成人界嵴形态与组织结构的观察

目的　观察和测量人右心房界嵴和梳状肌的形态和组织结构 ,以探讨其可能的功能。方法　肉眼观察、测量界嵴与梳状肌的有关形态学数据。利用光学显微镜 ,通过HE、Masson和磷钨酸 苏木素染色 ,对界嵴的细胞形态和纤维方向等进行细致观察。结果　①根据界嵴的隆起状况 ,界嵴可分为 4类 :A .全程隆起 (18.6 % ) ;B .上 2 / 3隆起 ,下1/ 3平坦 (2 7.9% ) ;C .上 1/ 3隆起 ,下 2 / 3平坦 (34.88% ) ;D .全程平坦 (18.6 % )。②界嵴的肌纤维可分深、浅两层 ,深层肌纤维纵行 ,与界嵴长轴平行 ;浅层纤维横行 ,仅见于界嵴的中、下部 ,深 浅层纤维之间互相联系。在界嵴各处可见P样细胞。③根据梳状肌的起止和走行 ,梳状肌可分为 3型 :汇聚型、网状型和混合型。结论　窦房结上、下及其深面借过渡纤维与界嵴的普通肌纤维相互联系 ,界嵴纤维可能与结间冲动传导有关。梳状肌走行方向的多样性 ,可能与临床上心脏电流传导的多向异性有关     

A New Proposal of Inverse-Time Characteristics for Overcurrent Relay Based on Microcomputer

The conventional time function of electromechanical relays is hard to coordinate with other relays．In order to promote the application of inverse-time overcurrent relays，a new time function for microprocessor-type relay is proposed．The setting of the trip time for this relay is performed by determining the shortest trip time and the longest trip time，respectively．The results of analysis show that with the new time function，the inverse-time overcurrent relay is easy to coordinate with other relays and has a comparatively shorter trip time，and that the fault happens in the protective zone．     

改善北京公交迎接奥运盛会

本文介绍一种公共交通规划的新模式。它采用单一线路、单一方向、最多换乘一次，就可从城市的一处方便地到达城市的另一处。由于减少了公交线路和车辆，从而提高了公共交通运行速度，达到方便、快捷的目的。希望本文有益于北京公共交通的改善，迎接2008年奥林匹克运动会。     

城市中心地区单向交通系统研究

在城市中心区道路建设基本完成的情况下,通过优化交通组织提高道路运行效率是缓解中心区交通矛盾的必然选择.首先分析了我国城市单向交通的特点,并总结了单向交通的系统模式和基本要求,进而提出了中心区单向交通组织的基本原则.在中心区现状交通问题分析的基础上,进行了单向交通方案及评价体系等方面的研究,提出了中心区实施单向交通的建议,对我国大城市中心区交通改善有一定的借鉴作用.     

Study of the mechanism on the apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase

Objective To investigate the mechanisms of apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase. Methods Human leukemia cell line K562 were exposed to indole-3-acetic acid （IAA） at 20, 40, 60, 80 or 100 mol/L and horseradish peroxidase（HRP） at 1.2 g/mL for varying times. MTT assay was applied to detect the cell proliferation. Flow cytometry was performed to detect the arrest of cell cycle. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） assay was used to measure apoptosis. 2, 7-dichlorofluorescin diacetate （DCFH-DA） uptake was measured to determine free radical by confocal microscope. Content of malondiadehyde （MDA） and activity of superoxide dismutase （SOD） were measured by biochemical methods. Results IAA/HRP initiated growth inhibition of K562 cells in a dose- and time-dependent manner. Flow cytometry revealed that cell cycle arrested at G1/G0 after 24 hours treatment. After 72 hours treatment, apoptotic rate of 100 mol/L IAA group increased to 43.9 %, which was 5 times that of control（P〈0.01）. Content of MDA and activity of SOD increased respectively in treatments compared with control. Meanwhile, IAA/HRP stimulated the formation of free radical, which was increased by IAA concentration-dependently. Conclusion The combination of IAAand HRP can inhibit the growth of Human leukemia cell line K562 in vitro by inducing apoptosis which is associated with the increase of free radical. The combination of IAA and HRP might be a promising chemopreventive and chemotherapeutic agent against human leukemia.     

基于小波变换的船用雷达海杂波小目标检测

强海浪中小目标回波的检测一直是船用雷达目标识别的难点,但现有的统计方法难以准确和全面地描述复杂的海杂波特性.要突破这一局限性,以获得对复杂现象更有效的描述,就迫切要求使用新技术.文中利用小波理论,针对强海浪下点目标和低矮宽大目标二类以往难以检测的目标,通过区分噪声、点目标、低矮宽大目标在小波变换下不同的奇异特征、设计了一套能够识别出点目标和低矮宽大目标的方案.     

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1.Institute of Transportation Engineering, Tsinghua University, Beijing 100084,China； 2.Bureau of Lanzhou Urban Planning and Management, Lanzhou 730030,China     

多采样率EKF及其在感应电机转速估计中的应用

在深入研究EKF算法和多采样率数字控制系统的基础上,建立了多采样率EKF算法,分别推导了其输入和输出算法,并将其应用于感应电机的转速估计中.通过仿真验证了该算法比单采样率扩展Kalm an滤波算法具有更高的信息获取和状态估计能力,并能有效抑止噪声,转速估计误差减小41.7%~87.6%.     

基于可持续发展的城市交通网络定量设计研究

基于可持续发展思想，提出可持续发展的城市交通网络宏观优化模型，对网络设计中的路段变量进行宏观控制具有一定的指导意义。     

非理想电压下有源电力滤波器的电流检测

分析了有源电力滤波器（APF）电流（ip-iq）检测法中影响检测精度的因素，包括低通滤波器和锁相环的频率及相位检测误差．为消除电流检测中非理想电压带来的锁相环检测误差，提出改进的电流（ip-iq）检测法．在该方法中，将APF直流侧电压的调整部分单独考虑，调整量加入到经过低通滤波器滤波并经反变换环节得到的基波电流信息中．这样，未经过反变换的直流侧电压调整值不受锁相环误差的影响．仿真验证了改进方案能有效降低非理想电压对电流检测精度的影响，提高APF性能．