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   412篇
  免费   0篇
安全科学   6篇
废物处理   51篇
环保管理   27篇
综合类   20篇
基础理论   48篇
环境理论   1篇
污染及防治   114篇
评价与监测   118篇
社会与环境   24篇
灾害及防治   3篇
  2023年   20篇
  2022年   34篇
  2021年   22篇
  2020年   5篇
  2019年   9篇
  2018年   23篇
  2017年   14篇
  2016年   26篇
  2015年   10篇
  2014年   25篇
  2013年   38篇
  2012年   9篇
  2011年   12篇
  2010年   29篇
  2009年   31篇
  2008年   27篇
  2007年   17篇
  2006年   7篇
  2005年   6篇
  2004年   5篇
  2003年   13篇
  2002年   11篇
  2001年   5篇
  2000年   4篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1993年   1篇
  1990年   1篇
  1984年   1篇
  1979年   1篇
  1973年   1篇
排序方式: 共有412条查询结果,搜索用时 31 毫秒
91.
Performances of gas engines operated with landfill gas (LFG) are affected by the impurities in the LFG, reducing the economic viability of energy recovery. The purpose of this study was to characterize the trace compounds in the LFG at the Odayeri Landfill, Istanbul, Turkey which is used for energy recovery. Composite gas samples were collected and analyzed for trace compounds (hydrocarbons, siloxanes, and volatile halogenated hydrocarbons) over a 3-year period. Trace compounds entering the gas engines, their impact on the engine performance were evaluated. The operational problems included deposit formation in the combustion chamber, turbocharger, and intercooler of engine before the scheduled maintenance times. High levels of hydrogen sulfide, as well as chlorinated and fluorinated compounds cause corrosion of the engine parts and decrease life of the engine oils. Persistence of siloxanes results in deposit formation, increasing engine maintenance costs. Pretreatment of LFG is necessary to protect the engines at the waste-to-energy facilities with persistence levels of siloxanes and volatile halogenated hydrocarbons.  相似文献   
92.
The overall objective of this study was to explore the utility of waste plastics as a potential source of diesel fuel. An experimental study was conducted to evaluate the use of various blends of plastic oil produced from waste polyethylene (WPE) with diesel fuel (D). WPE was degraded thermally and catalytically using sodium aluminum silicate as a catalyst. The oil collected at optimum conditions (414°C–480°C range and 1 h reaction time) was fractionated at different temperatures and fuel properties of the fractions were measured. Plastic oil was blended with diesel fuel at the volumetric ratios of 5%, 10%, 15%, 20%, and 100%. Fuel properties of blends are found comparable with those of diesel fuel within the EN 590 Diesel Fuel standard and they can also be used as fuel in compression ignition engines without any modification. Engine performance and exhaust emission studies of 5% WPE-D (WPE5) blend were performed. Experimental results showed that carbon monoxide (CO) emission is decreased by 20.63%, carbon dioxide (CO2) emission is increased by 3.34%, and oxides of nitrogen (NOx) emission is increased by 9.17% with WPE-D (WPE5) blend compared to diesel fuel.  相似文献   
93.
Hatchling sex ratios in the loggerhead turtle (Caretta caretta) were estimated by placing electronic temperature recorders in 21 nests at Fethiye beach during 2000–2002. Over the seasons, the mean temperature in the middle third of the incubation period ranged from 26.7 to 32.1°C, and incubation periods ranged from 49 to 67 days. Based on the mean temperatures during the middle third of the incubation period, and on histologically sexed dead hatchlings, the sex ratios of hatchlings at Fethiye beach were roughly equal, i.e. 60–65% of the hatchlings were females. This contrasts with the highly female-skewed sex ratios in loggerhead turtles elsewhere; Fethiye has a relatively high proportion of male hatchlings. For endangered sea turtles, the knowledge of hatchling sex ratios at different beaches, coupled with appropriate conservation measures, can make an important contribution to their survival.  相似文献   
94.
The aim of this study is the treatment of Basic Red 29 (BR29) dye solution using hybrid iron-aluminum electrodes by electrocoagulation and electro-Fenton methods. The effect of current density, initial pH, supporting electrolyte, H2O2, and initial dye concentration on dye removal efficiency was investigated, and the best experimental conditions were obtained. Time-coarse variation of UV-Vis spectra and toxicity and chemical oxygen demand (COD) removal were also examined at the best experimental conditions. Both systems were found very successful for the removal of BR29 dye. The removal efficiency of >95 % for BR29 dye solution was reached easily in a short time. At the best experimental conditions, for the initial BR29 concentration of 100 mg/L, >95 % BR29 dye and 71.43 % COD removal were obtained after 20 and 40 min of electrolysis, respectively. Additionally, toxicity results for electro-Fenton treatment of 100 mg/L BR29 were also very promising. According to the results obtained, although electro-Fenton is more effective, both systems can be used successfully to treat textile wastewater including dyes.  相似文献   
95.
Abstract

The purpose of this study was to investigate the T‐2 toxin contaminated grain and grain products consumed especially by Turkish population. The T‐2 toxin was detected using the high performance liquid chromatography (HPLC) with UV detector at 208 nm and the identify of T‐2 was further confirmed by thin layer chromatography (TLC). The recovery was 91 ±4.24% for corn flour fortified with the known amount of T‐2 toxin (1 ppm). The detection limits of T‐2 toxin for the HPLC and the TLC were 25 ng and 50 ng, respectively. A total of 30 commercially available grain and grain product samples were analyzed. Two corn flour samples were found to contain detectable levels of T‐2 toxin at a level of 1.60 ppm and 4.08 ppm.  相似文献   
96.
ABSTRACT

Stirling engines maintain attraction because of their high energy conversion efficiencies. In this study, experimental comparison of a beta-type Stirling engine for two different rhombic-drive mechanisms was presented. In one of the rhombic mechanisms, spur gears were used and the gear shaft was supported in bearings from one side. In the other mechanism, two helical gears were placed on crankshafts and the crankshafts were supported in bearings from both sides. Rhombus lengths of the mechanisms were determined as 66 mm and 80 mm to provide same constant compression ratio of 2.5 for both configurations. Both mechanisms were used in the same beta-type Stirling engine having same cylinder, piston and displacer dimensions. Performance parameters of the engines were evaluated at different helium charge pressures (2–4 bar) and hot-end temperatures (400–600°C). The hot-end of the displacer cylinder was heated by a liquefied petroleum gas (LPG) burner. The engine power increased by 132%, friction losses and gear noses were reduced by supporting the rhombic-drive mechanism from both side and using helical gears. The maximum output torque and power of the engine were obtained as 13.14 Nm at 428 rpm engine speed and 663 W at 800 rpm engine speed, respectively, at 600°C hot-end temperature and 4 bar charge pressure.  相似文献   
97.
Data on the short-term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.  相似文献   
98.
Nose-level measurements of air toxics were made along a busy urban street in Ottawa, Canada for 2 hr periods during morning, noon, and afternoon rush hours in the winter and summer of 2000. Measurements were also made in a commuter car and a transit bus during morning and afternoon commutes in 2000. The main objectives of the study were to establish a database, to determine temporal and seasonal variations and to determine the contribution of motor vehicle traffic to the measured toxic substance concentrations. Ottawa is an appropriate choice of location for the measurement of motor vehicle related toxic and reactive compounds, as it has virtually no industrial sources that could be contributing to the ambient loadings. Samples were collected for a total of 165 volatile organic compounds and 25 carbonyl compounds. Sampling and analytical methodologyare discussed and results are presented. Toluene, ethylene andformaldehyde were the most abundant pollutants in Ottawa during both winter and summer. Total non-methane hydrocarbon concentrationwas measured as 100 g m-3 at nose-level measurements in Ottawa.  相似文献   
99.
Cell-wall components and solubility characteristics of the heartwood and sapwood of Taxus baccata L. were determined by methods of wood analysis and the differences between heartwood and sapwood were established. When we observe the data obtained, it is seen that the amount of extractive material found in the heartwood is substantially higher than the sapwood. The extractive material in Taxus baccata L. is originated from the hidden epithelial cells surrounded by resin canals.  相似文献   
100.
Various techniques have been applied to air pollution modelling. In this study, a model was developed by applying a continuity equation to the air control volume over Erzurum city centre. Model parameters were calculated by regression analysis, using SO2 and particle concentrations taken in 1989-1990 and 1990-1991 winter seasons. Multiple correlation coefficients, R2, for all analyses were of the same order of 97%. According to this model, daily polluting concentrations are not only influenced by daily meterological parameters but also by the values of previous days. The proposed model allows estimation of daily polluting concentrations by means of meteorological data.  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