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   464篇
  免费   12篇
  国内免费   15篇
安全科学   24篇
废物处理   8篇
环保管理   123篇
综合类   187篇
基础理论   68篇
环境理论   4篇
污染及防治   40篇
评价与监测   13篇
社会与环境   22篇
灾害及防治   2篇
  2024年   2篇
  2023年   5篇
  2022年   3篇
  2021年   14篇
  2020年   13篇
  2019年   10篇
  2018年   11篇
  2017年   16篇
  2016年   32篇
  2015年   18篇
  2014年   20篇
  2013年   34篇
  2012年   25篇
  2011年   47篇
  2010年   14篇
  2009年   27篇
  2008年   24篇
  2007年   20篇
  2006年   33篇
  2005年   11篇
  2004年   10篇
  2003年   19篇
  2002年   21篇
  2001年   15篇
  2000年   15篇
  1999年   8篇
  1998年   9篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1980年   1篇
排序方式: 共有491条查询结果,搜索用时 546 毫秒
441.
Traditional construction practices provide little opportunity for environmental remediation to occur in urban areas. As concerns for environmental improvement in urban areas become more prevalent, innovative practices which create ecosystem services and ecologically functional land cover in cities will be in higher demand. Green roofs are a prime example of one of these practices. The past decade has seen the North American green roof industry rapidly expand through international green roof conferences, demonstration sites, case studies, and scientific research. This study evaluates existing international and North American green roof policies at the federal, municipal, and community levels. Green roof policies fall into a number of general categories, including direct and indirect regulation, direct and indirect financial incentives, and funding of demonstration or research projects. Advantages and disadvantages of each category are discussed. Salient features and a list of prompting standards common to successfully implemented green roof strategies are then distilled from these existing policies. By combining these features with data collected from an experimental green roof site in Athens, Georgia, the planning and regulatory framework for widespread green roof infrastructure can be developed. The authors propose policy instruments be multi-faceted and spatially focused, and also propose the following recommendations: (1) Identification of green roof overlay zones with specifications for green roofs built in these zones. This spatial analysis is important for prioritizing areas of the jurisdiction where green roofs will most efficiently function; (2) Offer financial incentives in the form of density credits and stormwater utility fee credits to help overcome the barriers to entry of the new technology; (3) Construct demonstration projects and institutionalize a commitment greening roofs on publicly-owned buildings as an effective way of establishing an educated roofing industry and experienced installers for future green roof construction.  相似文献   
442.
The aim of this study was to determine how the potential to rely on arbuscular mycorrhiza (AM) for plant nutrition differs between a conventional and a low-input cropping system in the long term. The roles of fertilisation rate, composting of recycled plant residues and stage of the rotations in the overall impact of the cropping systems on soil quality and AM were also identified. The conventional cropping system with a non-leguminous crop rotation (barley–barley–rye–oat–potato–oat) was fertilised at either full or half the recommended rate. In the low-input cropping system, one year with barley was replaced by clover, and oat was cultivated mixed with pea. Straw and clover were returned to the soil either with or without composting. In the low-input system, biotite and rock phosphate were used to compensate for K and P in the harvested yield, while animal manure was applied at the start only. After 15 years, crop growth and nutrition, AMF colonisation and soil quality were assessed in the field, while the AM contribution to growth and nutrient uptake were determined in a bioassay in a growth chamber. AM functioning made a higher contribution to soil quality in terms of crop performance and environmental benefits in the low-input cropping system than at either fertilisation rate in the conventional system. Halving fertilisation in the conventional system prevented some costs and enhanced some of the benefits of AM in comparison with full fertilisation. However, only the low-input system with composting conclusively favoured AM in comparison with the conventional system. It resulted in the highest percentage colonisation and, in a bioassay with flax and clover, gave a relative average contribution to growth of 27% and to P uptake of 68% in comparison with 4 and 36%, respectively, for the conventional cropping system with full fertilisation. Rye yield was in the low-input system without composting similar to that in the conventional system with full fertilisation, and with composting 87% of the latter one. Incorporation of clover green manure without composting inhibited AM functioning, leading to a temporary loss of AM contribution to crop performance. This effect draws attention to the impact of the form of recycled organic matter on supporting ecosystem services such as nutrient cycling.  相似文献   
443.
As part of Ontario's Toxics Reduction Strategy, the Ontario Ministry of the Environment provided funding for two years to a partnership of the Ontario Centre for Environmental Technology Advancement (OCETA) and the Canadian Manufacturers & Exporters (CME) to deliver a Cleaner and Greener Manufacturing Program, which will include the development and delivery of training and technical assistance programs on toxics reduction and pollution prevention (P2). Over the next two years, OCETA and CME will be working with small-to-medium sized manufacturers to demonstrate the business value of toxics reduction and pollution prevention planning to help motivate businesses to move into a greener economy.  相似文献   
444.
This article deals with the use of the procurement or purchasing power of governments to protect the environment. The focus is on South Africa and the aim is to show that South African organs of state can use procurement as an environmental policy tool to contribute to sustainable development as they have commendably done so to address past discriminatory policies and practices. It is argued that such use does not fall outside the current legislative framework governing procurement and suggestions are made as to how environmental considerations could be incorporated throughout the procurement process, namely the preparatory stage; the drawing up of tender or technical specifications; ensuring the capability or responsibility of contractors; the use of criteria to compare different tenders; and ensuring that eventual performance under a contract is environmentally sound.  相似文献   
445.
This study focused on using scale inhibitors for calcium sulfate that are not only highly effective, but also comply with present restrictive environmental control legislations. In this respect, some biodegradable compounds-based biopolymers, such as carboxymethyl starch (CMS), carboxymethyl cellulose (CMC), and chitosan (Ch), were evaluated at temperatures 90–95 and 130°C. The results obtained were compared with the performance of polyaspartic acid (PAA), which is well known in this application, as well as other chelating synthetic polymers (polyacrylamide and amphoteric polyacrylamide). The role of the degree of substitution (DS) of carboxymethylated biopolymer and the charge density of polyacrylamide (AmPAM-30 and AmPAM-50) on inhibition performance of scale were also examined. The synergistic effect of PAA with investigated inhibitors was studied for economic and environmental purposes. The results revealed that both the degree of substitution of carboxymethylated biopolymers and charge density of polyacrylamide have a profound effect on improving the performance of the investigated scale inhibitors. The efficiency values were correlated to the thermal degradation behavior (TGA) of biopolymers. PAA had the highest synergistic effect of all investigated inhibitors, where the inhibition efficiency was found to range from 98% to 100%, at a temperature of 130°C, with low doses of both PAA (2 ppm) together with biopolymers. This efficiency is observed using 20–40 ppm of PAA. The synergistic effect of PAA (2 ppm) also showed enhancement of the performance of low doses of polyacrylamides (5 ppm) in maintaining soluble Ca2+ in solutions, increasing the efficiency from ∼57% to ∼100%, as well as its ecotoxicological property.  相似文献   
446.
With increasing environmental issues and depleting resources, the effective application of green government procurement (GGP) is urgently needed and potentially can have greater impacts in the developing world rather than in the developed world. Such an approach can help promote the general goal of sustainable development and address environmental issues through purchasing and facilitating the use of environmentally friendly services and products. This paper addresses this issue by employing a case study on China. We first trace the development of the GGP concept, its spread to Asian countries, and a number of approaches used to expand GGP adoption. We then review current practices in China on GGP, and analyze and identify some of the current barriers and problems in promoting green procurement in the Chinese governmental sector. We finally seek to identify possible appropriate capacity-building solutions, in order to facilitate the application of GGP in China.  相似文献   
447.
阐述了信用销售的概念和两类信用销售风险,分析了我国企业面临的信用销售风险状况及根源。笔者提出了降低或规避企业信用销售风险的创新性思路和观点对尚未建立规范信用管理制度的企业,应尽早开发适合企业自身实际的信用信息管理系统;对于已构建信用信息管理系统的企业,应及时更新客户的信用信息,不断加以完善;通过构建和完善该系统,可以增强我国企业防范信用风险的能力,提高企业应收账款回收率和竞争力,最终实现企业的可持续发展。  相似文献   
448.
本文对环境保护的公信体系建设进行了探索。首先,对环境保护公信体系的概念作出了解释;其次,对环境保护公信体系的建设内容、建设框架做出了思考;最后,在对环境保护公信体系的建设方法方面,结合电子政务系统的优势,探索了建立电子环境保护公信体系平台的可能性。  相似文献   
449.
危化品企业安全信用及信用制度的探讨   总被引:1,自引:1,他引:0  
通过对"信用"与"信用制度"内涵的探讨,给出危化品企业安全信用概念、危化品企业安全信用及信用制度的内涵;指出危化品企业安全信用制度建设应包括企业内部安全信用制度建设和企业外部安全信用制度建设,其中企业外部安全信用制度建设包括社会公众和政府部门两部分;提出危化品企业安全信用方面存在的问题,并对建设危化品企业安全信用制度的可能性与必要性进行分析。笔者认为,危化品企业安全信用及信用制度的建设对危化品企业投资、融资具有现实的意义,同时促进了政府对企业的监管。  相似文献   
450.
论文基于Odum创立的生态经济系统能值理论和方法,对2003-2012年商洛市绿色GDP进行定量核算。核算结果如下:① 2003-2012年商洛市传统GDP分别在1.12×109 ~ 6.72×109美元之间,绿色GDP分别在9.80×108~ 3.35×109美元之间,各年度绿色GDP占GDP比重在49.85%~ 87.50%之间;② 自2003年以来,商洛市经济增长对自然资源(包括不可更新环境资源与不可更新资源产品)及环境资源价值消耗的持续增长,造成10 a间绿色GDP发生了很大程度的变化,各年度对自然资源价值消耗占GDP的比重处于6.55%~31.77%之间,各年度环境资源价值损耗占GDP的比重处于5.18%~24.39%之间,其中2008、2009年环境资源价值损耗对绿色GDP核算的影响大于自然资源损耗对绿色GDP核算的影响,其余年份均是自然资源的损耗大于环境资源的损耗;③ 输入资源包括从外部输入的汽油、柴油、化肥、农药等,对绿色GDP核算的影响较小,各年度占GDP比重保持在0.83%~1.30%之间。绿色GDP核算结果表明:近年来商洛市的经济发展存在两个方面的问题,第一是经济增长严重依赖于对资源(包括自然资源和输入资源)的消耗,第二是商洛市经济增长造成了对环境的严重污染。因此商洛市经济发展的模式是不可持续的,如果继续延续这种依赖资源和环境的发展模式,就会使当地经济陷入恶性循环的怪圈。  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