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   194篇
  免费   4篇
  国内免费   1篇
安全科学   4篇
废物处理   17篇
环保管理   27篇
综合类   17篇
基础理论   54篇
污染及防治   50篇
评价与监测   14篇
社会与环境   12篇
灾害及防治   4篇
  2023年   4篇
  2022年   8篇
  2021年   11篇
  2020年   3篇
  2019年   10篇
  2018年   12篇
  2017年   11篇
  2016年   12篇
  2015年   6篇
  2014年   11篇
  2013年   9篇
  2012年   9篇
  2011年   15篇
  2010年   17篇
  2009年   10篇
  2008年   12篇
  2007年   13篇
  2006年   4篇
  2005年   4篇
  2004年   4篇
  2003年   3篇
  2002年   4篇
  2001年   3篇
  1999年   2篇
  1995年   1篇
  1994年   1篇
排序方式: 共有199条查询结果,搜索用时 203 毫秒
71.
Over 400tons of Pb enters Swiss soils annually at some 2000 military shooting ranges (MSRs). We measured elements in the leaves of 10 plant species and associated rhizospheric soil on the stop butt of a disused MSR. The geometric mean concentrations of Pb, Sb, Cu, Ni in rhizospheric soils were 10,171mg/kg, 5067mg/kg, 4125mg/kg and 917mg/kg. Some species contained Pb, Cu and Ni, above concentrations (30mg/kg, 25mg/kg and 50mg/kg) shown to be toxic to livestock. Most contaminants in leaves resulted from surface deposition. However, at soil Pb concentrations >60,000mg/kg, Equisetum arvense and Tussilago farfara took up >1000mg/kg Pb into the leaves. These plants are not hyperaccumulators, having <100mg/kg Pb in leaves at lower soil concentrations. Removal of soil with more than 30,000 Pb, from which one could smelt this metal to offset remediation costs, followed by revegetation, would minimise dust and hence leaf-borne contaminants.  相似文献   
72.
73.
74.
Concentrations of potential pollutant elements Na, Cl, and S were investigated in needles of Pinus canariensis grown at 55 field plots in Tenerife. Microelement concentrations (including heavy metals) were measured at a subset of 18 plots. Na and Cl concentrations were high at low elevations (up to 8 mg g(-1) Cl and 5.5 mg g(-1) Na). Na/Cl ratio close to standard seawater indicated sea spray influence up to 1200 m a.s.l. Only at few plots, sulphur concentrations indicated possible pollutant impact. Cluster and correlation analyses identified a related group of V, As, Cr, Fe, Mo, Ni, Cu, Pb, and Al, possibly related to traffic exhaust aggregated with soil particles. Mainly north-eastern, lower elevated plots were exposed to those immissions, but metal concentrations were generally low compared to data from other studies. In conclusion, seawater and soil particles explained most of the element distribution pattern in pine needles in Tenerife, but strong indications for some effect of local sources of air pollutants were detected.  相似文献   
75.
Ambient halocarbon mixing ratios in 45 Chinese cities   总被引:4,自引:0,他引:4  
During this study 158 whole air samples were collected in 45 Chinese cities in January and February 2001. The spatial distribution of different classes of halocarbons in the Chinese urban atmosphere, including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), Halon-1211, and other chlorinated compounds is presented and discussed. Most of these compounds were enhanced compared to background levels. However, the mean enhancement of CFCs was relatively small, with CFC-12 and CFC-11 increases of 6% (range 1–31%) and 10% (range 2–89%), respectively, with respect to the global background. On the contrary, strongly enhanced levels of CFC replacement compounds and halogenated compounds used as solvents were measured. The average Halon-1211 concentration exceeded the background of 4.3 pptv by 75% and was higher than 10 pptv in several cities. Methyl chloride mixing ratios were also strongly elevated (78% higher than background levels), which is likely related to the widespread use of coal and biofuel in China.  相似文献   
76.
Optimal spatial sampling schemes for environmental surveys   总被引:4,自引:0,他引:4  
A practical problem in spatial statistics is that of constructing spatial sampling designs for environmental monitoring network. This paper presents a fractal-based criterion for the construction of coverage designs to optimize the location of sampling points. The algorithm does not depend on the covariance structure of the process and provides desirable results for situations in which a poor prior knowledge is available. The statistical characteristics of the method are explored by a simulation study while a design exercise concerning the Pescara area monitoring network is used to demonstrate potential designs under realistic assumptions.  相似文献   
77.
This research aims to map Brazilian companies that have business models aligned with the concept of the circular economy. Data were collected for this study through use of a survey and additional research based on the survey results. Within these businesses’ models, an emphasis on the second use of materials as well as the marketing of the product as a service has been highlighted.  相似文献   
78.
Purpose. A newly developed questionnaire assessing limitations in activity of daily living (LADL–Q) that should improve assessment of LADL is tested in a large population-based validation study. Methods. This survey was paper-based. Overall, 16,634 individuals who were representative of the working population in the German-speaking part of Switzerland participated in the study. Item analysis was used the final version of the LADL–Q to four items per subscale that correspond to potential problems in three body regions (back and neck, upper extremities, lower extremities). Analysis included tests for reliability, internal consistency, dimensionality and convergent validity. Results. Test–retest reliability coefficients after 2 weeks ranged from 0.82 to 0.99 (Mdn?=?0.87), with no item having a coefficient below 0.60. The median item-total coefficients ranged between moderate and good. Correlation coefficients between LADL–Q subscales and three validated clinical instruments (Western Ontario and McMaster Universities osteoarthritis index, shoulder pain disability index, Oswestry) ranged from 0.63 to 0.81. In structural equation modeling the three subscales were significantly related with two important outcomes in occupational rehabilitation: self-reported general health and daily task performance. Conclusion. The new LADL–Q is a brief, reliable and valid tool for assessment of LADL in studies on musculoskeletal health.  相似文献   
79.
The twentieth century saw a dramatic increase in the production of urban solid waste, reflecting unprecedented global levels of economic activity. Despite some efforts to reduce and recover the waste, disposal in landfills is still the most usual destination. However, landfill has become more difficult to implement because of its increasing cost, community opposition to landfill siting, and more restrictive environmental regulations regarding the siting and operation of landfills. Moreover, disposal in landfill is the waste destination method with the largest demand for land, while land is a resource whose availability has been decreasing in urban systems. Shortage of land for landfills is a problem frequently cited in the literature as a physical constraint. Nonetheless, the shortage of land for waste disposal has not been fully studied and, in particular, quantified. This paper presents a method to quantify the relationship between the demand and supply of suitable land for waste disposal over time using a geographic information system and modelling techniques. Based on projections of population growth, urban sprawl and waste generation the method can allow policy and decision-makers to measure the dimension of the problem of shortage of land into the future. The procedure can provide information to guide the design and schedule of programs to reduce and recover waste, and can potentially lead to a better use of the land resource. Porto Alegre City, Brazil was used as the case study to illustrate and analyse the approach. By testing different waste management scenarios, the results indicated that the demand for land for waste disposal overcomes the supply of suitable land for this use in the study area before the year 2050.  相似文献   
80.
Multiyear (2000–2006) seasonal measurements of carbon monoxide, hydrocarbons, halogenated species, dimethyl sulfide, carbonyl sulfide and C1–C4 alkyl nitrates at the South Pole are presented for the first time. At the South Pole, short-lived species (such as the alkenes) typically were not observed above their limits of detection because of long transit times from source regions. Peak mixing ratios of the longer lived species with anthropogenic sources were measured in late winter (August and September) with decreasing mixing ratios throughout the spring. In comparison, compounds with a strong oceanic source, such as bromoform and methyl iodide, had peak mixing ratios earlier in the winter (June and July) because of decreased oceanic production during the winter months. Dimethyl sulfide (DMS), which is also oceanically emitted but has a short lifetime, was rarely measured above 5 pptv. This is in contrast to high DMS mixing ratios at coastal locations and shows the importance of photochemical removal during transport to the pole. Alkyl nitrate mixing ratios peaked during April and then decreased throughout the winter. The dominant source of the alkyl nitrates in the region is believed to be oceanic emissions rather than photochemical production due to low alkane levels.Sampling of other tropospheric environments via a Twin Otter aircraft included the west coast of the Ross Sea and large stretches of the Antarctic Plateau. In the coastal atmosphere, a vertical gradient was found with the highest mixing ratios of marine emitted compounds at low altitudes. Conversely, for anthropogenically produced species the highest mixing ratios were measured at the highest altitudes, suggesting long-range transport to the continent. Flights flown through the plume of Mount Erebus, an active volcano, revealed that both carbon monoxide and carbonyl sulfide are emitted with an OCS/CO molar ratio of 3.3 × 10?3 consistent with direct observations by other investigators within the crater rim.  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