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61.
本文采用产生柱法测定取代苯乙酮类有机物的水溶解度和正辛醇-水分配系数,与静态法和振荡法测定的水溶解度、摇瓶法测定的正辛醇-水分配系数相比较,证明此方法是可行的,并和分子连接性指数呈良好的相关性。 相似文献
62.
QSAR计算中的分子连接性指数法 总被引:4,自引:1,他引:4
本文介绍了分子连接性指数法和原理及各阶指数的计算方法,以及在QSAR计算中的应用实例,并对特殊连接性指数的用法作了分析。 相似文献
63.
DUAN Guang-ming ZHAO Jing-zhu * LIU Guo-hua KE Bing XIAO Han WU Gang D ENG Hong |bing 《环境科学学报(英文版)》2004,(2)
IntroductionInordertoalleviateseverewatershortagesinnorthChina ,ChinesecentralgovernmenthavestartedtoimplementtheSouth NorthWaterTransferScheme(SNWT) ,whichwilltransferwaterfromYangtzeRiverbasininthesouthtoHuang Huai Hai(YellowRiver ,HuaiheRiverandHaiheRi… 相似文献
64.
Manuela Baumgarten Christian Huber Patrick Büker Hans-Peter Dietrich Christian Heerdt Rainer Matyssek 《Environmental pollution (Barking, Essex : 1987)》2009,157(7):2091-2107
Exposure and flux-based indices of O3 risk were compared, at 19 forest locations across Bavaria in southern Germany from 2002 to 2005; leaf symptoms on mature beech trees found at these locations were also examined for O3 injury. O3 flux modelling was performed using continuously recorded O3 concentrations in combination with meteorological and soil moisture data collected from Level II forest sites. O3 measurements at nearby rural open-field sites proved appropriate as surrogates in cases where O3 data were lacking at forest sites (with altitude-dependent average differences of about 10% between O3 concentrations). Operational thresholds of biomass loss for both O3 indices were exceeded at the majority of the forest locations, suggesting similar risk under long-term average climate conditions. However, exposure-based indices estimated higher O3 risk during dry years as compared to the flux-based approach. In comparison, minor O3-like leaf injury symptoms were detected only at a few of the forest sites investigated. Relationships between flux-based risk thresholds and tree response need to be established for mature forest stands for validation of predicted growth reductions under the prevailing O3 regimes. 相似文献
65.
Environmental quality of mussel farms in the Vigo estuary: pollution by PAHs, origin and effects on reproduction 总被引:1,自引:0,他引:1
Ruiz Y Suarez P Alonso A Longo E Villaverde A San Juan F 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):250-265
This work analyzes the influence of environmental and physiological parameters on PAHs accumulation in cultured mussels. Lipid content and reproductive stage are directly related with PAHs accumulation pattern. We observed a rapid accumulation and depuration of PAHs, mainly during periods of nutrients accumulation, spawns and gonadic restorations. Correlations between PAHs accumulation and physiological status indicate when mussels are more susceptible to adverse effects of these pollutants. A positive correlation between mutagenic congener’s accumulation and occurrence of gonadic neoplastic disorders is shown for the first time in mussels. Molecular indices were used to identify the origin of hydrocarbons accumulated by Mytilus, showing a chronic pyrolytic pollution and pollutant episodes by petrogenic sources and biomass combustion in the studied area. Multivariate analysis suggests the possibility of including physiological parameters of sentinel organisms in environmental biomonitoring programs, mainly in aquaculture areas, taking into account their two aspects: farms productivity and human food safety. 相似文献
66.
Alarm systems are critically important for safe and efficient operations of industrial plants, but many industrial alarm systems are suffering from too many nuisance alarms. This paper proposes a method to classify normal and abnormal data segments and evaluate performance indices for the most commonly used univariate alarm systems. The proposed method consists of three steps. First, piece-wise linear representations are exploited in separating historical data samples of an analog process variable configured with alarms into data segments with same qualitative trends. Second, data segments are classified into normal, abnormal and unclassified conditions via a mean hypothesis test; a required assumption is that data segments in normal and abnormal conditions have different mean values being distinguishable from alarm thresholds. Third, based on the normal and abnormal data, performance indices of univariate alarm systems are calculated, including two newly formulated ones as the false alarm duration ratio and the missed alarm duration ratio. The effectiveness of the proposed method is illustrated by numerical and industrial examples. 相似文献
67.
首先提出了生态城市规划实效性的内涵,包含规划目标实现程度、规划效益、公众主观感受和规划实施过程合理性等4个方面。在此基础上建立包括规划编制过程、规划实施过程和规划实施结果3个阶段,涵盖政府、企业和公众等不同主体行为和利益特征的从过程到结果,具有复合价值观的规划实效性评价指标体系。通过太仓生态市建设规划实效性评价案例研究做了进一步论证:①生态城市规划主管部门是规划实效评价的主要推动者;②从过程到结果的评价思路和评价指标具有可操作性和灵活性;③规划过程评价方法的不成熟使其受到的关注有所降低。最后提出了若干规划编制和管理建议,以促进生态规划长效管理机制的形成。 相似文献
68.
武汉市夏季湖泊水体理化指标主成份和聚类分析 总被引:2,自引:0,他引:2
为深入了解湖泊水体理化因子的变化规律,为湖泊渔业和湖泊水质管理提供基础数据,于2007年夏季测定了武汉市梁子湖、斧头湖、柴泊湖、〖JP2〗南湖和野芷湖5个养殖湖泊的TN、NH+4 N、NO-2 N、NO-3 N、TP、〖JP〗PO3-4 P、DO、pH、CODMn、WT、SD和EC,应用SPSS软件,对测定结果从事了主成份分析和聚类分析。主成份分析结果表明,3个主成份分别为营养环境因子(包括TN、NO-2 N、NO-3 N、TP、pH、CODMn和EC)、生存因子(DC)和铵吸收因子(NH+4 N)。Q型聚类结果表明,5个湖泊的13个点可聚为4大类,即第1类为9、10、11、12、13号点;第2类是1、2、4号点;第3类是5、6、7、8号点;第4类是3号点。可将5个湖泊分为3类,即斧头湖和梁子湖为一类,柴泊湖为一类,野芷湖和南湖为一类。这一结果是城市废水、生活污水和养殖生产所致。 相似文献
69.
通过分析1994~2009年16 a逐年DMSP/OLS的静态平均灯光数据的DN值分布情况,考虑实际空间格局分布数据需求和数据质量,选择1994、2000、2005、2009年4个年度为代表,进行江西省城镇空间格局分布应用研究,并对数据质量进行评价。结果表明:1994~2009年度江西省城镇建设用地总量数值尽管与统计数据之间存在一定的波动,但总体扩展趋势基本一致;在城镇化增长速度上,2000~2005年比1994~2000年大29.53%,2005~2009年比1994~2000年大4357%,说明江西省城镇化发展正逐步提速,并有加快发展的趋势;景观指数分析表明江西省城镇化扩张过程中,面积越来越大,城镇间聚集度越来越高,相互影响也越来越大;城镇化形状越来越复杂;城镇间联系越来越紧密,破碎度逐步减小,城镇斑块形状变化逐步加大,发展无序程度加重。最后,针对江西省城镇空间格局发展现状,研究提出了积极发展中型城市、集约化发展特大城市、稳步扩大小城镇发展规模的建议 相似文献
70.
Korie S. Clark S.J Perry J.N Mugglestone M. A. Bartlett P .W. Marshall E. J . P. Mann J. A. 《Environmental and Ecological Statistics》1998,5(4):317-344
The spatial pattern of organisms may be used to characterize their dispersal, quantify spread or estimate the point of introduction of an alien species. Their distribution may be represented by maps of individuals, or by counts or by presence/absence at known positions within a sampled area. The problems and relative merits of these different forms of data for spatial inference are discussed. Three datasets concerning dispersal from a single focus are analyzed: counts of aphids, Rhopalosiphum padi and Sitobion avenae, on barley plants, Hordeum vulgare, grown in experi- mental trays; mapped locations of couch grass, Elymus repens, tillers within plots of a field experiment; locations of sightings of the lupin aphid, Macrosiphum albifrons, as it invaded Great Britain between 1981 and 1984. A method for generating maps from counts is proposed to overcome problems caused by recording imprecision. Several statistics are used to quantify dispersal and spatial pattern in the experimental data and together provide a clear picture of the spatial pattern observed; they enabled several effects of the experimental treatments to be identified. The value of the statistics are compared. Estimates of the source of the lupin aphid invasion are obtained using the backtracking methods of Perry (1995b) and do not contradict previous suggestions. 相似文献