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   4552篇
  免费   534篇
  国内免费   700篇
安全科学   1426篇
废物处理   457篇
环保管理   591篇
综合类   2164篇
基础理论   258篇
环境理论   4篇
污染及防治   407篇
评价与监测   347篇
社会与环境   82篇
灾害及防治   50篇
  2024年   10篇
  2023年   60篇
  2022年   108篇
  2021年   165篇
  2020年   172篇
  2019年   151篇
  2018年   127篇
  2017年   196篇
  2016年   208篇
  2015年   266篇
  2014年   274篇
  2013年   348篇
  2012年   415篇
  2011年   382篇
  2010年   274篇
  2009年   293篇
  2008年   170篇
  2007年   291篇
  2006年   310篇
  2005年   212篇
  2004年   168篇
  2003年   188篇
  2002年   164篇
  2001年   144篇
  2000年   141篇
  1999年   104篇
  1998年   88篇
  1997年   84篇
  1996年   83篇
  1995年   54篇
  1994年   42篇
  1993年   34篇
  1992年   23篇
  1991年   14篇
  1990年   14篇
  1989年   4篇
  1988年   3篇
  1987年   2篇
排序方式: 共有5786条查询结果,搜索用时 593 毫秒
891.
本文对发改委颁布的(《温室气体自愿减排交易管理暂行办法》进行了解读、分析其特点并指出尚需进一步解决的问题。  相似文献   
892.
The engagement of UK local authorities is vital if national government is to meet its climate change commitments. However, with no mandatory targets at local government level, other drivers must explain engagement. Using a Geographic Information System, this study compares the spatial distribution of action on climate change based on past actions and stated intentions to a suite of relevant independent variables. The Action Index created is among the first to quantify climate change engagement beyond a simple binary measure and provides a useful comparative study to recent work in the USA. The Index enables investigation of both mitigation and adaptation, which show different trends in relation to some variables. The study shows that action is strongest where the voting habits of the local population suggest environmental concern and where neighbouring local authorities are also engaging in action on climate change. Physical vulnerability to the effects of climate change is a motivator for action only where the dangers are obvious. Action is less likely where other resource-intensive issues such as crime and housing exist within a local authority area.  相似文献   
893.
对影响玻璃熔窑SCR烟气脱硝设计的几个主要因素,如烟气条件(烟气量和NOx初始浓度)、还原剂、催化剂、SCR反应器布置方式及催化剂吹灰方式等进行了分析与讨论,指出在对玻璃熔窑进行SCR烟气脱硝设计时应根据燃料情况、烟气条件、生产工艺、环保法规及污染物减排要求等合理进行选择,以确保玻璃熔窑SCR烟气脱硝系统安全运行及工程投资、运行费用的经济合理性。  相似文献   
894.
简述了中国锰矿资源的特点,简析了锰矿中的杂质对软锰矿烟气脱硫体系的影响,并在矿石中杂质对体系pH缓冲能力分析的基础上,将软锰矿分为高碱性矿石、中碱性矿石和低碱性矿石。  相似文献   
895.
气相色谱经加装双ECD检测器,实现单塔双柱双检测器测定农产品中有机氯、拟除虫菊酯类农药残留,在不须关机换色谱柱情况下实现双柱定性定量分析。该方法可节约大量定性分析时间,通过百菌清、氯氟氰菊酯、三唑酮、氯氰菊酯的加标回收试验,平均回收率为95.0%~102.5%,相对标准偏差为1.88%~3.72%,方法稳定可靠。  相似文献   
896.
This paper presents results from a gate-to-gate analysis of the energy balance, greenhouse gas (GHG) emissions and economic efficiency of biochar production from palm oil empty fruit bunches (EFB). The analysis is based on data obtained from EFB combustion in a slow pyrolysis plant in Selangor, Malaysia. The outputs of the slow pyrolysis plant are biochar, syngas, bio-oil and water vapor. The net energy yield of the biochar produced in the Selangor plant is 11.47 MJ kg−1 EFB. The energy content of the biochar produced is higher than the energy required for producing the biochar, i.e. the energy balance of biochar production is positive. The combustion of EFB using diesel fuel has the largest energy demand of 2.31 MJ kg−1 EFB in the pyrolysis process. Comparatively smaller amounts of energy are required as electricity (0.39 MJ kg−1 EFB) and for transportation of biochar to the warehouse and the field (0.13 MJ kg−1 EFB). The net greenhouse gas emissions of the studied biochar production account for 0.046 kg CO2-equiv. kg−1 EFB yr−1 without considering fertilizer substitution effects and carbon accumulation from biochar in the soil. The studied biochar production is profitable where biochar can be sold for at least 533 US-$ t−1. Potential measures for improvement are discussed, including higher productivity of biochar production, reduced energy consumption and efficient use of the byproducts from the slow pyrolysis.  相似文献   
897.
Controlled atmospheric storage is a widely popular technique for storage of fruits and vegetables. In this paper, the experimental studies on biomass powered absorption systems for cold storage applications using ammonia water as a working fluid pair is presented. The heat input to the absorption system is supplied by a producer gas obtained from a downdraft gasifier, using firewood as fuel. The system is designed and fabricated to store about 15 MT of fruits and vegetables, having a cooling capacity of 3 TR. The effect of sink temperature, solution flow rate, cooling water flow rate and biomass consumption on the performance of the system has been analyzed. It is found that the real co-efficient of performance of the system is around 0.35 - 0.2, considering the source-site factor for auxiliary power consumption. The operating Cost/h for the biomass based cold storage system is lower than the presently available conventional compression based units.  相似文献   
898.
Abstract

This article describes a novel flat plate heat-pipe solar collector, namely, the hybrid heat-pipe solar collector. An analytical model has been developed to calculate the collector efficiency as well as simulate the heat transfer processes occurring in the collector. The effects of heat pipes/absorber, top cover, flue gas channel geometry, and flue gas temperature and flow rate, on the collector efficiency were investigated based on three modes of operation, i.e., solar only operation, solar/exhaust gas combined, and solar, exhaust gas and boiler combined. Experimental testing of the collector was also carried out for each of these modes of operation under real climatic conditions. The results were used to estimate the efficiency of the collector and determine the relation between the efficiency and general external parameter. The modeling and experimental results were compared and a correlation factor was used to modify the theoretical predictions. It was found that the efficiency of the collector was increased by about 20–30% compared to a conventional flat-plate heat pipe solar collector.  相似文献   
899.
This article is concerned with control issues related to the design of a semi-closed O 2/CO 2 gas turbine cycle for CO 2 capture. Some control strategies and their interaction with the process design are discussed. One control structure is implemented on a dynamic simulation model using a predictive controller, and simulations assess the performance and compare its merits with a conventional PI structure. The results indicate that it can be advantageous for operability to allow a varying (as opposed to fixed) compressor inlet pressure, at the cost of a more expensive design. Furthermore, the results show that a predictive controller has some advantages with respect to the simpler conventional PI control structure, in particular in terms of constraint handling.  相似文献   
900.
环境温度是研究车用压缩天然气瓶火烧试验机理的一个重要因素,因此有必要定量的研究环境温度对火烧试验的影响。在已有火烧试验数据的基础上,分析了环境温度对车用压缩天然气瓶火烧试验安全泄放压力和火烧持续时间两个关键指标的影响,结果表明安全泄放压力、火烧持续时间和环境温度均呈反比关系。  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