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51.
In the Pacific northwestern (PNW) region of North America, climatic conditions have significantly warmed since a predominantly cool phase of the Pacific North American circulation patterns between 1950 and 1975. What are the implications of this shift in climate for the vulnerability of native tree species? To address this question, we combined mechanistic and statistical models to assess where a variety of native tree species might be more vulnerable within their recorded ranges and where they might potentially migrate. For long-lived species that are well adapted to compete, seasonal differences in photosynthesis and water use offer insights helpful in predicting their distributions. To evaluate the general response of conifers to climatic variation across the region, we previously applied a process-based model (3-PG), to simulate the growth and maximum leaf area index that Douglas-fir could attain within recognized forested areas. We then constructed automated decision tree models to define and map the ecological distributions of 15 tree species based on differences in how photosynthesis was constrained by drought, daytime temperatures, high evaporative demand, and the frequency of frost. For the baseline climate period (1950-1975), the decision tree models predicted presence and absence of each species at ∼23,000 observations with an average accuracy of 81%, with an average kappa statistic of 0.74. In this paper the same models were run annually for the period between 1976 and 2006 for each species, and the areas defined as remaining suitable or becoming vulnerable to disturbance were identified based on whether more or less than half of the years fell within the originally defined limits. Based on these criteria, 70% of the species recorded ranges remained suitable, with 30% deemed vulnerable. Results varied notably by species with western red cedar and western hemlock remaining highly adapted, with potential for range expansion in area of up to 50% relative to the baseline period. In contrast, ponderosa pine, lodgepole pine, grand, and noble fir were classified as vulnerable with potential net contractions in their ranges. The analysis was extended through the rest of the 21st century using climatic projections from the Canadian global circulation model with a high fossil fuel emission scenario (A2) and compared to other previously published species range predictions.  相似文献   
52.
Man‐made disasters such as acts of terrorism may affect a society's resiliency and sensitivity to prolonged physical and psychological stress. The Israeli Tel Aviv stock market TA‐100 Index was used as an indicator of reactivity to suicide terror bombings. After accounting for factors such as world market changes and attack severity and intensity, the analysis reveals that although Israel's financial base remained sensitive to each act of terror across the entire period of the Second Intifada (2000–06), sustained psychological resilience was indicated with no apparent overall market shift. In other words, we saw a ‘normalisation of terror’ following an extended period of continued suicide bombings. The results suggest that investors responded to less transitory global market forces, indicating sustained resilience and long‐term market confidence. Future studies directly measuring investor expectations and reactions to man‐made disasters, such as terrorism, are warranted.  相似文献   
53.
产业转型是资源枯竭型城市面临的重要发展问题,探究资源枯竭型城市产业转型及其经济韧性的演化机制,对实现城市高质量发展具有重要意义。从演化经济韧性视角出发,以湖北省大冶市为例,构建资源枯竭型城市经济韧性评价指标体系,采取熵值法和PLS偏最小二乘法,定量揭示2000—2019年湖北省大冶市产业转型过程中经济韧性的演化特征及驱动机制。结果显示:(1)研究区经济韧性经历了衰退适应、抵御恢复、响应提升的演化阶段,分别对应其经济衰退转变期(2000—2009年)、发展恢复期(2010—2014年)、高效提升期(2015—2019年),经济韧性水平呈现出“缓慢→快速”的上升态势。(2)2000—2019年研究区经济韧性演化的驱动因子由产业结构转变和创新水平提升转向多要素共同推动,其中居民收入、市场规模、政府调控能力、产业技术水平等因子是推进研究区经济韧性演进的关键因素。(3)产业多元化转型是研究区经济韧性提升的直接动力,以产业相关多样化为传导路径,在多要素驱动下研究区向更高层次的城市生命阶段演进。当压力要素消解、城市状态调整、响应方式优化时,经济韧性将通过激活产业要素、均衡化拓展驱动力来推动产业的“路...  相似文献   
54.
新形势下城市巨系统面临更多不确定性风险与未知扰动,要求安全防灾规划从目标对象、战略定位、技术手段与规划理念等方面做出适应调整,通过韧性城市建设引领区域安全稳定发展。对韧性城市的概念起源、理论发展与实践探索进行了梳理和评述,并结合我国“多规合一”后的国土空间规划体系改革,对空间治理背景下韧性规划的内涵特征、层级类型、流程形式与公共治理进行认识与思考;并从深化韧性城市的理论构建与机理研究、转变规划编制的设计思路和实践流程、完善韧性实践中的规划传导和尺度治理、关注韧性建设中的基层治理和公众参与四个方面,提出韧性规划的实践路径展望,力求有序推进我国城市公共安全现代化治理建设。  相似文献   
55.
Conservation of biodiversity in managed forest landscapes needs to be complemented with new approaches given the threat from rapid climate change. Most frameworks for adaptation of biodiversity conservation to climate change include two major strategies. The first is the resistance strategy, which focuses on actions to increase the capacity of species and communities to resist change. The second is the transformation strategy and includes actions that ease the transformation of communities to a set of species that are well adapted to the novel environmental conditions. We suggest a number of concrete actions policy makers and managers can take. Under the resistance strategy, five tools are introduced, including: identifying and protecting forest climate refugia with cold-favored species; reducing the effects of drought by protecting the hydrological network; and actively removing competitors when they threaten cold-favored species. Under the transformation strategy, we suggest three tools, including: enhancing conditions for forest species favored by the new climate, but currently disfavored by forest management, by planting them at suitable sites outside their main range; and increasing connectivity across the landscape to enhance the expansion of warm-favored species to sites that have become suitable. Finally, we suggest applying a landscape perspective and simultaneously managing for both retreating and expanding species. The two different strategies (resistance and transformation) should be seen as complementary ways to maintain a rich biodiversity in future forest ecosystems.  相似文献   
56.
为提升地铁车站防火安全韧性,以设计方案为切入视角,基于防火安全韧性的吸收、抵抗、恢复和适应能力4个维度,构建基于ANP-熵权法面向设计的地铁防火安全韧性评价指标体系,运用逼近理想解法建立地铁车站防火安全韧性设计评价模型,通过3个已建地铁车站(青岛、沈阳、福州某地铁车站)的设计案例验证该模型的有效性和可行性。研究结果表明:3个应用案例中,沈阳某地铁车站设计防火安全韧性最高,福州某地铁车站设计防火安全韧性最低,需进一步提升防火安全能力。评价结果与各案例的实际运行阶段基本吻合,研究思路和结果对改善地铁车站的防火安全设计具有一定参考意义。  相似文献   
57.
Deployment in a crisis zone is a perilous undertaking. Little is known right now about how humanitarian workers relate social and professional goals to lived experiences of high-risk environments. In South Sudan, ranked as the most dangerous country globally for aid workers, 20 international humanitarian staff were interviewed to examine their sense of place, well-being, and vocation, using thematic and interpretative phenomenological analysis. Subjectivities of humanitarian space hinged upon negotiating physical hardships and social relationships: Juba, the capital, was described as a ‘prison’ and a ‘party hotspot’. For expatriate staff, making sense of spatial, social, and professional transience was sharply gendered and rooted in the subjectivities of risk-taking, crisis management, and career-building. Two policy measures are highlighted here to address the implications of transience for human well-being and organisational effectiveness. Efforts to support teams and structure work environments, altering the humanitarian and vocational bubble, will help to develop resilience at the heart of humanitarian systems.  相似文献   
58.
One way to make development pathways more resilient in the face of a changing climate has been through mainstreaming adaptation into government policies, planning and sectoral decision‐making. To date, many of the transferable lessons have taken the form of technical approaches such as risk assessments and toolkits. This article instead draws on evidence from South Asia to emphasise some of the more tacit and informal approaches used to influence adaptation policy. Despite their apparent significance in policy processes, such tactics are often neither planned for nor well reported in resilience‐building projects and programme documents. Using evidence to populate a typology of influencing strategies, this article looks particularly at the role of policy entrepreneurs who navigate the political complexity of both formal and informal governance systems to promote successful adaptation mainstreaming. It concludes with recommendations for adaptation and resilience programming that can more effectively harness the breadth of influencing strategies.  相似文献   
59.
重点生态功能区对维护国家和区域生态安全至关重要,农户作为该区最主要的经济活动主体和最基本的生态环境保护单元,其对生计压力的适应性直接关系到重点生态功能区主体功能的发挥。本文以地处青藏高原东缘的甘南黄河水源补给区为例,基于入户调查数据,分析了农户的生计压力、适应能力及适应策略,并利用多元logistic回归模型探明了影响适应策略选择的关键因素。结果表明:①甘南黄河水源补给区有近90%的农户遭受多重生计压力的冲击,其中,“自然+社会+经济”型压力是该区农户面临最多的生计压力组合。②经济示范区农户的适应能力最高,恢复治理区次之,重点保护区最低;遭受“自然+社会”型压力冲击的农户适应能力最高,遭受“自然+社会+经济+政策”型压力冲击的农户适应能力最低。③甘南黄河水源补给区有87.45%的农户采取多种适应策略来应对生计压力,其中,选择“扩张+援助+收缩”型适应策略的农户占比最大。④自然资本、人力资本、社会资本、自然压力的严重程度和生计压力的多样化程度是影响适应策略的关键因素。鉴于此,政府应加大生态环境保护力度,拓宽农户增收渠道,建立多元化信贷机制,加强偏远地区基础设施建设,完善社会保障体系,提高农户在面临生计压力时的适应能力,促进生计可持续发展。  相似文献   
60.
Abstract:  Recent episodes of coral bleaching have led to wide-scale loss of reef corals and raised concerns over the effectiveness of existing conservation and management efforts. The 1998 bleaching event was most severe in the western Indian Ocean, where coral declined by up to 90% in some locations. Using fisheries-independent data, we assessed the long-term impacts of this event on fishery target species in the Seychelles, the overall size structure of the fish assemblage, and the effectiveness of two marine protected areas (MPAs) in protecting fish communities. The biomass of fished species above the size retained in fish traps changed little between 1994 and 2005, indicating no current effect on fishery yields. Biomass remained higher in MPAs, indicating they were effective in protecting fish stocks. Nevertheless, the size structure of the fish communities, as described with size-spectra analysis, changed in both fished areas and MPAs, with a decline in smaller fish (<30 cm) and an increase in larger fish (>45 cm). We believe this represents a time-lag response to a reduction in reef structural complexity brought about because fishes are being lost through natural mortality and fishing, and are not being replaced by juveniles. This effect is expected to be greater in terms of fisheries productivity and, because congruent patterns are observed for herbivores, suggests that MPAs do not offer coral reefs long-term resilience to bleaching events. Corallivores and planktivores declined strikingly in abundance, particularly in MPAs, and this decline was associated with a similar pattern of decline in their preferred corals. We suggest that climate-mediated disturbances, such as coral bleaching, be at the fore of conservation planning for coral reefs.  相似文献   
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