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   2569篇
  免费   198篇
  国内免费   366篇
安全科学   307篇
废物处理   86篇
环保管理   645篇
综合类   1149篇
基础理论   337篇
环境理论   19篇
污染及防治   147篇
评价与监测   30篇
社会与环境   363篇
灾害及防治   50篇
  2024年   9篇
  2023年   48篇
  2022年   62篇
  2021年   65篇
  2020年   105篇
  2019年   101篇
  2018年   95篇
  2017年   158篇
  2016年   176篇
  2015年   140篇
  2014年   111篇
  2013年   303篇
  2012年   208篇
  2011年   263篇
  2010年   184篇
  2009年   144篇
  2008年   107篇
  2007年   142篇
  2006年   111篇
  2005年   83篇
  2004年   65篇
  2003年   67篇
  2002年   50篇
  2001年   54篇
  2000年   45篇
  1999年   43篇
  1998年   24篇
  1997年   20篇
  1996年   21篇
  1995年   19篇
  1994年   23篇
  1993年   9篇
  1992年   10篇
  1991年   8篇
  1990年   10篇
  1989年   4篇
  1987年   2篇
  1985年   2篇
  1984年   4篇
  1982年   4篇
  1981年   3篇
  1980年   4篇
  1979年   8篇
  1978年   7篇
  1977年   3篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有3133条查询结果,搜索用时 15 毫秒
91.
Biomass is one of the renewable energy sources on which policy makers are greatly dependent on since it is a flexible feedstock capable of conversion into electricity, transport liquid fuels and heat by chemical and biological processes on demand. Though numerous publications have examined the relationship of economic growth with renewable energy and other parameters, biomass energy has never been included in these studies. Then, this study examines the causal relationship within a multivariate panel cointegration/error correction framework which combines the cross-section and time series data while allowing for heterogeneity across different provinces. After employing panel data regression model ranging from 2003 through 2012 to examine the relationships of biofuels production with sustainable development in China, the paper concludes that the development of biofuel energy production integrated with the consideration of the improvement of income per capita, and the attraction of more capital investment, does make a significant contribution to economic growth. However, some negative side effects including the increase of greenhouse emissions and the decrease of marginal land still coexist with the economic development. Of course, the importance of these findings lies on their implications and their adoption on strategic policies.  相似文献   
92.
Universal two-child policy has been implemented since the end of 2015 in China. This policy is anticipated to bring a significant increase in the total population, with profound influences on the resources and environment in the future. This paper analyzes the changing dynamics of urban and rural population, and forecasts urban and rural population from 2016 to 2030 at national and provincial scale using a double log linear regression model. Drawing upon the results of these two predictions, the impact of the population policy change on Chinese resources consumption and environmental pollution are predicted quantitatively. Given the future total population maintains current levels on resources consumption and environmental emission, the additional demand of resources and environment demand for the new population is forecasted and compared against the capacity on supply side. The findings are as follows: after implementing the universal two-child policy, China’s grain, energy consumption, domestic water demand, and pollutant emissions are projected to increase at different rates across provinces. To meet the needs arising from future population growth, food and energy self-sufficiency rate will be significantly reduced in the future, while relying more on imports. Stability of the water supply needs to be improved, especially in Beijing, Henan, Jiangsu, Qinghai, and Sichuan where the gap in future domestic water demand is comparatively larger. Environmental protection and associated governing capability are in urgent need of upgrade not least due to the increasing pressure of pollution.  相似文献   
93.
汪俊岭  王鑫  宋磊  胡源 《火灾科学》2019,28(4):211-221
棉花是纺织业的重要原料,是人民群众生活不可或缺的必需品,同时也是我国进出口重要的商品。研究如何安全有效地进行棉花的储备具有十分重要的现实意义。棉纤维本身含有脂肪、蜡质和果胶等适合微生物生长繁殖的营养物质。在棉花储备中,高的回潮率会加速微生物的繁殖,进而产生热量。热量的累积会引起温度升高以及棉花霉变,不利于棉花的安全有效储存。因此,通过静电吸附法将安全无毒的有机锌络合物附着在棉纤维表面,研究表明,相同条件下,处理棉的霉变状况明显得到抑制。加速发霉条件下,未处理棉的相对于白纸的平均色差值为28.10,而双乙酸锌以及苯甲酸锌防霉处理棉的色差值分别为5.16和5.86,下降了81.6%和79.1%。自然发霉条件下,双乙酸锌以及苯甲酸锌防霉处理棉的色差值分别下降了53.8%和50.7%。同时研究了纯棉以及处理棉氮气下的热分解动力学,相比于未处理棉,双乙酸锌防霉处理后活化能下降了15.8%,而苯甲酸锌防霉处理后活化能下降了10.9%。此外,利用实时红外和热重红外联用技术得到了样品在热解过程中固相以及气相的裂解产物的红外谱图,发现防霉处理能一定程度上抑制棉花热解。  相似文献   
94.
促进废旧资源循环利用是加快推进我国生态文明建设,完成节能减排目标的必然选择。本文基于生命周期评价模式,从微观企业层面入手,构建产品全生命周期基准流程,引入能量输入与环境输出参数,建立废旧资源循环利用节能减排效果量化核算模型,评估再生产品的节能减排经济成效,并以吉林省某钢铁企业为例,评估"废钢-电炉"短流程和"铁矿石-高炉-转炉"长流程的能源、环境、成本差异,辨识影响废钢再循环节能减排效果的主要因素和重要环节。结果显示,再生钢铁全生命周期与原生钢铁全生命周期相比,节能588.48kgce/t,节能率为84%;主要污染物中SO2减排率最高,达92%;CO2总减排1 180.92 kg/t,减排率为67%;总成本却高出198元/t。其中,炼铁工序的节能量和减碳量最大,烧结工序SO2、NOx和烟(粉)尘减排量最大,焦化工序COD和氨氮减排量最大,回收、加工处理、炼钢环节节能量和减碳量以及SO2、NOx和烟(粉)尘减排量均为负。成本方面,再生钢铁生产成本高于原生钢铁308元/t,虽然再生钢铁由于污染减排可节省56元/t的排污费并获取54元/t的碳交易收益,但都不足以扭转电炉炼钢费用较高的现状。因此,国家应在电炉炼钢方面给予钢企及相关企业适当的财税扶持政策,在电价方面给予钢企一定的优惠或补贴,并完善废钢回收加工体系等,以促进废钢循环利用。基于LCA的废旧资源循环利用节能减排效果评估可以实现对产品生命周期全过程的资源、环境、成本的优化管理。  相似文献   
95.
With the foregrounding of “clean energy” policies by climate change concerns, the rhetorical constitution of “America” as a collective subject, mobilized to adopt the clean energy economy (CEE), becomes crucial. Here, I analyze the constitutive rhetoric of Pew Charitable Trusts’ landmark 2009 report on the CEE, drawing from the ventriloqual perspective to communication. I argue that this approach provides a more pragmatic, conversational understanding of the interpellative process constituting “America,” noting it to be hybridized and composed of various human and nonhuman agents. Tracing the ingoing interaction among agents—some manifest in the text, others spectral—sheds light on the complex relations of power at stake, recognizes the open-ended possibilities (and restrictions) of agency, and the role of material structures shaping environmental communication and policy.  相似文献   
96.
Remote or off-grid communities in Canada primarily rely on diesel generators for the provision of their electricity. Often surrounded by potential renewable resources, they are characterised as the low-hanging fruit of greenhouse gas mitigation strategies. While much is said about the promises of community energy projects, as well as technologies and policy mechanisms for addressing the needs of these communities, little attention has been paid to what communities, themselves, might want for their energy projects and what the implications of those desires might be for both technology development and community energy policies. This paper aims to fill this gap by exploring the on-going energy pursuits of a number of remote First Nations communities in British Columbia. It identifies a desire for community self-sufficiency as a primary motivation for engaging with energy projects on the part of the communities and discusses the various meanings and implications of self-sufficiency in the context of community energy projects. These meanings and implications primarily include the two dimensions of material self-sufficiency and political self-determination, the latter of which suggests a view of community energy projects as processes of decolonisation among First Nation communities in British Columbia. It then suggests that the pursuit of this goal is somewhat incongruent with the approach that government and industry have taken in addressing community energy, especially the way in which remote communities are viewed as the low-hanging fruit of various sustainability projects.  相似文献   
97.
This research presents a method to determine the maximum potential for the capturing of solar radiation on the rooftop of buildings in an urban environment. This involves the modeling of solar energy potential and comparison to historical building energy demand profiles through the use of 3-D solar simulation software tools and geographic information systems (GIS). The objective is to accurately identify the amount of surface area that is suitable for solar photovoltaic (PV) installations and to estimate the hourly PV electricity generation potential of existing building rooftops in an urban environment. This study demonstrates a viable approach for modeling urban solar energy and offers valuable information for electricity distributors, policy makers, and urban energy planners to facilitate the substantial design of a green built environment. The developed methodology is comprised of three main sections: (1) determination of suitable rooftop area, (2) determination of the amount of incident solar radiation available per rooftop, and (3) estimation of hourly solar PV electricity generation potential. A case study was performed using this method for Ryerson University, located in Toronto, Canada. It was found that solar PV could supply up to 19% of the study area’s electricity demands during peak consumption hours. The potential benefits of solar PV was also estimated based upon hourly greenhouse gas emission intensity factors as well as Time-of-Use (TOU) savings through the Ontario Feed-in-Tariff (FIT) program, which allows for better representation of the positive impacts of solar technologies.  相似文献   
98.
The increasing capacity of distributed electricity generation brings new challenges in maintaining a high security and quality of electricity supply. New techniques are required for grid support and power balance. The highest potential for these techniques is to be found on the part of the electricity distribution grid.

This article addresses this potential and presents the EEPOS project’s approach to the automated management of flexible electrical loads in neighborhoods. The management goals are (i) maximum utilization of distributed generation in the local grid, (ii) peak load shaving/congestion management, and (iii) reduction of electricity distribution losses. Contribution to the power balance is considered by applying two-tariff pricing for electricity.

The presented approach to energy management is tested in a hypothetical sensitivity analysis of a distribution feeder with 10 households and 10 photovoltaic (PV) plants with an average daily consumption of electricity of 4.54 kWh per household and a peak PV panel output of 0.38 kW per plant. Energy management shows efficient performance at relatively low capacities of flexible load. At a flexible load capacity of 2.5% (of the average daily electricity consumption), PV generation surplus is compensated by 34–100% depending on solar irradiance. Peak load is reduced by 30% on average. The article also presents the load shifting effect on electricity distribution losses and electricity costs for the grid user.  相似文献   

99.
Waste from wastewater treatment plants (WWTP) for Helianthus annuus L. production may be a viable solution to obtain biodiesel. This study achieved two objectives: assess the agronomical viability of waste (wastewater and sludge) from the Alcázar de San Juan WWTP in central Spain for H. annuus L. production; use H. annuus L. seeds grown in this way to obtain biodiesel. Five study plots, each measuring 6 m × 6 m (36 m2), were set up on the agricultural land near the Alcázar de San Juan WWTP. Five fertilizer treatment types were considered: drinking water, as the control; treated wastewater; 10 t ha?1 of air-dried sewage sludge; 20 t ha?1 of air-dried sewage sludge; 0.6 t ha?1 of commercial inorganic fertilizer. Soil, irrigation water, sewage sludge, crop development and fatty acid composition in achenes oil were monitored. The 20 t ha–1 dose of sewage sludge proved effective to grow H. annuus L. with similar results to those grown with a commercial fertilizer. However, precautions should be taken when irrigating with wastewater because of high salinity and nutrient deficiency. Sunflower oil was composed mostly of linoleic and oleic acid. The remaining fatty acids were linolenic, estearic, nervonic, palmitoleic, and palmitic.  相似文献   
100.
河南省秸秆能源化利用研究   总被引:1,自引:0,他引:1  
在日益严峻的能源短缺和环境污染的双重压力下,进行秸秆能源化的开发和利用对于河南新型城镇化建设具有重大战略意义.河南秸秆资源丰富,但秸秆能源化利用尚处于初级阶段,利用率非常低,只有健全秸秆收储体系,改进各种秸秆能源化利用方式的技术性能,加强应用和推广,提升秸秆能源化利用的经济效益,加大对秸秆能源化利用相关主体的引导和扶持,提供政策和资金支持,才能为河南秸秆能源化发展提供良好的环境.  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