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   817篇
  免费   52篇
  国内免费   154篇
安全科学   43篇
废物处理   44篇
环保管理   64篇
综合类   341篇
基础理论   184篇
污染及防治   207篇
评价与监测   50篇
社会与环境   63篇
灾害及防治   27篇
  2024年   4篇
  2023年   14篇
  2022年   54篇
  2021年   32篇
  2020年   45篇
  2019年   39篇
  2018年   28篇
  2017年   38篇
  2016年   58篇
  2015年   39篇
  2014年   66篇
  2013年   63篇
  2012年   53篇
  2011年   66篇
  2010年   46篇
  2009年   53篇
  2008年   45篇
  2007年   45篇
  2006年   34篇
  2005年   34篇
  2004年   18篇
  2003年   17篇
  2002年   23篇
  2001年   16篇
  2000年   17篇
  1999年   7篇
  1998年   4篇
  1997年   1篇
  1996年   5篇
  1995年   5篇
  1994年   6篇
  1993年   6篇
  1992年   2篇
  1991年   4篇
  1990年   7篇
  1989年   6篇
  1988年   4篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
  1976年   2篇
  1974年   2篇
  1973年   3篇
排序方式: 共有1023条查询结果,搜索用时 15 毫秒
111.
Different water Acts (e.g., the European Water Framework Directive) and stakeholders involved in aquatic affairs have promoted integrated river basin management over recent decades. However, few studies have provided feedback on these policies. The aim of the current article is to fill this gap by exploring how local newspapers reflect the implementation of a broad public participation within a catchment of France known for its innovation with regard to this domain. The media coverage of a water management strategy in the Drôme watershed from 1981 to 2008 was investigated using a content analysis and a geographic information system. We sought to determine what public participation and decentralized decision-making can be in practice. The results showed that this policy was integrated because of its social perspective, the high number of involved stakeholders, the willingness to handle water issues, and the local scale suitable for participation. We emphasized the prominence of the watershed scale guaranteed by the local water authority. This area was also characterized by compromise, arrangements, and power dynamics on a fine scale. We examined the most politically engaged writings regarding water management, which topics of each group emphasized, and how the groups agreed and disagreed on issues based on their values and context. The temporal pattern of participation implementation was progressive but worked by fits and starts.  相似文献   
112.
Many countries are confronting climate change that threatens agricultural production and farmers’ lives. Farmers’ perceived risks of climate change and factors influencing those perceived risks are critical to their adaptive behavior and well-planned adaptation strategies. However, there is limited understanding of these issues. In this paper, we attempt to quantitatively measure farmers’ perceived risks of climate change and explore the influences of risk experience, information, belief in climate change, and trust in public adaptation to those perceived risks. Data are from structured interviews with 598 farmers in the Mekong Delta. The study shows that perceived risks to production, physical health, and income dimensions receive greater priority while farmers pay less attention to risks to happiness and social relationships. Experiences of the events that can be attributed to climate change increase farmers’ perceived risks. Information variables can increase or decrease perceived risks, depending on the sources of information. Farmers who believe that climate change is actually happening and influencing their family’s lives, perceive higher risks in most dimensions. Farmers who think that climate change is not their concern but the government’s, perceive lower risks to physical health, finance, and production. As to trust in public adaptation, farmers who believe that public adaptive measures are well co-ordinated, perceive lower risks to production and psychology. Interestingly, those who believe that the disaster warning system is working well, perceive higher risks to finance, production, and social relationships. Further attention is suggested for the quality, timing, and channels of information about climate change and adaptation.  相似文献   
113.
114.
115.
The development of predictive models for the long term evolution of nuclear waste glass requires the complete knowledge of the glass dissolution at the laboratory scale. A new approach was developed to determine the initial reaction during the first steps of experience, a new concept was developed, based on the combination of dynamic leaching test and the characterization of the altered materials. With this experimental set-up it is possible to follow in real time the glass alteration process at a fine temporal scale. The results put in evidence a singular behaviour of the lanthanide, shown by a concentration peak of La, Nd and Ce after 2 h and a quick decrease of their concentration measured on line in the solution during the leaching test. This fact is directly linked to the development of an interphase (altered layer which differs from the initial solid by its texture, structure and chemical composition) at the interface of the glass surface and the leaching solution. This work is an attempt to integrate the formation of the alteration products (here the interphase) during leaching into the dissolution mechanisms of a nuclear waste glass. A model is proposed and discussed.  相似文献   
116.
117.
118.
五种水生植物对水中铀的去除作用   总被引:3,自引:1,他引:2  
采用水培实验,研究了浮叶植物野生水葫芦(Eichhornia crassipes)、漂浮植物浮萍(Lemna minor L)、满江红(Azolla imbircata)、沉水植物菹草(Potamogeton crispus)、挺水植物空心莲子草(Alligator Alternanthera Herb)在初始铀浓度分别为0.15、1.50和15.00 mg·L-1水中的生长状况及它们对水中铀的去除能力.结果表明,在21 d的水培试验期内,满江红对铀表现出了最强的抗性,0.15、1.50和15.00 mg·L-1的铀对满江红的生长抑制率分别只有4.56%、2.48%和6.79%,而满江红对水中铀的去除率分别达到了94%、97%和92%.进一步的试验表明,每1 L水中种植7.5 g满江红,可以获得最大的铀去除率,将初始铀浓度为1.25、2.50、5.00和10.00 mg·L-1的水体降至国家排放标准(GB 23727—2009)规定值(0.05 mg·L-1)以下分别需要17、19、23和25 d.研究结果为进一步开展铀污染水体植物修复的研究打下了基础.  相似文献   
119.
国外气候变化对旅游业影响的定量研究进展与启示   总被引:1,自引:1,他引:0  
加强气候变化对旅游业影响的定量研究,有助于旅游业在气候变化背景下实现可持续发展。基于SCI/SSCI文献数据库,梳理分析国外气候变化对旅游业影响的定量研究进展。结果显示,30余年来国外主要采用指标方法、需求模型与选择分析方法开展相关研究。20世纪80年代末出现的指标方法是运用最早、最广泛的方法,主要用于旅游资源环境变化等研究,呈现由单项指标转向综合指标的应用趋势;20世纪90年代末兴起的需求模型主要用于天气状况对旅游需求的影响等研究,呈现由时间序列模型转向累计需求模型的应用趋势;21世纪兴起的选择分析主要用于气候变化背景下的行为意愿等研究,呈现由描述统计转向离散选择模型的应用趋势。这些给我国研究的启示是:在研究方法与研究领域上,重点加强累计需求模型在旅游流相关研究中的运用,加强离散选择模型在旅游市场结构相关研究中的运用,加强系统科学方法与大数据技术在相关研究中的运用;在研究对象上,丰富中国境内气候敏感型旅游活动的相关研究,加强“一带一路”沿线国家、地区及青藏高原的相关研究。  相似文献   
120.
选取我国南方生物质发电厂的灰渣为原料,经物理和化学改性制成重金属钝化剂,针对我国南方重金属Cd污染的土壤开展钝化修复研究.底灰中Cd等重金属含量明显低于其对应的飞灰,这是选择底灰作原料的重要原因.用其制备的BFA型钝化剂在水中对Cd的吸附量可达16mg/g以上.室内盆栽试验中,添加土壤干重1%的钝化剂,第一季稻米Cd含量降低80%以上,从超标2.8倍降至达标;第二季小麦籽粒Cd降低70%,从超标0.9倍降至达标.在我国南方Cd重度污染的农田中开展的原位修复试验表明,添加1%的钝化剂,稻米和小麦籽粒中Cd降低70%~90%,其中稻米Cd持续降低,2017年降低率相较2016年继续提升10%~20%,最终从超标20倍降至达标;Ni降低60%以上,且保留有益的Cu、Zn元素不受明显影响;此BFA型钝化剂还能促进作物生长,第一季稻米产量提高40%~60%,第二季仍有一定的增长效果.综合安全性考虑,我国南方生物质电厂的灰渣重金属含量很低,经过改性加工可制成安全高效的重金属钝化剂.可为钝化修复我国南方重金属污染农田提供一种经济有效的方法,也为现阶段难以处置的灰渣提供一个重要的利用途径.  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