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   896篇
  免费   108篇
  国内免费   296篇
安全科学   27篇
废物处理   41篇
环保管理   181篇
综合类   661篇
基础理论   82篇
环境理论   3篇
污染及防治   85篇
评价与监测   60篇
社会与环境   160篇
  2024年   12篇
  2023年   61篇
  2022年   54篇
  2021年   67篇
  2020年   57篇
  2019年   46篇
  2018年   55篇
  2017年   63篇
  2016年   81篇
  2015年   86篇
  2014年   64篇
  2013年   105篇
  2012年   74篇
  2011年   113篇
  2010年   32篇
  2009年   36篇
  2008年   33篇
  2007年   31篇
  2006年   31篇
  2005年   24篇
  2004年   22篇
  2003年   22篇
  2002年   25篇
  2001年   26篇
  2000年   24篇
  1999年   12篇
  1998年   6篇
  1997年   11篇
  1996年   9篇
  1995年   7篇
  1994年   2篇
  1993年   1篇
  1991年   3篇
  1990年   2篇
  1986年   1篇
  1985年   1篇
  1977年   1篇
排序方式: 共有1300条查询结果,搜索用时 718 毫秒
281.
Perpetuation of the South-North divide over climate change threatens to undermine the sustainability of the planet's vulnerable ecosystems. The current focus of international attention is on the USA and the PRC since both countries are in a position to negate or clinch the global warming mitigation efforts of the rest of the world community and because the two governments are primarily responsible for the entrenched global impasse over greenhouse gas (GHG) abatement. This contribution illustrates how transnational non-state actors, specifically Chinese American transmigrants, can make a difference in surmounting the US-China divide over GHG emissions, even in a time of state stalemate. Specific opportunities to shape sustainable development outcomes are explored by reference to energy efficiency, renewable energy, transportation, GHG capture, and public education projects. The discussion shows that, by teaming up with the NGOs, universities, foundations and firms engaged in or contemplating involvement in GHG emission mitigation projects in China, Chinese Americans from many walks of life who can manoeuvre skilfully along the climate change frontier occupy a potentially decisive position in terms of supporting sustainable development.  相似文献   
282.
283.
This paper analyses CO2 emissions reduction costs based on project data from the Climate Cent Foundation (CCF), a climate policy instrument in Switzerland. Four conclusions are drawn. First, for the projects investigated, the CCF on average pays €63/ton. Due to the Kyoto Protocol, the CCF buys reductions only until 2012. This cut-off increases reported per ton reduction costs, as the additional lifetime project costs are set in relation to reductions only until 2012, rather than to reductions realised over the whole lifetime. Lifetime reduction costs are €45/t. Second, correlation between CCF's payments and lifetime reduction costs per ton is low. Projects with low per ton reduction costs should thus be identified based on lifetime per ton reduction costs. Third, the wide range of project costs per ton observed casts doubts on the widely used identification of the merit order of reduction measures based on average per ton costs for technology types. Finally, the CCF covers only a fraction of additional reduction costs. Decisions to take reduction efforts thus depend on additional, non-observable and/or non-economic motives. Any generalisation of results has to consider that this analysis is based on prospective costs of a sub-sample of projects in Switzerland.  相似文献   
284.
Wuhan Tianhe International Airport (WUH) was suspended to contain the spread of COVID-19, while Shanghai Hongqiao International Airport (SHA) saw a tremendous flight reduction. Closure of a major international airport is extremely rare and thus represents a unique opportunity to straightforwardly observe the impact of airport emissions on local air quality. In this study, a series of statistical tools were applied to analyze the variations in air pollutant levels in the vicinity of WUH and SHA. The results of bivariate polar plots show that airport SHA and WUH are a major source of nitrogen oxides. NOx, NO2 and NO diminished by 55.8%, 44.1%, 76.9%, and 40.4%, 33.3% and 59.4% during the COVID-19 lockdown compared to those in the same period of 2018 and 2019, under a reduction in aircraft activities by 58.6% and 61.4%. The concentration of NO2, SO2 and PM2.5 decreased by 77.3%, 8.2%, 29.5%, right after the closure of airport WUH on 23 January 2020. The average concentrations of NO, NO2 and NOx scatter plots at downwind of SHA after the lockdown were 78.0%, 47.9%, 57.4% and 62.3%, 34.8%, 41.8% lower than those during the same period in 2018 and 2019. However, a significant increase in O3 levels by 50.0% and 25.9% at WUH and SHA was observed, respectively. These results evidently show decreased nitrogen oxides concentrations in the airport vicinity due to reduced aircraft activities, while amplified O3 pollution due to a lower titration by NO under strong reduction in NOx emissions.  相似文献   
285.
巴黎协定下中国碳排放权省域分配及减排潜力评估研究   总被引:1,自引:0,他引:1  
通过构建碳排放权区域分配模型完成了省域分配,在此基础上与当前各地实际碳排放量进行比对,明晰了各自初始空间余额;而后对碳排放权欠缺地区的碳减排潜力进行了综合评估。研究结果表明:(1)我国30个省区碳排放权分配存在较大差异,其中云南配额最高,占比高达10.53%;宁夏配额最少,占比仅为0.28%。(2)全国有14个省区碳排放权初始空间余额表现出盈余状态,根据成因差异可大致分为“低排放、高配额”“低排放、低配额”以及“高排放、高配额”等三种类型;其他16个地区均表现出一定程度的欠缺,结合数值差异可划分为以江苏等4地为代表的轻度欠缺地区,以天津等7地为代表的中度欠缺地区,以及以辽宁等5地为代表的重度欠缺地区。(3)浙江、天津、山东等3地目前所具备的碳减排潜力要明显高于其他地区,而各地区的碳减排潜力水平虽与其碳排放权欠缺量表现出了一定趋同性但并非完全一致。  相似文献   
286.
Abstract: Economic growth‐the increase in production and consumption of goods and services‐must be considered within its biophysical context. Economic growth is fueled by biophysical inputs and its outputs degrade ecological processes, such as the global climate system. Economic growth is currently the principal cause of increased climate change, and climate change is a primary mechanism of biodiversity loss. Therefore, economic growth is a prime catalyst of biodiversity loss. Because people desire economic growth for dissimilar reasons‐some for the increased accumulation of wealth, others for basic needs‐how we limit economic growth becomes an ethical problem. Principles of distributive justice can help construct an international climate‐change regime based on principles of equity. An equity‐based framework that caps economic growth in the most polluting economies will lessen human impact on biodiversity. When coupled with a cap‐and‐trade mechanism, the framework can also provide a powerful tool for redistribution of wealth. Such an equity‐based framework promises to be more inclusive and therefore more effective because it accounts for the disparate developmental conditions of the global north and south.  相似文献   
287.
In situ aeration by means of the Airflow technology was proposed for landfill conditioning before landfill mining in the framework of a reclamation project in Northern Italy. A 1-year aeration project was carried out on part of the landfill with the objective of evaluating the effectiveness of the Airflow technology for landfill aerobization, the evolution of waste biological stability during aeration and the effects on leachate and biogas quality and emissions.The main outcomes of the 1-year aeration project are presented in the paper.The beneficial effect of the aeration on waste biological stability was clear (63% reduction of the respiration index); however, the effectiveness of aeration on the lower part of the landfill is questionable, due to the limited potential for air migration into the leachate saturated layers.During the 1-year in situ aeration project approx. 275 MgC were discharged from the landfill body with the extracted gas, corresponding to 4.6 gC/kgDM. However, due to the presence of anaerobic niches in the aerated landfill, approx. 46% of this amount was extracted as CH4, which is higher than reported in other aeration projects. The O2 conversion quota was lower than reported in other similar projects, mainly due to the higher air flow rates applied.The results obtained enabled valuable recommendations to be made for the subsequent application of the Airflow technology to the whole landfill.  相似文献   
288.
In the electricity sector, innovation in large-scale storage is anticipated to reduce costs and improve performance. The effect on greenhouse gas emissions of lower storage costs depends on the interactions between storage and the entire grid. The literature has disagreed on the role of storage in reducing emissions. In this paper we present a stylized model, which suggests that the effect of storage costs on emissions depends on the supply responsiveness of both fossil and renewable generators. Under common conditions in the United States, lower storage costs are more likely to reduce emissions when wind investment responds to equilibrium electricity prices and when solar investment does not. Simulations of a computational model of grid investment and operation confirm these intuitions. Moreover, because of its effect on coal and natural gas–fired supply responsiveness, introducing a carbon dioxide emissions price may increase the likelihood that lower storage costs reduce emissions.  相似文献   
289.
The objective of the research was to create improved understanding of the significance of diverse factors for the total greenhouse gas (GHG) emissions of buildings. The specific focus of the study was on the assessment of the significance of building materials and embodied carbon. The scope of the study covers multi-storey residential buildings in Finland. This research was based on a literature survey and supported by a parametric case study. The parametric study assessed the building-material-related GHG emissions relative to total GHG emissions and the possible range of variation. The research assesses the minimum and maximum GHG emissions for production of buildings with similar spaces, to reveal the likely range of variation for the emissions. The calculations for the ‘minimum’ and ‘maximum’ scenarios assume a similar purpose of use, occupancy and spaces in the building, while the production methods, materials, site conditions and location are varied. The research also assesses the relative importance of various building components and other calculation parameters in terms of GHGs. Total material-related GHG emissions were compared with the GHG emissions caused by the operation of the building, at three distinct levels of energy performance. In addition, the material- and operation-related GHG emissions were compared with the location-related GHG emissions arising from people's mobility.  相似文献   
290.
CeO_2-TiO_2复合纳米纤维光催化降解醛酮类污染物的研究   总被引:1,自引:1,他引:0  
采用同轴静电纺丝法制备了CeO2-TiO2复合纳米纤维,并用X射线衍射仪、扫描电子显微镜、程序升温脱附仪和紫外-可见光谱能谱(UVVis)仪表征了CeO2-TiO2纳米纤维的相组成和微观形貌,分析了CeO2-TiO2纳米纤维对醛酮的吸附强度与光电化学特性.同时,研究了CeO2配比量、光源条件和重复使用性对降解甲醛污染物的影响规律.结果表明,CeO2质量配比为50%的CeO2-TiO2催化剂对甲醛降解效率最高;在无光和可见光条件下,CeO2-TiO2催化剂对甲醛的降解效率分别为13.5%和25.3%,在紫外光下CeO2-TiO2催化剂对甲醛的降解效率为92.5%;随着光催化循环次数的增加,可见光下CeO2-TiO2催化剂对甲醛的降解效率逐渐增高,紫外光下CeO2-TiO2催化剂对甲醛的降解效率维持在92.5%左右.利用催化剂样品CT50对柴油机尾气中醛酮类排放污染物进行光催化降解的应用发现,CeO2-TiO2催化剂对醛类污染物的降解效率为85.4%,酮类污染物的降解效率为81.3%,苯甲醛和甲基苯甲醛的降解效率分别为80.4%和80.3%.表明CeO2-TiO2催化剂具有较强的光催化降解醛酮类污染物的能力.  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