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   116篇
  免费   9篇
  国内免费   9篇
电工技术   8篇
化学工业   26篇
金属工艺   4篇
机械仪表   9篇
建筑科学   3篇
能源动力   1篇
轻工业   9篇
无线电   14篇
一般工业技术   17篇
原子能技术   22篇
自动化技术   21篇
  2023年   1篇
  2021年   5篇
  2020年   2篇
  2019年   5篇
  2018年   2篇
  2017年   5篇
  2016年   3篇
  2015年   2篇
  2014年   6篇
  2013年   10篇
  2012年   10篇
  2011年   13篇
  2010年   17篇
  2008年   7篇
  2007年   5篇
  2006年   4篇
  2005年   6篇
  2004年   4篇
  2003年   2篇
  2002年   2篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   5篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1991年   1篇
  1988年   1篇
排序方式: 共有134条查询结果,搜索用时 15 毫秒
1.
以循环内皮细胞(CEC)作为血管内皮细胞(VEC)损伤的指示物,以血浆内皮素(ET)和前列环素(PGI2)反映VEC的功能变化,对85例冠心病患者与30例正常人进行对比研究,并对50例不稳定型心绞痛及20例急性心肌梗塞进行了动态观察.结果表明:冠心病外周血中CEC、ET明显升高(P<0.001),PGI2明显下降(P<0.001),尤以不稳定型心绞痛和急性心肌梗塞更显著,与病情的严重程度相一致.提示冠心病VEC损伤,以及它所分泌的内皮源性舒缩因子失平衡参与了冠心病的病理过程。  相似文献   
2.
张英男  李洪胜 《核技术》1993,16(11):665-668
用平衡法核素心室造影自动左心室功能测定法检查了23例正常人、37例无心肌梗塞(CAD-NMI)和14例有心肌梗塞(CAD-MI)冠心病人左心室功能。结果表明,PFR反映心肌缺血改变比其他心功能参数敏感。CAD-NMI组与正常对照组比较,PFR的灵敏度为94.59%,P〈0.001,其他参数的灵敏度依次为TPFR54.05%,P〈0.01;PER54.05,P〈0.01;TPER49.95%,P〈0  相似文献   
3.
研究中医冠心病医案,高效挖掘有益信息规则问题,由于中医医案数据量大、关联性强,针对传统的关联规则挖掘算法处理中医医案数据时存在效率低、收敛速度慢及漏报规则等问题,提出一种小生境技术和基因表达式编程相结合的挖掘关联规则的方法。通过惩罚函数设置支持度阈值,利用小生境技术执行小生境演化、融合算法,结合基因表达式编程算法操作简单、鲁棒性强的优势搜索强关联规则,有效避免了算法早熟,解决了规则冗余。针对治疗冠心病的中医医案进行了验证性实验,实验结果表明,改进算法在提取有效信息的效率上有较大的提高,挖掘结果对冠心病中医临床诊治具有一定的参考价值。  相似文献   
4.
Coronary artery disease (CAD) is a condition in which the heart is not fed sufficiently as a result of the accumulation of fatty matter. As reported by the World Health Organization, around 32% of the total deaths in the world are caused by CAD, and it is estimated that approximately 23.6 million people will die from this disease in 2030. CAD develops over time, and the diagnosis of this disease is difficult until a blockage or a heart attack occurs. In order to bypass the side effects and high costs of the current methods, researchers have proposed to diagnose CADs with computer-aided systems, which analyze some physical and biochemical values at a lower cost. In this study, for the CAD diagnosis, (i) seven different computational feature selection (FS) methods, one domain knowledge-based FS method, and different classification algorithms have been evaluated; (ii) an exhaustive ensemble FS method and a probabilistic ensemble FS method have been proposed. The proposed approach is tested on three publicly available CAD data sets using six different classification algorithms and four different variants of voting algorithms. The performance metrics have been comparatively evaluated with numerous combinations of classifiers and FS methods. The multi-layer perceptron classifier obtained satisfactory results on three data sets. Performance evaluations show that the proposed approach resulted in 91.78%, 85.55%, and 85.47% accuracy for the Z-Alizadeh Sani, Statlog, and Cleveland data sets, respectively.  相似文献   
5.
Stents are very commonly used in the treatment of coronary heart disease. They are permanent vascular support structures that offer a preferred alternative to bypass surgery in certain situations. The purpose of this work is to examine the mechanical behaviour of a stainless steel balloon expandable stent design using computational micromechanics in the context of the finite element method. Deployment and cardiac pulsing loading conditions are considered. Classical phenomenological plasticity theory (J2 flow theory) and physically based crystal plasticity theory are used to describe the stent material behaviour. Parametric studies are carried out using both constitutive theories with a view to determining important stent deployment characteristics such as recoil and foreshortening. Comparisons of the results obtained using both theories illustrate differences, with the crystal plasticity theory models showing closer agreement to published performance data. The implications of this for stent design are discussed.  相似文献   
6.
心音信号是一种典型的非平稳信号,传统信号处理方法的应用受到很大限制。针对此本文提出了基于 Hilbert - Huang Transform(HHT) 的心音信号的分析方法,对冠心病患者的心音信号进行了分析。通过把心音信号分 解为内蕴模式函数,利用Hilbert 变换建立了心音信号的时间- 频率- 能量三维Hilbert 谱分布以及边界谱分布; Hilbert 谱及其边界谱在时域以及频域以较高的分辨率表征了心音信号的时频变化特性,揭示了冠心病患者心音信 号的病理特征;为冠心病的早期无损诊断奠定了坚实基础,临床实践中有较大的指导价值。  相似文献   
7.
The catabolism and structure of high‐density lipoproteins (HDL) may be the determining factor of their atheroprotective properties. To better understand the role of the kidney in HDL catabolism, here we characterized HDL subclasses and the catabolic rates of apo A‐I in a rabbit model of proteinuria. Proteinuria was induced by intravenous administration of doxorubicin in New Zealand white rabbits (n = 10). HDL size and HDL subclass lipids were assessed by electrophoresis of the isolated lipoproteins. The catabolic rate of HDL‐apo A‐I was evaluated by exogenous radiolabelling with iodine‐131. Doxorubicin induced significant proteinuria after 4 weeks (4.47 ± 0.55 vs. 0.30 ± 0.02 g/L of protein in urine, P < 0.001) associated with increased uremia, creatininemia, and cardiotoxicity. Large HDL2b augmented significantly during proteinuria, whereas small HDL3b and HDL3c decreased compared to basal conditions. HDL2b, HDL2a, and HDL3a subclasses were enriched with triacylglycerols in proteinuric animals as determined by the triacylglycerol‐to‐phospholipid ratio; the cholesterol content in HDL subclasses remained unchanged. The fractional catabolic rate (FCR) of [131I]‐apo A‐I in the proteinuric rabbits was faster (FCR = 0.036 h?1) compared to control rabbits group (FCR = 0.026 h?1, P < 0.05). Apo E increased and apo A‐I decreased in HDL, whereas PON‐1 activity increased in proteinuric rabbits. Proteinuria was associated with an increased number of large HDL2b particles and a decreased number of small HDL3b and 3c. Proteinuria was also connected to an alteration in HDL subclass lipids, apolipoprotein content of HDL, high paraoxonase‐1 activity, and a rise in the fractional catabolic rate of the [131I]‐apo A‐I.  相似文献   
8.
9.
目的探讨老年冠心病患者踝臂血压指数与冠脉病变相关性研究。方法造影剂均选用威视派克,按照几支冠状动脉血管存在≥50%的狭窄,分为一支、二支和三支病变,比较冠心病患者的各项指标。结果 2组患者ABI有显著差异(P<0.05)。结论 ABI和冠状动脉病变严重程度呈负相关,是预测冠状动脉硬化程度的一种简单可靠的指标。  相似文献   
10.
目的探讨不同质子泵抑制剂对氯吡格雷抗血小板作用的影响。方法286例在我院实施冠状动脉支架植入术的患者随机分为奥美拉唑40mg/d+氯吡格雷75mg/d组(146例)和泮托拉唑40mg/d+氯吡格雷75mg/d组(140例),连续用药30d,观察主要不良心脑血管事件。结果奥美拉唑组心性死亡、非致死性急性心肌梗死、紧急靶血管血运重建、脑卒中发生率分别为1.37%、2.05%、3.42%、0.68%;泮托拉唑组分别为0.71%、2.85%、2.85%、0.71%,两组无统计学差异(P>0.05)。奥美拉唑组主要不良心脑血管事件、急性亚急性血栓形成发生率分别为7.53%、1.37%,泮托拉唑组分别为7.14%、0.71%,两组亦无统计学差异(P>0.05)。两组出血事件发生率分别为9(6.16%)和9(6.42%),差异无统计学意义(P=0.926)。结论冠心病患者支架植入术后采用氯吡格雷联合奥美拉唑或泮托拉唑治疗的近期疗效相近。  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