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   138篇
  免费   2篇
  国内免费   2篇
安全科学   8篇
废物处理   15篇
环保管理   12篇
综合类   6篇
基础理论   27篇
污染及防治   49篇
评价与监测   17篇
社会与环境   7篇
灾害及防治   1篇
  2023年   7篇
  2022年   15篇
  2021年   11篇
  2020年   6篇
  2019年   10篇
  2018年   6篇
  2017年   9篇
  2016年   13篇
  2015年   4篇
  2014年   11篇
  2013年   18篇
  2012年   6篇
  2011年   5篇
  2010年   5篇
  2009年   4篇
  2008年   5篇
  2007年   1篇
  2006年   1篇
  2002年   1篇
  2000年   2篇
  1990年   1篇
  1982年   1篇
排序方式: 共有142条查询结果,搜索用时 31 毫秒
41.
42.
In this research, an experimental study of reinforcing alumina nano-particles into the aluminum alloy matrix was implemented to verify the accuracy of modeling results obtained by feed forward neural networks. Artificial neural network combined with numerical technique were used to predict the various parameters of mechanical properties such as hardness, tensile and compressive yield stress, UTS and elongation percentage. Much experimentation were taken to discover a suitable number of hidden neurons, avoid detraction from the trainability and enable feed forward neural networks to solve more complex problems. The predictions were found to be consistent with experimental measurements.  相似文献   
43.
Environmental Science and Pollution Research - We reported the tin (II) tungstate nanoparticles as the photocatalyst and sensor modifier that were synthesized via chemical precipitation reaction...  相似文献   
44.
This article has investigated the propagation and extinction of aluminum dust cloud flame in a narrow channel. The burned and burning dust particles act as heat sources and the channel walls act as heat sinks. In this method, discrete heat source has been used to analyze dust combustion in a narrow channel. Using the superposition of sources and sinks, the preheat zone temperature is predicted as an indicator of flame propagation or extinction. Dust concentration and channel width are two major parameters which affect the quenching distance and flame propagating speed. Wall temperature affects the heat loss; and by preheating the walls, quenching distance is reduced and flame propagation speed is increased.  相似文献   
45.
Benzene removal evaluated using Fe304 nano continuous condition. A 44 initial benzene concentration, from aqueous solutions was magnetic particles (NM) in factorial design including NM dose, contact time and pH was investigated in 16 experiments (Taguchi OA design). The results indicated that all factors were significant and the optimum condition was: pH 8, NM dose of 2000 mg.L-1, benzene concentrations of 100 mg.L-1 and contact time of 14min. The maximum benzene uptake and distribution ratio in the optimum situation were 49.4mg.g-1 and 38.4L.g-1, respectively. The nano particles were shown to capture 98.7% of the benzene in optimum batch condition and 94.5% in continuous condition. The isotherm data proved that the Bmnauer-Emmett-Teller model fit more closely and produced an isotherm constant (b) less than one, indicating favorable adsorption. Regeneration studies verified that the benzene adsorbed by the NM could be easily desorbed by temperature, and thereby, NM can be employed repeatedly in water and wastewater management.  相似文献   
46.
Understanding communicational behavior of rangelands’ stakeholders is fundamental for effective development of rangeland management plans. This study aimed to understand differences between stakeholders’ relations among various actors involved in rangeland management using social network analysis (SNA). A survey was conducted on 334 stakeholders (89 extension agents, 110 researchers and 135 executive agents) in the Tehran province, Iran. Results showed that all the three groups of stakeholders are interested in making contact mainly within their own group. Furthermore, while the executive agents have shared the strongest technical and friendship relations with the two other groups, the extension agents established the strongest administrative interactions. The researchers, however, made a poor link especially with the extension agents. The study concluded that SNA could be an efficient tool to assess communicational behavior in rangeland management.  相似文献   
47.
In this study, the volume and the cash value of water loss, and reduction of water loss as a result of enforcement action during 2011–2013 in the drinking water network of villages in Kermanshah Province, Iran, have been investigated. Date collected by referring to the different parts of rural water and waste water company of Kermanshah Province and checklist were completed. The study showed the volume of produced water and sold water has increased and the water loss percentage has decreased. High cost of water production compared to revenue of sold water and water loss resulted in significant detriments in terms of the water production costs. Water loss level decreased from 33% to 30% as result of measures taken to reduce water loss but, it is still 15% higher than the world average level. Also the reduction in number of water resources and increase in the number and volume of reservoirs indicates a lack of water and a growing need. As result of high water loss, waste of costs in the contrast of water production cost and also because physical water loss accounts for most of the water loss of villages, necessary measures can be effective in reducing loss and have economic justification.  相似文献   
48.
This article explains that the nature of commodity price determination and the characteristics of the link between commodity prices and prices of manufactured goods are such that they have an inflationary and recessionary impact on the world economy. Subsequently, it argues that International Commodity Price Agreements (ICAs) and the Common Fund are not only in the interest of developing countries but are also in the vital interest of developed countries. They assist in stabilizing economic activities and sustaining recovery at a higher rate of growth of output and employment in these countries. Nevertheless, to be effective for these purposes, ICAs should cover a wide range of commodities and adequate financial resources should be available to the First Account of the Common Fund.  相似文献   
49.
Environment, Development and Sustainability - Water resources allocation policies can create cooperation or tension among different stakeholders in a large basin. Thus, integrated water resources...  相似文献   
50.
Environmental Science and Pollution Research - The possibility of using different densities of cherry tomato as a bio-filter in a simple media-based aquaponic system to recycle nutrients from pearl...  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