全文获取类型
收费全文 | 234篇 |
免费 | 60篇 |
国内免费 | 80篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 12篇 |
环保管理 | 70篇 |
综合类 | 191篇 |
基础理论 | 9篇 |
污染及防治 | 19篇 |
评价与监测 | 8篇 |
社会与环境 | 18篇 |
灾害及防治 | 2篇 |
出版年
2024年 | 4篇 |
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 22篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 21篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 11篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 16篇 |
2006年 | 8篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有374条查询结果,搜索用时 62 毫秒
171.
Yasin Şöhret Olcay Kıncay T. Hikmet Karakoç 《International Journal of Green Energy》2018,15(3):145-150
Emitted exhaust gases from aircraft are an issue of concern from an environmental perspective. Many research studies have been conducted aiming to reduce aircraft emissions in the hope of preventing any further increase in climate change and global warming. Within this scope, the present study intends to present a methodology for an optimum gas turbine engine selection with regard to emitted exhaust gases. The methodology focuses on five different turbofan engines which constitute the power unit of a commonly used passenger aircraft. At the end of the study, it is considered to be impossible to achieve a minimum exhaust emission for each gas. For this reason, it is considered to be better to optimize the engine with the aim of reducing nitrogen oxide emissions or other exhaust emissions. 相似文献
172.
173.
《International Journal of Sustainable Engineering》2013,6(4):265-274
During recent decades, considerable effort has been expended world-wide to reduce dependency on petroleum fuels for power generation and transportation through the search for suitable alternative fuels that are environmentally friendly. In this respect, vegetable oils are a promising alternative to diesel fuel. However, the high viscosity, poor volatility and cold flow characteristics of vegetable oils can cause some problems such as injector coking, severe engine deposits, filter gumming and piston ring sticking and thickening of lubrication from long-term use in diesel engines. These problems can be eliminated or minimised by transesterification of the vegetable oils to form monoesters. Although transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than those of petroleum diesel fuel. The performance of a diesel engine with such biodiesel operation can be improved further with the concept of the low heat rejection (LHR) engine. In the LHR engine, combustion surfaces on the pistons, cylinder walls and valves can be coated with ceramic materials. The objective of this study was to apply the LHR engine concept for improving engine performance when either honge biodiesel, known as honge oil methyl ester (HOME), or neem biodiesel, known as neem oil methyl ester (NOME) oils was used as an alternative fuel. For this purpose, experiments were conducted on a single cylinder, four-stroke, direct injection, water-cooled compression ignition engine using diesel, HOME and NOME oils at different injection timings of 19, 23 and 27° before top dead centre (BTDC) with and without the induction of exhaust gas recirculation (EGR). The percentage of EGR was varied from 5 to 20% in steps of 5%. The results showed that specific fuel consumption and brake thermal efficiency were improved for both of the biodiesel fuels in the LHR engine. An EGR of 10% resulted in better performance with trade-off between oxides of nitrogen and hydrocarbons/carbon monoxide emissions and hence 10% EGR is taken as the best of the range from 5 to 20%. However, readings with other EGR ratios are not reported. 相似文献
174.
《International Journal of Sustainable Engineering》2013,6(6):341-348
Due to energy crisis and shortage of fossil fuel, there is a growing interest in alternative fuel for internal combustion engine. Producer gas presents a very promising alternative fuel to diesel since it is a renewable and clean burning fuel having properties similar to that of diesel. In this study, a twin cylinder dual fuel diesel engine is experimentally optimized for maximum diesel saving and lower emissions, without any undue vibration of engine using woody biomass producer gas. The test is carried out to study the performance and emission parameters of the engine in diesel mode and dual fuel mode at different gas flow rates under different load conditions. The study reveals that maximum diesel savings is found to be 83% at optimum gas flow rate and 8 kW load. Carbon monoxide, hydrocarbon and carbon dioxide emissions in dual fuel mode were higher compared with diesel mode at all test ranges. However, the main pollutants, such as nitrogen oxide and smoke, decrease substantially in the dual fuel mode compared with the diesel mode. Lower brake thermal efficiency and higher brake-specific energy consumption as well as exhaust gas temperature are observed in dual fuel mode compared with diesel mode. 相似文献
175.
《International Journal of Sustainable Engineering》2013,6(6):332-340
Alternative fuels for diesel engine applications are gaining more prominence as they have numerous advantages compared to fossil fuels. They are renewable, biodegradable; provide food and energy security and foreign exchange savings. They address environmental concerns and socio-economic issues as well. Gaseous fuels such as compressed natural gas and hydrogenated compressed natural gas (HCNG) appear more attractive fuels for diesel engine applications operated in dual-fuel mode. Such dual fuel engines can replace considerable amount of liquid-injected pilot fuels by gaseous fuels besides being friendly to the environment. A small quantity of liquid fuel injected towards the end of the compression stroke initiates combustion of the inducted gas in the dual-fuel engines. The main advantage of dual-fuel engines is their lower nitrogen oxides (NOx) and particulate emissions. Hence renewable fuels such as biodiesels and gaseous fuels can be used predominantly for transportation and power generation applications. Gaseous fuels are clean burning and are more economical as well. A suitable carburettor was designed to supply a stoichiometric mixture of air and HCNG to the modified diesel engine operated in dual-fuel mode. The biodiesel used in this study is derived from Honge oil called the Honge oil methyl ester (HOME). This paper presents the performance, combustion and exhaust emission characteristics of a single cylinder, four stroke, direct injection, stationary diesel engine operated on HOME and HCNG in dual-fuel mode. From the results it is observed that HOME–HCNG combination gave lower brake thermal efficiency (BTE) and improved emission levels when compared with diesel/HOME in single fuel operation. Lower smoke and particulate matter were obtained with dual-fuel operation. Comparative measures of BTE, peak pressure, pressure–crank angle variation, smoke opacity, hydrocarbon, carbon monoxide and NOx emissions have been made and analysed. 相似文献
176.
M. Shafiquzzaman Khan Örjan Johansson Ulrik Sundbäck 《International journal of occupational safety and ergonomics》2013,19(1):16-26
Subjective annoyance response to diesel engine sound during idling conditions was evaluated by 80 participants. Eight different sound spectra were presented to the participants at a constant level of 80 dB(A) in a paired comparison procedure. Stereo-recorded sound stimuli were played back through a pair of loudspeakers in an anechoic room. Four objective parameters of loudness, sharpness, impulsiveness, and roughness were found to be the determining factors that cause subjective annoyance. An annoyance prediction model for the test stimuli of an idling diesel engine was developed on the basis of these factors. The objective parameters and their interactions have a significant effect on the annoyance prediction model. The spectral distribution indicated by test participants to be pleasant can be used as a basis for appropriate modification of engine sound. A single microphone measurement in free field conditions can be used to estimate objective parameters for defining the cause of annoyance. 相似文献
177.
178.
179.
180.
目的系统研究可变喷嘴涡轮增压器(VNT)对运行在高原地区的车用柴油机动力性、经济性以及排放性能的影响关系,为高原地区电控柴油机与VNT的匹配控制以及降低其污染物排放提供一定的理论指导。方法在海拔高度约为1960 m的高原地区,选取柴油机的典型运行工况,即低速1400 r/min全负荷、2200 r/min全负荷(最大转矩工况)以及4000 r/min全负荷(额定功率工况),通过试验研究VNT对柴油机性能与排放的影响。结果在低速工况,随着VNT喷嘴环开度的增大,动力性降低,经济性恶化;在最大转矩与额定功率工况,均存在一个最佳的VNT喷嘴环开度使得转矩最大,同时油耗最低。随着VNT喷嘴环开度的增大,进气流量、空燃比、中冷前压力、中冷前温度以及涡前压力均降低,而涡前温度升高。在三个典型运行工况下,随着VNT喷嘴环开度的增大,氮氧化物(NO_x)比排放逐渐降低,而烟度、一氧化碳(CO)以及碳氢(HC)比排放逐渐升高,VNT对HC排放的影响较小。结论在高原地区,通过减小VNT喷嘴环开度可以降低涡前温度,进而降低柴油机的热负荷,提高其可靠性,合理调节VNT喷嘴环开度可以获得较为满意的NO_x比排放与烟度排放。 相似文献