首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   280篇
  免费   10篇
  国内免费   16篇
安全科学   27篇
环保管理   118篇
综合类   55篇
基础理论   48篇
污染及防治   14篇
评价与监测   19篇
社会与环境   6篇
灾害及防治   19篇
  2023年   1篇
  2022年   1篇
  2021年   2篇
  2020年   4篇
  2019年   3篇
  2018年   2篇
  2017年   4篇
  2016年   5篇
  2015年   3篇
  2014年   4篇
  2013年   9篇
  2012年   8篇
  2011年   18篇
  2010年   11篇
  2009年   23篇
  2008年   21篇
  2007年   22篇
  2006年   18篇
  2005年   12篇
  2004年   22篇
  2003年   7篇
  2002年   16篇
  2001年   12篇
  2000年   12篇
  1999年   5篇
  1998年   12篇
  1997年   7篇
  1996年   5篇
  1995年   2篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   12篇
  1990年   3篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
排序方式: 共有306条查询结果,搜索用时 828 毫秒
171.
Great concern has been raised with respect to the 13 traplines that constitute the traditional territory of the Ouje-Bougoumou Cree located in the James Bay region of northern Quebec, Canada, with respect to mine wastes originating from three local mines. As a result, an “Integrative Risk Assessment” was initiated consisting of three interrelated components: a comprehensive human health study, an assessment of the existing ecological/environmental database, and a land use/potential sites of concern study. In this paper, we document past and present land use in the traditional territory of the Ouje-Bougoumou Cree for 72 heads of households, including 13 tallymen, and use a Geographic Information System (GIS) to layer harvest/hunting and gathering/collecting data over known mining areas and potential sites of concern. In this way, potential receptors of contamination and routes of human exposure were identified. Areas of overlap with respect to land use activity and mining operations were relatively extensive for certain harvesting activities (e.g., beaver, Castor canadensis and various species of game birds), less so for fish harvesting (all species) and water collection, and relatively restrictive for large mammal harvesting and collection of firewood (and other collection activities). Potential receptors of contaminants associated with mining activity (e.g., fish and small mammals) and potential routes of exposure (e.g., ingestion of contaminated game and drinking of contaminated water) were identified.  相似文献   
172.
The intent of this paper is to operationalize some aspects of local sustainability in a suitable development scenario and to compare its energy-use and environmental impacts to trend development. After a discussion of suburban sprawl, local sustainability, and the current state of the Pennypack Creek Watershed in the Philadelphia metro region, these residential location scenarios are presented. The latter were created using geographic information systems software and are based on projections from the Delaware Valley Regional Planning Commission. The impacts of the scenarios on energy use, air emissions, greenhouse gas emissions, water quality, and biological integrity were estimated with very few data, and the effect on the value of generic ecosystem services was assessed. The suitable development scenario was 29% better in terms of energy use and air and greenhouse gas emissions, 2.4% worse on water quality, and 2.6% better with respect to biological integrity. Given its net beneficial results, recommendations for policies to engender suitable development are made, and an outline of an implementation plan is proposed. Thoughts regarding refinements of the present work and the applicability of the methods used here to other watersheds conclude the work.  相似文献   
173.
In this study an effort has been made to use plant polyphenol oxidases; potato (Solanum tuberosum) and brinjal (Solanum melongena), for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.  相似文献   
174.
小城镇基础设施防灾减灾决策支持系统的研究与开发   总被引:15,自引:5,他引:15  
利用信息技术研究灾害问题成为研究热点之一 ,但在小城镇防灾减灾方面仍缺少应有的关注和重视。笔者将地理信息系统 (GIS)和决策支持系统 (DSS)集成应用于开发“基于GIS的小城镇基础设施防灾减灾决策支持系统” ,简要介绍了该系统研制目标和原则、系统结构框架及各子系统的功能 ,解决了系统实现过程中的一系列关键技术 :快速、高效构建小城镇基础空间数据库及三维可视化、应急预案及历史灾情库的电子化及各类灾害分析模拟的专业模型等。实践证明 ,基于基础设施、灾害源、防护保卫目标、应急救援力量的可视化与数字化 ,该系统能够实现对其进行科学管理、对各单一灾种的模拟分析以及应急决策支持 ,有效提高小城镇政府的应急指挥决策水平 ,增强其灾害应急反应能力。  相似文献   
175.
交通事故信息管理与时空分布分析   总被引:1,自引:0,他引:1  
交通事故发生点具有明确的空间位置属性 ,其在空间和时间上的分布具有不均匀性 ,利用GIS技术能实现交通事故信息管理及其时空分布规律的研究。笔者在分析道路交通事故信息的基础上 ,采用全新的管理模式 ,利用空间数据库技术实现交通事故的空间、时间信息以及造成交通事故的人、车、路和环境等因素的一体化管理 ;通过GIS技术进行道路交通事故的时空分布分析 ,发现其在空间和时间上的分布规律 ;最后提出了交通事故管理与分析中需要进一步解决的几个问题。  相似文献   
176.
Impact of Urban Sprawl on Water Quality in Eastern Massachusetts,USA   总被引:5,自引:0,他引:5  
A study of water quality, land use, and population variations over the past three decades was conducted in eastern Massachusetts to examine the impact of urban sprawl on water quality using geographic information system and statistical analyses. Since 1970, eastern Massachusetts has experienced pronounced urban sprawl, which has a substantial impact on water quality. High spatial correlations are found between water quality indicators (especially specific conductance, dissolved ions, including Ca, Mg, Na, and Cl, and dissolved solid) and urban sprawl indicators. Urbanized watersheds with high population density, high percentage of developed land use, and low per capita developed land use tended to have high concentrations of water pollutants. The impact of urban sprawl also shows clear spatial difference between suburban areas and central cities: The central cities experienced lower increases over time in specific conductance concentration, compared to suburban and rural areas. The impact of urban sprawl on water quality is attributed to the combined effects of population and land-use change. Per capita developed land use is a very important indicator for studying the impact of urban sprawl and improving land use and watershed management, because inclusion of this indicator can better explain the temporal and spatial variations of more water quality parameters than using individual land use or/and population density.  相似文献   
177.
选择有代表性的城市场地,运用网格法土壤采样,并通过实验室化学分析得出土壤的重金属等污染物质含量,运用地物光谱仪在实验室设定条件下测定土壤反射光谱,应用偏最小二乘法(PLS)建立高光谱遥感(HRS)影像定量反演模型,预测场地土壤中各种污染物的含量,并在遥感影像中直观表示。结果表明,HRS技术能提供大量、连续性的光谱信息;PLS模型为大尺度城市场地污染快速评价与监测提供了可能性;并通过结合G IS技术可实现城市污染场地的动态监测,为城市公共管理提供决策支持。  相似文献   
178.
Geographic information systems (GIS) use is presented in the problem of sitting areas for construction of natural systems such as stabilization ponds (SPs) for domestic wastewater treatment. For this purpose, several variables, such as topography, land use, type of geological formation, distance to major rivers or lakes, distance to existing cities and villages, existence of environmentally protected areas, mean minimum monthly temperatures and required wastewater effluent characteristics were analyzed with the GIS, in order to accept or reject a particular area within a region. The method is applied in the region of Thrace (Northeast Greece) at the municipal level. The required area for SP systems was calculated in each of the 36 municipalities of Thrace (including two islands, Thassos and Samothraki) as a function of the population of each municipality, temperature and local wastewater effluent discharge criteria. Based on the GIS analysis, suitable locations were identified in each municipality first, and then the total required surface area of these systems was compared to the available surface area of each municipality, in order to decide whether SP systems could be a viable solution to the wastewater management problem in the particular region. In that way the present methodology offers a fast and simple method to check the suitability of new areas for construction of such systems.  相似文献   
179.
This paper presents an overview and process for developing an Internet Map Server (IMS) application for a local volunteer watershed group using an Internal Internet Map Server (IIMS) strategy. The paper illustrates that modern GIS architectures utilizing an internal Internet map server coupled with a spatial SQL command language allow for rapid development of IMS applications. The implication of this approach means that powerful IMS applications can be rapidly and affordably developed for volunteer organizations that lack significant funds or a full time information technology staff.  相似文献   
180.
Habitat loss and fragmentation are causing widespread population declines, but identifying how and when to intervene remains challenging. Predicting where extirpations are likely to occur and implementing management actions before losses result may be more cost‐effective than trying to reestablish lost populations. Early indicators of pressure on populations could be used to make such predictions. Previous work conducted in 2009 and 2010 identified that the presence of Eastern Yellow Robins (Eopsaltria australis) in 42 sites in a fragmented region of eastern Australia was unrelated to woodland extent within 500 m of a site, but the robins’ heterophil:lymphocyte (H:L) ratios (an indicator of chronic stress) were elevated at sites with low levels of surrounding woodland. We resurveyed these 42 sites in 2013 and 2014 for robin presence to determine whether the H:L ratios obtained in 2009 and 2010 predicted the locations of extirpations and whether the previous pattern in H:L ratios was an early sign that woodland extent would become an important predictor of occupancy. We also surveyed for robins at 43 additional sites to determine whether current occupancy could be better predicted by landscape context at a larger scale, relevant to dispersal movements. At the original 42 sites, H:L ratios and extirpations were not related, although only 4 extirpations were observed. Woodland extent within 500 m had become a strong predictor of occupancy. Taken together, these results provide mixed evidence as to whether patterns of individual condition can reveal habitat relationships that become evident as local shifts in occupancy occur but that are not revealed by a single snapshot of species distribution. Across all 85 sites, woodland extent at scales relevant to dispersal (5 km) was not related to occurrence. We recommend that conservation actions focus on regenerating areas of habitat large enough to support robin territories rather than increasing connectivity within the landscape.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号