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   59篇
  免费   0篇
  国内免费   1篇
安全科学   1篇
废物处理   6篇
环保管理   6篇
综合类   5篇
基础理论   8篇
污染及防治   11篇
评价与监测   20篇
社会与环境   3篇
  2023年   1篇
  2022年   3篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2017年   3篇
  2016年   2篇
  2015年   2篇
  2014年   8篇
  2013年   6篇
  2012年   2篇
  2011年   4篇
  2010年   2篇
  2009年   2篇
  2008年   3篇
  2007年   5篇
  2006年   2篇
  2005年   2篇
  2003年   2篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1992年   1篇
排序方式: 共有60条查询结果,搜索用时 62 毫秒
11.
In the present study, the impact of the flyover construction to curb traffic congestion problem has been assessed in terms of traffic decongestion, time saving, fuel saving and emission reduction. A flyover has also been constructed over four signalized junctions in the main commercial area in Nagpur city, India. It was found that about 35% of the total traffic is diverted to the flyover, which results in a reduction of about 32% in the total emission generation. Travel on the flyover resulted in as much as 60-70% saving in time, compared to the travel on the main road, particularly when all the four signals are found to be in the red phase. The loss of fuel for combustion and the associated cost resulting from waiting for the signal to change are also estimated, and these are found to be significant.  相似文献   
12.
Eighteen sites impacted by abandoned mine drainage (AMD) in Pennsylvania were sampled and measured for pH, acidity, alkalinity, metal ions, and sulfate. This study compared the accuracy of four acidity calculation methods with measured hot peroxide acidity and identified the most accurate calculation method for each site as a function of pH and sulfate concentration. Method E1 was the sum of proton and acidity based on total metal concentrations; method E2 added alkalinity; method E3 also accounted for aluminum speciation and temperature effects; and method E4 accounted for sulfate speciation. To evaluate errors between measured and predicted acidity, the Nash-Sutcliffe efficiency (NSE), the coefficient of determination (R 2), and the root mean square error to standard deviation ratio (RSR) methods were applied. The error evaluation results show that E1, E2, E3, and E4 sites were most accurate at 0, 9, 4, and 5 of the sites, respectively. Sites where E2 was most accurate had pH greater than 4.0 and less than 400 mg/L of sulfate. Sites where E3 was most accurate had pH greater than 4.0 and sulfate greater than 400 mg/L with two exceptions. Sites where E4 was most accurate had pH less than 4.0 and more than 400 mg/L sulfate with one exception. The results indicate that acidity in AMD-affected streams can be accurately predicted by using pH, alkalinity, sulfate, Fe(II), Mn(II), and Al(III) concentrations in one or more of the identified equations, and that the appropriate equation for prediction can be selected based on pH and sulfate concentration.  相似文献   
13.
In this work, an attempt has been made to harvest green energy from piezoelectric material using fluid flow in a conduit. Piezoelectric Energy Harvesting using Fluid Flow (PEHF) experimental model has been designed and the outputs obtained are compared with results obtained from simulations using ANSYS (computational fluid dynamics) and also with the mathematical modeling. The PEHF model has been utilized to analyze the effect of flow rate of water with reference to energy extracted. The full wave bridge rectifier and voltage doubler circuits have been used to obtain the direct current (DC) from the PEHF model. It is observed that the output obtained using experiments holds good in agreement with the results retrieved through simulations and mathematical results. The increase in flow rate of fluid leads to initially increase and then decrease in output of PEHF model as the maximum energy generated when flow rates (external force) matches with the frequency of excitation of the systems, i.e., at its resonance. The maximum energy output is generated at its resonance frequencies. It is observed that the full wave bridge rectifier circuit gives greater output as compared to a voltage doubler circuit.  相似文献   
14.
Livestock populations in protected areas are viewed negatively because of their interaction with native ungulates through direct competition for food resources. However, livestock and native prey can also interact indirectly through their shared predator. Indirect interactions between two prey species occur when one prey modifies either the functional or numerical responses of a shared predator. This interaction is often manifested as negative effects (apparent competition) on one or both prey species through increased predation risk. But indirect interactions can also yield positive effects on a focal prey if the shared predator modifies its functional response toward increased consumption of an abundant and higher-quality alternative prey. Such a phenomenon between two prey species is underappreciated and overlooked in nature. Positive indirect effects can be expected to occur in livestock-dominated wildlife reserves containing large carnivores. We searched for such positive effects in Acacia-Zizhypus forests of India's Gir sanctuary where livestock (Bubalus bubalis and Bos indicus) and a coexisting native prey (chital deer, Axis axis) are consumed by Asiatic lions (Panthera leo persica). Chital vigilance was higher in areas with low livestock density than in areas with high livestock density. This positive indirect effect occurred because lion predation rates on livestock were twice as great where livestock were abundant than where livestock density was low. Positive indirect interactions mediated by shared predators may be more common than generally thought with rather major consequences for ecological understanding and conservation. We encourage further studies to understand outcomes of indirect interactions on long-term predator-prey dynamics in livestock-dominated protected areas.  相似文献   
15.
Contribution of pollution from different types of sources in Jamshedpur, the steel city of India, has been estimated in winter 1993 using two approaches in order to delineate and prioritize air quality management strategies for the development of region in an environmental friendly manner. The first approach mainly aims at preparation of a comprehensive emission inventory and estimation of spatial distribution of pollution loads in terms of SO2 and NO2 from different types of industrial, domestic and vehicular sources in the region. The results indicate that industrial sources account for 77% and 68% of the total emissions of SO2 and NO2, respectively, in the region, whereas vehicular emissions contributed to about 28% of the total NO2 emissions. In the second approach, contribution of these sources to ambient air quality levels to which the people are exposed to, was assessed through air pollution dispersion modelling. Ambient concentration levels of SO2 and NO2 have been predicted in winter season using the ISCST3 model. The analysis indicates that emissions from industrial sources are responsible for more than 50% of the total SO2 and NO2 concentration levels. Vehicular activities contributed to about 40% of NO2 pollution and domestic fuel combustion contributed to about 38% of SO2 pollution. Predicted 24-h concentrations were compared with measured concentrations at 11 ambient air monitoring stations and good agreement was noted between the two values. In-depth zone-wise analysis of the above indicates that for effective air quality management, industrial source emissions should be given highest priority, followed by vehicular and domestic sources in Jamshedpur region.  相似文献   
16.
Adults Swiss mice were administered 5% solution of textile industry wastewater orally for 25 days and haematological parameters like RBC, WBC, Hb, and PCV were studied. Red cell indices like MCV, MCH and MCHC were calculated. Results indicate significant reduction in RBC, Hb and PCV levels. It is inferred that toxic effluents cause metabolic alteration in erythrocytes and reduce their Hb carrying capacity.  相似文献   
17.
18.
Environmental impact evaluation is an essential component in environmental impact assessment (EIA) study for any developmental project, wherein importance assignment to various parameters depends on human judgement/experts opinion, which involves a high order of subjectivity. In order to minimise bias and subjectivity in evaluation of impacts, and hence in decision making, three different methods, viz. Battelle environmental evaluation system (BEES), importance scale matrix (ISM), and a combination of both, are considered in the present study. A case study for a development project (setting up a new industry) in an industrial belt situated in a region, which is rich in biological resources with good agricultural productivity and having high potential for further industrial development, is presented. The results of the other two methods are compared with the widely used method of BEES. Both methods are found comparable to the BEES method. However, it is observed that the ISM approach provides a better tool for reducing bias and subjectivity occurring in human judgement.  相似文献   
19.
Effect of pressure on the hydropyrolysis of Jatropha seed deoiled cake   总被引:1,自引:1,他引:0  
The necessity to move towards a sustainable economy is increasing day by day owing to various problems like climate change, increasing crude oil prices, etc. In this line, hydropyrolysis of Jatropha seed deoiled cake has been carried out at various pressures of hydrogen (1, 20, 40 and 52 bar) at 450 °C. With an increase in pressure under the experimental conditions of present study from 1 to 40 bar, the yield of bio-oil is found to have increased and beyond 40 bar the bio-oil yields have decreased. It has been observed that the liquid bio-oil yield is highest at 17 wt% at 40 bar. The FTIR spectrum of the bio-oil and char at 40 bar shows maximum functionality, indicating the clear opening of the macromolecular structure. The EDAX analysis of the hydropyrolysis char obtained at 40 bar pressure show a maximum of 85 wt% carbon and minimum of oxygen 13 wt%.  相似文献   
20.
Urbanisation is a ubiquitous phenomenon with greater prominence in developing nations. Urban expansion involves land conversions from vegetated moisture-rich to impervious moisture-deficient land surfaces. The urban land transformations alter biophysical parameters in a mode that promotes development of heat islands and degrades environmental health. This study elaborates relationships among various environmental variables using remote sensing dataset to study spatio-temporal footprint of urbanisation in Surat city. Landsat Thematic Mapper satellite data were used in conjugation with geo-spatial techniques to study urbanisation and correlation among various satellite-derived biophysical parameters, [Normalised Difference Vegetation Index, Normalised Difference Built-up Index, Normalised Difference Water Index, Normalised Difference Bareness Index, Modified NDWI and land surface temperature (LST)]. Land use land cover was prepared using hierarchical decision tree classification with an accuracy of 90.4 % (kappa?=?0.88) for 1990 and 85 % (kappa?=?0.81) for 2009. It was found that the city has expanded over 42.75 km2 within a decade, and these changes resulted in elevated surface temperatures. For example, transformation from vegetation to built-up has resulted in 5.5?±?2.6 °C increase in land surface temperature, vegetation to fallow 6.7?±?3 °C, fallow to built-up is 3.5?±?2.9 °C and built-up to dense built-up is 5.3?±?2.8 °C. Directional profiling for LST was done to study spatial patterns of LST in and around Surat city. Emergence of two new LST peaks for 2009 was observed in N–S and NE–SW profiles.  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