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131.
Sung Su Kim 《Journal of the Air & Waste Management Association (1995)》2013,63(3):362-369
In this study, the authors investigated the influence of the valence state of Mn on the efficacy of selective catalytic reduction using a Mn-based catalyst. The nitrogen oxides (NOx) conversion rate of the catalyst was found to be dependent on the type of TiO2 support employed and on the temperature, as the catalyst showed an excellent conversion of > 80% at a space velocity of 60,000 hr?1 when the temperature was above 200 °C. Brunauer-Emmett-Teller, X-ray diffraction, and X-ray photoelectron spectroscopy analyses confirmed that catalyst displaying the highest activity contained the Mn4+ species and that its valence state was highly dependent on the pH during the catalyst preparation.
Implications Recently, various Mn catalysts have been evaluated as selective catalyst reduction (SCR) catalysts. However, in these previous studies, only the reaction characteristics and catalytic activity on the NH3 SCR over Mn catalysts were evaluated. There have been no studies on the effect of pH during catalyst preparation. Therefore, in this study, the effect of pH during the catalyst preparation process was examined and a new application of the Mn catalysts was proposed based on the current findings. 相似文献
132.
Kim SS Kang YS Lee HD Kim JK Hong SC 《Journal of the Air & Waste Management Association (1995)》2011,61(3):254-259
Eight types of coals of different rank were selected and their fundamental combustion characteristics were examined along with the conversion of volatile nitrogen (N) to nitrogen oxides (NOx)/fuel N to NOx. The activation energy, onset temperature, and burnout temperature were obtained from the differential thermogravimetry curve and Arrhenius plot, which were derived through thermo-gravimetric analysis. In addition, to derive the combustion of volatile N to NOx/fuel N to NOx, the coal sample, which was pretreated at various temperatures, was burned, and the results were compared with previously derived fundamental combustion characteristics. The authors' experimental results confirmed that coal rank was highly correlated with the combustion of volatile N to NOx/fuel N to NOx. 相似文献
133.
Jeong Huy Ko Yeon-Ho Kwak Kyung-Seun Yoo Jong-Ki Jeon Sung Hoon Park Young-Kwon Park 《Journal of Material Cycles and Waste Management》2011,13(3):173-179
Experiments were performed in order to investigate the possibility for the development of catalysts for low-temperature selective
catalytic reduction (SCR) using municipal waste char and RDF byproduct. Physical and chemical activations, using water, and
HCl and KOH, were employed to increase the catalytic activities. The characteristics of the activated catalysts were investigated
using N2 adsorption–desorption and FT-IR. The catalysts activated chemically using basic treatment showed higher NO
x
removal efficiencies than those activated physically or chemically using acidic treatment. The de-NO
x
performance of the activated catalysts was dependent on the chemical properties, such as oxygen functional groups as well
as physical properties, such as specific surface area and pore volume. In order to investigate the effect of MnO
x
, which has been reported to be efficient for the removal of NO
x
in low-temperature SCR processes, the chemically activated catalyst was impregnated with manganese. The Mn-impregnated catalyst
had the highest NO
x
conversion at all of the temperatures tested in this study. 相似文献
134.
Fenton氧化处理爆炸物污染土壤的实验研究 总被引:1,自引:0,他引:1
采用摇瓶和玻璃柱试验考察了Fenton氧化处理爆炸物污染土壤中2,4-DNT、2,6-DNT以及COD等的去除效果及其最佳参数.当3%H2O2投加量达到26.46mmol、FeSO4和H2O2的物质的量之比约为1∶73.56时,2,4-DNT和2,6-DNT均可被完全氧化,COD去除率可达到87%.对于2,4-DNT和2,6-DNT,反应时间只需要2h,但要同时去除其它芳香族硝基化合物,则反应时间需要超过8h.土壤直接Fenton氧化的效果并不理想,而对洗出液进行Fenton氧化可以取得很好的效果.通过反应动力学分析和丙酮抑制试验得出,2,4-DNT比2,6-DNT容易氧化.GC-MS分析结果表明,不仅土壤中的2,4-DNT、2,6-DNT可被氧化,其它的硝基芳香族有机化合物也可被氧化去除. 相似文献
135.
A soil washing process was applied to remediate arsenic (As)-contaminated stream sediments around an abandoned mine in Goro,
Korea. Laboratory scale soil washing experiments for As-contaminated stream sediments were performed under various washing
conditions in order to maximize As removal efficiency. Stream sediments were taken from two sites (S1 and S5) along the main
stream connected to an abandoned mine. Stream sediments at the two sites were divided into two groups (≥0.35 and <0.35 mm
in diameter), giving four types of sediments, which were thereupon used for soil washing experiments. The results of soil
washing experiments involving various pH conditions suggested that As removal efficiency is very high in both strongly acidic
and basic solutions (pH 1 and 13), regardless of sediment type. Removal efficiencies for fine sediments from S1 and S5 were
>95% after 1 h of washing with 0.2 M citric acid (C6H8O7). When using 0.2 M citric acid mixed with 0.1 M potassium phosphate (KH2PO4), the As removal efficiency increased to 100%. When recycled washing solution was applied, As removal efficiency was maintained
at a level greater than 70%, even after eight recycling events. This suggests that the recycling of washing solution could
be successfully applied as a means of decreasing the cost of the washing process. Results from the experiments suggest that
soil washing is a potentially useful process for the remediation of As-contaminated stream sediments around abandoned mines. 相似文献
136.
ABSTRACT: The purpose of this paper is to investigate the sensitivity of a hydrologic models to the type of DEM used. This was done while modeling basin water quality with 1:24,000 and 1:250,000 U.S. Geological Survey DEMs as input to model hydro‐logical processes. The manner in which the model results were sensitive to the choice of raster cell size (scale) is investigated in this study. The Broadhead watershed, located in New Jersey, USA, was chosen as a study area. Curve numbers were estimated by a trial and error to match simulated and observed total discharge. Monthly runoff for the watershed was used in the calibration process. Higher runoff volumes were simulated by the model when the 1:24,000 DEM were used as input data, probably due to the finer resolution which simulated increased average slope and hence higher estimated runoff from the watershed. As the simulated slope of the watershed is flatten with the 1:250,000 DEM, the response of stream flow was delayed and simulated less runoff volume. 相似文献
137.
Ahn JS 《Environmental geochemistry and health》2012,34(Z1):43-54
Bedrock groundwaters in Geumsan County, Korea, were surveyed to investigate the distribution and geochemical behaviors of arsenic and fluoride, mobilized through geogenic processes. The concentrations were enriched up to 113 μg/L for arsenic and 7.54 mg/L for fluoride, and 16% of 150 samples exceeded World Health Organization drinking water guidelines for each element. Simple Ca-HCO(3) groundwater types and positive correlations with pH, Ca, SO(4), and HCO(3) were characteristics of high (>10 μg/L) As groundwaters. The oxidation reaction of sulfide minerals in metasedimentary rocks and locally mineralized zones seems to be ultimately responsible for the existence of arsenic in groundwater. Desorption process under high pH conditions may also control the arsenic mobility in the study area. High (>1.5 mg/L) F groundwaters were found in the Na-HCO(3) type and with greater depth. Fluoride seemed to be enriched by deep groundwater interaction with granitic rocks, and continuous supply to shallow Ca-HCO(3)-type groundwater kept the concentration high. In the study area, drinking water management should include periodic As and F monitoring in groundwater. 相似文献
138.
Building on strategic human resource management literature, this study investigates the effects of various human resource development (HRD) dimensions on organizational performance. We identify four distinct dimensions of HRD that reflect either quantitative or qualitative approaches from either managerial or employee perspectives. Furthermore, we propose that HRD affects organizational performance by shaping employee outcomes, a prevailing but rarely tested assumption. Multi‐source data collected from 207 manufacturing companies at three time points over a 5‐year period largely support our theoretical propositions. A series of structural path analyses confirm that HRD improves employee commitment and competence, which in turn determine the financial performance of the organization. The quantitative dimensions of HRD (resource investment in HRD) predict only employee commitment. By contrast, the qualitative dimensions of HRD (management support for, and perceived benefits of, HRD) enhance both employee commitment and competence. Our analysis also demonstrates synergistic interactions between the quantitative and qualitative dimensions of HRD in predicting employee outcomes. This study elaborates the distinct values of different dimensions of HRD and highlights the significance of employee outcomes as the mediating mechanism between HRD and firm performance. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
139.
Sung‐Hyun Kwon 《毒物与环境化学》2013,95(1-2):17-23
A mixed microbial population in digested sewage culture under strict anaerobic conditions degraded TNT (2,4,6‐trinitrotoluene) effectively. An initial concentration of 110 mg/L of TNT was reduced to a non‐detectable amount (> 99% removal) in 6 days of incubation. Red color due to the electron charge of NO2 groups becomes colorless after 6 days of incubation, while the autoclave control remained red in color. Further stepwise deamination and subsequent mineralization by ring cleavage occurred by mixed nitroreductase which is available from many of the denitrifying bacteria predominantly in sewage culture. 相似文献
140.
Palle Paul Mejame Mejame Young Mo Kim Dae Sung Lee Seong-Rin Lim 《Journal of Material Cycles and Waste Management》2018,20(1):100-109
Technology development has brought beneficial changes in the functions of smartphones but has the potential to impact the environment due to the high generation of waste smartphones. Thus, this study evaluates and compares environmental impact potentials from metals in waste smartphones to figure out the effect of smartphone model replacements on hazardous waste, resource depletion, and toxicity potentials. The total threshold limit concentration (TTLC) analysis is used to determine whether the waste smartphones would be classified as hazardous waste, and the life-cycle impact assessment methods are used to evaluate resource depletion, cancer, non-cancer, and ecotoxicity potentials. The TTLC results showed that the smartphone technology development did not reduce hazardous waste potentials. The life-cycle impact assessment results showed that the technology development overall reduced resource depletion potential but increased toxicity potential. In addition, priority metals contributing to the potentials were identified to effectively manage their environmental impacts. This study can provide fundamental information for smartphone manufacturers, waste smartphone recyclers and disposers, and e-waste policymakers to circulate resources and to prevent environmental pollutions from hazardous and toxic materials. 相似文献