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   1645篇
  免费   17篇
  国内免费   40篇
安全科学   24篇
废物处理   108篇
环保管理   167篇
综合类   148篇
基础理论   291篇
环境理论   2篇
污染及防治   553篇
评价与监测   300篇
社会与环境   105篇
灾害及防治   4篇
  2023年   60篇
  2022年   173篇
  2021年   119篇
  2020年   25篇
  2019年   47篇
  2018年   82篇
  2017年   88篇
  2016年   108篇
  2015年   46篇
  2014年   80篇
  2013年   174篇
  2012年   77篇
  2011年   95篇
  2010年   69篇
  2009年   60篇
  2008年   74篇
  2007年   56篇
  2006年   63篇
  2005年   35篇
  2004年   23篇
  2003年   20篇
  2002年   30篇
  2001年   8篇
  2000年   8篇
  1999年   5篇
  1998年   3篇
  1997年   4篇
  1996年   7篇
  1995年   3篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1989年   2篇
  1988年   3篇
  1985年   2篇
  1984年   2篇
  1983年   4篇
  1982年   5篇
  1979年   2篇
  1969年   1篇
  1966年   1篇
  1965年   2篇
  1964年   2篇
  1962年   2篇
  1961年   4篇
  1958年   3篇
  1957年   3篇
  1956年   2篇
  1955年   4篇
  1953年   1篇
排序方式: 共有1702条查询结果,搜索用时 15 毫秒
821.
This paper studies the effect of environmental regulation on the productive efficiency of water polluting industries in India. The panel data of 92 firms belonging to sugar industry of India during the period 1996-99 are used to test the Porter hypothesis of having win-win opportunities for the firms subjected to the regulation. The main empirical result is that the technical efficiency of firms increases with the degree of compliance of firms to the environmental regulation and the water conservation efforts there by supporting the Porter hypothesis.  相似文献   
822.
Federal regulations require operators of nuclear and coal-fired power-generating stations to estimate the number of fish impinged on intake screens. During winter months, impingement may range into the hundreds of thousands for certain species, making it impossible to count all intake screens completely. We present graphs for determinig the appropriateoptimal subsample that must be obtained to estimate the total number impinged. Since the number of fish impinged tends to change drastically within a short time period, the subsample size is determined based on the most recent data. This allows for the changing nature of the species-age composition of the impinged fish. These graphs can also be used for subsampling fish catches in an aquatic system when the size of the catch is too large to sample completely.  相似文献   
823.
This study presents the salient results of the oceanographic investigations carried out along the west coast of India to locate a dumping site for the dredged material generated from the capital of the proposed development of the all weather port. Based on the results of movement of disposed material obtained from a 2 dimensional coastal circulation model and considering the possibility of having a navigational channel later on in line with the port, a dumping site is recommended at the 15 m water depth contour with coordinates: Latitude 11 degrees 07.00'; Longitude 75 degrees 45.60', where the environmental impacts on the ecosystem due to dumping operations is considered to be minimum.  相似文献   
824.
In most developing countries, at the household level, traditional burning of biomass or use of inefficient technologies for domestic applications like lighting is common, triggering concerns related to fuel or technology switching. The paper focuses on opportunities to promote cleaner energy options through development of value chains delivering improved energy efficiency and access in developing countries. We discuss the example of Uttam Urja, a field project involving the dissemination of photovoltaic lighting technologies in rural areas of India. We focus on the challenges of introducing radical innovations into the residential energy sector in developing countries. For the purpose of this paper the Uttam Urja project is conceptualized as an ‘experiment’ and analysed using the Strategic Niche Management (SNM) framework. The paper emphasizes that to effect socio-technical transitions to clean energy options on the ground, it is desirable to focus on technology customization and innovative financing to cater to the needs and concerns of end users.  相似文献   
825.
In an urban-transit bus,fueled by biodiesel in Toledo,Ohio,single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry(SEM/EDS).Particle size analysis found bimodal distribution at 0.2 and 0.5 μm.The particle morphology was characterized by 14 different shape clusters:square,pentagon,hexagon,heptagon,octagon,nonagon,decagon,agglomerate,sphere,triangle,oblong,strip,line or stick,and unknown,by quantitative order.The square particles were common in the samples.Round and triangle particles are more,and pentagon,hexagon,heptagon,octagon,nonagon,decagon,strip,line or sticks are less.Agglomerate particles were found in abundance.The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment.The three sorts of surface patterns of squares were smooth,semi-smooth,and coarse.The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo.The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.  相似文献   
826.
Accounting the changes in the net carbon (C) sink-source balance is an important component for greenhouse gas emissions (GHG) inventories. However, carbon emission due to the vegetation biomass extraction for household purposes is generally not accounted in forest carbon budget analysis due to miniscule volume and non-availability of data. However, if vegetation remains in the forests, then vegetation biomass decomposes after natural death and decay and fixes some carbon to soil and releases some directly to the atmosphere. The study attempts to quantify the carbon removal against the biomass extraction for livestock feed by collecting primary data on feed from 316 randomly selected households engaged in livestock rearing in the lower Himalayas, Uttarakhand, India and carbon flow components due to livestock production. The analysis results that average daily forest fodder consumption was 13 kg per Adult Cattle Unit (ACU) and total of 20.31 Million tonnes (Mt) consumption of forest biomass by total livestock of Uttarakhand. This results into absolute annual carbon removal of 3.25 Mt from Uttarakhand forests against the livestock fodder. However, overall carbon flow including the enteric fermentation and manure management system of livestock estimated as per IPCC guidelines, results into emissions of 9.42 Mt CO2 eq. Therefore, biomass extraction for household purposes should be accounted in regional carbon flow analysis and properly addressed in the GHG inventories of the forests and livestock sector. Suitable measures should be taken for emissions reduction generated due to forest based livestock production.  相似文献   
827.
828.
829.
Environmental Chemistry Letters - The global energy demand has been projected to rise over 28% by 2040, calling for more renewable resources such as lignocellulosic biomass to produce biofuels, and...  相似文献   
830.
Environmental Chemistry Letters - Modern biomass and organic waste are becoming major, carbon-neutral sources of fine chemicals, biomolecules and fuels to replace fossil fuel products. As a...  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