全文获取类型
收费全文 | 2627篇 |
免费 | 201篇 |
国内免费 | 185篇 |
专业分类
安全科学 | 69篇 |
废物处理 | 32篇 |
环保管理 | 1074篇 |
综合类 | 747篇 |
基础理论 | 424篇 |
环境理论 | 45篇 |
污染及防治 | 167篇 |
评价与监测 | 47篇 |
社会与环境 | 302篇 |
灾害及防治 | 106篇 |
出版年
2024年 | 6篇 |
2023年 | 41篇 |
2022年 | 59篇 |
2021年 | 81篇 |
2020年 | 88篇 |
2019年 | 119篇 |
2018年 | 106篇 |
2017年 | 201篇 |
2016年 | 158篇 |
2015年 | 115篇 |
2014年 | 101篇 |
2013年 | 216篇 |
2012年 | 123篇 |
2011年 | 137篇 |
2010年 | 84篇 |
2009年 | 128篇 |
2008年 | 118篇 |
2007年 | 122篇 |
2006年 | 112篇 |
2005年 | 105篇 |
2004年 | 69篇 |
2003年 | 77篇 |
2002年 | 91篇 |
2001年 | 75篇 |
2000年 | 78篇 |
1999年 | 53篇 |
1998年 | 42篇 |
1997年 | 31篇 |
1996年 | 36篇 |
1995年 | 38篇 |
1994年 | 22篇 |
1993年 | 24篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 17篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1973年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有3013条查询结果,搜索用时 937 毫秒
991.
中国城乡居民食品消费变化趋势分析 总被引:1,自引:0,他引:1
基于能值理论,对比动物性荤食和植物性素食重量形态、能量形态和能值形态的数量关系,定量分析我国城乡居民食品消费的变化趋势及特征。研究表明: 2010年我国城乡居民热量、重量和能值形态的动物性荤食分别占食品消费总量的1190%、911%和7029%,一方面我国城乡居民食品消费中动物性荤食的重量形态和能量形态的数值远低于其植物性素食,说明我国城乡居民食品消费仍然以素食消费为主,另一方面其动物性荤食的能值形态数值已经远超其植物性素食,表明其居民食物消费方式已经向营养均衡多样化方向演替,畜牧业的健康发展是保障居民食品消费和国家粮食安全的重要部分。2010年城镇和农村居民荤食消费能值分别为110 E+15和631 E+14 sej,分别是其素食消费的172和079倍,说明我国城乡居民食品消费整体还表现出二元性特征,按城乡居民荤素食品结构变化演变趋势可推断城乡食品消费品质相差约20 a,并且近年来城乡人均食品消费结构差异程度呈逐年增加的趋势,同时农民且有农产品生产者和消费者的双重身份,因此相对而言农村居民对食品消费的增长趋势更加稳定。又由于相同数量的动物性荤食在生产过程中需要占用更多的农业资源,因此我国城乡居民食品消费变化对其农业生产和粮食安全生产必将产生更大的压力 相似文献
992.
993.
This paper draws on climate justice principles developed in the context of international negotiations between national governments to assess the distribution of carbon reduction roles between different actors involved in residential energy use within the UK. In so doing, it aims to provide a new understanding of equity aspects of current residential policy and to highlight opportunities for more effective and equitable policy. The paper uses three criteria: rights and corresponding duties; mitigation responsibilities and capabilities. It applies them systematically to assess the roles of five key actors involved in residential energy use in the UK. The assessment finds a suboptimal distribution of actors’ duties, responsibilities and capabilities and roles and discusses whether and how a more effective and fair allocation of outcomes, in terms of carbon reduction and fuel poverty, could be achieved. In particular, it raises questions about whether the right actors are being legally obliged or incentivised to deliver energy efficiency improvements, and suggests that particular actors – local authorities and community groups – are under-used and require greater government support with capability. The paper represents the first use of international climate justice frameworks to investigate residential energy policy within a country. 相似文献
994.
This paper reviews the progress in climate change adaptation (CCA) policies both under the United Nations Framework Convention on Climate Change (UNFCCC) and in major regions and countries, including the EU and its major member countries, the influential developed countries in the Asia-Pacific region, the emerging economies and the least developed countries (LDCs). The progress made in China in CCA policies is also reviewed and compared with that in other countries. Finally, good international practices are proposed for China’s policy development. It is found that adaptation has been given the same priority as mitigation since the twenty-first century with regard to climate change-related actions. The topics related to adaptation in the international climate change negotiations under the UNFCCC have evolved from mechanisms for finance and technology development and transfer exclusively in the early stages to implementation of practical adaptation programs and actions. Since 2006, major developed and developing countries have frequently set forward specific CCA policies or general climate change policies involving adaptation in the form of laws, frameworks, strategies, and plans. The LDCs have also been working on National Adaptation Programmes of Action and subsequent National Adaptation Plans with the support from the financial mechanisms under the UNFCCC. Therefore, globally, it has become a common practice to develop national or regional policies to plan and guide CCA actions. China has established climate change policies involving adaptation at the national, regional, and sectorial levels since 2007. However, these policies have strong limitations in their knowledge base, strategic positioning, contents, and implementation mechanisms, e.g. lack of a sound knowledge base, an international perspective, clear responsibilities for policy implementation, and appropriate monitoring and evaluation mechanisms. It is recommended that China should further strengthen its technical capabilities in climate change projections as well as impact, vulnerability, and risk assessment, and develop methodologies and techniques for the preparation, impact assessment and implementation of CCA policies. Furthermore, future CCA strategies or plans should be developed with an emphasis on China’s vision and strategic position on the world stage. 相似文献
995.
Companies bear primary responsibility for low-carbon economy, thus relevant low-carbon policies should be set properly to guide them and to ensure their low-carbon production effectively. To solve the problems generated during low-carbon development, this article verifies the existence of the transmission path and strength. This verification includes mediating variables of companies’ willingness and capacity to conduct low-carbon production, a transmission mechanism through incentive path and resources protection, and questionnaire data of agricultural companies. Conclusions show that the low-carbon policies have obvious positive effects on willingness of corporation; the basic service-oriented policy has a significantly promoting effect on low-carbon production capacity; and low-carbon production performance is positively influenced by willingness as well as capability. Aiming at a better transmission path, some corresponding recommendations have been put forward in the end. 相似文献
996.
This paper discusses the environment as a unit under threat of negative externalities (largely climate change and air pollution) induced by the many sectors albeit with a special reference to transport, bearing in mind that transport is an economic driver. We pay particular reference to the developments in the developed nations in as much as they can provide a framework upon which Africa can draw lessons for public policy and management. While the context may be different, this review is an attempt to inform transport policy and management for environmental sustainability in Africa. The review uses case studies of South Africa, Zimbabwe, Rwanda, Nigeria, Ethiopia and Kenya. 相似文献
997.
当前,在中国奋力实现"碳达峰"碳中和"目标的背景下,不仅给碳排放量相对较高的工业企业带来较大环境治理压力,同时也给其在经济增长方面带来较大冲击.对其随着碳交易政策的提出,是否能够产生"减碳促经"效果展开深入研究.基于2005~2019年30个省市数据,通过双重差分等方法和多重中介效应模型对碳交易政策与工业碳生产率的影响效果和作用路径展开深入分析.结果表明,碳交易政策能够明显提升工业碳生产率水平;同时该种作用效果会随着试点区域的不同存在明显差异;该政策能够产生显著的环境规制、结构优化、技术和能源结构优化效应.建议通过加速完善环境规制层面法律制度、加快构建环保产业发展新体系、加强绿色技术创新研发力度和加速优化能源结构方面促进中国工业经济向低碳化发展转型. 相似文献
998.
国际湿地保护政策及形式的演变研究 总被引:2,自引:0,他引:2
湿地丧失与退化已被公认为全球性的生态环境和社会问题。本文在综述相关文献的基础上,将国际湿地政策的演变划分为三个阶段:20世纪60年代以前的湿地开发期,20世纪60年代至90年代间的政策转型期以及20世纪90年代至今的湿地全面保护期。湿地被围垦、转换为农地是湿地开发期最主要的特质,是导致湿地大量丧失与退化的主要肇因;《湿地公约》的签署标志着国际湿地政策进入转型期阶段,倡导湿地保护与合理利用;而美国政府于上个世纪90年代初期提出的湿地“零净损失”政策目标,成为继《湿地公约》签署后推动全球湿地政策发生深刻改变的最主要驱动力之一,标志着国际湿地政策进入全面保护期阶段。 相似文献
999.
接种比例对酒糟与餐厨垃圾混合厌氧发酵产沼气的影响 总被引:1,自引:0,他引:1
采用酒糟与餐厨垃圾作为混合发酵物料,并接种消化污泥进行厌氧干式发酵,比较接种比例(inoculum to substrate ratios,ISRs)(VS质量比)分别为0.5、0.8、1.0、2.0时的甲烷产率和产量、体系VFA、碱度、游离氨等指标。结果表明:接种比例的提高可有效提高甲烷产生速率,缩短发酵周期,减弱较高浓度VFA引起的抑制作用。当ISRs=1.0时产甲烷效果较好,累计产甲烷率为222.58mL/g,VS去除率达83.4%,继续增加接种比例对发酵效果影响不显著。此外,试验中适宜的VFA/碱度值为0.3~1.2,过大或过小都有可能抑制产甲烷过程。 相似文献
1000.
This article proposes to analyze the quantitative effects of a gradual physical and "social" exhaustion of a landfill site on an equilibrium waste management service. A gradual social exhaustion of a landfill is defined here as an upward shift of a "subjective factor" associated with the amount of waste, based on the plausible hypothesis that an individual will not accept excessive presence of landfilled waste. Physical exhaustion occurs when the absolute capacity of a landfill site decreases. The paper shows some numerical examples using specific functions and parameters, and proposes appropriate directions for three policy objectives: to decrease the equilibrium waste disposal, to increase the economic surplus of the individual and/or the waste management firm, and to lower the equilibrium collection fee. 相似文献