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991.
本文根据西安市阎良区及周围地区的地震地质环境,在地震危险性分析的基础上,采用等效线性一维波动方法进行土层地震反应分析.计算得出50年超越概率63%、10%和2%的地面水平向峰值加速度,该结果为该地区抗震设计提供了依据,具有应用价值. 相似文献
992.
汽车排放标准与控制技术的发展 总被引:3,自引:0,他引:3
介绍汽车排放标准发展趋势,分析实现排放控制指标的相关支撑技术,从中可以看到排放问题在很长一段时间内,仍将主导汽车发动机的研制与开发,国内汽车排放控制尚处于起步阶段,与国际接轨还有很长的路要走。 相似文献
993.
探讨开发基于新一代B/S计算模式的环保信息管理系统,增强信息技术在环保中的应用,最大限度地实现信息资源共享,为环保管理与决策提供数据支持与服务。 相似文献
994.
稀土金属离子对梨形四膜虫的24小时生长影响 总被引:1,自引:0,他引:1
应用4种方法(细胞直计计数法、中性红试验、重蛋白及核酸含量测定)研究不同浓度稀土金属离子La^2+、Sm^3+、Y^3+、Gd^3+处理24h后,对梨形四膜虫的生长影响,结果表明,在低浓度时La^3+、Sm^3+、Y^3+,对四膜虫具有刺激生长的作用。随着浓度的升高,4种稀土金属离子均表现出毒性效应;高浓度时,抑制生长艇特别明显。计算La^3+、Sm^3+、Y^3+、Gd^3+的半数抑制浓度(IC 相似文献
995.
996.
997.
Chon TS Chung N Kwak IS Kim JS Koh SC Lee SK Leem JB Cha EY 《Environmental monitoring and assessment》2005,101(1-3):1-21
Behavioural changes of medaka (Oryzias latipes) treated with an anticholinesterase insecticide, diazinon (0.1 mg L- 1), were continuously observed for 4 days in semi-natural conditions. Although variations occurred in individual specimens, the movement tracks appeared differently with typical short-range movement with irregular turns and shaking after the treatments. Eight movement patterns frequently observed before and after the treatments were selected, and the variables characterising the movement patterns were compared quantitatively. The variables were clearly differentiated when the movement patterns were correspondingly matched before and after the treatments (e.g., vertical movements, horizontal movements, etc). Meander and stop duration were highly different among the selected movement patterns. Additionally, different degree of toxic response behaviours could also be detected by quantitative characterisation of the variables. Response behaviour was confirmed with toxicological experiments that show the decrease in the acetylcholine esterase activity in the head and body of specimens. Quantitative investigations on the variables of the movement tracks suggested the usefulness of response behaviour as a monitoring tool for environmental assessment. 相似文献
998.
V. Alexandrov A. Sameh Y. Siddique Z. Zlatev 《Environmental Modeling and Assessment》1997,2(4):365-377
The numerical treatment of a regional air pollution model (such models are, as a rule, described mathematically by systems of partial differential equations) leads to the solution of very large computational problems. The chemical submodel of an air pollution model is normally the most timeconsuming part of the computational work. The application of appropriate discretization and splitting procedures reduces the chemical submodel to a large number of relatively small ODE systems (one such system per gridpoint). In the process of searching for efficient numerical algorithms for the chemical submodels one can carry out experiments by using only one such ODE system in order to facilitate the work. This approach has been used in connection with a particular chemical scheme, the condensed CBM IV scheme, which is used in several large air pollution models. Six integration algorithms have been tested on a set of typical scenarios (consisting of different starting concentrations and/or of different values of the emissions). The advantages and the disadvantages of the algorithms tested are discussed. The final decision about the most efficient algorithm, among the algorithms tested, should be made after a second series of experiments. The coupling of the chemical process with the transport of air pollution (on, at least, a twodimensional domain) together with the application of highspeed computers has to be studied in the second series of experiments, which will be performed in a subsequent paper. 相似文献
999.
A.C.D. Ertsen 《Environmental Modeling and Assessment》1999,4(1):13-22
In the Netherlands the increasing demand for ecohydrological models on a regional (provincial) scale has resulted in the development
of an empirical statistical impact–assessment model for semi-natural terrestrial herbaceous ecosystems. This model, called
ITORS, describes the relationship between plant species and site factors such as soil, groundwater and management. The model,
developed for the region of Noord-Holland, is applied to support provincial policy on soil and water management.
The empirical statistical approach required the collection of a large set of field data, describing the biotic and environmental
variation of a variety of semi-natural terrestrial ecosystems in Noord-Holland. These data were used to calculate species
response models with help of logistic regression, resulting in significant models for 130 out of 144 species.
Significant species response models were incorporated in the computer program ITORS. With help of ITORS the effect of various
management scenarios can be easily evaluated, which is demonstrated by an example.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
1000.
Ecological Monitoring and Assessment Network's Proposed Core Monitoring Variables: An Early Warning of Environmental Change 总被引:6,自引:0,他引:6
This article reports on the evaluation of existing ecologicalmonitoring variables from a variety of sources to select a suiteof core variables suitable for monitoring at the Ecological Monitoring and Assessment Network (EMAN) sites located acrossCanada. The purpose of EMAN is to promote the acquisition of relevant and consistent data that can be used to report on national trends and provide an early warning of ecosystem change. Existing monitoring variables were evaluated in twosteps. In the first step, three primary criteria were used to pre-screen preliminary variables. In the second step, a moredetailed evaluation considered twenty criteria based on dataquality, applicability, data collection methods, data analysisand interpretation, existing data and programs, and cost effectiveness to select a draft set of core monitoring variables(CMV). An ecological framework was developed to organize the CMVin a manner that permitted a gap analysis to confirm the CMV assessed a wide range of relevant environment components. Thesuite of CMV were then tested to determine their effectiveness in detecting ecosystem change caused by stressors with ecosystemresponses that have been well documented in the literature. Thisproject is part of a process lead by Environment Canada to select CMV to detect and track ecosystem change at EMAN sites. It is anticipated that the proposed CMV will undergo future discussion and development leading to the final selection of asuite of CMV for use at EMAN sites. 相似文献