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   3220篇
  免费   378篇
  国内免费   254篇
安全科学   182篇
废物处理   38篇
环保管理   724篇
综合类   1091篇
基础理论   1247篇
环境理论   3篇
污染及防治   107篇
评价与监测   139篇
社会与环境   283篇
灾害及防治   38篇
  2024年   7篇
  2023年   83篇
  2022年   100篇
  2021年   121篇
  2020年   117篇
  2019年   112篇
  2018年   113篇
  2017年   136篇
  2016年   147篇
  2015年   167篇
  2014年   142篇
  2013年   195篇
  2012年   179篇
  2011年   203篇
  2010年   221篇
  2009年   199篇
  2008年   171篇
  2007年   253篇
  2006年   185篇
  2005年   142篇
  2004年   120篇
  2003年   80篇
  2002年   75篇
  2001年   75篇
  2000年   77篇
  1999年   55篇
  1998年   46篇
  1997年   42篇
  1996年   44篇
  1995年   36篇
  1994年   27篇
  1993年   34篇
  1992年   28篇
  1991年   13篇
  1990年   9篇
  1989年   6篇
  1988年   5篇
  1987年   13篇
  1986年   4篇
  1985年   6篇
  1984年   4篇
  1983年   11篇
  1982年   8篇
  1981年   9篇
  1980年   10篇
  1979年   4篇
  1978年   4篇
  1973年   2篇
  1972年   2篇
  1971年   4篇
排序方式: 共有3852条查询结果,搜索用时 15 毫秒
971.
This paper aims at exploring the local background of and solutions to the forest conflict in upland areas inhabited by ethnic minorities, who are called hill tribes, in northern Thailand. A so-called hill tribe problem has been officially identified as a result of the slash-and-burn cultivation and other perceived problems, such as opium poppy cultivation, illegal immigration, and the suspicion of disloyalty to the state. This has created distrust and tension between the groups and authorities. The local conflict has recently been related to the dilemma of conserving the forest from all human interference, while many people live and make their livelihood within and adjacent to the protected areas. Furthermore, as the results imply, strictly protected areas and reforestation have also increased the competition over land and natural resources and, thereby, the likelihood of local conflicts. The scarcity and pollution of water, illegal logging, and poor fire control have contributed to the conflicts between local communities. The conflicts between the local communities and officials have been nourished by political and public discussions. Using definitions and terms with negative connotations and ignoring the heterogeneity between the groups or labeling some groups as malevolent have increased distrust and strengthened existing stereotypical images. Conflict resolution starts with efforts toward better mutual understanding, and changes in structures and attitudes are necessary. Local cooperation, utilization of traditional methods, and local institutions are central to conflict solving.  相似文献   
972.
Abstract: There is a growing recognition that conservation often entails trade‐offs. A focus on trade‐offs can open the way to more complete consideration of the variety of positive and negative effects associated with conservation initiatives. In analyzing and working through conservation trade‐offs, however, it is important to embrace the complexities inherent in the social context of conservation. In particular, it is important to recognize that the consequences of conservation activities are experienced, perceived, and understood differently from different perspectives, and that these perspectives are embedded in social systems and preexisting power relations. We illustrate the role of trade‐offs in conservation and the complexities involved in understanding them with recent debates surrounding REDD (Reducing Emissions from Deforestation and Degradation), a global conservation policy designed to create incentives to reduce tropical deforestation. Often portrayed in terms of the multiple benefits it may provide: poverty alleviation, biodiversity conservation, and climate‐change mitigation; REDD may involve substantial trade‐offs. The gains of REDD may be associated with a reduction in incentives for industrialized countries to decrease carbon emissions; relocation of deforestation to places unaffected by REDD; increased inequality in places where people who make their livelihood from forests have insecure land tenure; loss of biological and cultural diversity that does not directly align with REDD measurement schemes; and erosion of community‐based means of protecting forests. We believe it is important to acknowledge the potential trade‐offs involved in conservation initiatives such as REDD and to examine these trade‐offs in an open and integrative way that includes a variety of tools, methods, and points of view.  相似文献   
973.
金属矿山企业在为国民经济发展做出重大贡献的同时,安全工作的作用更加突出,安全事故频繁发生,会直接影响企业的经济效益和社会效益。从人的生命经济价值出发,通过对人身伤亡赔偿费用的确定,分析人身伤亡赔偿与安全效益之间的经济关系,论证了提高职工的人身伤亡赔偿,可以给企业带来经济效益,为企业制定安全措施方案提供可靠的依据。  相似文献   
974.
湖泊水体悬浮物中痕量砷的测定方法   总被引:1,自引:0,他引:1  
重金属在悬浮物和水相中的分配是水体重金属形态研究的重要组成部分,对于追踪水体中重金属元素的来源、迁移转化规律以及重金属生态与健康效应具有重要意义.水中砷元素以其极强的毒性严重危害人类的健康,已越来越引起政府和社会的广泛关注.然而,目前关于痕量悬浮物中砷测定的前处理过程及室内分析的方法与质量控制的叙述不够详尽,有必要对此做深入的研究.本文针对悬浮物较少的水域,选用7个滇池水样,采用不同滤膜、不同预处理方法、不同消解用酸及消解时间,测定并比较砷空白值,试图通过改变实验条件降低空白值,探索前处理的最佳条件及步骤.结果表明,对于悬浮物较少的湖泊水域,采用预称重的醋酸纤维膜过滤水样、载有颗粒物的滤膜冷冻干燥、HNO3-HCl O4加热共消解36 h,消解上清液用氢化物发生原子荧光光度计测定砷空白值低于悬浮物一个数量级以上,膜空白砷相对标准偏差为2.80%~11.38%,膜空白加标回收率为83%~103%;与滇池5个实际样品验证误差范围0.27%~6.92%.此方法可以可靠地获得悬浮物中的砷含量,在砷含量较低的水体悬浮物测定方面具有优势.  相似文献   
975.
生态系统服务价值损失评估是流域突发水污染事件生态损害定量、污染事故责任认定的重要依据.针对流域突发污染事件损失定量问题,基于生态系统服务价值理论,构建了包含不同主导服务偏好的生态系统服务价值损失指标评估方法,提出了受损服务识别、评估指标筛选、损失价值核算三步评估程序,并以浙江省某河段苯酚泄漏事件造成的流域生态系统服务损失为例进行实际测算,结合实例以1-9标度层次分析法(AHP)验证了该方法偏好系数计算方法的可靠性.结果表明,本方法与AHP法的水体生态系统服务损失评估额相对偏差为2.5%,单项指标损失额排序相同,并且在保证评估结果可靠性的前提下更具易操作性优势.  相似文献   
976.
以天津市某化工厂液氨罐泄漏为背景,在氨泄漏后果分析的基础上,用ALOHA(有害大气区域定位)模拟软件对事故影响范围进行模拟,得到可能事故场景下的氨气扩散区域、闪火可燃区域和蒸气云爆炸超压影响区域,以及射火和BLEVE火球热辐射影响.结果表明,液氨爆炸和火灾事故中BLEVE事故造成的危害范围最大,其次是蒸气云、闪火,最后是射火.液氨泄漏扩散事故影响范围可达几千米,应针对不同伤害区域采取不同方式和不同程度的救援措施.  相似文献   
977.
Beijing's local water resources have been overexploited and the ecological and environmental pressures exceed the carrying capacity of this densely populated megacity. This article examines the current status of Beijing's water resources with respect to its industrial, residential, and eco‐environmental water usage and the challenges it may face in the near future. The article describes the context of water uses, the steps taken by Beijing to alleviate the water shortage problems, and challenges to Beijing's abilities to meet its urgent and future water needs. A multipronged strategy is proposed that aims at both the present problems and the anticipated future challenges. In particular, engineering and institutional approaches for Beijing's successful transition from overexploitation to sustainable utilization of water resources are explained. Actions include reasonable water utilization, water conservation, reclaimed wastewater, and importing water from neighboring areas. We conclude that Beijing must take additional steps in water resource management to ensure its sustainable development that involves continued urbanization sprawls and population growth. Future water resource management strategies should focus on strengthening water demand management through water conservation, efficient interbasin water transfers, use of nontraditional water resources, strategically reserving water supply, and promoting rehabilitation of the eco‐environments.  相似文献   
978.
Targeting of agricultural conservation practices to cost‐effective locations has long been of interest to watershed managers, yet its implementation cannot succeed without meaningful engagement of agricultural producers who are decision makers on the lands they farm. In this study, we engaged 14 west‐central Indiana producers and landowners in an adaptive targeting experiment. Interviews carried out prior to targeting provided rich spatial information on existing conservation practices as well as producers' preferences for future conservation projects. We targeted six of the most accepted conservation practices using the Soil and Water Assessment Tool and spatial optimization using a genetic algorithm approach. Fairly optimal conservation scenarios were possible with even the most limiting constraints of farmer‐accepted practices. We presented in follow‐up interviews a total of 176 conservation practice recommendations on 103 farm fields to 10 farmers whose lands were targeted for conservation. Primary findings indicated producers were interested in the project, were open to hearing recommendations about their lands, and expressed a high likelihood of adopting 35% of targeted recommendations. Farmers generally viewed the interview process and presentation of results quite favorably, and the interviews were found to build trust and make the targeting process more acceptable to them.  相似文献   
979.
The accelerated eutrophication of freshwaters and to a lesser extent some coastal waters is primarily driven by phosphorus (P) inputs. While efforts to identify and limit point source inputs of P to surface waters have seen some success, nonpoint sources remain difficult to identify, target, and remediate. As further improvements in wastewater treatment technologies becomes increasingly costly, attention has focused more on nonpoint source reduction, particularly the role of agriculture. This attention was heightened over the last 10 to 20 years by a number of highly visible cases of nutrient-related water quality degradation; including the Lake Taihu, Baltic Sea, Chesapeake Bay, and Gulf of Mexico. Thus, there has been a shift to targeted management of critical sources of P loss. In both the U.S. and China, there has been an intensification of agricultural production systems in certain areas concentrate large amounts of nutrients in excess of local crop and forage needs, which has increased the potential for P loss from these areas. To address this, innovative technologies are emerging that recycle water P back to land as fertilizer. For example, in the watershed of Lake Taihu, China one of the largest surface fresh waters for drinking water supply in China, local governments have encouraged innovation and various technical trials to harvest harmful algal blooms and use them for bio-gas, agricultural fertilizers, and biofuel production. In any country, however, the economics of remediation will remain a key limitation to substantial changes in agricultural production.  相似文献   
980.
建筑行业的迅速发展,造成了大量资源耗损和环境污染.将节能环保理念应用到建筑和园区建设中,节约资源减少污染势在必行.分别从建筑保温、可再生能源的利用和生态建设三大方面介绍了节能环保技术在园区中的应用,并计算节能效果,结果表明,采用节能环保技术能大大减少碳及烟尘的排放量,有效地保护了环境.  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