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   281篇
  免费   7篇
  国内免费   3篇
安全科学   27篇
废物处理   15篇
环保管理   52篇
综合类   44篇
基础理论   78篇
污染及防治   45篇
评价与监测   14篇
社会与环境   12篇
灾害及防治   4篇
  2023年   5篇
  2022年   3篇
  2021年   6篇
  2020年   6篇
  2019年   6篇
  2018年   5篇
  2017年   12篇
  2016年   19篇
  2015年   10篇
  2014年   7篇
  2013年   25篇
  2012年   12篇
  2011年   17篇
  2010年   15篇
  2009年   10篇
  2008年   12篇
  2007年   14篇
  2006年   14篇
  2005年   8篇
  2004年   5篇
  2003年   7篇
  2002年   6篇
  2001年   9篇
  2000年   2篇
  1999年   3篇
  1998年   6篇
  1997年   5篇
  1996年   2篇
  1995年   11篇
  1994年   6篇
  1993年   5篇
  1992年   4篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1979年   2篇
  1974年   1篇
  1958年   1篇
排序方式: 共有291条查询结果,搜索用时 375 毫秒
211.
In the space of three to four years, gas has changed from being a premium fuel, not to be utilized in power stations, to virtually the only fuel being considered for future electricity generation in the UK. This paper reviews the growth in the use of gas for electricity generation within the UK, with particular regard to the adoption of the gas-fired combined cycle power station. The environmental, economic and strategic issues associated with the proposed development of approximately 27 GW of new gas-fired plant are analysed and the resulting effects on existing base load power plant within the UK are considered.Dr James W.S. Longhurst is Director of the Atmospheric Research and Information Centre, ARIC, at Manchester Metropolitan University He is an environmental scientist who has specialized in the air quality impacts of transport and energy. He holds a BSc, MSc and PhD in Environmental Science from, Plymouth Polytechnic, Aston University and Birmingham University, respectively. He has written numerous papers, consultancy reports, books and technical reports since 1986.Jane Bantock joined ARIC in 1992 with a degree in Environmental Studies from Manchester Polytechnic. She jointly manages ARIC's information and education programmes. Her research interests include the inter-relationship of UK energy policy and emission control in the electricity generating sector, the subject of her part time PhD, and urban air quality issues.  相似文献   
212.
The Prairie Pothole Region of the northern GreatPlains is an important region for waterfowl production becauseof the abundance of shallow wetlands. The ecologicalsignificance of the region and impacts from intensiveagriculture prompted the U.S. Environmental Protection Agency to select it as one ofthe first areas for developing and evaluating ecologicalindicators of wetland condition. We examined hypothesizedrelations between indicators of landscape and wetlandconditions and waterfowl abundance on 45 40 km2 study sites in North Dakota for1995–1996. Landscape condition was defined a priori as the ratio of cropland area to total upland area surroundingwetlands. Measures of waterfowl abundance included estimatednumbers of breeding pairs (by species and total numbers) and , a species-specific correction factor which effectively adjusts breedingpair estimates for annual or area-related differences in pondsize. Landscape indicators and waterfowl measures varied among regions. Results indicated that most areas in the Coteau region are ofmuch higher quality for ducks than those in the Drift Plain,and areas in the Red River Valley are of the poorest qualityfor ducks. Regression models demonstrated the impact ofagricultural development on breeding duck populations in the PrairiePothole Region. The most consistent landscape indicators ofwaterfowl abundance were percent of cropland and grassland. Models were inconsistent among years and species. Thepotential biotic indicators of landscape and wetland condition examined here wouldbe appropriate for temporal trend analyses, but because ofinherent geographic variability would not be appropriate forsingle-year geographic trend analyses without more extensiveevaluations to improve explanatory models.  相似文献   
213.
Objective: Despite successes in the 1980s and early 1990s, progress in reducing impaired driving fatalities in the United States has stagnated in recent years. Since 1997, the percentage of drivers involved in fatal crashes with illegal blood alcohol concentration (BAC) levels has remained at approximately 20 to 22%. Many experts believe that public complacency, competing social and public health issues, and the lack of political fortitude have all contributed to this stagnation. The number of alcohol-related crashes, injuries, and fatalities is still unacceptable, and most are preventable. The public needs to be aware that the problem presented by drinking drivers has not been solved. Political leaders need guidance on which measures will affect the problem, and stakeholders need to be motivated once again to implement effective strategies.

Methods: The National Academy of Sciences (NAS) Transportation Research Board (TRB), Alcohol, Other Drugs, and Transportation Committee (ANB50) sponsored a workshop held at the NAS facility in Woods Hole, Massachusetts, on August 24–25, 2015, to discuss the lack of progress in reducing impaired driving and to make recommendations for future progress. A total of 26 experts in research and policy related to alcohol-impaired driving participated in the workshop. The workshop began by examining the static situation in the rate of alcohol-impaired driving fatal crashes to determine what factors may be inhibiting further progress. The workshop then discussed 8 effective strategies that have not been fully implemented in the United States. Workshop participants (16 of the 26) rated their top 3 strategies.

Results: 3 strategies received the most support: 1. Impose administrative sanctions for drivers with BACs = 0.05 to 0.08 g/dL.

2. Require alcohol ignition interlocks for all alcohol-impaired driving offenders.

3. Increase the frequency of sobriety checkpoints, including enacting legislation to allow them in the 11 states that currently prohibit them.

5 other important strategies included the following: (1) increase alcohol taxes to raise the price and reduce alcohol consumption; (2) reengage the public and raise the priority of impaired driving; (3) lower the illegal per se BAC limit to 0.05 for a criminal offense; (4) develop and implement in-vehicle alcohol detection systems; and (5) expand the use of screening and brief interventions in medical facilities.

Conclusions: Each of these strategies is proven to be effective, yet all are substantially underutilized. Each is used in some jurisdictions in the United States or Canada, but none is used extensively. Any one of the 3 strategies implemented on a widespread basis would decrease impaired driving crashes, injuries, and fatalities. Based on the research, all 3 together would have a substantial impact on the problem.  相似文献   

214.
/ The management of industrial reservoirs for hydroelectric energy can cause severe impacts to surrounding communities. This study examines the generation of dust along the northern foreshore zones of Williston Reservoir in northern British Columbia. The dust is generated in the spring when the reservoir levels are low and impacts a relocated First Nations' village (Tsay Keh) at the north end of the reservoir. Data were gathered to provide an overview of the physical conditions that contribute to the dust problem, including a social survey, soil analysis, and vegetation inventory. The study provides a scoping method to assess a large-scale and complex problem with respect to dust management along a large reservoir. Methods for dust control include short- and long-term solutions that integrate the use of native vegetation along the foreshore zones of the reservoir.  相似文献   
215.
Ecosystems are often modeled as stocks of matter or energy connected by flows. Network environ analysis (NEA) is a set of mathematical methods for using powers of matrices to trace energy and material flows through such models. NEA has revealed several interesting properties of flow–storage networks, including dominance of indirect effects and the tendency for networks to create mutually positive interactions between species. However, the applicability of NEA is greatly limited by the fact that it can only be applied to models at constant steady states. In this paper, we present a new, computationally oriented approach to environ analysis called dynamic environ approximation (DEA). As a test of DEA, we use it to compute compartment throughflow in two implementations of a model of energy flow through an oyster reef ecosystem. We use a newly derived equation to compute model throughflow and compare its output to that of DEA. We find that DEA approximates the exact results given by this equation quite closely – in this particular case, with a mean Euclidean error ranging between 0.0008 and 0.21 – which gives a sense of how closely it reproduces other NEA-related quantities that cannot be exactly computed and discuss how to reduce this error. An application to calculating indirect flows in ecosystems is also discussed and dominance of indirect effects in a nonlinear model is demonstrated.  相似文献   
216.
Doucett RR  Marks JC  Blinn DW  Caron M  Hungate BA 《Ecology》2007,88(6):1587-1592
Understanding river food webs requires distinguishing energy derived from primary production in the river itself (autochthonous) from that produced externally (allochthonous), yet there are no universally applicable and reliable techniques for doing so. We compared the natural abundance stable isotope ratios of hydrogen (deltaD) of allochthonous and autochthonous energy sources in four different aquatic ecosystems. We found that autochthonous organic matter is uniformly far more depleted in deuterium (lower deltaD values) than allochthonous: an average difference of approximately 100% per hundred. We also found that organisms at higher trophic levels, including both aquatic invertebrates and fish, have deltaD values intermediate between aquatic algae and terrestrial plants. The consistent differences between leaves and algae in deltaD among these four watersheds, along with the intermediate values in higher trophic levels, indicate that natural abundance hydrogen isotope signatures are a powerful tool for partitioning energy flow in aquatic ecosystems.  相似文献   
217.
Maps of canopy nitrogen obtained through analysis of high-resolution, hyperspectral, remotely sensed images now offer a powerful means to make landscape-scale to regional-scale estimates of forest N cycling and net primary production (NPP). Moreover, recent research has suggested that the spatial variability within maps of canopy N may be driven by environmental gradients in such features as historic forest disturbance, temperature, species composition, moisture, geology, and atmospheric N deposition. Using the wide variation in these six features found within the diverse forest ecosystems of the 2.5 million ha Adirondack Park, New York, USA, we examined linkages among environmental gradients and three measures of N cycling collected during the 2003 growing season: (1) field survey of canopy N, (2) field survey of soil C:N, and (3) canopy N measured through analysis of two 185 x 7.5 km Hyperion hyperspectral images. These three measures of N cycling strongly related to forest type but related poorly to all other environmental gradients. Further analysis revealed that the spatial pattern in N cycling appears to have distinct inter- and intraspecific components of variability. The interspecific component, or the proportional contribution of species functional traits to canopy biomass, explained 93% of spatial variability within the field canopy N survey and 37% of variability within the soil C:N survey. Residual analysis revealed that N deposition accounted for an additional 2% of variability in soil C:N, and N deposition and historical forest disturbance accounted for an additional 2.8% of variability in canopy N. Given our finding that 95.8% of the variability in the field canopy N survey could be attributed to variation in the physical environment, our research suggests that remotely sensed maps of canopy N may be useful not only to assess the spatial variability in N cycling and NPP, but also to unravel the relative importance of their multiple controlling factors.  相似文献   
218.
Australian resource-extraction industries—mining, fisheries and forestry—operate year-round in the natural environment with all three exposed to climate extremes and to long-term climatic change. However, the industries differ in terms of size, ownership and mobility. Although mining companies are ‘mobile,’ a commitment to a mine site makes them immobile at a location dictated by the presence of a mineral; forestry of natural and managed trees takes place in a specifically selected location that can be changed given a reasonably long time-frame and high financial investment; fishing is the last of the major hunting industries, and despite operating from fixed ports, fishers chase fish across the ocean. All three industries as employers and product providers seek a sustainable future under a changing climate but are subject to environmental variability that impacts on their activities. As each industry has historically dealt with and survived major climate impacts, they typically consider themselves to be resilient, although we illustrate in several case studies that recent climate variability significantly impacts productivity and current resilience is limited. Projected climate change and variability are likely to exacerbate impacts on these industries through new or intensified hazards. Although each industry performs risk management controls to minimize climate-related impacts, a new approach incorporating future climate projections in addition to historical experiences would better prepare each to reduce vulnerability to changing climate. We find that wholesale transformation may not be appropriate or necessary at this time for these industries, and in most cases anticipatory, incremental adaptation should be encouraged, while larger-scale changes are considered in the longer term. Additionally, to overcome some of the barriers and promote the drivers of adaptation, we suggest that a model of adaptive governance coupled with greater use of climate champions may be the most effective method for improving adaptation uptake in these industries.  相似文献   
219.
220.
Basing on the material emission data obtained in a test chamber, chemical mass balance (CMB) was used to assess the source apportionment of volatile organic compound (VOC) concentrations in three newly built timber frame houses. CMB has been proven to be able to discriminate the source contributions for two contrasted environmental conditions (with and without ventilation). The shutdown of the ventilation system caused an increase in the VOC concentrations due to the increased contribution of indoor surface materials like the door material and furniture explaining together over 65% of total VOCs. While the increase in formaldehyde concentration is mainly due to furniture (contribution of 70%), the increase in α-pinene concentration is almost exclusively attributable to the emission of door material (up to 84%). The apportionment of VOC source contributions appears as highly dependent on the position of source materials in the building (surface materials or internal materials) and the ventilation conditions explaining that the concentrations of compounds after the shutdown of ventilation system do not increase in equivalent proportion. Knowledge of indoor sources and its contributions in real conditions may help in the selection of materials and in the improvement of construction operations to reduce the indoor air pollution.  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