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   883篇
  免费   37篇
  国内免费   9篇
耳鼻咽喉   5篇
儿科学   42篇
妇产科学   7篇
基础医学   127篇
口腔科学   11篇
临床医学   93篇
内科学   207篇
皮肤病学   46篇
神经病学   30篇
特种医学   100篇
外科学   54篇
综合类   1篇
预防医学   85篇
眼科学   10篇
药学   79篇
中国医学   1篇
肿瘤学   31篇
  2022年   3篇
  2020年   4篇
  2018年   8篇
  2017年   4篇
  2015年   6篇
  2014年   10篇
  2013年   24篇
  2012年   16篇
  2011年   27篇
  2010年   19篇
  2009年   18篇
  2008年   15篇
  2007年   27篇
  2006年   16篇
  2005年   21篇
  2004年   14篇
  2003年   27篇
  2002年   15篇
  2001年   24篇
  2000年   24篇
  1999年   24篇
  1998年   30篇
  1997年   36篇
  1996年   38篇
  1995年   30篇
  1994年   30篇
  1993年   20篇
  1992年   15篇
  1991年   25篇
  1990年   23篇
  1989年   31篇
  1988年   34篇
  1987年   33篇
  1986年   23篇
  1985年   28篇
  1984年   15篇
  1983年   6篇
  1982年   14篇
  1981年   16篇
  1980年   15篇
  1979年   13篇
  1978年   9篇
  1977年   9篇
  1976年   13篇
  1975年   13篇
  1974年   7篇
  1973年   4篇
  1972年   5篇
  1969年   3篇
  1966年   6篇
排序方式: 共有929条查询结果,搜索用时 22 毫秒
81.
目的:动脉弹性与高血压颈动脉粥样硬化的发病以及最终的心脑血管事件密切相关。试验采用血管弹性量化分析技术-血管回声跟踪技术观察苯磺酸氨氯地平对老年高血压患者动脉弹性功能的影响。方法:选取2006-06/12井冈山学院附属医院就诊的52例符合WHO/ISH原发性高血压诊断标准的老年患者为高血压组,入选患者未服用过降压药物或已停用降压药1周以上。高血压组服用苯磺酸氨氯地平,5~10mg/d,服药观察时间24周,治疗前后测定收缩压、舒张压、脉压差及心率,并应用ALOKA超声波诊断装置和血管回声跟踪技术获取动脉弹性功能指标,包括僵硬度指数、颈动脉脉搏波传导速度、反射波增强指数、压力-应变弹性指数、动脉顺应性、颈动脉内膜中层厚度。以51例血压水平正常的老年人为对照组。所有受试者对试验及检测项目知情同意。结果:103例受试者全部进入结果分析。①治疗前高血压组的收缩压、颈动脉内膜中层厚度、僵硬度指数、颈动脉脉搏波传导速度、压力-应变弹性指数各项指标均值都比对照组高,动脉顺应性低于对照组,差异都有显著性意义(P<0.05)。高血压组反射波增强指数与对照组相比差异没有显著性意义(P>0.05)。②高血压组使用苯磺酸氨氯地平24周后,收缩压、颈动脉内膜中层厚度、僵硬度指数、颈动脉脉搏波传导速度、压力-应变弹性指数比用药前降低,差异有显著性意义(P<0.05)。动脉顺应性动脉顺应性升高,差异有显著性意义(P<0.05)。反射波增强指数虽有升高,但差异无显著性意义(P>0.05)。结论:①应用彩色多普勒血管回声跟踪技术可无创、直观监测患者动脉弹性功能。②苯磺酸氨氯地平有改善老年高血压患者动脉弹性的作用。  相似文献   
82.
目的:神经生长因子和脑源性神经营养因子同属神经营养素家族,在神经系统发育及维持正常神经元功能中有重要作用。实验拟证实脊髓全横断损伤三七皂苷对大鼠神经生长因子及脑源性神经营养因子蛋白水平的表达变化产生了影响。方法:实验于2005-06/09在昆明医学院神经科学研究所完成。①实验材料:清洁级健康雌性SD大鼠72只,质量(200±20)g;三七皂苷由云南植物药业提供。②分组及实验过程:大鼠被随机分为4组:假手术组、单纯脊髓全横断损伤组、脊髓全横断损伤 生理盐水(0.5mL/次)组、脊髓全横断损伤 三七皂苷(100mg/kg/次)组,每组18只。于T10水平横断大鼠脊髓,假手术组仅剪开硬脊膜而不损伤脊髓。后2组于术后30min,4,24,48,72h腹腔注射给药各1次。③实验评估:各组于术后3,7及21d分别取6只大鼠L1~2段脊髓制作冰冻切片,采用免疫组织化学ABC法染色。观察并计数脊髓腹角神经生长因子、脑源性神经营养因子蛋白的表达变化;常规苏木精伊红染色观察脊髓的组织病理变化。结果:72只大鼠全部进入结果分析:①脊髓全横断损伤后脊髓出现明显的神经变性坏死、炎性浸润等病理变化,三七皂苷可减轻这些变化。②神经生长因子蛋白主要分布于灰质神经元胞浆及胶质细胞胞核中。在正常脊髓有少量表达,脊髓损伤后7d表达明显升高,直到伤后21d仍高于假手术组(P<0.05);三七皂苷可明显促进其表达,伤后3,7d均明显高于其他各组(P<0.05),在21d时下降但仍高于假手术组(P<0.05)。③脑源性神经营养因子蛋白主要分布于腹角的运动神经元胞浆中,胶质细胞未见着色。在正常脊髓有少量表达,脊髓损伤后7d表达明显升高(P<0.05),伤后21d已下降,同假手术组相比差异无显著性(P>0.05);三七皂苷可明显促进其表达,伤后3,7,21d均明显高于所有对照组(P<0.05)。结论:三七皂苷可减轻脊髓横断性损伤后继发损害,增加神经生长因子、脑源性神经营养因子表达量及提前神经生长因子、脑源性神经营养因子表达时间,提示其可以促进脊髓损伤早期修复。  相似文献   
83.
Left atrium (LA) size is a well-studied predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). Yet, there is still little agreement on the best imaging technique to size the LA, and on the most appropriate sizing parameter. Volumetric assessment of LA with three-dimensional rotational angiography (3DRA LA volume index) might be a valid alternative to the commonly used transthoracic echocardiography (TTE LA volume index). The aim of our study was to investigate whether LA volume by 3DRA at the time of PVI is able to predict the risk of atrial fibrillation recurrence. We analysed 352 consecutive patients with symptomatic paroxysmal or persistent atrial fibrillation referred for PVI to our Institution. In all patients, LA volume index (LAVI) was assessed by TTE and by 3DRA. Sinus rhythm was restored after PVI in 348 patients (99%). Average TTE-LAVI and 3DRA-LAVI were 37?±?12 and 83?±?18 ml/m2, respectively. At a median follow-up of 19 (12, 24) months, 27% of patients had AF recurrence after the first PVI. At the univariate analysis, persistent AF (p?<?0.01), use of anti-arrhythmic drugs (AAD) (p?<?0.05) and 3DRA-LAVI (p?<?0.01) were significantly associated with AF recurrence. In contrast, none of the echocardiographic parameters considered, including TTE-LAVI, was associated with AF recurrence (p?=?0.29). At the multivariate analysis, 3DRA-LAVI was the only independent predictor for AF recurrence (HR 1.01 [1.00–1.03], p?=?0.017). Left atrial volume measured with 3DRA is superior to TTE assessment and to AF history in predicting atrial fibrillation recurrence after PVI.  相似文献   
84.
The aim of the present study was to assess whether cGMP release to ANP stimulation can be a biochemical marker of subsequent successful electrical cardioversion of lone atrial fibrillation to sinus rhythm. For this purpose, we studied 13 patients with chronic, lone atrial fibrillation of less than one year's duration who presented to our laboratory for electrical therapy of their arrhythmia. Prior to electrical cardioversion, peripheral venous cGMP levels were assessed at baseline and following an tntravenous challenge of 50 Ug human ANP. Venous blood samples for cGMP assessment were taken a) at baseline, b) 5 and 10 mins after the end of ANP infusion. ANOVA of repeated measures was used for statistical analysis. Eight of the study patients were successfully cardioverted to sinus rhythm, while the remaining 5 were not. Although no difference was noted between the two groups regarding the mean time of arrhythmia duration as well as left atrial and ventricular dimensions, ANP stimulation provoked significantly greater cGMP release in patients whose arrhythmia reverted to sinus rhythm, when compared with that of patients whose arrhythmia persisted (p<0.001). Therefore, cGMP levels following ANP challenge might discriminate between patients with chronic AF who are going to be successfully cardioverted and those who are not. These findings imply that the underlying atrial disease might be different in extent/nature between patients with lone AF responsive to cardioversion and those with resistant arrhythmia.  相似文献   
85.
BACKGROUND: The aim of cardiac resynchronization therapy is correction of left ventricular (LV) dyssynchrony. However, little is known about the optimal timing of LV and right ventricular (RV) stimulation. OBJECTIVES: The purpose of this study was to evaluate the acute hemodynamic effects of biventricular pacing, using a range of interventricular delays in patients with advanced heart failure. METHODS: Twenty patients with dilated ischemic (n = 12) and idiopathic (n = 8) cardiomyopathy (age 66 +/- 6 years, New York Heart Association class III-IV, LV end-diastolic diameter >55 mm, ejection fraction 22% +/- 18%, and QRS 200 +/- 32 ms) were implanted with a biventricular resynchronization device with sequential RV and LV timing (VV) capabilities. Tissue Doppler echocardiographic parameters were measured during sinus rhythm before implantation and following an optimal AV interval with both simultaneous and sequential biventricular pacing. The interventricular interval was modified by advancing the LV stimulus (LV first) or RV stimulus (RV first) up to 60 ms. For each stimulation protocol, standard echocardiographic Doppler and tissue Doppler imaging (TDI) echo were used to measure the LV outflow tract velocity-time integral, LV filling time, intraventricular delay, and interventricular delay. RESULTS: The highest velocity-time integral was found in 12 patients with LV first stimulation, 5 patients with RV first stimulation, and 3 patients with simultaneous biventricular activation. Compared with simultaneous biventricular pacing, the optimized sequential biventricular pacing significantly increased the velocity-time integral (P <.001) and LV filling time (P = .001) and decreased interventricular delay (P = .013) and intraventricular delay (P = .010). The optimal VV interval could not be predicted by any clinical nor echocardiographic parameter. At 6-month follow-up, the incidence of nonresponders was 10%. CONCLUSION: Optimal timing of the interventricular interval results in prolongation of the LV filling time, reduction of interventricular asynchrony, and an increase in stroke volume. In patients with advanced heart failure undergoing cardiac resynchronization therapy, LV hemodynamics may be further improved by optimizing LV-RV delay.  相似文献   
86.
87.

Objectives

The aim of this study was to appreciate the safety and effectiveness of transradial percutaneous coronary intervention (PCI) with rotational atherectomy for highly calcified left main coronary artery (LMCA) disease in octogenarians.

Background

Conventional surgery is still considered the preferred management for LMCA disease; but, when the lesion is severely calcified, and the patient is unsuitable for surgery, the interventional cardiologist faces a complex PCI traditionally approached by femoral access.

Methods

Between June 2004 and December 2010, octogenarians with calcified LMCA disease who were primary denied for surgical revascularization were enrolled. Procedural success and major adverse cerebral and cardiovascular events (MACCE) including death, nonfatal myocardial infarction, target lesion revascularization (TLR), or stroke during long‐term follow‐up were evaluated.

Results

Forty‐two consecutive patients≥80 years had undergone stenting for calcified LMCA disease (13 with rotational atherectomy, the “Rota” group, and 29 without rotational atherectomy, the “without Rota” group). Procedural success was good (92.3% vs. 96.6%, respectively, p = NS). Mean follow‐up time was 25.7 ± 21.4 and 28 ± 32.3 months, respectively. There was a TLR in 25% and 11.1%, respectively; p = NS. No difference was detected in terms of overall in‐hospital or long‐term mortality or MACCE.

Conclusion

Rotational atherectomy followed by stent implantation by transradial approach, when applied to heavily calcified lesions, appeared to be a safe and effective strategy for the treatment of LMCA disease in octogenarians who were refused for surgery. (J Interven Cardiol 2013;26:173–182)
  相似文献   
88.
A newborn with pulmonary atresia with intact ventricular septum (PA-IVS) was treated with radiofrequency current perforation of the atretic pulmonary valve. As the right ventricle was hypoplastic (z-value of the tricuspid valve: —4) the arterial duct was stented with a Gianturco-Roubin GR II stent. Early postinterventionally, the patient became cyunotic and compromised blood flow across the stented ductus arteriosus despite adequate stent position was detected echographically. The newborn was treated successfully with the implantation of a Palmaz stent (Johnson & Johnson Interventional Systems, Warren, NJ, USA) into the obstructed Gianturco-Roubin GR II stent. The Gianturco-Roubin GR II stents might be associated with the risk of early stent stenosis after implantation in actively contracting tissues like the ductus arteriosus. In patients with early stent stenosis after ductal stenting, bailout implantation of a subsequent stent can be performed. Transcatheter procedures can be effective means for therapy of PA-IVS . (J Interven Cardiol 2000;13:39–44)  相似文献   
89.
90.
The effectiveness of inhaled corticosteroids in the control of daytime symptoms in asthma is well established, but the specific use against nocturnal asthma has not been systematically studied in Asian patients. This study examined the effect of treatment with inhaled budesonide on the nocturnal variation in measurements of airway calibre, bronchial hyperresponsiveness to inhaled histamine and circulating neutrophil chemotactic activity in Asian patients with nocturnal asthma. Thirty patients, with nocturnal asthma, were randomized into a 2-month, double-blind, parallel group study. Twice as many subjects were allocated to the group who received two consecutive months of inhaled budesonide 1600 μg daily as to the group who received placebo followed by budesonide. Spirometry, lung mechanics, bronchial hyperresponsiveness and serum neutrophil chemotactic factor (NCA) were measured at 16.00 h, 22.00 h and at 04.00 h on 3 days and nights, 4 weeks apart before and after either placebo or budesonide. The combined measurements for the two groups at 04.00 h before and after treatment with budesonide were: forced expiratory volume in 1 s (FEV1) mean (SEM) litres 1.34 (0.17) before, 2.00 (0.19) after; thoracic gas volume (TGV) litres 3.05 (0.32) before, 2.25 (0.14) after; specific airway conductance (sGaw) (cmH20.0 sec)?1 0.39 (0.07) before, 1.16 (0.17) after; PD20μg geometric mean 1.16 before, 44.74 after; neutrophil chemotactic activity (NCA) in units of graduations of migration 98.8 (4.2) before, 101 (14.2) after. The data showed that short and intermediate term high dose inhaled budesonide is an effective specific treatment for nocturnal asthma in Asian patients, resulting in marked improvements in symptoms and in lung mechanics, and reductions in the diurnal variations in bronchial hyperresponsiveness, before any change could be demonstrated in a circulating marker of airway inflammation.  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