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611.
Animal populations are exposed to large-scale anthropogenic impact from e.g. climate change, habitat alteration and supplemental stocking. All of these may affect body condition in wintering dabbling ducks, which in turn may affect an individual’s survival and reproductive success. The aim of this study was to assess whether there have been morphometric changes in Mallard (Anas platyrhynchos) and Teal (Anas crecca) over the last 30 years at a major wintering site. Body mass and condition increased from the 1950s–1960s to the 2000s in both species. The increase in body mass amounted to as much as 11.7%, with no corresponding change in body size. Improved body condition was maintained from early to mid-winter, but then converged with historical values for late winter. Our interpretation is that increasingly benign ambient winter conditions permit ducks to maintain better energetic “safety margins” throughout winter, and that converging spring departure values may be related to evolutionary flight energetic optima. The observed changes are consistent with large-scale climate amelioration and local/regional habitat improvement (both anthropogenic).  相似文献   
612.
Amory B. Lovins 《Ambio》2010,39(3):236-248
Protecting the climate is not costly but profitable (even if avoided climate change is worth zero), mainly because saving fuel costs less than buying fuel. The two biggest opportunities, both sufficiently fast, are oil and electricity. The US, for example, can eliminate its oil use by the 2040s at an average cost of 15 per barrel (200015 per barrel (2000), half by redoubled efficiency and half by alternative supplies, and can save three-fourths of its electricity more cheaply than operating a thermal power station. Integrative design permits this by making big energy savings cheaper than small ones, turning traditionally assumed diminishing returns into empirically observed expanding returns. Such efficiency choices accelerate climate-safe, inexhaustible, and resilient energy supply—notably the “micropower” now delivering about a sixth of the world’s electricity and 90% of its new electricity. These cheap, fast, market-financeable, globally applicable options offer the most effective, yet most underestimated and overlooked, solutions for climate, proliferation, and poverty.  相似文献   
613.
Dosskey, Michael G., Philippe Vidon, Noel P. Gurwick, Craig J. Allan, Tim P. Duval, and Richard Lowrance, 2010. The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams. Journal of the American Water Resources Association (JAWRA) 46(2):261-277. DOI: 10.1111/j.1752-1688.2010.00419.x Abstract: We review the research literature and summarize the major processes by which riparian vegetation influences chemical water quality in streams, as well as how these processes vary among vegetation types, and discuss how these processes respond to removal and restoration of riparian vegetation and thereby determine the timing and level of response in stream water quality. Our emphasis is on the role that riparian vegetation plays in protecting streams from nonpoint source pollutants and in improving the quality of degraded stream water. Riparian vegetation influences stream water chemistry through diverse processes including direct chemical uptake and indirect influences such as by supply of organic matter to soils and channels, modification of water movement, and stabilization of soil. Some processes are more strongly expressed under certain site conditions, such as denitrification where groundwater is shallow, and by certain kinds of vegetation, such as channel stabilization by large wood and nutrient uptake by faster-growing species. Whether stream chemistry can be managed effectively through deliberate selection and management of vegetation type, however, remains uncertain because few studies have been conducted on broad suites of processes that may include compensating or reinforcing interactions. Scant research has focused directly on the response of stream water chemistry to the loss of riparian vegetation or its restoration. Our analysis suggests that the level and time frame of a response to restoration depends strongly on the degree and time frame of vegetation loss. Legacy effects of past vegetation can continue to influence water quality for many years or decades and control the potential level and timing of water quality improvement after vegetation is restored. Through the collective action of many processes, vegetation exerts substantial influence over the well-documented effect that riparian zones have on stream water quality. However, the degree to which stream water quality can be managed through the management of riparian vegetation remains to be clarified. An understanding of the underlying processes is important for effectively using vegetation condition as an indicator of water quality protection and for accurately gauging prospects for water quality improvement through restoration of permanent vegetation.  相似文献   
614.
This paper examines the impact of climate change on the decision of farmers to engage or not to engage in livestock activities and also on the choice of different livestock species in Kenya. To this end, cross‐sectional household level data supplemented by long‐term averages of climate data are used. The probit model is employed to derive the response of the probability of engaging in livestock activities to climate change. Probit and multivariate probit methods are employed to model the choice of different livestock species. Atmosphere–ocean global circulation models are used to project the impact of different climate scenarios on the probability of engaging in livestock activities and also of adopting different livestock species according to variations in climate. The results suggest that farmers adapt livestock management decisions to climate change. At low levels of temperature increase, the probability of engaging in livestock activities falls, but at higher levels of climate change, the probability rises. The results further show that as it gets hotter, farmers change their livestock choices from dairy cattle and sheep to beef cattle and goats.  相似文献   
615.
Climate change poses many challenges for ecosystem and resource management. In particular, coastal planners are struggling to find ways to prepare for the potential impacts of future climate change while dealing with immediate pressures. Decisions on how to respond to future risks are complicated by the long time horizons and the uncertainty associated with the distribution of impacts. Existing coastal zone management approaches in the UK either do not adequately incorporate changing stakeholder preferences, or effectively ensure that stakeholders are aware of the trade-offs inherent in any coastal management decision. Using a novel method, scenario-based stakeholder engagement, which brings together stakeholder analysis, climate change management scenarios and deliberative techniques, the necessary trade-offs associated with long term coastal planning are explored. The method is applied to two case studies of coastal planning in Christchurch Bay on the south coast of England and the Orkney Islands off the north coast of Scotland. A range of conflicting preferences exist on the ideal governance structure to manage the coast under different climate change scenarios. In addition, the results show that public understanding of the trade-offs that have to be made is critical in gaining some degree of public support for long term coastal decision-making. We conclude that scenario-based stakeholder engagement is a useful tool to facilitate coastal management planning that takes into account the complexities and challenges of climate change, and could be used in conjunction with existing approaches such as the Shoreline Management Planning process.  相似文献   
616.
美国作为世界政治经济大国和世界第一大温室气体排放国家,其温室气体减排政策备受关注。布什政府上台后不久宣布拒绝接受《京都议定书》,并于2002年2月提出“全球气候变化计划”。布什政府实际上在以各种借口推托美国应该承担的温室气体减排国际责任,这将对以UNFCCC为基础的全球气候合作产生消极影响,并对全球气候政策提出挑战。  相似文献   
617.
张磊 《灾害学》2021,(2):159-165,175
韧性理论引入灾害风险管理领域,为世界防灾减灾实践提供了新理念,并在国内外韧性城市社区建设中得到广泛应用,但针对乡村地区,尤其是高脆弱性的贫困村韧性社区建设的研究还较为鲜见.该文以韧性理论为基础,结合乡村振兴战略规划,通过对贫困村社会生态系统特征的分析,探讨了新时期我国贫困村灾后恢复重建与灾害风险管理发展方向及特点.研究...  相似文献   
618.
Transaction costs and the clean development mechanism   总被引:2,自引:0,他引:2  
The emissions trading provisions of the Kyoto Protocol and its clean development mechanism (CDM) are designed to permit greenhouse gas (GHG) emission reductions at the lowest cost globally. However, to ensure climate integrity, these reductions must pass through vigilant approval, monitoring and evaluation procedures that create additional transaction costs unrelated to the physical process of eliminating GHGs. Moreover, the CDM's additionality criterion creates constraints that magnify the influence of these transaction costs on project viability. If these costs are extreme, they could undermine the success of the CDM, and possibly of the Kyoto Protocol itself. This article describes the trading provisions of the treaty, creates a working definition of transaction costs, and discusses their effects. It then analyzes the process of creating a CDM project to identify the sources of transaction costs, illustrated by an example of a fuel substitution project in Ghana. The conditions for project profitability are analyzed and compared with recent GHG emission credit prices in Europe. The specific Ghanaian results are not generalizable to all CDM projects, but the model does suggest a template that can be used to analyze the effects of project and transaction costs in other contexts.  相似文献   
619.
This project was designed to establish baseline aquatic biological community structure and physical habitat conditions in select wadeable streams within the California Central Valley. A secondary objective was to evaluate possible water quality differences between site types and seasons. Two agricultural and two urban streams were monitored in spring and fall for two consecutive years beginning in the fall of 2002. Bioassessment sampling was conducted according to modified US EPA methods. The study included physical habitat assessment, water and sediment chemical analysis and characterization of the benthic macroinvertebrate community at each site. Water samples were analyzed for selected organophosphate insecticides, pyrethroid insecticides and herbicides, while sediment samples were analyzed for pyrethroids only. All sites had substantial physical habitat and water quality impairments, and the absence of pollution intolerant macroinvertebrates and dominance of pollution tolerant macroinvertebrates were indications of biological impairment. Due to the limited amount of water quality and pesticide data collected, it was not possible to definitively demonstrate any cause and effect relationships between BMI community structure and water quality or pesticide concentrations. Though most physical habitat parameters were similar and EPA physical habitat scores revealed on no significant differences between urban and agricultural sites (P? = ?0.290), a significant difference was seen in substrate embeddedness (P? = ?0.020). Dominant taxon found at all sites were chironomids, amphipods, and oligochaetes. Benthic macroinvertebrate metrics were significantly different between both types of sites (P? = ?0.001) and seasons (P? = ?0.014). Chironomidae taxon and those of the functional feeding group scrapers were greater at urban sites, while those of the functional feeding group filterers were greater at agricultural sites. In addition, the metric groups Chironomidae, filterers, and predators were found in greater numbers in the spring than the fall.  相似文献   
620.
传播模拟是基于动力学视角认知网络结构韧性的重要途径,探究网络结构差异与网络传播状态的关系对网络结构韧性提升和国土开发空间优化意义重大。构建最近邻网络、WS小世界网络、BA无标度网络和随机网络四类典型的城市网络模型,运用复杂网络理论和SIS病毒传播模型,借助于MATLAB和Gephi进行传染病传播模拟,分析四类网络在网络形态、节点规模和度值数量差异下感染数量和感染时间的变化特征,并对其影响机制进行探究。结果表明:(1)从总体特征来看,网络的结构差异影响网络传播强度。非规则网络的异质度值分布、高度局部聚类和较短路径长度将扩大感染规模,缩短感染时间。(2)从分解特征来看,规模并非是影响网络传播的核心因素,而"度"才是,高"度"且呈幂律度分布的城市网络是区域和城市抑制消极传播的风险所在。(3)从时空特征来看,异质网络与规则网络存在鲁棒和脆弱的双重特性。应通过网络的平疫"切换"来扬长避短,充分发挥异质网络在平时的优势和规则网络在疫时的优势。基于此,从区域和城市两个层面提出国土开发空间网络结构韧性的优化策略。  相似文献   
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