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   217篇
  免费   6篇
  国内免费   27篇
安全科学   3篇
废物处理   1篇
环保管理   81篇
综合类   63篇
基础理论   55篇
污染及防治   6篇
评价与监测   6篇
社会与环境   27篇
灾害及防治   8篇
  2024年   1篇
  2022年   1篇
  2021年   6篇
  2020年   12篇
  2019年   6篇
  2018年   6篇
  2017年   11篇
  2016年   25篇
  2015年   8篇
  2014年   6篇
  2013年   14篇
  2012年   6篇
  2011年   22篇
  2010年   10篇
  2009年   14篇
  2008年   11篇
  2007年   25篇
  2006年   7篇
  2005年   14篇
  2004年   10篇
  2003年   4篇
  2002年   6篇
  2001年   4篇
  2000年   9篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1989年   2篇
  1987年   1篇
  1984年   1篇
  1982年   1篇
排序方式: 共有250条查询结果,搜索用时 15 毫秒
41.
基于“三生”适宜性的县域土地利用冲突识别与分析   总被引:1,自引:0,他引:1  
精准识别潜在土地利用冲突有利于预警权衡和协调冲突用地,有利于科学进行国土空间规划。以“三调”修正数据为基础,基于生产、生活、生态视角,构建高植被覆盖率县域生产、生活、生态即“三生”适宜性评价模型与土地利用冲突识别矩阵,并选取横峰县进行实证分析。结果表明:(1)横峰县“三生”适宜性用地的空间分布与面积构成差异显著,且存在明显的空间叠加特征,暗示着研究区土地利用存在冲突;(2)从潜在冲突识别的结果来看,土地利用适宜区、冲突激烈区、冲突中度区、冲突一般区及冲突微弱区面积占比分别为64.02%、9.66%、17.19%、1.66%、7.48%;(3)各个冲突类型区空间分布、表现形式的差异性决定了冲突和解的对策也需因地制宜。研究结果可为相关及类似县域的国土空间规划提供理论参考。  相似文献   
42.
选取东北三江平原沼泽湿地5种土地利用方式,共16个土壤剖面,对土壤有机碳储量分布特征进行了研究.结果表明,不同土地利用方式下,土壤剖面有机碳含量与有机碳密度均呈自上而下降低的趋势,且随着深度的增加,垂直差异变小.开垦降低了土壤有机碳含量和有机碳密度,并改变了其在表层的分布结构特征.初步估算5种土地利用方式下土壤有机碳储量分别为:沼泽湿地1.58×104t/km2、退耕还湿地1.23×104t/km2、林地1.01×104t/km2、水田0.85×104t/km2、旱田0.99×104t/km2.开垦降低了湿地土壤有机碳储量,且对耕地的影响大于林地,而退耕还湿有利于土壤有机碳的固定及储量的增加.  相似文献   
43.
区域土地利用规划的适宜性   总被引:8,自引:0,他引:8       下载免费PDF全文
为合理分析、评价区域土地利用规划的生态合理性,建立了包括生态环境因子在内的工业用地适宜性分析指标体系,并以专家调查意见为基础确定了各指标的权重.在此基础上,以宁波市北仑区区域发展总体规划中的土地利用规划为例,在地理信息系统的支持下,对工业用地的适宜性、环境合理性、科学性进行分析和评价.结果表明,区域工业用地规划基本合理,3种工业类型大都布局在生态适宜区内.规划中存在的主要问题是,东片区三类工业布局与宁波市总体规划不符,不能很好地实现与周边地区的协调发展.城市规划中要综合考虑社会经济环境因素的作用,才能实现发展的科学性、合理性和可持续性.  相似文献   
44.
Land degradation continues to be a major threat to local and national food security. With limited potential to develop new land, any increase in agricultural production must be sought largely through the better use of land already under cultivation. Concerns for the global environment associated with agriculture worldwide have also increased in recent years and require more coordinated efforts at global and national levels with decentralisation of activities at the local level.
This article presents an overview of land resources potential for food production, the processes and extent of land degradation and its economic and environmental costs and impacts, and highlights some macro-economic policies and institutional measures for the prevention of land degradation and rehabilitation of degraded lands. A people-centred programme is presented as a basis for decentralising activities for sustainable land use and land management. Finally, the need for better coordinated efforts of concerned UN, multinational agencies and NGOs for the implementation of Agenda 21 and related conventions is stressed.  相似文献   
45.
ABSTRACT

Land-use conflict has become a topical issue due to an increase in the number of stakeholders having incompatible interests related to particular land uses. Competing land-uses include those for conservation, irrigation, game and livestock farming, settlements and mining. These groupings of land-uses have different interests and objectives. This study aims to investigate the basis for the land-use conflict, and to get insights into how various stakeholders perceive and interpret existing conflicts. Empirical results were drawn from observation, interviews and documents collected between 2011 and 2018. The interviews were held with various stakeholders involved in land-use decisions. Qualitative data were analysed through thematic content analysis, and observations assisted with the corroboration of information collected through interviews. The study recorded four central land-use conflicts: irrigation farming with conservation; game farming with conservation; settlements/livestock farming with conservation; and mining with conservation/game farming/irrigation farming. The study also explains how local stakeholders understand these conflicts.  相似文献   
46.
土地利用方式对土壤碳库影响的敏感性评价指标   总被引:44,自引:5,他引:44  
张金波  宋长春 《生态环境》2003,12(4):500-504
综述了目前国内外在监测土地利用方式对土壤有机碳动态的影响时所采用的一些敏感性指标:微生物量碳和微生物商、CO2通量和qCO2、轻组有机质和颗粒态有机质、溶解态有机碳(DOC)。大量的研究表明,与土壤有机碳相比,微生物量碳库的周转率更大,周转时间更短,在土壤总有机碳变化可检测之前,土壤微生物部分的变化可能被检测到,是土壤碳动态的敏感性指标。轻组和颗粒态有机质是自然土壤肥力的决定因素,也是土地管理方式影响最明显的部分,对于准确评价土地利用变化对土壤碳过程的影响具有重要意义。CO2,通量和qCO2,可以综合反映土壤微生物的活性、利用土壤有机碳的效率及土壤中碳的代谢作用等,也是土壤碳动态的敏感性指标。DOC通量比全球植物和大气间碳交换量小1-2个数量级,所以生物圈碳平衡的很小变化会导致DOC的巨大变化,DOC浓度和通量是土壤温度和湿度变化的敏感指标。  相似文献   
47.
Global warming mitigation calculationsrequire consistent procedures for handlingtime in order to compare `permanent' gainsfrom energy-sector mitigation options with`impermanent' gains from many forest-sectoroptions. A critical part of carbonaccounting methodologies such as thosebased on `ton-years' (the product of thenumber of tons of carbon times the numberof years that each ton is held out of theatmosphere) is definition of a timehorizon, or the time period over whichcarbon impacts and benefits are considered. Here a case is made for using a timehorizon of 100 years. This choice avoidsdistortions created by much longer timehorizons that would lead to decisionsinconsistent with societal behavior inother spheres; it also avoids a rapidincrease in the implied value of time ifhorizons shorter than 100 years are used.Selection of a time horizon affectsdecisions on financial mechanisms andcarbon credit. Simple adaptations canallow a time horizon to be specified andused to calculate mitigation benefits andat the same time reserve a given percentageof weight in decision making forgenerations beyond the end of the timehorizon. The choice of a time horizon willheavily influence whether mitigationoptions such as avoided deforestation areconsidered viable.  相似文献   
48.
Should forest-based climate mitigationmeasures be approved for crediting through the CleanDevelopment Mechanism (CDM), they could offer anopportunity to accomplish three important objectives:cost-effective reductions in carbon emissions andsequestration of atmospheric carbon; conservation andrestoration of forests and their biological diversity;and, the assistance of host countries and communitiesin their socioeconomic development. However,prospective investors in CDM projects, host countriesand other CDM `stakeholders' might be expected toplace widely different priorities on achieving theseobjectives. This paper describes several factors thatwill affect investor interest in CDM projects, thecharacteristics of forest-based CDM projects that willattract investments, and an approach to identifyingprojects that meet the key objectives of multiplestakeholders. This approach entails identifyingsites, such as degraded watersheds, where CDMfinancing for forest conservation and restoration cangenerate readily monetizable local and regionalsocioeconomic benefits, while mitigating carbonemissions in forests with importance for conservingbiodiversity.  相似文献   
49.
以安徽省泗县开发区为例,从土地利用状况、用地效益、管理绩效和可持续发展状况4个方面构建开发区土地集约利用评价指标体系,运用GIS技术、特尔斐法,选择评价模型确定权重后对泗县开发区进行土地集约利用评价,研究泗县开发区土地集约利用状况.结果显示,泗县开发区土地集约利用总体水平为中等集约利用,土地利用状况和用地效益度方面存在着一定问题.基于反映的问题,提出相应的措施.  相似文献   
50.
Parks, waterways, and vegetation enhance the well-being of urbanites and thus warrant consideration in planning and policy-making. It is, however, difficult to assess how land-use change may impact these features and how this in turn may impact well-being. I use a case-study approach to present a framework that combines geospatial and economic valuation techniques to generate indicators of the effects of land-use policies that alter these amenities on community well-being. This framework quantifies the impacts of land-use change on urban environmental amenities in a way that could help communities plan land use so as to maintain well-being as they urbanise.  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