体操运动训练对机体心血管功能的影响     

梁伟怡  熊若虹  李岩 《成都体育学院学报》1997,(4)

采用超声多普勒和多道生理记录仪研究了１８名高校体操运动员和１２名普通大学生在安静时、运动负荷后即刻和恢复期心血管系统功能的变化情况。结果表明，体操运动训练能有效地提高每搏输出量，降低心率，减小运动负荷心肌紧张性改变。提示高校体操训练对机体心血管机能有良好的作用。  相似文献   

人体姿势对脑血流速度的影响     

姚宝元  许可 《吉林体育学院学报》2006,22(3):71-72

为探讨姿势对脑血流速度（cerebral blood flow velocity, CBFV）的影响，应用CBS-Ⅱ经颅多普勒诊断系统，分别在卧位、坐位、蹲位和站位安静时，对20名男女大学：主的大脑中动脉平均血流速度（MCAVmean）进行了检测，并对检测值进行了方差分析。得出不同的姿势对脑血流速度的影响不同，由一种姿势转换成另一种姿势时，脑血流速度会发生显著的变化的结论。  相似文献   

用光子模型讨论多普勒效应     

罗淦权 《湖州师范学院学报》1991,(6)

本文用光子模型来讨论多普勒效应及相位不变性,与波动法有殊途同归的效果.  相似文献   

多普勒效应测速实验仪的开发   总被引：2，自引：1，他引：2  

韩超  李亭  李华 《实验室研究与探索》2007,26(1):19-21

介绍了一种基于多普勒效应的大学物理实验用测速系统。运动小车反射的超声信号经A/D采样后通过USB2.0进行数据传输,在PC端进行声波信号的频谱分析,最终得到小车的速度和位置信息。本文还讨论了多种算法在实验分析中的应用。  相似文献   

深奥原理浅显化，抽象知识直观化——“科学有曰之多普勒效应”教育活动设计          下载免费PDF全文

张哲侨 《自然科学博物馆研究》2020,(1):69-76

在科技馆基于展览的教育活动中经常会遇到科学内容比较深奥、抽象,难以直接观察、体验的问题。山西科技馆“科学有曰之多普勒效应”教育活动将深奥的科学原理转化为浅显的基础知识,将抽象知识转化为可观察、可体验的直观现象,并采用“5E教学模式”,综合运用体验式学习和情境教学等教学方法。引导学生自主探究有关多普勒效应的知识,利用所学知识解释多普勒效应原理并了解其在天文学和生活中的应用。  相似文献   

Effect of Ultrafine particles on Flow Field and Transport Properties near the nterface Around a Moving Bubble     

马友光  徐世昌  冯惠生 《天津大学学报(英文版)》2004,10(1)

Laser Doppler Anemometer has been used to measure the flow field characteristics near the interface around a moving bubble in the presence of ultrafine particles. In order to model a moving bubble, the bubble was fixed into the counter-flow liquid by a metal mesh. Experimental materials are air and water, and the particles are complex oxidate powder. Experiments were carried out under the operating conditions: the liquid flow velocity u0 is 12.6 cm/s, the equivalent diameter de is 0.6 cm, the mass concentration of particle is 0.2%,the average particle diameter is about 10 nm and the density is 2 g/cm3. The velocity profiles of both frontal and tail-vortex areas were measured respectively. The experimental results show that the velocity fields are obviously changed in the existence of particles. In the frontal area of the bubble, both tangential and normal velocities decrease due to the presence of particles, but in tail vortex area, the tangential velocities increase remarkably, and normal velocities rise gradually from the center towards the fringe in the opposite tendency to that of no particles. The influences of flow field change in the presence of particles on gas-liquid mass transfer are analyzed and discussed.  相似文献   

Benefits of combination of electroencephalography, short latency somatosensory evoked potentials, and transcranial Doppler techniques for confirming brain death   总被引：1，自引：0，他引：1  

Wang K  Yuan Y  Xu ZQ  Wu XL  Luo BY 《Journal of Zhejiang University. Science. B》2008,9(11):916-920

Objective: Optimization of combining electroencephalography (EEG), short latency somatosensory evoked potentials (SLSEP) and transcranial Doppler (TCD) techniques to diagnose brain death. Methods: One hundred and eleven patients (69 males, 42 females) from the major hospitals of Zhejiang Province were examined with portable EEG, SLSEP and TCD devices. Re-examinations occurred ≤12 h later. Results: The first examination revealed that the combination of SLSEP and EEG led to more sensitive diagnoses than the c...  相似文献   

多普勒效应教学研究     

方保龙 《合肥联合大学学报》2005,15(4):69-71

在多普勒效应教学中，利用波源与观察者之间的相对运动，对波源和观察者建立不同的坐标系，写出不同坐标系波函数的表达式；根据波传播过程中在两个坐标系中有相同的相位，分析导出多普勒效应，并引伸至相对论下的多普勒效应。  相似文献   

Haemodynamic changes after prolonged water immersion     

Alain Boussuges  Laurent Mourot  Yves Jammes  Bruno Melin  Jacques Regnard 《Journal of sports sciences》2013,31(6):641-649

Abstract

Thermoneutral water immersion increases cardiac preload and changes the neuroendocrine settings of blood volume regulation. The resulting marked diuresis may lead to significant haemodynamic changes after the end of a prolonged water immersion. Ten volunteers underwent 6 h of complete thermoneutral water immersion. Changes in cardiovascular status were assessed 1 h and 16 h after water immersion. Haemodynamic changes were assessed by Doppler echocardiography. Arterial wall distensibility was estimated by pulse wave velocity analysis. One hour after water immersion, mean weight loss was 1.78 kg and urine volume amounted to 1.5 litres. Echocardiographic measurements evidenced a significant decrease in dimensions of the left cardiac chambers and inferior vena cava. The decreased cardiac preload was paralleled by a lower stroke volume and cardiac output. A peripheral vasoconstriction associated with a relative decrease in the lower limb blood flow was evidenced by an increase in carotid-pedal pulse wave velocity and by a decrease in ankle brachial index. Sixteen hours after water immersion, cardiac preload and cardiac output remained below baseline values and peripheral vascular tone was still higher than at baseline. Marked haemodynamic changes had not returned to baseline 16 h after water immersion. There is a need to design fluid-replacement protocols to improve this recovery.  相似文献   

基于RD域分块的改进距离徙动成像算法     

徐海胜  宋红军  华斌  袁志辉 《中国科学院大学学报》2011,28(4):498-504

研究了二维频域成像算法,提出一种基于RD域分块的改进距离徙动成像算法,并将该算法与近似算法和一般逆变标算法进行了点阵目标仿真和运算效率比较.当测绘带较宽且距离徙动较大时,该算法聚焦性能优于近似算法和一般逆变标算法.通过比较还可看出该算法运算效率高于逆变标算法.最后用实测数据仿真验证了该算法是可行的.  相似文献