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901.
为构建辽宁省典型城市道路尘源成分谱,分别采集了鞍山市和盘锦市道路尘样品,分析了其化学组分特征,用富集因子法和比值法分析了其主要来源,用分歧系数法分析了两个城市成分谱的相似度.结果表明:盘锦市和鞍山市道路尘PM2.5中的化学组成以有机碳组分(OC)和地壳类元素(Al、Ca、Mg、Fe和K)为主.除Cu和V元素外,其余元素均表现为鞍山市的富集因子大于盘锦市.由比值法可得,盘锦市和鞍山市OC/EC分别为(13.20±6.26)和(3.94±0.63),均存在二次污染现象;NO3-/SO42-的均值分别为(0.52±0.55)和(0.46±0.13),说明其道路尘PM2.5受固定源影响更大.盘锦市与鞍山市道路尘成分谱分歧系数为0.354,说明两个源成分谱可能相似. 相似文献
902.
Testes mass in megachiropteran bats varies in accordance with sperm competition theory 总被引:4,自引:0,他引:4
D. J. Hosken 《Behavioral ecology and sociobiology》1998,44(3):169-177
Sperm competition is a widespread phenomenon influencing a range of characters, including investment in gonadal tissue. Conspecific
proximity is one factor which can influence the risk of sperm competition and hence testicular investment, and decreased confidence
of paternity may be one cost of group living. Aspects of female biology may also influence spermatogenic investment and sperm
morphology. This study examines the associations between relative testes mass and roost-group size across 17 species of Megachiroptera.
Associations between breeding season duration and investment in spermatogenesis are also examined, as are associations between
female reproductive tract dimensions and testes mass and dimensions of spermatozoa across all bats. Relative testes mass was
significantly positively associated with roost-group size at a species level and after appropriate phylogenetic control (pairwise
comparisons and comparison of independent contrasts). There were no significant relationships between breeding season duration
and relative testes mass. Across all bats, neither testes mass nor sperm length were significantly related to dimensions of
the female tract. The results are discussed in the context of sperm competition.
Received: 7 January 1998 / Accepted after revision: 8 August 1998 相似文献
903.
Waldon R. Kerns Randall A. Kramer 《Journal of the American Water Resources Association》1985,21(2):207-215
The success of government programs to control nonpoint source pollution depends upon attitudes toward those programs and the availability of technical and financial assistance. Applicants for the Rural Clean Water Program cost-share funding in Virginia possess different personal and operational characteristics than do nonapplicants. Factors associated with participation in the Rural Clean Water Program differed from those associated with the more traditional soil conservation programs. Discriminant analysis was used to differentiate between other farmers who may become applicants and nonapplicants. Farmers' attitudes toward various policy options for inducing implementation of nonpoint source management practices varied greatly. Farmers were most favorable to cost sharing, low-interest loans and tax credits, and least favorable to a soil loss tax. They were either very favorably or very unfavorably inclined toward cross-compliance between pollution control and other agricultural programs. 相似文献
904.
A. A. Khan 《Journal of Loss Prevention in the Process Industries》1990,3(4):406-408
An assignment to carry out a hazard study and risk analysis of a gas processing complex has been described briefly, wherein well known procedures have been used to identify and investigate potential hazards. A method of avoiding unintentional overfilling of LPG storage tanks has been recommended, which utilizes the existing level control instruments. 相似文献
905.
为了在事故发生之前对苯储罐进行风险评价,提出1种基于BP神经网络的泄漏事故风险评价方法,利用该方法构建了苯储罐的风险评价模型,并对模型进行了训练及验证。研究结果表明:BP神经网络成功完成了建模任务,且模型训练结果较好,可利用基于BP神经网络所构建的苯泄漏事故风险评价模型对苯储罐发生泄漏事故的风险进行评价。 相似文献
906.
Calls to strengthen flood risk governance are echoed across Europe amidst a growing consensus that floods will increase in the future. Accompanying the pursuit of societal resilience, other normative agendas relating legitimacy (e.g. accountability and public participation), and resource efficiency, have become attached to discussions concerning flood risk governance. Whilst these represent goals against which ‘success’ is socially and politically judged, lacking from the literature is a coherent framework to operationalise these concepts and evaluate the degree to which these are achieved. Drawing from cross-disciplinary and cross-country research conducted within the EU project STAR-FLOOD, this paper presents a framework for evaluating the extent to which flood risk governance arrangements support societal resilience, and demonstrate efficiency and legitimacy. Through empirical research in England, this paper critically reflects on the value of this approach in terms of identifying entry points to strengthen governance in the pursuit of these goals. 相似文献
907.
908.
909.
The EU Flood Directive 2007/60 requires the assessment and delineation of flood risk maps. The latter should provide the required knowledge for the development of flood risk management plans (FRMPs), that should deal with all features of risk management: e.g. preparation, protection and prevention, comprising also the phase of the flood forecasting and warning systems, in addition to the emergency management. The risk maps, delineated through the expert-drive qualitative (EDQ) approach currently adopted in several European countries, such as Italy, fail to represent the information base that needed by stakeholders for selecting the suitable objectives and designing the appropriate mitigation actions for flood risk management. In the EDQ approach, the flood hazard and the potential damage degree maps are combined by means of a matrix to obtain a qualitative flood risk map. However, the performance of the risk matrix is not usually rigorous validated and, therefore, presents limits, such as subjective and not careful explained interpretation of rating and poor resolution, (due to range compression), that can produce errors in comparative ranking of risk areas. In this context, this paper proposes the FloodRisk approach that aims to improve the efficacy of flood risk map overcoming the limits of EDQ approach in supplying the knowledge base that allow to analyze costs and benefits of potential mitigation measures. However, the proposed approach is also able to involve the citizens in the flood management process, enhancing their awareness. An application of FloodRisk procedure is showed on a pilot case in “Serio” Valley, (North Italy), and its strengths and limits, in terms of additional efforts required in its application compared with EDQ procedure, have been discussed focusing on the efficacy of the outcomes provided for the fulfillment of FRMPs. The results have demonstrated the ability of FloodRisk, respect to EDQ approach, to distinguish successfully different levels of vulnerability of exposure elements, thanks to the use of asset value and depth-damage curves, that allows a suitably evaluation of the effectiveness of risk mitigation strategies. In this light, a successfully application of a cost-benefit analysis of FloodRisk approach on a portfolio of alternative mitigation actions, (i.e. structural and non-structural measurements), has been demonstrated on the proposed study case. However, FloodRisk requires additional information, e.g. water depths assessment and assets values, and it needs a proper analysis and communication of the uncertainty in its results. Although they still exist limitations that impede, at present, the FloodRisk application without an adequate understanding and a critical consideration of the hazard, exposure and vulnerability characteristics of the study area, considerations are supplied on how the utilization of this approach can be maximized in the light of the next flood risk maps revision due by December 2019. 相似文献
910.