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   75篇
  免费   0篇
废物处理   6篇
环保管理   9篇
综合类   2篇
基础理论   21篇
污染及防治   20篇
评价与监测   10篇
社会与环境   7篇
  2023年   1篇
  2022年   5篇
  2021年   6篇
  2019年   2篇
  2018年   3篇
  2017年   2篇
  2016年   1篇
  2015年   4篇
  2014年   4篇
  2013年   14篇
  2012年   1篇
  2011年   5篇
  2010年   3篇
  2008年   2篇
  2007年   5篇
  2006年   2篇
  2005年   2篇
  2004年   2篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1996年   2篇
  1993年   1篇
  1984年   1篇
  1979年   1篇
  1976年   1篇
排序方式: 共有75条查询结果,搜索用时 468 毫秒
41.
Environmental Science and Pollution Research - Advancements in telecommunication sector result in increasing exposure to electromagnetic (EM) radiation, which has been correlated with incidence of...  相似文献   
42.
43.
The effect of calcium and magnesium either singly or in combination on accumulation of cadmium and copper in Labeo rohita (rohu) and Catla catla (catla) was investigated in this study under laboratory conditions. The investigation showed that copper accumulation in rohu exposed to 0.25 mg L?1 of copper for 14 days reduced from 31.0 ± 0.4 mg kg?1 at no calcium/magnesium treatment to 3.5 ± 0.2 and 2.2 ± 0.1 mg kg?1, respectively, at 75 mg L?1 calcium or magnesium treatment. The copper level in catla exposed to 0.20 mg L?1 of copper for 14 days reduced from 5.7 ± 0.1 mg kg?1 at no calcium/magnesium treatment to 3.4 ± 0.2 and 3.3 ± 0.1 mg kg?1, respectively, at 300 mg L?1 calcium or magnesium treatment. The cadmium accumulation in rohu exposed to 0.20 mg L?1 of cadmium for 14 days reduced from 1.7 ± 0.1 mg kg?1 at no magnesium treatment to 1.4 ± 0.1 mg kg?1 at 120 mg L?1 magnesium treatment. The cadmium accumulation in catla exposed to 0.20 mg L?1 of cadmium for 14 days reduced from 0.8 ± 0.2 mg kg?1 at no magnesium treatment to 0.6 ± 0.2 mg kg?1 at 80 mg L?1 magnesium treatment. Copper and cadmium treatments also reduced some essential microelements of rohu and catla. Both the fishes restored these elements at different levels of calcium and magnesium.  相似文献   
44.
Environmental Chemistry Letters - Diminishing petroleum reserves, increasing carbon emissions, and the growing demand for fuels are calling for alternative fuels. Global diesel consumption...  相似文献   
45.
Abstract: The International Union for Conservation of Nature (IUCN) Red List of Threatened Species was increasingly used during the 1980s to assess the conservation status of species for policy and planning purposes. This use stimulated the development of a new set of quantitative criteria for listing species in the categories of threat: critically endangered, endangered, and vulnerable. These criteria, which were intended to be applicable to all species except microorganisms, were part of a broader system for classifying threatened species and were fully implemented by IUCN in 2000. The system and the criteria have been widely used by conservation practitioners and scientists and now underpin one indicator being used to assess the Convention on Biological Diversity 2010 biodiversity target. We describe the process and the technical background to the IUCN Red List system. The criteria refer to fundamental biological processes underlying population decline and extinction. But given major differences between species, the threatening processes affecting them, and the paucity of knowledge relating to most species, the IUCN system had to be both broad and flexible to be applicable to the majority of described species. The system was designed to measure the symptoms of extinction risk, and uses 5 independent criteria relating to aspects of population loss and decline of range size. A species is assigned to a threat category if it meets the quantitative threshold for at least one criterion. The criteria and the accompanying rules and guidelines used by IUCN are intended to increase the consistency, transparency, and validity of its categorization system, but it necessitates some compromises that affect the applicability of the system and the species lists that result. In particular, choices were made over the assessment of uncertainty, poorly known species, depleted species, population decline, restricted ranges, and rarity; all of these affect the way red lists should be viewed and used. Processes related to priority setting and the development of national red lists need to take account of some assumptions in the formulation of the criteria.  相似文献   
46.
Cattle grazing nearby coal-fired power stations are exposed to fly ash. The present investigation aims to assess the environmental and health impacts of fly ash containing mercury emitted from thermal power plant. The health effect of fly ash were studied using 20 lactating cattle reared within a 5-km radius of s thermal power plant for the possible effect of fly ash such as the alterations in hematological and biochemical parameters of blood, milk, and urine. Results indicated that the hemoglobin levels (6.65?±?0.40?g/dl) were significantly reduced in all the exposed animals. Biochemical parameters viz., blood urea nitrogen (27.35?±?1.19?mg/dl), serum glutamate oxaloacetate transaminase (43.39?±?3.08?IU/l), albumin, and creatinine were found to be increased, whereas serum glutamate pyruvic transaminase (29.26?±?2.02) and Ca2+ were observed to be statistically insignificant in exposed animals. Mercury concentrations estimated in the blood, milk, and urine of exposed (n?=?20) and control (n?=?20) animals were 7.41?±?0.86, 4.75?±?0.57, 2.08?±?0.18, and 1.05?±?0.07, 0.54?±?0.03, 0.20?±?0.02?μg/kg, respectively. The significant increase (P?<?0.01) in the levels of mercury in blood, milk, and urine of exposed animals in comparison to control indicated that the alterations of biochemical parameters in exposed cattle could be due to their long term exposure to fly ash mercury which may have direct or indirect impact on human populations via food chain.  相似文献   
47.
Abstract

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted [~20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted ~35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idleCO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by ~100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75%of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.  相似文献   
48.
Various studies have been conducted in the past on the fresh waters related to the various aspects of limnology, physico-chemistry, primary productivity, plankton etc. in relation to environmental conditions and ecology, flora and fauna of River Ganga. In the present investigation some recent approach have been made to study the various parts of fishes like gill structures, scales for age determination, length and weight of fish for growth assessments etc. The SEM study of scales in relation to pollution and environmental conditions is a recent approach. At this stage, in the present study the scales of two most common fishes found in the study stretch were involved to create a base line.  相似文献   
49.
A study was carried out in Nawa tehsil of Nagaur district to assess the prevalence of dental fluorosis and its crippling effect due to ingestion and prolonged exposure of fluoride over a long period of time. During the survey of the study area, high concentration of fluoride (14.62 ppm) has been recorded. The presence of fluoride in quantities in excess of limits is a serious matter of concern from a public health point of view. Due to higher fluoride level in groundwater, several cases of dental fluorosis have appeared at alarming rate in the study area. The children’s teeth are damaged and are characterized by black and brown stains as well as cracking and pitting of the teeth have been observed. In the study area, 93.12% population suffered from dental fluorosis, and it was more prevalent in men (94.90%) than in women (90.00%). Dental fluorosis was also examined according to different grades. Out of the total 72 afflicted, in the 4–16-year age group, 41.46% were suffering from Grade I, Grade II was more prevalent in 33.85% of the 17–28-year age group and similarly Grade II was more prevalent in 39.13% of the 29–40-year age group. In the age group of above 40 years, grade III and grade IV were more prevalent. Thus, in the higher age group, the prevalence and severity of fluorosis is almost certainly due to longer exposure to fluoride. The major risk factor consistently identified for dental fluorosis was the consumption of fluoridated drinks and fluoride supplements. Ingestion of calcium, vitamin D and vitamin C is effective in protection from fluoride toxicity to certain extent.  相似文献   
50.
Arsenic in groundwater in six districts of West Bengal,India   总被引:9,自引:0,他引:9  
Arsenic in groundwater above the WHO maximum permissible limit of 0.05 mg l–1 has been found in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present, 37 administrative blocks by the side of the River Ganga and adjoining areas are affected. Areas affected by arsenic contamination in groundwater are all located in the upper delta plain, and are mostly in the abandoned meander belt. More than 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people show arsenical skin lesions. Thousands of tube-well water in these six districts have been analysed for arsenic species. Hair, nails, scales, urine, liver tissue analyses show elevated concentrations of arsenic in people drinking arsenic-contaminated water for a longer period. The source of the arsenic is geological. Bore-hole sediment analyses show high arsenic concentrations in only few soil layers which is found to be associated with iron-pyrites. Various social problems arise due to arsenical skin lesions in these districts. Malnutrition, poor socio-economic conditions, illiteracy, food habits and intake of arsenic-contaminated water for many years have aggravated the arsenic toxicity. In all these districts, major water demands are met from groundwater and the geochemical reaction, caused by high withdrawal of water may be the cause of arsenic leaching from the source. If alternative water resources are not utilised, a good percentage of the 30 million people of these six districts may suffer from arsenic toxicity in the near future.  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