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排序方式: 共有1213条查询结果,搜索用时 15 毫秒
941.
基于重庆主城区2010-2012年逐日的气象要素和大气环境质量监测数据,对气象条件与空气污染指数(API)进行相关性研究,分析气象条件影响空气质量的机制及协同作用,明确显著影响空气质量的气象要素。结果表明,当天的空气质量与前一天的空气质量相关性非常显著;各气象要素之间存在明显的协同作用,共同影响主城的空气质量;主城空气质量与大部分气象要素之间存在着相关性。其中空气污染指数与降雨、风速的相关性尤为密切。以期本研究成果能为重庆蓝天行动提供技术支持。  相似文献   
942.
张浩 《四川环境》2012,(1):70-75
深入考察水环境质量变化的情况、分析水环境质量变化的规律,需要比较分析水环境质量的变化及与社会经济发展、自然条件的相关性,才能更准确地把握水环境的变化轨迹。对常州市"十一五"期间水环境环境质量变化与社会经济发展及水资源量等指标进行比较和相关性分析。结果表明:"十一五"期间,常州市通过大力开展主要污染物减排,调整产业结构,加强污水集中处理力度等有效措施,主要污染物排放量明显下降,水环境质量明显改善。  相似文献   
943.
浙江省太湖交界断面藻类预警应急监测指标特征分析   总被引:1,自引:0,他引:1  
太湖藻类的爆发呈现一定的阶段性,根据2008年太湖藻类的时空分布,将藻类爆发划分为5个阶段。在太湖流域藻类预警应急监测期间,连续监测湖州市新塘港与太湖交界断面的8项水质指标,研究藻类爆发不同阶段交界断面水质指标的变化情况,采用Pearson相关分析法分析各水质指标间的相关性,探讨不同时期太湖流域藻类预警应急监测应重点关注的水质指标,为浙江省太湖流域藻类防控提供理论依据。  相似文献   
944.
With the rapid changes of demographic and socio-economic structure, various ecological and environmental problems have emerged in peri-urban areas. Studies on the correlation between socio-economic development and eco-environmental preservation are inadequate. This paper analyzes the landscape pattern of peri-urban areas to address this issue. First, it studies the differentiation of economic development levels in Beijing peri-urban areas. Then, it explores the correlation between economic development level...  相似文献   
945.
Kar S  Roy K 《Chemosphere》2012,87(4):339-355
Different regulatory agencies in food and drug administration and environmental protection worldwide are employing quantitative structure-activity relationship (QSAR) models to fill the data gaps related with properties of chemicals affecting the environment and human health. Carcinogenicity is a toxicity endpoint of major concern in recent times. Interspecies toxicity correlations may provide a tool for estimating sensitivity towards toxic chemical exposure with known levels of uncertainty for a diversity of wildlife species. In this background, we have developed quantitative interspecies structure-carcinogenicity correlation models for rat and mouse [rodent species according to the Organization for Economic Cooperation and Development (OECD) guidelines] based on the carcinogenic potential of 166 organic chemicals with wide diversity of molecular structures, spanning a large number of chemical classes and biological mechanisms. All the developed models have been assessed according to the OECD principles for the validation of QSAR models. Consensus predictions for carcinogenicity of the individual compounds are presented here for any one species when the data for the other species are available. Informative illustrations of the contributing structural fragments of chemicals which are responsible for specific carcinogenicity endpoints are identified by the developed models. The models have also been used to predict mouse carcinogenicities of 247 organic chemicals (for which rat carcinogenicities are present) and rat carcinogenicities of 150 chemicals (for which mouse carcinogenicities are present). Discriminatory features for rat and mouse carcinogenicity values have also been explored.  相似文献   
946.
Hur J  Lee BM 《Chemosphere》2011,83(11):1603-1611
The heterogeneity of copper binding characteristics for dissolved organic matter (DOM) fractions was investigated based on the fluorescence quenching of the synchronous fluorescence spectra upon the addition of copper and two-dimensional correlation spectroscopy (2D-COS). Hydrophobic acid (HoA) and hydrophilic (Hi) fractions of two different DOM (algal and leaf litter DOM) were used for this study. For both DOM, fluorescence quenching occurred at a wider range of wavelengths for the HoA fractions compared to the Hi fractions. The combined information of the synchronous and asynchronous maps derived from 2D-COS provided a clear picture of the heterogeneous distribution of the copper binding sites within each DOM fraction, which was not readily recognized by a simple comparison of the changes in the synchronous fluorescence spectra upon the addition of copper. For the algal DOM, higher stability constants were exhibited for the HoA versus the Hi fractions. The logarithms of the stability constants ranged from 4.8 to 6.1 and from 4.5 to 5.0 for the HoA and the Hi fractions of the algal DOM, respectively, depending on the associated wavelength and the fitted models. In contrast, no distinctive difference in the binding characteristics was found between the two fractions of the leaf litter DOM. This suggests that influences of the structural and chemical properties of DOM on copper binding may differ for DOM from different sources. The relative difference of the calculated stability constants within the DOM fractions were consistent with the sequential orders interpreted from the asynchronous 2D-COS. It is expected that 2D-COS will be widely applied to other DOM studies requiring detailed information on the heterogeneous nature and subsequent effects under a range of environmental conditions.  相似文献   
947.
1998年 ,长江流域发生了类似 195 4年的百年一遇全江性大洪水 ,1999年长江又发生了较大洪水。在上述背景下 ,长江中下游地区是否会发生中强震 ,需要进行认真的探讨。初步研究结果表明 ,长江大洪水之后 3年内 ,鄂、湘沿江地区中强地震受长江大洪水的“耦合振荡”作用较大。  相似文献   
948.
对夏季太湖野外水华蓝藻样本进行梯度稀释,将自动监测法与手工监测法(人工镜检法和分光光度法)进行比对分析,同时通过对野外样品的连续监测对实验结果进行验证.结果表明,对于以微囊藻为绝对优势种的夏季太湖水体,YSI-6600型和EXO2型便携式水质监测仪测得的叶绿素与人工镜检法测得的藻密度的调整后相关系数(R2adj)均值分...  相似文献   
949.
Objective: This study looks at mitigating and aggravating factors that are associated with the injury severity of pedestrians when they have crashes with another road user and overcomes existing limitations in the literature by focusing attention on the built environment and considering spatial correlation across crashes.

Method: Reports for 6,539 pedestrian crashes occurred in Denmark between 2006 and 2015 were merged with geographic information system resources containing detailed information about the built environment and exposure at the crash locations. A linearized spatial logit model estimated the probability of pedestrians sustaining a severe or fatal injury conditional on the occurrence of a crash with another road user.

Results: This study confirms previous findings about older pedestrians and intoxicated pedestrians being the most vulnerable road users and crashes with heavy vehicles and in roads with higher speed limits being related to the most severe outcomes. This study provides novel perspectives by showing positive spatial correlations of crashes with the same severity outcomes and emphasizing the role of the built environment in the proximity of the crash.

Conclusions: This study emphasizes the need for thinking about traffic calming measures, illumination solutions, road maintenance programs, and speed limit reductions. Moreover, this study emphasizes the role of the built environment, because shopping areas, residential areas, and walking traffic density are positively related to a reduction in pedestrian injury severity. Often, these areas have in common a larger pedestrian mass that is more likely to make other road users more aware and attentive, whereas the same does not seem to apply to areas with lower pedestrian density.  相似文献   

950.
针对尾矿库安全综合评价中“定性定量评价尾矿库安全等级”和“客观描述尾矿库安全状态变化趋势”的要求,采用集对分析方法和可拓理论,利用可拓距计算原理,建立尾矿库集对可拓耦合安全评价模型和尾矿库集对势的计算方法。利用RSCIE权重计算方法确定尾矿库评价指标的权重,将基于集对可拓耦合算法的尾矿库安全评价模型用于尾矿库各安全等级集对可拓联系度的分析中,并基于最大隶属度原则确定案例中的尾矿库为正常库,其集对可拓联系度为0.040 6,安全状态的集对势为9.26。结果表明:该尾矿库的安全等级为正常库,且其安全状态发展趋势为弱同势,说明尾矿库的安全状况发展趋势为正常库的态势不强,且向不安全状态转变的可能非常大,应该加强该尾矿库的日常安全管理。这与实际情况相符合,有效验证了该评价模型的可行性和实用性。  相似文献   
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