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31.
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We evaluated performance of species distribution models for predictive mapping, and how models can be used to integrate human pressures into ecological and economic assessments. A selection of 77 biological variables (species, groups of species, and measures of biodiversity) across the Baltic Sea were modeled. Differences among methods, areas, predictor, and response variables were evaluated. Several methods successfully predicted abundance and occurrence of vegetation, invertebrates, fish, and functional aspects of biodiversity. Depth and substrate were among the most important predictors. Models incorporating water clarity were used to predict increasing cover of the brown alga bladderwrack Fucus vesiculosus and increasing reproduction area of perch Perca fluviatilis, but decreasing reproduction areas for pikeperch Sander lucioperca following successful implementation of the Baltic Sea Action Plan. Despite variability in estimated non-market benefits among countries, such changes were highly valued by citizens in the three Baltic countries investigated. We conclude that predictive models are powerful and useful tools for science-based management of the Baltic Sea.  相似文献   
33.
In the 1990s, the obligation to assess transboundary environmental impacts has become part of international law. The UN/ECE Convention on environmental impact assessment (EIA) in a transboundary context, which entered into force in 1997, is one of the key documents. In this study, we show that difficulties with the practical implementation of the Convention arise partly from an incomplete sharing of the concept of EIA, and partly from different material interests on the part of the Parties to the Convention. Attempts to improve the practical implementation should recognize both aspects. Several approaches are thus needed for improving the implementation. Some will help in developing a mutual understanding of impact assessments, whereas others may help in overcoming differences in material interests.  相似文献   
34.
The current downturn of the arctic cryosphere, such as the strong loss of sea ice, melting of ice sheets and glaciers, and permafrost thaw, affects the marine and terrestrial carbon cycles in numerous interconnected ways. Nonetheless, processes in the ocean and on land have been too often considered in isolation while it has become increasingly clear that the two environments are strongly connected: Sea ice decline is one of the main causes of the rapid warming of the Arctic, and the flow of carbon from rivers into the Arctic Ocean affects marine processes and the air–sea exchange of CO2. This review, therefore, provides an overview of the current state of knowledge of the arctic terrestrial and marine carbon cycle, connections in between, and how this complex system is affected by climate change and a declining cryosphere. Ultimately, better knowledge of biogeochemical processes combined with improved model representations of ocean–land interactions are essential to accurately predict the development of arctic ecosystems and associated climate feedbacks.  相似文献   
35.
瑞典约有55%的土地面积被森林所覆盖.目前,瑞典的森林覆盖没有统一的和地理学上明晰的描述.现存的独立性数据源是Landsat TM和SPOT HRV卫星数据、地图蒙片(map mask)和森林清查样地.它们在一起,使森林变量(如材枳和林分年龄)的计算机估计成为可能.这些估计的精确度在像素水平上是低的,但在林分水平上较高.在规划木材资源应如何加以利用或出于监测目的时,这类基于栅格的森林数据对政府来说是有帮助的.本文描述了以有效成本建立森林变量估计全国数据库的生成流程.我们在林分水平上评价了瑞典西南部某地森林变量估计的精确度.结果表明,总材积估计的整体均方根误差为33%,年龄估计的整体均方根误差为23%.  相似文献   
36.
Adaptation is increasingly recognised as essential when dealing with the adverse impacts of climate change on societies, economies and the environment. However, there is insufficient information about the effectiveness of adaption policies, measures and actions. For this reason, the establishment of monitoring programmes is considered to be necessary. Such programmes can contribute to knowledge, learning and data to support adaptation governance. In the European Union (EU), member states are encouraged to develop National Adaptation Strategies (NASs). The NASs developed so far vary widely because of differing views, approaches and policies. A number of member states have progressed to monitoring and evaluating the implementation of their NAS. It is possible to identify key elements in these monitoring programmes that can inform the wider policy learning process. In this paper, four generic building blocks for creating a monitoring and evaluation programme are proposed: (1) definition of the system of interest, (2) selection of a set of indicators, (3) identification of the organisations responsible for monitoring and (4) definition of monitoring and evaluation procedures. The monitoring programmes for NAS in three member states—Finland, the UK and Germany—were analysed to show how these elements have been used in practice, taking into account their specific contexts. It is asserted that the provision of a common framework incorporating these elements will help other member states and organisations within them in setting up and improving their adaptation monitoring programmes.  相似文献   
37.
Most metapopulation models neglect the local dynamics, and systems characterized by slow population turnover, time lags and non-equilibrium, are only rarely examined within a metapopulation context. In this study we used a realistic, spatially explicit, dynamic metapopulation model of a long-lived grassland plant, Succisa pratensis, to examine the relative importance of local population dynamics, and short and long-distance dispersal of seeds.  相似文献   
38.
Lack of parental experience or differences in reproductive effort may lead to variation in nest defence behaviour among individuals in a prey population. In this experimental study, we analysed nest defence behaviour using a model of an American mink, Mustela vison, a non-native predator, at colonies of arctic terns, Sterna paradisaea, in two large areas where mink had been removed and two comparable control areas with mink in the south-western archipelago of Finland, Baltic Sea, in June 2000. Furthermore, we recorded breeding success of arctic terns in the same four areas during 1998–2001. Arctic terns took higher risks in nest defence in control areas and in a short-term (mink-free for 2 years) removal area than in the long-term (mink-free for 8 years) removal area. Thus, colonies with recent experience of mink were more active in defending their offspring. The breeding success of arctic terns was significantly higher in mink-removal areas than in control areas. We conclude that arctic terns modify their nest defence behaviour in the presence of mink. However, they cannot defend their nests sufficiently against this mainly nocturnal predator, since their breeding success is reduced in areas where mink are present.Communicated by J. Graves  相似文献   
39.
40.
Composites consisting of 30 vol% PLA and 70 vol% cellulose fibres were prepared with compression moulding. In the first part of the study, the recyclability of this composite material was investigated by grinding the material and using the recyclate obtained as a filler for PLA. Thus, the recyclate was compounded with PLA in loadings ranging from 20 to 50 wt%. The composites obtained were characterised by tensile tests, Charpy impact tests, DMTA, and SEM. Tests showed that the recyclate had a relatively good reinforcing effect. Stress at break increased from about 50 to 77 MPa and the modulus increased from 3.6 to 8.5 GPa. In the second part of the study, the ability to mechanically recycle the composites obtained was evaluated by repeated processing. Composite with two loadings of the recyclate (20 wt% and 50 %) was injection moulded repeatedly, six times. Tests showed that the composite material with 20 wt% recyclate could withstand six cycles relatively well, while the composite with the higher load degraded much more quickly. For the composites with 50 wt% recyclate, signs of polymer degradation could be seen already after reprocessing the composite once.  相似文献   
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