关于非线性机床再生颤振的Hopf分支

本文讨论机床再生颤振的方程变形后的方程在参数空间(a,b,c)中周期分支的情况.给出分支曲面的轮廓,还给出在原点邻域内周期解和周期的近似表达式.     

相对论Dirac粒子的颤动—自旋耦合算符

本文根据相对论量子理论中自由Dirac粒子的自旋角动量并非运动常数的问题进行了探讨,考虑粒子的颤动运动对其自旋的影响,提出相对论粒子的颤动—自旋耦合算符,并证明该算符是一运动常数,在过渡到非相对论情况下,脱耦为普遍量子理论中的自旋算符,并对它的物理性质和代数性质进行了讨论。     

浅谈剩余电流动作保护器

剩余电流动作保护器（RCD）在我国是从80年代新兴发展的一种保护电器。随着我国引进IEC标准后开始采用TN-S、TN-C-S、TT系统和IT系统,这些系统都具有单独的PE线,并且该保护开关体积小、造价低、便于维护和安装,能有效地保护人身及设备的安全等特点,引起了广大电力同行和用户的关注和青睐,掀起了一场低压配电网络安全保护的技术革命,RCD也随之大量装用。本文试图通过我国对漏电保护开关的原理及应用分析,探讨漏电保护开关的正确设置安装、维护和使用方法,以供同行及用户参考。     

论《颓败线的颤动》的时间境域与意义生成

鲁迅《野草》中的名篇《颓败线的颤动》建构了具有现代品质的时间意识,“空无的时间”和“充实的时间”是其并存的两种时间经验,分别体现了两种不同的意义建构模式。“抛入的此在时间”和“断裂的梦幻时间”是其共有的两种现在的瞬时类型,使时间经验呈“空间化”的聚集和撒播。这种“执着现在”的时间意识与文本所生成的意义结构联系在一起,共同参与和介入了作家个人时间的觉醒,这种主观时间的绽出与确信具有现代品质。     

噪声整形滤波器的优化设计

量化误差或再量化误差常被认为具有白噪声的特性。由于人耳对这种低电平宽频带噪声的灵敏度并不随频率均匀变化，所以在设计噪声整形滤波器时，人们采用了一种频率计权曲线来反映低电平噪声对听觉的影响。本文将介绍如何优化设计满足人耳听音的噪声整形滤波器。     

Ultrasound ablation of pulmonary veins for treatment of paroxysmal atrial fibrillation

Objective: to evaluate the efficacy and safety of ultrasound ablation of pulmonary veins for treatment of paroxysmal atrial fibrillation. Methods: The study population consisted of 9 patients with 5 males and 4 females enrolled consecutively who had idiopathic paroxysmal atrial fibrillation(AF). The ultrasound balloon was positioned through a special sheath to the orifice of the target vein by a transseptal procedure. The balloon was inflated with contrast-mixed saline (contrast:saline = 1:4) whose volume was decided by the diameter of the target pulmonary vein. The ablation energy was usually set up at 35 to 40 watts with temperature controlled at 60 degrees C. The duration of each ablation was about 120 seconds which was repeated not over 10 times. Results: The average duration of the total procedure was 132+/-68 min for our patients. The average fluoroscopy time was 33+/-17 min. With a mean follow-up of 16+/-8 months after the procedure, AF was completely eliminated in 4 patients without antiarrhythmic drugs. The episodes of atrial fibrillation were eliminated in 2 patients with low dosage of oral amiodarone (0.1, once daily) which was ineffective before the procedure. The frequency of episodes was similar to that before the procedure in 3 patients. There were no complications such as hemopericardium, air embolism and stenosis of the pulmonary veins by angiography, related to the procedure. Conclusion: Ultrasound ablation of the pulmonary veins is a new approach to treat paroxysmal atrial fibrillation. Before we determined its value, we need to do more researches with bigger sample, randomization and comparison design.     

心房纤维性颤动电生理重构机制研究进展

心房纤维性颤动(AF)是临床上常见的持续性快速心律失常,近年研究显示其具有自身延续性,即有心房电生理重构,对其发病机理有新的理解。形成心房电生理重构的主要机制是离子通道的重构。其中,在影响心房电生理重构的过程中,不同的钠离子通道、钾离子通道和钙离子通道均表现出重构现象。而mRNA浓度下降会导致通道电流密度降低。离子通道的变化既是AF的结果,又是维持AF的电生理基础。许多抑制AF的药物作用机理是减少电生理重构,故AF电生理重构的机制是十分复杂的问题。     

对照与对立并举艺术背后的矛盾和抗争——重读《颓败线的颤动》

《颓败线的颤动》在鲁迅的散文诗集《野草》中是非常独特的一篇。无论是其修辞手法的运用还是思维方式的展现都有其鲜明之处,特别是对照与对立并举的运用。这种手法和思维的运用对于表现整篇散文诗的矛盾主题——牺牲与杀戮、绝望与抗战,有着不可忽视的推动力。     

迷走神经的抗心律失常研究

迷走神经的抗心律失常研究符史干（海南医学院生理教研室，海口５７０００５）关键词迷走神经，心律失常，受体，心室纤维颤动，心肌缺血中图分类号Ｒ３３８．５心脏既有自律性，又受神经和体液因素的影响。过去对迷走神经的心脏效应已有深入的认识。近年来，迷走神经的抗...