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   176篇
  免费   11篇
  国内免费   3篇
安全科学   4篇
废物处理   10篇
环保管理   57篇
综合类   19篇
基础理论   39篇
环境理论   1篇
污染及防治   36篇
评价与监测   16篇
社会与环境   5篇
灾害及防治   3篇
  2022年   4篇
  2021年   6篇
  2020年   3篇
  2019年   5篇
  2018年   4篇
  2017年   8篇
  2016年   10篇
  2015年   7篇
  2014年   5篇
  2013年   15篇
  2012年   7篇
  2011年   12篇
  2010年   7篇
  2009年   12篇
  2008年   10篇
  2007年   5篇
  2006年   6篇
  2005年   15篇
  2004年   3篇
  2003年   5篇
  2002年   4篇
  2001年   3篇
  2000年   6篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1996年   3篇
  1995年   5篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
  1976年   1篇
  1968年   2篇
排序方式: 共有190条查询结果,搜索用时 33 毫秒
111.
The 2015–2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a ‘non-event’. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015–2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01321-z) contains supplementary material, which is available to authorized users.  相似文献   
112.
A field and laboratory geotechnical characterization study of a Municipal Solid Waste Incineration Ash disposed of at the Carleton Farms monofill in Michigan was performed. Field characterization consisted of field observations, collection of four bulk samples and performance of shear wave velocity measurements at two locations. Laboratory characterization consisted of basic geotechnical characterization, i.e., grain size distribution, Atterberg limits, specific gravity tests, compaction tests as well as moisture and organic content assessment followed by direct shear and triaxial shear testing. The test results of this investigation are compared to results in the literature. The grain size distribution of the samples was found to be very similar and consistent with the grain size distribution data available in the literature, but the compaction characteristics were found to vary significantly. Specific gravities were also lower than specific gravities of silicic soils. Shear strengths were higher than typically reported for sandy soils, even for MSWI ash specimens at a loose state. Strain rate was not found to impact the shear resistance. Significant differences in triaxial shear were observed between a dry and a saturated specimen not only in terms of peak shear resistance, but also in terms of stress–strain response. In situ shear wave velocities ranged from 500 to 800 m/s at a depth of about 8 m, to 1100–1200 m/s at a depth of 50 m. These high shear wave velocities are consistent with field observations indicating the formation of cemented blocks of ash with time, but this “ageing” process in MSWI ash is still not well understood and additional research is needed. An improved understanding of the long-term behavior of MSWI ash, including the effects of moisture and ash chemical composition on the ageing process, as well as the leaching characteristics of the material, may promote unbound utilization of the ash in civil infrastructure.  相似文献   
113.
114.
Municipal waste management in the UK has undergone rapid transformation in recent years in pursuit of greater sustainability. In this paper we explore the environmental justice issues and tensions involved in this shift. After a brief overview of environmental justice debates and how they have been related to issues of waste management, we describe how the policies and processes underlying the transformation from an overwhelming dependence on landfill disposal towards more sustainable methods of management has been driven by European legislation embodying principles premised on fundamental environmental concerns of inter- and intra-generational equity. We analyse the key means through which these principles have been translated to restructure local authority practices and the environmental justice issues arising from the implementation of international policy in regional and local context. Finally, we reflect on the implications of this case study for implementation of policies intended to advance both sustainability and environmental justice.  相似文献   
115.
A major feature of our living environment consists of the domesticated animals. As their use intensifies so too does the obligation to them — and to their basic life practices — which we acquired at the moment of their domestication. Much of the behaviour of farm animals is concerned with self-maintenance, indeed, highly successful self-maintenance is the basis of animal productivity. Activities involved in such maintenance appear to fall into eight primary categories. These are basically of innate origin and include much instinctive behaviour. The use of these behaviours of reactivity, ingestion, exploration, movement, association, body care, territorialism and rest are vital to the animal in its integration and mediation with its environment. Within these eight primary systems of behaviour, numerous specific behaviours are exhibited in natural free-ranging conditions. Cattle exhibit 44 specific behaviours related to maintenance; sheep have 43 and pigs show 48. All of these above behaviours require environmental facility and where this is deficient, deficits occur in behaviour.Ethological deficits have been determined for methods of husbandry relating to the intensive production of calves, steers, sheep and pigs. Veal calves had 25 behavioural deficits, feedlot cattle had 11, housed sheep had 13 and enstalled swine had 26. These figures give indices of behavioural deprivation ranging from 25% in feedlot cattle to 56% in veal calves in stalls.Anomalous behaviour is now increasingly seen among animals which are managed under close confinement; restricted accommodation in an essentially featureles environment. Much of the anomalous behaviour which has been investigated is found to be the result of aversive environments. Anomalous behaviours are typically found in those forms of husbandry which involve intense grouping of animals and also a lack of what might be termed diversionary facilities in their environment. Reduced input of environmental stimulation and opportunity is evidently capable of acting with adverse effect on functional mediation, so as to generate anomalous forms of behaviour such as “orosthenia” — pathological oral activity. Such abnormal behaviour serves as a symptom of confinement stress. In animal production the application of ethology can provide a monitoring operation for livestock care to ensure welfare and ethological entitlement.  相似文献   
116.
Summary Populations of guppies, Poecilia reticulata and Hart's rivulus, Rivulus harti, in Trinidad experience different levels of predation hazard from piscivorous fish. Those from the larger rivers (downstream sites) experience chronically high predation hazard, while those from headwater streams (upstream sites) have few predators. Guppies and Hart's rivulus, collected from downstream and upstream sites, were assayed for their feeding rate in the presence and absence of predators. We defined tenacity as the ratio of the feeding rates in the presence and absence of a predator stimulus. Thus, tenacity expresses the degree to which the forager maintains its feeding rate when a predator stimulus is present. Previous work by Seghers (1973) showed that non-feeding guppies from downstream sites responded more strongly to predators than did guppies from upstream sites. Based on this, we initially hypothesized that fish from downstream sites would show lower tenacities than fish from upstream sites. However, we found the opposite in every case. When confronted with a predator stimulus, guppies and Hart's rivulus from downstream sites fed at consistently greater rates and displayed greater tenacities than did those from upstream sites. These differences were found in experiments using both live and model predators. The results suggest that upstream fish readily trade off feeding for hiding and avoiding predation hazard, a likely response when predators appear infrequently, while downstream fish appear to be selected for boldness and tenacity while foraging under chronically high hazard.  相似文献   
117.
Many migratory animals are experiencing rapid population declines, but migration data with the geographic scope and resolution to quantify the complex network of movements between breeding and nonbreeding regions are often lacking. Determining the most frequently used migration routes and nonbreeding regions for a species is critical for understanding population dynamics and making effective conservation decisions. We tracked the migration of individual Wood Thrushes (Hylocichla mustelina) (n = 102) from across their range with light‐level geolocators and, for the first time, quantified migration routes and wintering regions for distinct breeding populations. We identified regional and species‐level migratory connectivity networks for this declining songbird by combining our tracking results with range‐wide breeding abundance estimates and forest cover data. More than 50% of the species occupied the eastern wintering range (Honduras to Costa Rica), a region that includes only one‐third of all wintering habitat and that is undergoing intensive deforestation. We estimated that half of all Wood Thrushes in North America migrate south through Florida in fall, whereas in spring approximately 73% funnel northward through a narrow span along the central U.S. Gulf Coast (88–93°W). Identifying migratory networks is a critical step for conservation of songbirds and we demonstrated with Wood Thrushes how it can highlight conservation hotspots for regional populations and species as a whole. Conectividad de Sitios de Reproducción, Invierno y Migración del Zorzal con Base en Rastreo de Cobertura Amplia  相似文献   
118.
Armed sibling rivalry among suckling piglets   总被引:3,自引:2,他引:1  
Summary A piglet's most precious possession Is the teat that he fattens his flesh on. He fights for his teat with tenacity Against any sibling's audacity. The piglet, to arm for this mission, Is born with a warlike dentition Of eight tiny tusks, sharp as sabres, Which help in impressing the neighbors; But to render these weapons less harrowing, Most farmers remove them at farrowing. We studied pig sisters and brothers When some had their teeth, but not others. We found that when siblings aren't many, The weapons help little if any, But when there are many per litter, The teeth help their owners grow fitter. But how did selection begin To make weapons to use against kin? Offprint requests to: D. Fraser  相似文献   
119.
The United States Forest Service is required to analyze road systems on each of the national forests for potential environmental impacts. We have developed a novel and inexpensive way to do this using the Ecosystem Management Decision Support program (EMDS). We used EMDS to integrate a user-developed fuzzy logic knowledge base with a grid-based geographic information system to evaluate the degree of truth for assertions about a roads environmental impact. Using spatial data for natural and human processes in the Tahoc National Forest (TNF, California, USA), we evaluated the assertion the road has a high potential for impacting the environment. We found a high level of agreement between the products of this evaluation and ground observations of a TNF transportation engineer, as well as occurrences of road failures. We used the modeled potential environmental impact to negatively weight roads for a least-cost path network analysis to 1573 points of interest in the forest. The network analysis showed that out of 8233 km of road analyzed in the forest, 3483 km (42%) must be kept in a modified road network to ensure access to these points. We found that the modified network had improved patch characteristics, such as significantly fewer cherry stem roads intruding into patches, an improved area-weighted mean shape index, and larger mean patch sizes, as compared to the original network. This analysis system could be used by any public agency to analyze infrastructure for environmental or other risk and included in other mandated analyses such as risks to watersheds.  相似文献   
120.
Airborne particulate matter has been collected from within,and proximal to, an opencast coal mine in south Wales. Thiswork forms the first part of a three year project to collectand characterise, then determine the possible toxicology ofairborne particles in the south Wales region. High-resolutionField Emission SEM has shown that the coal mine dusts consistlargely of an assemblage of mineral grains and vehicle exhaustparticles. SEM-EDX has shown that the mineralogical make-up ofthe PM10 is complex, heterogeneous, and constantly changing.These findings are supported by analytical TEM-EPXMA.However, patterns can be determined relating the mineralogicalcomposition of the airborne particles to collection locationsand mining activities within the opencast. At our studyopencast, Park Slip West, quartz, which has known healtheffects, never exceeded 30% of the total collection mass, andaverage levels were much less. Vehicle exhaust emissions wasthe largest source in terms of particle numbers. The mass ofairborne particulate matter within the pit averagedapproximately twice that of outside the pit: importantlyhowever, this higher mass was due to relatively large, andnon-respirable, mineral grains. This study demonstrates that the physicochemical andmineralogical characterisation of airborne particles frommining and quarrying is essential to quantify the respirablefraction, and to identify potentially hazardous componentswithin the PM10.  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