收费全文 | 46971篇 |
免费 | 5075篇 |
国内免费 | 443篇 |
耳鼻咽喉 | 1076篇 |
儿科学 | 1431篇 |
妇产科学 | 1222篇 |
基础医学 | 3859篇 |
口腔科学 | 1516篇 |
临床医学 | 4856篇 |
内科学 | 10337篇 |
皮肤病学 | 1185篇 |
神经病学 | 3346篇 |
特种医学 | 1830篇 |
外国民族医学 | 4篇 |
外科学 | 9817篇 |
综合类 | 891篇 |
现状与发展 | 5篇 |
一般理论 | 27篇 |
预防医学 | 3238篇 |
眼科学 | 1698篇 |
药学 | 2930篇 |
1篇 | |
中国医学 | 266篇 |
肿瘤学 | 2954篇 |
2024年 | 104篇 |
2023年 | 860篇 |
2022年 | 968篇 |
2021年 | 1926篇 |
2020年 | 1704篇 |
2019年 | 1460篇 |
2018年 | 2217篇 |
2017年 | 1753篇 |
2016年 | 2005篇 |
2015年 | 2017篇 |
2014年 | 2621篇 |
2013年 | 3094篇 |
2012年 | 3425篇 |
2011年 | 3257篇 |
2010年 | 2314篇 |
2009年 | 2296篇 |
2008年 | 2533篇 |
2007年 | 2483篇 |
2006年 | 2310篇 |
2005年 | 1953篇 |
2004年 | 1739篇 |
2003年 | 1443篇 |
2002年 | 1268篇 |
2001年 | 536篇 |
2000年 | 412篇 |
1999年 | 450篇 |
1998年 | 448篇 |
1997年 | 401篇 |
1996年 | 457篇 |
1995年 | 393篇 |
1994年 | 273篇 |
1993年 | 205篇 |
1992年 | 274篇 |
1991年 | 290篇 |
1990年 | 197篇 |
1989年 | 248篇 |
1988年 | 202篇 |
1987年 | 174篇 |
1986年 | 174篇 |
1985年 | 202篇 |
1984年 | 163篇 |
1983年 | 121篇 |
1982年 | 127篇 |
1981年 | 104篇 |
1980年 | 94篇 |
1979年 | 79篇 |
1978年 | 85篇 |
1977年 | 79篇 |
1976年 | 64篇 |
1975年 | 78篇 |
Objective
Arch obstruction after the Norwood procedure is common and contributes to mortality. We determined the prevalence, associated factors, and practice variability of arch reintervention and assessed whether arch reintervention is associated with mortality.Methods
From 2005 to 2017, 593 neonates in the Congenital Heart Surgeons' Society Critical Left Heart Obstruction cohort underwent a Norwood procedure. Median follow-up was 3.7 years. Multivariable parametric models, including a modulated renewal analysis, were performed.Results
Of the 593 neonates, 146 (25%) underwent 218 reinterventions for arch obstruction after the Norwood procedure: catheter-based (n = 168) or surgical (n = 50) at a median age of 4.3 months (quartile 1-quartile 3, 2.6-5.7). Interdigitation of the distal aortic anastomosis was protective against arch reintervention. Development of ≥ moderate tricuspid valve regurgitation and right ventricular dysfunction at any point was associated with arch reintervention. Nonsignificant variables for arch reintervention included shunt type and preoperative aortic measurements. Surgical arch reintervention was protective against arch reintervention, but transcatheter reintervention was associated with increased reintervention. Arch reintervention was not associated with increased mortality. There was wide institutional variation in incidence of arch reintervention (range, 0-40 reinterventions per 100 years patient follow-up) and in preintervention gradient (range, 0-64 mm Hg).Conclusions
Interdigitation of the distal aortic anastomosis during the Norwood procedure decreased the risk of arch reintervention. Surgical arch reintervention is more definitive than transcatheter. Arch reintervention after the Norwood procedure is not associated with increased mortality. Serial surveillance for arch obstruction, integrated with changes in right ventricular function and tricuspid valve regurgitation, is recommended after the Norwood procedure to improve outcomes. 相似文献Methods: This Case-Control study was carried out on 96 patients with esophageal cancer and 187 controls. Controls were matched to cases by age and sex. Data were collected through structured interview. Data were analyzed by using chi-square test, T-test and logistic regression, in Stata software version 12.
Results: Our findings show Hookah smoking [OR = 6.1(CI95%:1.2–13.1)] and opium consumption [OR = 2.1(CI95%:1.2–3.5)] were associated with esophageal cancer. Cigarette and pipe smoking, age of onset of smoking, duration of smoking, number of smoking per day, leaving history of smoking, years of leaving smoking, drug withdrawal, number of times of drug withdrawal, a history of drug relapse, alcohol consumption and alcohol dose–response were not related to esophageal cancer.
Conclusion: According to our results, hookah smoking and opium consumption enhance the risk of esophageal cancer in North Khorasan of Iran. We suggest appropriate planning to prevent the esophageal cancer in this district. 相似文献