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221.
222.
Many ecologists focus on the effects of roads on landscapes, yet few consider how landscapes affect road systems. In this
study, therefore, we quantitatively evaluated how land cover, topography, and building density affected the length density,
node density, spatial pattern, and location of roads in Dongzhi Yuan, a typical loess region in China. Landscape factors and
roads were mapped using images from SPOT satellite (Système Probatoire d’Observation de la Terre), initiated by the French
space agency and a digital elevation model (DEM). Detrended canonical correspondence analysis (DCCA), a useful ordination
technique to explain species–environment relations in community ecology, was applied to evaluate the ways in which landscapes
may influence roads. The results showed that both farmland area and building density were positively correlated with road
variables, whereas gully density and the coefficient of variation (CV of DEM) showed negative correlations. The CV of DEM,
farmland area, grassland area, and building density explained variation in node density, length density, and the spatial pattern
of roads, whereas gully density and building density explained variation in variables representing road location. In addition,
node density, rather than length density, was the primary road variable affected by landscape variables. The results showed
that the DCCA was effective in explaining road–landscape relations. Understanding these relations can provide information
for landscape managers and transportation planners. 相似文献
223.
Beibei Liu Qinqin Yu Bing Zhang Jun Bi Junjie Ge Zengwei Yuan Yang Yu 《Journal of Cleaner Production》2010,18(5):454-461
The GreenWatch program has been implemented nationally in China. However, whether the program and its process have been effective in improving firms' environmental performance remains unclear. Based on the stakeholder theory, this paper conducts a comparative analysis between firms participating in the program and those that do not, all of which are based in Changshu City in the developed part of Jiangsu Province, China. Data suggest that GreenWatch encourages firms to improve and disclose their environmental performance. Through pressures imposed by different stakeholders—from the government, investors, and consumers, to the public, such as the community and media—this program has become the main driving force for improving the firms' environmental performance. The current study also provides substantial evidence that public disclosure in China opens up channels for effective public participation. Therefore, the GreenWatch program deserves to be promoted in China. 相似文献
224.
LI Zhi-an ZOU Bi XIA Han-ping DING Yong-zhen TAN Wan-neng MA Zhen-rong 《环境科学学报(英文版)》2005,17(6):970-976
Introduction Nitrousoxide(N2O)isoneofthemostimportantgreen housegases,whichcontributestoglobalwarmingand consumptionofO3inthestratosphere(Breuer,2000,Solomon,1999).N2Oconcentrationincreasesatarateof0.25%peryear,57%ofwhichisderivedfromthesoildue tonitrific… 相似文献
225.
江汉平原小麦开花前降水分布特点及同期渍害的产量效应 总被引:1,自引:0,他引:1
江汉平原小麦生长期易受渍害导致减产。在系统分析1983~2012年江汉平原腹地荆州市小麦生育期降水分布特点的基础上,于2011~2012年度及2012~2013年度,以郑麦9023为试验材料,通过田间试验与盆栽试验相结合的方法,分别在拔节期及孕穗期进行渍水处理,探讨其对株高、旗叶光合速率、叶片黄化进程的影响及其与干物质积累量和籽粒产量的关系。结果表明:江汉平原1983~2013年小麦拔节期至孕穗期1/3以上年份同期降水量在802 mm以上,极限降雨量达1944 mm,即较多年份有渍害风险;进一步研究表明拔节期渍水和孕穗期渍水均导致旗叶光合速率降低,叶片黄化进程加快,其中孕穗期渍水对以上指标的影响大于拔节期;拔节期渍水和孕穗期渍水均导致株高降低、干物质积累量降低,最终籽粒产量显著降低,其中拔节期渍水处理成熟期籽粒产量比对照降低163%,孕穗期渍水处理籽粒产量比对照降低218%。在本试验条件下,拔节期渍水处理和孕穗期渍水处理均导致小麦植株各种光合指标降低,最终干物质积累量和籽粒产量均显著降低,且孕穗期渍水处理对产量等的影响大于拔节期渍水处理 相似文献
226.
Multi-angle Indicators System of Non-point Pollution Source Assessment in Rural Areas: A Case Study Near Taihu Lake 总被引:1,自引:0,他引:1
This study aims to identify key environmental risk sources contributing to water eutrophication and to suggest certain risk management strategies for rural areas. The multi-angle indicators included in the risk source assessment system were non-point source pollution, deficient waste treatment, and public awareness of environmental risk, which combined psychometric paradigm methods, the contingent valuation method, and personal interviews to describe the environmental sensitivity of local residents. Total risk values of different villages near Taihu Lake were calculated in the case study, which resulted in a geographic risk map showing which village was the critical risk source of Taihu eutrophication. The increased application of phosphorus (P) and nitrogen (N), loss vulnerability of pollutant, and a lack of environmental risk awareness led to more serious non-point pollution, especially in rural China. Interesting results revealed by the quotient between the scores of objective risk sources and subjective risk sources showed what should be improved for each study village. More environmental investments, control of agricultural activities, and promotion of environmental education are critical considerations for rural environmental management. These findings are helpful for developing targeted and effective risk management strategies in rural areas. 相似文献
227.
228.
导弹核武器核事故应急有关问题研究 总被引:1,自引:0,他引:1
对导弹核武器核事故应急的主要任务、特点、组织指挥以及力量运用等问题进行了探讨 ,导弹核武器核事故的应急问题是一项涉及体制、人员、装备、技术、科学理论等方面的复杂系统工程 ,笔者结合实际 ,有针对性的研究了事故应急有关的问题 ,可为导弹核武器核事故应急提供理论指导 相似文献
229.
淮河流域可持续发展状态评价 总被引:4,自引:1,他引:3
本文在距离指数法和层次分析法的基础上 ,构建了距离指数———层次综合分析法 ,用以评估淮河流域及其子系统的可持续发展状态。评估结果表明 :评估年 (1997年 )相对于参照年 (2 0 0 5年 )而言 ,环境子系统处于不可持续状态 ,资源子系统处于弱可持续状态 ,经济子系统和社会子系统相对较好 ,均处于中度可持续状态 ,整个流域处于弱可持续状态 相似文献
230.
介绍了安全仪表系统在现代过程工业中的作用以及与基本控制系统的区别,阐述了安全完整性等级(SIL)和误停车率(STR)的概念,重点分析了可靠性评估中SIL验证和STR计算方法。 相似文献