TCD study of hemodynamic changes in PCA response to photic stimulation     

郑旭宁  朱雄超  徐秋芳  黄一宁  柳扬 《浙江大学学报(A卷英文版)》2003,4(2):228-231

Objectives: During visual stimulation, the elevated metabolism rate will couple with increase of blood flow velocity(BFV) in posterior cerebral artery(PCA). This study with TCD was aimed to investigate whether the coupling might change according to the different vasoneuronal conditions. Methods: Ninety-nine volunteers including 24 hypertension(HT) patients and 2 patients suffering from both HT and diabetes mellitus(DM) were enrolled in this trial. BFV and pulse indexes(PI) in P2 segments of PCA on both sides were monitored during visual stimulation. Results: In all subjects, Mean BFV increased and PI went down in response to visual stimulation. The percentages of changes (ΔV and ΔP) of both mean BFV and PI were larger in young group(<55 years old) than in old one(≥55 years old). There was significant positive correlation between ΔV and ΔP. Multivariated regression analysis did not show HT and DM, but age related to ΔV(ΔP). We did not find significant difference of ΔV(ΔP) between left and right sides. Conclusions: Blood flow velocity in PCA P2 segment increased due to decreased cerebrovascular resistance during visual stimulation and the response weakened with aging of the patient.  相似文献   

从会计信息失真角度谈权责发生制与现金流动制的运用     

龙霞 《湖北广播电视大学学报》2006,23(2):115-117

现金流动制是一个比权责发生制更为合理的确认基础。现金流动制若破解技术操作难题,对权责发生制进行补充和修正,更能确保会计信息质量,从而更好地满足企业内外部信息使用者的需要。  相似文献   

Physical modelling and scale effects of air-water flows on stepped spillways     

CHANSONHubert GONZALEZCarlosA. 《浙江大学学报(A卷英文版)》2005,6(3):243-250

INTRODUCTION The stepped channel design has been used fomore than 3500 years. Greek and Minoan engineerswere probably the first to design an overflow steppedweir and stepped storm waterways respectively(Chanson, 2001). Later, Roman, Moslem, Mughaand Spanish designers used a similar technique. Thesteps increase significantly the rate of energy dissipation taking place on the channel face, reducing thesize of the required downstream energy dissipationand the risks of scouring. Rec…  相似文献   

平衡阀的应用   总被引：1，自引：0，他引：1  

周俊丰 《河北职业技术学院学报》2007,7(2):13-14

平衡阀是一种具有特殊功能的阀门,它具有良好的特性,能够合理分配流量,实现流量定量,有效地解决供热系统中存在的室温冷热不均问题。  相似文献   

两级传播理论与全球化时代的对外报道     

唐佳梅 《新闻界》2008,(5):13-15

本文探讨如何运用两级传播理论,通过影响对外报道中的意见领袖来间接影响国际受众,获得更好的对外传播效果,提高中国媒体的国际影响力,营造有利于国家发展的良好国际舆论环境。  相似文献   

组织知识创新能力开发的内在心智基础及演化过程分析     

龙飞  戴昌钧 《图书情报知识》2008,(2):85-91

组织知识创新能力是指组织作为一个整体通过对各类与组织发展相关的新知识的发现与发明,从而创造产生出新的组织知识的能力。在组织知识创新能力开发过程中,组织共享心智模型既为组织中各种知识的复杂协作与一体化提供着潜在的认知背景,又为组织知识载体———知识员工的创造力的激发提供着内在的精神意义支持。本文正是基于这一假设出发,按照组织知识创新流程的不同阶段,对组织共享心智模型在组织知识创新能力开发过程中的作用进行了系统的分析,最后给出一个拓扑算子模型进行了数理实证。  相似文献   

Low frequency oscillatory flow in a rotating curved pipe     

陈华军  章本照  苏霄燕 《浙江大学学报(A卷英文版)》2003,4(4):407-414

The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of biparameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on the low frequency oscillatory flow were examined in detail. The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without rotation. During a period, four secondary vortexes may exist on the circular cross-section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis force to centrifugal force and the axial pressure gradient. Project (No: 10272096) supported by the National Natural Science Fundation of China  相似文献   

Three dimensional free convection couette flow with transpiration cooling     

JAIN N.C. GUPTA P. 《浙江大学学报(A卷英文版)》2006,7(3):340-346

INTRODUCTION In recent years, the subject of free convection flow has attracted the attention of a number of scholars because of its possible applications to several geophysical problems. In view of these applications, a series of investigations were made to study the flow past a vertical wall. Transpiration cooling can very effectively pro-tect certain structural elements in turbojet and rocket engines, like combustion chamber walls, exhaust nozzles or gas turbine blades from hot gases. …  相似文献   

基于动态能力视角的知识流动过程模型构建     

孙红霞  生帆  李军 《图书情报工作》2016,60(14):39-46

[目的/意义]在知识经济时代,知识作为组织竞争优势的源泉,需要得到更深入的研究和理解。从动态能力视角研究知识流动过程,以期为组织完善知识流动过程提供理论支持。[方法/过程]对知识在组织内与组织间的流动进行综合分析,考虑知识在不同层次的流动,深入理解知识的流动模式。在此基础之上,考虑动态能力对组织间和组织内知识流动的影响,从而从动态能力视角构建出多层次的知识流动模型。[结果/结论]基于动态能力视角的知识流动过程模型表明,组织需要重视知识流动的作用,这对组织知识库的扩充与利用知识形成竞争优势至关重要;而且,组织还需要在知识流动过程中着重构建并发展相关能力,从而将能力与不同层次的知识流动过程相结合,促进知识流动。  相似文献   

基于改进支持向量机模型的交通拥堵情况预测     

辜丽琼  宋祖康  杨阳 《教育技术导刊》2019,18(12):61-64

随着机动车数量的迅猛增加,城市交通拥堵状况日益严峻,城市道路拥堵严重影响着居民的日常工作和生活,因此研究道路拥堵程度,以及对道路拥堵变化进行预测则显得尤为重要。为此,构建一个基于拥堵指标的MM-SVR模型,在考虑下一时段可能到达路段的潜在车流量情况下,对道路拥堵情况进行深入探究。首先,融合速度、区域内交通流量构建道路拥堵程度指标,然后基于历史数据构建将马尔科夫链与支持向量机预测相结合的MM-SVR模型对道路拥堵进行预测,以向前[n]阶状态的交通流量和速度作为输入量,将道路拥堵程度指标作为输出量。在实例验证中,使用广州市某片区的实时交通流数据对模型效果进行评测,并且使用SVR以及Adaboosting模型进行对比实验。实验结果表明,该模型无论是在拟合优度还是预测误差上均优于对比模型,在实时反映交通流拥堵情况方面有着良好表现。  相似文献