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   1792篇
  免费   17篇
  国内免费   23篇
安全科学   46篇
废物处理   62篇
环保管理   244篇
综合类   401篇
基础理论   346篇
环境理论   1篇
污染及防治   514篇
评价与监测   95篇
社会与环境   109篇
灾害及防治   14篇
  2023年   20篇
  2022年   18篇
  2021年   29篇
  2020年   21篇
  2019年   25篇
  2018年   47篇
  2017年   50篇
  2016年   60篇
  2015年   72篇
  2014年   76篇
  2013年   84篇
  2012年   80篇
  2011年   115篇
  2010年   97篇
  2009年   99篇
  2008年   90篇
  2007年   98篇
  2006年   80篇
  2005年   54篇
  2004年   80篇
  2003年   44篇
  2002年   64篇
  2001年   67篇
  2000年   30篇
  1999年   17篇
  1998年   17篇
  1997年   25篇
  1996年   19篇
  1995年   31篇
  1994年   19篇
  1993年   6篇
  1992年   14篇
  1991年   24篇
  1990年   11篇
  1989年   18篇
  1988年   7篇
  1987年   4篇
  1985年   5篇
  1984年   5篇
  1982年   10篇
  1981年   10篇
  1979年   9篇
  1970年   6篇
  1969年   4篇
  1966年   3篇
  1965年   4篇
  1962年   3篇
  1960年   4篇
  1959年   3篇
  1954年   3篇
排序方式: 共有1832条查询结果,搜索用时 15 毫秒
371.
372.
373.
374.
Environmental federalism considers what level of government should optimally regulate pollution. This paper addresses this question for accidental pollution, which government regulates through the ex post liability regimes of either negligence or strict liability. We find that decentralizing the choice between these regimes does not, in general, induce the socially optimal outcome. When firms can pay all damages, all regions may choose negligence and impose an overly strict standard of due care. When firms may be bankrupted by damages, all regions may choose strict liability, which induces too little care. In addition, asymmetric equilibria are possible in which some regions choose negligence, others strict liability. Combining negligence with a Pigovian tax, or strict liability with a bonding requirement can align regional authorities' incentives with those of a central government.  相似文献   
375.
The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work has been done on the economic aspects and consequences of invasions. This paper reviews what is known of the economic consequences of alien plant invasions in South Africa. These economic arguments have been used to successfully launch the largest environmental management programme in Africa.Ten million hectares of South Africa has been invaded by 180 alien species, but their impacts are not fully understood, although they are undoubtedly significant. The indications are that the total costs of these impacts are substantial. Selected studies show that invasions have reduced the value of fynbos ecosystems by over US$ 11.75 billion; that the total cost of invasion would be about US$ 3.2 billion on the Agulhas Plain alone; that the net present cost of invasion by black wattles amounts to US$ 1.4 billion; that invasions by red water fern have cost US$ 58 million; and that the cost to clear the alien plant invasions in South Africa is around US$ 1.2 billion. These few examples indicate that the economic consequences of invasions are huge.One of the unique aspects of invasive plant control programmes in South Africa has been the ability to leverage further benefits (mainly through employment) for the expensive control programmes from the government's poverty relief budget. This has made it possible to allocate substantial funding to a programme that would otherwise have struggled to obtain significant support. Biological control of invasive species also offers considerable benefits, but is often the subject of debate. We believe that, at least in the case of many invasive alien plant species in South Africa, biological control offers one of the best, and most cost-effective, interventions for addressing the problem.  相似文献   
376.
Urban forests are popular recreation areas in Europe. Several of these temperate broad-leaved forests also have a high conservation value due to sustainable management over many centuries. Recreational activities, particularly the use of fireplaces, can cause extensive damage to soil, ground vegetation, shrubs, and trees. Firewood collection depletes woody debris, leading to a loss of habitat for specialized organisms. We examined the effects of fireplace use on forest vegetation and the amount of woody debris by comparing disturbed and control plots in suburban forests in northwestern Switzerland. At frequently used fireplaces, we found reduced species densities in the ground vegetation and shrub layer and changes in plant species composition due to human trampling within an area of 150–200 m2. Picnicking and grilling also reduced the height and changed the age structure of shrubs and young trees. The amount of woody debris was lower in disturbed plots than in control plots. Pieces of wood with a diameter of 0.6–7.6 cm were preferentially collected by fireplace users. The reduction in woody debris volume extended up to a distance of 16 m from the fire ring, covering an area of 800 m2 at each picnic site. In order to preserve the ecological integrity of urban forests and to maintain their attractiveness as important recreation areas, we suggest depositing logging residues to be used as firewood and to restrict visitor movements near picnic sites.  相似文献   
377.
The impacts of agricultural land use are far-reaching and extend to areas outside production. This paper provides an overview of the ecological status of agricultural systems across the European Union in the light of recent policy changes. It builds on the previous review of 2001 devoted to the impacts of agricultural intensification in Western Europe. The focus countries are the UK, The Netherlands, Boreal and Baltic countries, Portugal, Hungary and Romania, representing a geographical spread across Europe, but additional reference is made to other countries. Despite many adjustments to agricultural policy, intensification of production in some regions and concurrent abandonment in others remain the major threat to the ecology of agro-ecosystems impairing the state of soil, water and air and reducing biological diversity in agricultural landscapes. The impacts also extend to surrounding terrestrial and aquatic systems through water and aerial contamination and development of agricultural infrastructures (e.g. dams and irrigation channels). Improvements are also documented regionally, such as successful support of farmland species, and improved condition of watercourses and landscapes. This was attributed to agricultural policy targeted at the environment, improved environmental legislation, and new market opportunities. Research into ecosystem services associated with agriculture may provide further pressure to develop policy that is targeted at their continuous provisioning, fostering motivation of land managers to continue to protect and enhance them.  相似文献   
378.
Land cover change has always had a central role in land change science. This central role is largely the result of the possibilities to map and characterize land cover based on observations and remote sensing. This paper argues that more attention should be given to land use and land functions and linkages between these. Consideration of land functions that provide a wide range of goods and services makes more integrated assessments of land change possible. The increasing attention to multifunctional land use is another incentive to develop methods to assess changes in land functions. A number of methods to quantify and map the spatial extent of land use and land functions are discussed and the implications for modeling are identified based on recent model approaches in land change science. The mixed use of land cover, land use and land function in maps and models leads to inconsistencies in land change assessments. Explicit attention to the non-linear relations between land cover, land use and land function is essential to consistently address land change. New methods to map and quantify land function dynamics will enhance our ability to understand and model land system change and adequately inform policies and planning.  相似文献   
379.
This paper explores the attitudes of landowners across Ireland to the wider provision of public access for recreational walking using a multinomial logit model. The study also investigates the level of compensation required to improve the supply of this public good. Results indicate that 51% of landowners are not willing to provide access (non-providers), 21% are willing to provide access free of charge (free providers) and 28% seek compensation (willing providers). The findings indicate that participation by landowners in a proposed public access scheme is influenced by landowners' experience with walkers, farm type, farm insurance costs, household demographics, regional variations, opportunity cost of land and participation in other agri-environment schemes. Mean willingness-to-accept for landowners willing to facilitate improved public access for walking was found to be €0.27 per metre of walkway.  相似文献   
380.
The application of engineered nanomaterials increases strongly. Development of analytical techniques and their application to environmental samples is essential for human and environmental risk assessment of the nanoparticles. The objective of this study was to develop a sensitive analytical method to quantify nC(60) in water, using accurate mass screening liquid chromatography-hybrid linear ion trap Orbitrap mass spectrometry. nC(60) can be transformed by oxidation, reduction and photochemical reaction. Therefore, the formation of some transformation products of nC(60) was studied as well. Finally, the developed analytical method was applied to surface water samples from several locations in the Netherlands. The developed method enabled to detect and quantify aqueous concentrations of the summed nC(60) and its transformation products as low as 5 ng/L. It was observed that nC(60) transformation products exceed quantities of the parent C(60). Despite the high sensitivity of the developed method, no nC(60) or transformation products were detected in an array of Dutch surface waters. This might be due to low emissions, losses in the aqueous phase by sedimentation, sorption or further transformation processes.  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