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711.
Rural areas face increasing pressures to deliver both private and public goods from land management. Multiple stakeholders seek different outcomes and there is substantial heterogeneity in values. Trade-offs, synergies and complementarities exist between different services and alternative bundles of goods. The resulting complex social-ecological systems (SES) therefore require adaptive co-management. In a governance context, no single organisation has oversight across the variety of interests involved, but the challenge remains as to how these interests can best be balanced and negotiated, to deliver socially beneficial outcomes. This paper analyses how this might be achieved by considering the perspective of a ‘social residual claimant’ (SRC). The SRC, as an ideal type, represents the ultimate ‘owner’ or steward of an ecosystem which sets the criteria to assess alternative outcomes, identifying best approaches and addressing uncertainty through adaptive management. A SRC cannot be a static construct, but must interact with and influence private land-holders and other stakeholders, adjusting actions as circumstances change. We identify the criteria that would be required in order for an SRC to act in the best interests of society. We then make a comparison of these criteria against the conditions applying in three contrasting approaches currently operating in the UK: National Parks, Landscape Partnerships and Nature Improvement Areas. This enables us to identify the differences between approaches and to suggest changes that could enhance capabilities, as well as ideas for further research. We suggest that the ideal of an SRC offers a simple method of benchmarking that has potential application across a wider range of different local contexts, beyond the UK. 相似文献
712.
Beaver–willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4 ha of willow (containing about10 stems m−2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community. 相似文献
713.
Impact significance determination is widely recognized as a vital and critical EIA activity. But impact significance related concepts are poorly understood. And the quality of approaches for impact significance determination in EIA practice remains highly variable. This article seeks to help establish a sound and practical conceptual foundation for formulating and evaluating impact significance determination approaches.It addresses the nature (what is impact significance?), the core characteristics (what are the major properties of significance determination?), the rationale (why are impact significance determinations necessary?), the procedural and substantive objectives (what do impact significance determinations seek to achieve?), and the process for making impact significance judgments (how is impact significance determination conducted?). By identifying fundamental attributes and key distinctions associated with impact significance determinations, a basis is provided for designing and evaluating impact significance determination procedures at both the regulatory and applied levels. 相似文献
714.
715.
Waste management for a sustainable society 总被引:1,自引:0,他引:1
716.
Trudy Steidl Pulley Del Wayne R. Nimmo John D. Tessari 《Journal of the American Water Resources Association》1998,34(5):1087-1098
ABSTRACT: Wilson's Creek has an extensive history of toxicity from both point and nonpoint sources. Seven-day chronic daphnid (Ceriodaphnia dubia) bioassays identified one toxic site in the Wilson's Creek watershed. Procedures for the characterization phase of a Toxicity Identification Evaluation (TIE) were modified for chronic assessment and performed on four water samples from the toxic site. The characterization involved chemical/physical alterations of samples, combined with bioassays, to help in identification of the class(es) of toxicants; followed by chemical analyses. To help understand the additivity of mixtures, toxic units were derived. Successive samples contained concentrations of copper, cadmium, nickel and zinc that literature values describe as being chronically toxic to daphnids. Summed chronic toxic units for these values greatly exceeded ambient toxic units, and more than accounted for observed toxicity. Substantial fluctuations in water quality occurred over the five sampling periods of the characterization studies and a Test of Methods, June through August, 1991. This variability illustrates the difficulty in detecting and documenting nonpoint sources of pollution. Tests using living organisms, in conjunction with toxicity identification methods, on samples taken over time appear to be appropriate for detecting acute and chronic toxicity in areas impacted by intermittent point and nonpoint-source toxicity. 相似文献
717.
着重说明自然灾害经济评价中利用影子价格的原因,简要说明我国目前在投资项目评价中采用的影子价格及计算方法,以及在自然灾害经济评价中如何利用影子价格进行计算. 相似文献
718.
719.
研究以多时序土地利用、遥感数据为基础,通过GIS技术结合土地利用动态度、空间叠置与转置模型分析1992-2009 年大连金石滩国家旅游度假区土地利用空间格局演变及驱动机制。研究表明:①土地利用数量变化模式呈现耕地面积大量减少,建设用地迅速增加:1992-2009 年各土地利用类型单一动态度中耕地减少速度最快,为4.66%;建设用地增加最快,为21.32%;耕地大部分转移为建设用地,1992-2009 年耕地转向建设用地的面积为891.35 hm2,占总耕地转移面积的54.76%;旅游用地面积增加了425.35 hm2,占建设用地增长面积的27.69%;②建设用地空间扩展呈现出沿交通干线和海岸线分布,且主要集中在龙山村、满家滩和陈家村的南部交通干线区域,并从该区域不断向周围地区扩张;③与非旅游城镇相比,金石滩逐步从原有单一土地利用类型向旅游主导的复合型用地转变,在“政府”、“企业”和“居民”三个主体影响下,经历了以“自然保护为主-旅游开发为主-保护为前提适度开发”的演化历程。 相似文献
720.
为提高施工期土石坝沉降安全性,研究其具有复杂非线性特征的施工期沉降规律和相应的预警标准。基于国内某在建高土石坝的沉降数据,采用R/S法分析坝体不同高程测点、同高程测点和同测点不同时期沉降数据的Hurst指数及分形维数,提出评价坝体施工期沉降安全性的预警标准。结果表明:各测点的Hurst指数最小值为0.763,坝内各处沉降仍处于快速增长阶段;坝体下部比上部、中部比下游堆石区沉降能更快趋于稳定,且坝体下部的沉降速率已经渐趋平缓。 相似文献