全射流喷头射流元件附壁频率

基于全射流喷头射流元件的工作原理和内部流动状况,分析射流元件附壁频率的影响因素.利用元件两侧压差大小,建立附壁频率计算式,通过射流元件壁面脉动压力测量获得的附壁频率试验数据,频率计算值与试验值符合较好.计算与试验结果表明,附壁频率随元件腔室容积增大,信号水导管长度的变长而减小,随喷头工作压力增大,信号水流量的增大而增大,对于PXH30全射流喷头射流元件,获得信号水流量与附壁频率的线性关系式.在无因次数计算与分析中,喷嘴雷诺数对斯特劳哈数影响较小,斯特劳哈数随欧拉数的增大而减小.附壁频率的研究能指导射流元件的设计和全射流喷头工作状态的调节.     

三峡库区消落区表层土壤重金属污染评价及源解析

三峡库区是我国重要的水源地, 研究库区水陆交错带消落区内土壤重金属污染程度并解析其来源,对水库的水环境和土壤环境具有重要意义。本研究采用地质累积指数, 对三峡库区消落区175 m 水位蓄水前12 个采样区表层68 个土样的土壤重金属Cu、Pb、Zn、Cd、Hg、As 和Cr 污染进行评价, 结果表明: 整个研究区不受Cr 污染, 研究区70%以上面积不受Pb、Cu 和Zn 污染; 研究区As 污染最严重, 其次为Cd 和Hg。利用因子分析法对这7 种重金属来源进行解析的结果表明, 库区消落区土壤重金属源可分为2 大类别:“自然因子”类别元素(Cr、Pb、Cu 和Zn)和“工业污染因子”类别元素(Hg、As 和Cd)。消落区表层土壤重金属污染评价及源解析可为消落区生态环境的综合治理提供参考。     

基于中国情境的食品工业企业信息责任——概念界定、履责行为与影响因素

为深入研究食品工业企业信息责任（Corporate information responsibility, CIR）、履责行为及影响行为的主要因素,基于文献研究与中国实际界定了CIR的概念,并通过对广西462家食品工业企业的调查数据,采用Multivariate Probit回归模型与Binary Logit回归模型稳健性检验研究了企业履责行为与影响行为的主要因素。结果表明,法律规章约束程度、履责成本与企业履责行为相关,且不同行为间具有一定的替代或互补关系。此外,企业决策者年龄与规模、消费者对食品安全信息的需求程度、外部监管力度、政策激励程度、信息技术成熟度与基础设施的便捷性均与企业履责行为相关。由此,提出完善法律规章体系、保持常态化的外部监管力度、有效发挥政策激励效应与提供充足便捷的信息基础设施的政策建议。     

信息不对称对农产品市场交易影响及对策研究

信息经济学的研究认为,市场交易主体拥有不对称信息,信息不对称应该既包括交易双方拥有不相同或不相等的信息,也包括决策主体拥有的信息未达到最有决策所需水平,即信息不对称是指市场主体之间的信息差异.为此,重点分析了农产品市场交易中信息不对称的现象和对农产品市场产生的负面影响,最后从加强制度建设、建立激励与约束机制、加强诚信建设等方面提出了对策.     

Sediment Aggregation and Regulation for Chongqing Reach of the Fluctuating Backwater District in Three Georges Reservoir

Chongqing downtown river reach lies in the fluctuating backwater district of Three Gorges Reservoir(TGR).After running on the 175M scheme of the TGR,it shows that the deposits increase accumulatively with the TGR running in the downtown reach,the bed sand will be finer,the river bar will be widen and higher,there will be bed evolution and the backwater area upwards.The sediment aggregation brings out important influence on harbor,navigation,the infrastructures and eco-environment along both banks of the reach.Combined with various respects of research achievements,the main engineering measurements are put forward in order to decrease the influence,such as soil conservation and building reservoirs upstream to prevent sand sedimentation,narrowing the flow to wash sand,bank regulation,harbor reconstruction and navigable channel treatment,etc.These measures have very good effect on decreasing deposition and eliminating the negative effects.     

我国食品安全中存在的信息不对称及其对策探究

我国食品安全过程存在着因多头监管导致的"政府失灵"和由于信息不对称引起的"市场失灵"的问题。多头监管现状由于受体制限制,改革成本高,且短期内收效甚微。以解决信息不对称入手,提出从制定《食品安全指南》,出台《食品安全信息管理条例》,建立国家食品安全信息网,以及引入"吹哨法案"等解决"市场失灵"问题,以期市场本身能够为消费者提供安全、优质的食品。     

医药卫生领域信息不对称现象及案例分析

通过回顾近年来医药卫生领域的重大案例，从信息不对称的角度全面深入地分析了其发生、发展、后果等，提出具体的对策，包括建立严格的信息披露制度，保障病人的知情权，建立私人医师制，建立中立的医疗服务监管考评机构，重视和完善信息（特别是不良反应）收集和网络传播体系等，并建议大力发展我国医药信息机构。

     

对我国小宗农产品市场建设问题的探讨

小宗农产品价格波动对农业经济发展和人民生活水平的提高产生极大的不利影响.本文在概述了我国小宗农产品价格波动原因的基础上,分析了我国应加强小宗农产品市场建设的问题.提出了应重点提升收购市场、规范批发市场、探索期货市场,以及推进信息化、培育经纪人、建立合作社、增加储备量、出台交易法等加强小宗农产品市场建设的措施和建议.     

PREVALENCE OF LATERAL VENTRICLE ASYMMETRY IN BRAIN MRI STUDIES OF NEUROLOGICALLY NORMAL DOGS AND DOGS WITH IDIOPATHIC EPILEPSY

Asymmetry of the cerebral lateral ventricles is a common finding in cross‐sectional imaging of otherwise normal canine brains and has been assumed to be incidental. The purpose of this retrospective study was to compare the prevalence of ventricular asymmetry in brain MRI studies of normal dogs and dogs with idiopathic epilepsy. Brain MRI archives were searched for 100 neurologically normal dogs (Group 1) and 100 dogs with idiopathic epilepsy (Group 2). For each dog, asymmetry of the lateral ventricles was subjectively classified as absent, mild, moderate, and severe based on a consensus of two observers who were unaware of group status. Ventricular areas were measured from transverse T1W images at the level of the interthalamic adhesion. An asymmetry ratio was calculated as the ratio of the larger to smaller ventricular transverse area. There was excellent agreement between subjective assessments of ventricular asymmetry and quantitative assessments using asymmetry ratios (k = 0.995). The prevalence of asymmetry was 38% in Group 1 dogs and 44% in Group 2 dogs. Assymmetry was scored as mild in the majority of Group 2 dogs. There was no significant association between presence/absence and degree of ventricular asymmetry vs. dog group, age, gender, or skull conformation. Findings from the current study supported previously published assumptions that asymmetry of the lateral cerebral ventricles is an incidental finding in MRI studies of the canine brain.