篇
  1986年   7篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1980年   3篇
  1979年   3篇
  1978年   4篇
  1974年   3篇
  1973年   4篇
  1967年   3篇
  1966年   3篇
  1957年   6篇
  1955年   3篇
排序方式: 共有4438条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.

Background

Few data are available on the prevalence of erosive and severe esophagitis in Western countries.

Objective

To retrospectively determine the prevalence and the factors predicting erosive esophagitis and severe esophagitis in a large series of endoscopies in Spain.

Design

Retrospective observational study. A multivariate analysis was performed to determine variables predicting severe esophagitis.

Setting

Databases of 29 Spanish endoscopy units.

Patients

Patients submitted to a diagnostic endoscopy during the year 2005.

Interventions

Retrospective review of the databases.

Main Outcome Measurements

Esophagitis severity (graded according to the Los Angeles classification) and associated endoscopic findings.

Results

Esophagitis was observed in 8.7% of the 93,699 endoscopies reviewed. Severe esophagitis (LA grade C or D) accounted for 22.5% of cases of the disease and was found in 1.9% of all endoscopies. Incidences of esophagitis and those of severe esophagitis were 86.2 and 18.7 cases per 100,000 inhabitants per year respectively. Male sex (OR 1.89) and advanced age (OR 4.2 for patients in the fourth age quartile) were the only variables associated with severe esophagitis. Associated peptic ulcer was present in 8.8% of cases.

Limitations

Retrospective study, no data on individual proton pump inhibitors use.

Conclusions

Severe esophagitis is an infrequent finding in Spain. It occurs predominantly in males and in older individuals. Peptic ulcer disease is frequently associated with erosive esophagitis.  相似文献   
995.
尿激酶原-RGDS双功能分子   总被引:1,自引:0,他引:1  
  相似文献   
996.
997.
BackgroundAlthough the short-term benefit of primary percutaneous coronary intervention (PCI) in elderly patients with ST-elevation myocardial infarction (STEMI) has been demonstrated, the final long-term survival benefit is as yet unknown.AimTo assess the final survival benefit of primary PCI as compared to thrombolytic therapy in patients over 75 years of age.MethodsPatients > 75 years with STEMI were randomised to either primary PCI or thrombolysis. Long-term data on survival were available for all patients.ResultsA total of 46 patients were randomised to primary PCI, 41 to thrombolysis. There were no significant differences in baseline variables. After a maximum of 20 years’ follow-up, all patients had passed away. The patients randomised to thrombolysis died after a mean follow-up duration of 5.2 years (SD 4.9) compared to 6.7 years (SD 4.8) in patients randomised to primary PCI (p = 0.15). Thus, the mean final survival benefit of primary PCI was 1.5 years.ConclusionThe final survival benefit of primary PCI as compared to thrombolysis in elderly patients with STEMI is 1.5 years and their life expectancy increases by 28.8%.  相似文献   
998.
The Gene Ontology (GO) is a collaborative effort that provides structured vocabularies for annotating the molecular function, biological role, and cellular location of gene products in a highly systematic way and in a species-neutral manner with the aim of unifying the representation of gene function across different organisms. Each contributing member of the GO Consortium independently associates GO terms to gene products from the organism(s) they are annotating. Here we introduce the Reference Genome project, which brings together those independent efforts into a unified framework based on the evolutionary relationships between genes in these different organisms. The Reference Genome project has two primary goals: to increase the depth and breadth of annotations for genes in each of the organisms in the project, and to create data sets and tools that enable other genome annotation efforts to infer GO annotations for homologous genes in their organisms. In addition, the project has several important incidental benefits, such as increasing annotation consistency across genome databases, and providing important improvements to the GO's logical structure and biological content.  相似文献   
999.
水稻覆膜旱作的生态生理效应   总被引:27,自引:0,他引:27  
  相似文献   
1000.
本文采用经颅多普勒超声(TCD)技术对三组足月初产孕妇共30例进行了TCD主要指标的测定,经统计学处理,正常组、轻度妊高征组的TCD主要指标均在正常人的范围内。而中度、重度妊高征组的TCD主要指标高于正常范围,有显著差异(P<0.0005),左右两侧血管的血流速度不相等,差异超过19.5cm/s。作者等认为TCD技术是一种操作简单,无创伤性、重复,性好、数据可靠的新型检测手段。将TCD作为中度,重度妊高征足月初产孕妇产前、产后的主要监护手段是有一定的现实临床意义。  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