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71.
Danuta Roman-Liu Krzysztof Kędzior 《International journal of occupational safety and ergonomics》2013,19(1):109-124
The aim of this study was to verify a theoretical model for upper extremity work space optimization. In order to do that, experimental studies were conducted in which two parameters of the electromyography (EMG) signal were analyzed: AMP (amplitude calculated as Root Mean Square) and SZC (coefficient of the slope of the regression line between time and Zero Crossing values). Values of forces in muscles (parameter MOD) were calculated from theoretical studies. A comparison of experimental (AMP, SZC) and theoretical (MOD) parameters was performed by analyzing the coefficient of correlation between those parameters and differentiation of muscular load according to external load value. Analysis showed that the theoretical and experimental results are in step, which means that the developed model can be used for upper extremity work space optimization. 相似文献
72.
《International Journal of Sustainable Engineering》2013,6(4):248-261
ABSTRACTRenewable and sustainable fuels for diesel engine applications provide energy protection, overseas exchange saving and address atmospheric and socio-economic concerns. This study presents the investigational work carried out on a single cylinder, four-stroke, direct injection diesel engine operated in dual fuel (DF) mode using renewable and sustainable fuels. In the first phase, a Y-shaped mixing chamber or venture was developed with varied angle facility for gas entry at 30°, 45° and 60°, respectively, to enable homogeneous air and gas mixing. Further effect of different gas and air mixture entry on the DF engine performance was studied. In the next phase of the work, hydrogen flow rate influence on the combustion and emission characteristics of a compression ignition (CI) engine operated in DF mode using diesel, neem oil methyl ester (NeOME) and producer gas has been investigated. During experimentation, hydrogen was mixed in different proportions varied from 3 to 12 l/min (lpm) in step of 3 lpm along with air-producer gas and the mixtures were directly inducted into engine cylinder during suction stroke. Experimental investigation showed that 45° Y-shaped mixing chamber resulted in improved performance with acceptable emission levels. Further, it is observed that investigation showed that at maximum operating conditions and hydrogen flow rate of 9 lpm, Diesel–producer gas and NeOME–producer gas combination showed increased thermal efficiency by 13.2% and 3.8%, respectively, compared to the DF operation without hydrogen addition. Further, it is noticed that hydrogen-enriched producer gas lowers the power derating by 5–10% and increases nitric oxide (NOx) emissions. However, increased hydrogen addition beyond the 12 lpm leads to sever knocking.Abbreviations: NeOME: Neem oil methyl ester; BTE: brake thermal efficiency; CI: compression ignition; ITE: indicated thermal efficiency; PG: producer gas; CA: crank angle; K: Kelvin; BP: brake power; IP: indicated power; H2: hydrogen; HC: unburnt hydrocarbon; CO: carbon dioxide; CO2: carbon dioxide; NOx: nitric oxide; HRR: heat release rate; %: percentage; PPM: parts per million; CMFIS: conventional mechanical fuel injection system. 相似文献
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74.
利用多级厌氧无污泥返混与多级厌氧有污泥返混系统处理高浓度焦化污水后 ,证明多级厌氧无污泥返混系统 (各步之间没有生物数量的混合 )的性能优于多级厌氧有污泥返混系统 (各步之间有生物数量混合 )。多级厌氧无污泥返混比多级厌氧有污泥返混系统更能抵抗冲击荷载 (pH值高、COD和NH3 N浓度高 )、产生更多的沼气 相似文献
75.
针对聚合硫酸铁(PFS)混凝-沉淀去除腐殖酸(HA)水样的过程,通过测定典型操作因素(PFS投加量、原水pH和搅拌方式)下微絮体的zeta电位、上清液的浊度、UV254、pH值及电导率和絮体沉降体积变化,探讨了这些因素对该过程的影响.结果表明:在原水pH=6.00时,PFS混凝HA的主要机制为电中和作用,搅拌方式对PFS的最佳投加范围没有明显的影响,但单一搅拌方式下HA的去除效果更好;在原水pH=8.00时,吸附络合-卷扫絮凝成为主要的混凝机制,复合搅拌方式下PFS的最佳投加量范围大于单一搅拌方式,且前者的HA去除效果更好.整体而言,几种混凝条件下PFS最佳投药量对应的微絮体zeta电位均在-12.00mV左右;原水pH=6.00时PFS混凝-沉淀去除HA的效果比原水pH=8.00时的好,且前者形成的PFS-HA沉淀絮体体积较小,但单一搅拌方式下絮体结构的重组过程并不是影响絮体体积的主要因素.复合搅拌方式中开始阶段的高强度搅拌有助于PFS组分在HA水样中的分散而有利于其电中和作用的发挥,但对PFS的水解过程影响不大. 相似文献
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78.
间歇曝气对人工垂直潜流湿地氮磷去除性能的影响 总被引:9,自引:2,他引:7
采用页岩和香蒲(Typha latifolia)构建人工垂直潜流湿地处理津河富营养化水体,研究间歇曝气对潜流湿地氮磷去除效果的影响.设计水力负荷800 mm/d,气水比5∶1.试验期间(2006-06~2006-11),氮磷月平均去除率在8月份达到最大值.与无曝气系统相比,中部曝气使氨氮(NH 4-N)、总氮(TN)、可溶性活性磷(SRP)和总磷(TP)月平均去除率分别提高10.1%、4.7%、10.2%和8.8%,底部曝气则为25.1%、10.0%、7.7%和7.4%,间歇曝气能够有效提高人工潜流湿地氮磷去除效率.曝气产生的有氧环境不利于硝酸盐氮(NO-3-N)去除,试验期间底部曝气和中部曝气NO-3-N月平均去除率一直低于无曝气系统.试验结束后收割香蒲地上组织(茎和叶),测定地上组织生物量及茎、叶中的氮磷含量,结果表明,间歇曝气虽然抑制香蒲地上组织生物量的增加,但却能够有效提高茎、叶中氮磷含量.与无曝气系统相比,通过收割香蒲地上组织可使TN去除分别增加11.6g·m-2(中部曝气)和12.6 g·m-2(底部曝气). 相似文献
79.
API standard 521 guidance on mixing of hot/cold liquids and prevention of superheat limit explosions
American Petroleum Institute (API) standards and recommended practices have identified inadvertent mixing of hot and cold liquids as a potential cause for equipment overpressure since 1955. The limited guidance has been informative but provides minimal if any details on conditions that could cause an overpressure and its potential severity. Therefore, the user must interpret how and when to prevent and/or mitigate the scenario. This guidance has changed little over the years. In June 2020, API published the 7th Edition of API Standard 521 which now provides specific guidance as to conditions whereby pressure relief devices can be considered for protection and conditions where prevention remains as the only recourse. This paper discusses the basis for the revised guidance in API Standard 521 and includes supplemental guidance. 相似文献
80.
Main R. Hutcheson 《Journal of the American Water Resources Association》1998,34(5):1025-1033
ABSTRACT: Acute criteria are assigned to the fish and wildlife propagation beneficial use in Oklahoma's water quality standards. Dye studies are analyzed to show that these criteria can be implemented through acute regulatory mixing zones. Acute regulatory mixing zones may be defined as areas in receiving streams where acute numerical criteria may be exceeded without causing acute toxicity. Acute regulatory mixing zones are used to obtain acute waste load allocations. If effluent loading does not exceed acute waste load allocation, acute criteria exceedance is confined to the acute regulatory mixing zone and there is no acute toxicity in the receiving stream. Waste load allocations for acute and chronic criteria are compared to determine which is appropriate to develop permit limits for the dye studies. 相似文献