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   3050篇
  免费   413篇
  国内免费   1123篇
安全科学   185篇
废物处理   129篇
环保管理   583篇
综合类   2476篇
基础理论   393篇
污染及防治   197篇
评价与监测   240篇
社会与环境   339篇
灾害及防治   44篇
  2024年   25篇
  2023年   96篇
  2022年   158篇
  2021年   198篇
  2020年   185篇
  2019年   176篇
  2018年   175篇
  2017年   195篇
  2016年   212篇
  2015年   210篇
  2014年   223篇
  2013年   299篇
  2012年   282篇
  2011年   318篇
  2010年   193篇
  2009年   167篇
  2008年   110篇
  2007年   150篇
  2006年   147篇
  2005年   120篇
  2004年   109篇
  2003年   132篇
  2002年   86篇
  2001年   115篇
  2000年   97篇
  1999年   91篇
  1998年   50篇
  1997年   58篇
  1996年   51篇
  1995年   42篇
  1994年   26篇
  1993年   27篇
  1992年   16篇
  1991年   13篇
  1990年   7篇
  1989年   2篇
  1988年   6篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有4586条查询结果,搜索用时 31 毫秒
911.
The performance of four dioxin emission monitors, including two long-term sampling devices, the Dioxin-MonitoringSystem (DMS) and AMESA (the adsorption method for sampling dioxins and furans), and two semireal-time continuous monitors, the resonance ionization with multimirror photon accumulation time-of-flight mass spectrometer (RIMMPA-TOFMS) and the jet resonance-enhanced multiphoton ionization (jet-REMPI) system were tested. A package boiler burning a simulated chlorinated hazardous waste was used for a total of nine tests. Reference samples were collected during each test and analyzed for polychlorinated dibenzodioxins and dibenzofurans (PCDDs/Fs) using gas chromatography mass spectrometry. The PCDD/F concentrations of the reference samples measured by EPA Method 23 ranged from 0.9 to 6.0 ng toxic equivalence (TEQ)/dry standard cubic meter. The relative accuracies achieved by DMS, AMESA, and jet-REMPI varied from 22.6% to 78.2%, with 100% data completeness. The RIMMPA-TOFMS produced no quantifiable results due to various difficulties associated with the instrument during the testing. The two long-term samplers were easy to install and operate and provided a cumulative, averaged emission for the sampling period. The operations of the two semi-real-time continuous monitors were relatively complex, but one of them provided on-site, real-time data for PCDD/F emissions from measurement of a TEQ correlative indicator compound. This article summarizes results from the individual Environmental Technology Verification reports for the four dioxin monitors. This work was presented, in part, at the Fourth International Conference on Combustion, Incineration/Pyrolysis and Emission Control (i-CIPEC)  相似文献   
912.
Sorbitol and glycerol were used to plasticize sugar beet pulp-poly(lactic acid) green composites. The plasticizer was incorporated into sugar beet pulp (SBP) at 0%, 10%, 20%, 30% and 40% w/w at low temperature and shear and then compounded with poly(lactic acid) (PLA) using twin-screw extrusion and injection molding. The SBP:PLA ratio was maintained at 30:70. As expected, tensile strength decreased by 25% and the elongation increased. Acoustic emission (AE) showed correlated debonding and fracture mechanisms for up to 20% w/w plasticizer and uncorrelated debonding and fracture for 30–40% sorbitol and 30% glycerol content in SBP–PLA composites. All samples had a well dispersed SBP phase with some aggregation in the PLA matrix. However, at 40% glycerol plasticized SBP–PLA composites exhibited unique AE behavior and confocal microscopy revealed the plasticized SBP and PLA formed a co-continuous two phase system.
V. L. FinkenstadtEmail:
  相似文献   
913.
The impact of air traffic on the global atmosphere is characterised by a high degree of uncertainty, concerning both the physico-chemical phenomena involved and the extent of the forcing due to anthropogenic emissions. The different effects of these emissions (e.g. on climate change, stratospheric ozone depletion, acidification, tropospheric ozone formation) are dealt with by different international bodies and conventions (e.g. IPCC, EMEP. . .) which are trying to define a standard methodology allowing countries to evaluate their contributions to global aircraft emissions and to report these figures in a standardised way. The paper compares different methodologies proposed by the joint EMEP/CORINAIR 'Atmospheric Emission Inventory Guidebook' for estimating aircraft emissions. Adjustments to these methodologies have been proposed, in order to integrate some additional data such as the total amount of flight hours per aircraft type or fuel consumption per trip. In case detailed information is not available, we recommend the use of a VERY SIMPLE methodology which may yield acceptable results, provided that every country makes adequate assumptions on the average aircraft type.  相似文献   
914.
The paper presents an emission inventory for Cochin, which is a highly industrialized area situated in the southern part of India. A proper emission inventory is very important for planning pollution control programmes, particularly in coastal sites like Cochin, where environmental situations are of growing concern owing to their typical meterorological conditions. In a systematic way the sources are broadly classified as point, line and area sources. The data on emissions from industries, fuel consumption for vehicular and domestic activities along with the respective emission factors are used for estimating the emissions. The study reveals that industrial sources are mainly responsible for emissions of particulate matter, oxides of sulphur and ammonia in the region. Automobiles are the prime sources of hydrocarbons, oxides of nitrogen and carbon monoxide emitting 95%, 77% and 70% respectively of their total emissions, while the contribution from domestic sources is not very significant.  相似文献   
915.
针对城市汽车尾气治理及化油器型车辆的排放现状 ,指出开发和运用闭环电控三元催化技术是目前解决城市化油器型车辆排放问题及时可行的过渡措施 ,并对电控三元催化技术的应用提出了建议与要求。  相似文献   
916.
917.
不同母质发育的水稻土中铁、锰对甲烷排放的影响   总被引:1,自引:0,他引:1  
盆栽结果表明,不同土壤类型铁、锰含量的差异是造成不同土壤类型间甲烷排放量差异甚大的重要因素之一。土壤中铁、锰通过对土壤氧化还原电位及根膜形成的影响而影响甲烷的排放。  相似文献   
918.
When accounting the CO2 emissions responsibility of the electricity sector at the provincial level in China,it is of great significance to consider the scope of both producers’ and the consumers’ responsibility,since this will promote fairness in defining emission responsibility and enhance cooperation in emission reduction among provinces.This paper proposes a new method for calculating carbon emissions from the power sector at the provincial level based on the shared responsibility principle and taking into account interregional power exchange.This method can not only be used to account the emission responsibility shared by both the electricity production side and the consumption side,but it is also applicable for calculating the corresponding emission responsibility undertaken by those provinces with net electricity outflow and inflow.This method has been used to account for the carbon emissions responsibilities of the power sector at the provincial level in China since 2011.The empirical results indicate that compared with the production-based accounting method,the carbon emissions of major power-generation provinces in China calculated by the shared responsibility accounting method are reduced by at least 10%,but those of other power-consumption provinces are increased by 20% or more.Secondly,based on the principle of shared responsibility accounting,Inner Mongolia has the highest carbon emissions from the power sector while Hainan has the lowest.Thirdly,four provinces,including Inner Mongolia,Shanxi,Hubei and Anhui,have the highest carbon emissions from net electricity outflow- 14 million t in 2011,accounting for 74.42% of total carbon emissions from net electricity outflow in China.Six provinces,including Hebei,Beijing,Guangdong,Liaoning,Shandong,and Jiangsu,have the highest carbon emissions from net electricity inflow- 11 million t in 2011,accounting for 71.44% of total carbon emissions from net electricity inflow in China.Lastly,this paper has estimated the emission factors of electricity consumption at the provincial level,which can avoid repeated calculations when accounting the emission responsibility of power consumption terminals(e.g.construction,automobile manufacturing and other industries).In addition,these emission factors can also be used to account the emission responsibilities of provincial power grids.  相似文献   
919.
研究10种不同价格香烟燃烧烟气的多环芳烃(PAHs)含量特征,结果表明,每种香烟烟气都含有多环芳烃,但是含量差别较大,平均值为405.405ng/g。在检测出来的多环芳烃中,主要是以2,3环多环芳烃为主,占据的比例达到80%左右。因此香烟烟气中的多环芳烃应该引起人们的广泛关注。  相似文献   
920.
通过分析化工企业典型开、停车过程的排污节点,表明停车过程中大气挥发性有机污染物主要来自装置退料结束后挂壁、底部滞留和内部空间蒸气等滞留在设备内部的残余物料。在总结化工装置停工放空过程中大气挥发性有机物来源的基础上,讨论并提出大气污染排放量估算方法。  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