排序方式: 共有62条查询结果,搜索用时 15 毫秒
21.
国内外产排污系数开发现状及其启示 总被引:9,自引:2,他引:7
通过对国外产排污系数开发应用现状的系统分析,重点研究了美国产排污系数的基本特征、开发方法和途径以及遇到的障碍,结合我国产排污系数的开发现状和存在的问题,得出了对我国该领域研究的启示:建立产排污系数开发和管理的官方常设机构,定期发布最新数据;构建国家产排污系数信息管理平台;细化行业污染源分类,完善污染物种类;深入对产排污系数开发的理论体系和技术方法的研究,建立产排污系数核算方法学.指出了产排污系数不确定性评估研究将是未来重要的研究内容. 相似文献
22.
The results of the census of stray dogs and data on their territorial distribution in the city of Petrozavodsk are reported. The population density of these animals has been found to vary within the urban area, depending mainly on the availability of secluded areas to live in and on population control by municipal services. 相似文献
23.
The distribution of activity of bank voles along a live-trap line can be approximated by the normal law. The standard deviation is a stable characteristic of the sizes of regularly used space. Occurrence of an animal beyond a distance of three standard deviations from the center of activity is regarded as an expression of nonresidence. Different types of space use have been found: equilibrium and drifting home ranges, movements, and excursions. Formal criteria for distinguishing space use patterns are presented. 相似文献
24.
A comparative analysis of spatial population structure in the northern red-backed vole (Clethrionomys rutilus Pall.) and large-toothed red-backed vole (Cl. rufocanus Sund.) has been performed in the middle taiga zone of the Middle Irtysh region (Omsk oblast). Populations of these species are represented by sets of territorial groups whose numbers and spatial distribution change from year to year depending on the ratio of these species in a biotope and their population density. There is no significant interspecific competition between cohabitant Cl. rutilus and Cl. rufocanus. In particular, this follows from the fact that the population density and distribution pattern of one species are independent of those of the other species. It has been found that the size of home ranges in Cl. rutilus inversely depends on its population density, with that in Cl. rufocanus remaining approximately the same at different population densities, and that the structure of the resident part of the population in both species changes during the season, as voles from neighboring habitats or dispersing voles settle in the study area. 相似文献
25.
《International Journal of Sustainable Engineering》2013,6(4):284-297
The increasing levels of global warming, depleting sources of fossil fuels and increasing energy costs are all having a large detrimental effect on today's society. Many efforts are being made to try and increase energy efficiency all over the world. One of the major problems is unnecessary and excessive energy utilisation. This problem has been identified by Loughborough University and they are making efforts to try and reduce energy wastage. One of their strategies, used up until recently, involved increasing energy awareness within students in halls of residence by means of a reward system called the Residential Halls Energy Efficiency League (Imago Services, Loughborough Students Union, Estates Services 2006). This scheme managed to reduce energy consumption by up to 10%, saving an estimated £9000 in only 52 days. Can those results be improved by targeting students more specifically? How much energy can be saved by increasing energy awareness? 相似文献
26.
国内外优秀企业安全文化建设分析 总被引:1,自引:0,他引:1
安全文化作为一种新的安全管理模式,正在被越来越多的企业所重视和接受。国内外优秀的大型企业集团,纷纷依据自身安全管理工作的特点,建立了特色鲜明的安全文化模型,为提升企业的安全管理水平中发挥了重要作用。从安全文化的基本内涵出发,分析了国内外几家优秀企业安全文化建设情况,并通过比对总结了优秀企业安全文化应具备的五个特点。研究结果有利于企业更好的结合自身实际开展安全文化建设工作,提高企业安全文化体系的科学性和实效性。 相似文献
27.
John W. Kern Trent L. McDonald Steven. C. Amstrup George M. Durner Wallace P. Erickson 《Environmental and Ecological Statistics》2003,10(4):405-418
Kernel density estimators are often used to estimate the utilization distributions (UDs) of animals. Kernel UD estimates have a strong theoretical basis and perform well, but are usually reported without estimates of error or uncertainty. It is intuitively and theoretically appealing to estimate the sampling error in kernel UD estimates using bootstrapping. However, standard equations for kernel density estimates are complicated and computationally expensive. Bootstrapping requires computing hundreds or thousands of probability densities and is impractical when the number of observations, or the area of interest is large. We used the fast Fourier transform (FFT) and discrete convolution theorem to create a bootstrapping algorithm fast enough to run on commonly available desktop or laptop computers. Application of the FFT method to a large (n>20,000) set of radio telemetry data would provide a 99.6% reduction in computation time (i.e., 1.6 as opposed to 444 hours) for 1000 bootstrap UD estimates. Bootstrap error contours were computed using data from a radio-collared polar bear (Ursus maritimus) in the Beaufort Sea north of Alaska. 相似文献
28.
人口、资源与环境经济学教材比较研究 总被引:1,自引:0,他引:1
人口、资源与环境经济学是理论经济学下设立的一个二级学科。自1997年设立以来,很多学者对其学科体系进行了探索。出版了一些著作和教材。本文以现代课程与教学论的观点为指导.采用文献研究、比较分析、统计分析的方法.从教材现状、体系结构、内容、表现形式和手段等方面对国内外人口、资源与环境经济学教材进行了详细的比较研究,并在此基础上为新教材建设提出了建议。以期为国内相关教材的改进和完善提供参考依据。这些建议是:统一并完善教材体系;理论要联系实际.培养学生学习兴趣和解决实际问题能力;注重学科领域最新成果的运用。增强教材的时代性和科学性;注重表现形式和手段多样性,帮助读者理解抽象的经济理论。 相似文献
29.
本研究基于1999-2010年中国省际面板数据,实证分析了中国对外直接投资的母国环境效应.基于联立方程及情景模拟的结果显示:①对外直接投资对规模、结构与技术的影响机制存在明显的区域差异,此外,规模、结构与技术对工业污染的影响机制也同样存在明显的区域差异,基于传导机制与终端影响的区域异质性,采用区域模型比采用全国模型更加合理;②对外直接投资对区域环境影响充满了不确定性,有赢家,有输家,也有许多地区输赢参半.其中,受益地区往往为经济发达地区(比如,华东),受损地区往往为经济欠发达地区(比如,东北).然而,赢者,其受益机制各有不同;输者,其受损机制也截然有异.③综合看来,对外直接投资产生积极母国环境效应的一般机制在于,产业结构优化效应与逆向技术溢出效应;对外直接投资产生消极母国环境效应的一般机制在于,技术效应与结构效应的非期望传导.可见,因地制宜地制定区域性开放经济政策,对中国对外直接投资向环境友好型转变具有重要意义. 相似文献
30.
借鉴国内外研究成果,结合中国实际界定了引发食源性疾病的家庭食品处理风险行为,并基于10省(区)2 163户家庭的横断面抽样调查数据,以实践理论为指导,运用因子分析和聚类分析方法,实证测度家庭食品处理风险行为特征。以食源性腹泻为研究病例,利用有序多分类Logit回归模型分析了家庭食品处理风险行为特征与食源性疾病之间的关系,确定家庭食品处理的关键风险行为特征与人群特征。结果表明,对应于食品处理安全行为,家庭食品处理风险行为特征主要为食品运输、食品冷藏与剩菜处理不当,厨房清洁用品交叉污染,生熟食品交叉污染,清洁卫生风险,烹调不彻底等七种类型,且生熟食品交叉污染与剩菜处理不当是引发家庭食源性腹泻的最主要风险行为特征,尤其是男性、已婚、年龄较大、家庭人口数较少、受教育程度和职业稳定度较低、以及个人和家庭年收入水平较低的家庭人群。家庭是预防食源性疾病的最后一道防线,政府应致力于与消费者进行风险沟通,提升消费者的责任认知,采用差异化策略改善风险消费者的家庭食品处理习惯,实施抗击食源性疾病战略。 相似文献