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   22篇
  免费   4篇
  国内免费   3篇
测绘学   3篇
大气科学   1篇
地球物理   8篇
地质学   6篇
海洋学   5篇
综合类   2篇
自然地理   4篇
  2021年   1篇
  2019年   1篇
  2018年   1篇
  2016年   2篇
  2014年   4篇
  2013年   1篇
  2012年   2篇
  2011年   2篇
  2009年   1篇
  2007年   1篇
  2006年   4篇
  2005年   1篇
  2004年   1篇
  2003年   2篇
  2001年   1篇
  1997年   2篇
  1994年   1篇
  1993年   1篇
排序方式: 共有29条查询结果,搜索用时 46 毫秒
1.
A methodological proposal for the assessment of impacts due to linear infrastructures such as motorways, railways, etc. is presented. The approach proposed includes a series of specific issues to be addressed for each geomorphological feature analysed—both ‘static’ and ‘dynamic’—as well as a series of steps to be followed in the process.Geomorphic characteristics potentially affected were initially identified on the basis of a conceptual activities/impacts model that helps to single out geomorphic impacts related to environmental concerns for the area. The following issues were addressed for each individual impact: nature of potential effects; indicators that can be used to measure impacts; criteria of ‘geomorphologic performance’; procedure for measurement/prediction of changes; translation of geomorphologic impacts into significant terms from the viewpoint of human concerns; possible mitigation and/or compensation measures.The procedure has been applied to a case study corresponding to a new motorway in the Basque Country, northern Spain. Geomorphological impacts considered in this analysis included: (1) consumable resources; (2) sites of geomorphological interest; (3) land units with high potential for use, high productivity or value for conservation; (4) visual landscape; (5) slope instability processes. The procedure has been designed for implementation in a Geographic Information System (GIS) environment. Details are given on the application of the method to each individual impact analysed and results are presented in both numerical and map form.Impacts assessed were initially expressed by means of heterogeneous magnitudes, depending on the geomorphological feature considered. Those geomorphological impacts were then translated into significant terms and homogeneous magnitudes. Integration was carried out on the basis of impact values thus obtained. Final integrated results were also expressed in numerical and map form.The method proposed enables comparison of alternatives as well as ‘prediction’ and assessment of impacts in terms directly related to geomorphic characteristics. It also facilitates the expression of those impacts in terms that allow integration with other types of environmental impacts.  相似文献   
2.
总电子含量赤道异常变化特性分析   总被引:1,自引:0,他引:1  
利用国际GNSS服务组织提供的总电子含量格网数据,从全球角度分析了电离层赤道异常的变化规律,并结合相关研究结论做了比较分析。首先,利用2011年3月21日(春分)的总电子含量格网数据分析了电离层赤道异常区域随时间变化的规律;然后,利用2000—2012年的总电子含量格网数据和太阳黑子数据,统计分析了120°E上空电离层赤道异常出现的地理纬度和强度的变化规律,并以2002年(太阳活动高年)和2008年(太阳活动低年)为例做了进一步分析。结果发现:电离层赤道异常区域随太阳直射点位置的变化,自东向西移动,分布在地磁赤道的两侧,具有南北半球的非对称特性;电离层赤道异常出现在当地时间T 12:00:00—T 16:00:00,日落后持续2~3h;电离层赤道异常峰值强度与太阳活动强度存在正相关关系;电离层赤道异常具有明显的季节变化规律,表现出了"半年度异常"和"冬季异常"现象。  相似文献   
3.
A highly sensitive and specific enzyme immunoassay (EIA) is described for the detection of the atrazine metabolite hydroxyatrazine. Polyclonal antibodies were raised in rabbits by immunization with a hapten-bovine serum albumin (BSA) conjugate containing 8 hapten residues per molecule of BSA. An EIA with a horseradish peroxidase (HRP) hapten tracer was optimized in microtitre plates. A concentration of 50% B/B0 was found at 0.10 μg/L for hydroxyatrazine. A limit of determination for hydroxyatrazine was reached at approximately 0.01 μg/L, i.e. well below the maximum concentration permitted by the EU guidelines for drinking water and the drinking water ordinance of the FRG. The assay did not require concentration or clean-up steps for drinking water or ground water samples. Validation experiments confirmed a good accuracy and precision. Hydroxyatrazine is reported to be the main atrazine metabolite found in soil samples. As organic solvents are usually employed for soil extraction, the influence of methanol as representative organic solvent on the assay was examined. Up to a concentration of 5% (v/v) methanol, the organic solvent did not affect the assay.  相似文献   
4.
张洪 《铀矿地质》2006,22(6):375-379
文章分析了铀矿地质勘探设施的特殊性及其对环境的影响,提出了环境影响评价中应当遵循的原则;针对存在的问题,提出了相关建议。  相似文献   
5.
????IGS????120??E???1999??2009??IONEX?????????????????????TEC?????????????С?????鷽??????????????????????????????????????TEC?????????????2009???TEC?????????????顣????????????????????????????????????TEC??仯?????????????????????Ч?????????????????????????????TEC?????????????????4.441 0??2.915 1 TECU??????????????23.26%??10.78%????????????????????????0.712 2??0.785 9??  相似文献   
6.
三峡水库重庆段一级支流回水河段富营养化潜势研究   总被引:21,自引:0,他引:21  
本文采用箱模型法分析三峡水库蓄水对重庆段主要一级支流回水河段富营养化的影响。结果表明,对于所预测的2010年以前的污染负荷水平,由于回水段平均水深达到15m左右,三峡水库重庆段主要支流回水段整体上不会出现富营养化现象;但对于水深小于1m的库岸附近,可能出现局部富营养化。根据日本国立公害研究所的富营养化指标的标准,当总磷(TP)浓度在0.05mg/L-0.11mg/L区间时,属于中-富营养。由于三峡水库一些支流回水段的TP浓度肯定超过0.05mg/L,虽然还达不到富营养的程度,但也已接近富营养化  相似文献   
7.
美国海洋油气环评贯穿于外大陆架油气区域租赁销售和开发的各个阶段。文章从美国外大陆架租赁范围界定入手,介绍油气区域租赁开发所经历的5年规划、区域销售、勘探和开发生产各阶段所涉及的环评文件类型。着重分析美国海洋油气开发环评体系、工作程序和文件内容,最后提出对我国海洋油气开发环评的启示,即:海洋油气规划环评在先;公众参与的早期介入;全过程政府环评;环评审查不等于排污许可。  相似文献   
8.
Since the early 1990s, there has been an active program in Hong Kong to manage and protect local populations of small cetaceans from the effects of massive development in the area. This paper reviews the progress that has been made. Only two species regularly occur there: the Indo-Pacific humpback dolphin and the finless porpoise. Because most development has occurred in the western waters of Hong Kong, where generally only the humpback dolphin occurs, most of the work has been conducted on that species. Development of large infrastructure projects (such as airports, bridges, expressways, power plants, fuel facilities, and container ports) in Hong Kong often results in land reclamation, dredging and dumping of spoils, pipe and cable laying, percussive and bored piling work, underwater blasting, large increases in vessel traffic, and other impacts. Several mitigation measures have been used with varying levels of success, including bubble curtains/jackets, exclusion zones, ramping up of piling hammers, acoustic decoupling of noisy equipment, vessel speed limits, no-dumping policies, and silt curtains. Baseline, construction-phase, and operational-phase cetacean monitoring is often conducted to evaluate the success of conservation measures put into place. The Environmental Impact Assessment process in Hong Kong has involved cetaceans to a degree perhaps higher than anywhere else in the world, and much can be learned from studying the successes and failures of this situation.  相似文献   
9.
Conventional sectoral management and piecemeal governance are considered less and less appropriate in pursuit of sustainable development. Ecosystem based marine spatial management (EB-MSM) is an approach that recognizes the full array of interactions within an ecosystem, including human uses, rather than considering single issues, species, or ecosystem services in isolation. Marine spatial planning and ocean zoning are emerging concepts that can support EB-MSM. EB-MSM is driven by high-level goals that managers aim to achieve through the implementation of measures. High-level goals and objectives need to be translated into more operational objectives before specific targets, limits and measures can be elaborated.Monitoring, evaluation and adaptation are necessary to ensure that marine management measures are both effective and efficient. Solid monitoring frameworks are the foundation of adaptive management, as they provide the necessary information to evaluate performance and the effectiveness of management actions. Marine protected areas (MPAs) - possibly set up in networks - constitute a key component in EB-MSM policies and practises and have been applied as a cornerstone in conservation of marine biodiversity, management of fish populations, development of coastal tourism, etc. Moreover, MPA experiences have provided methods and concepts (such as zoning) to a wider EB-MSM context. The assignment of values to biophysical features of the marine environment allows the direct assessment of related management choices and may assist EB-MSM.A range of monetary valuation techniques have been proposed to reduce attributes of goods and services to a single metric. However, in the marine environment such an approach is often over simplistic, and thus less reductive techniques may be necessary. Rather than producing a single metric, the results of non-monetary assessments guide policy allowing weight to be given as necessary to potential areas of conflict and consensus.Strategies to take into account climate change effects and geohazard risks in EB-MSM have been applied or proposed worldwide. EB-MSM regimes must be alert to such risks and flexible to account for changes.  相似文献   
10.
Defining impact significance is the main technical task that influences decision-making during the Environmental Licensing Procedure(ELP).The ELP begins with screening to determine potentially signif-icant impacts of the proposed project.Scoping then follows to address any interventions deemed worthy of attention in the production of an Environmental Impact Assessment(EIA).This will include consider-ation of relevant landforms and geomorphological processes.However,preliminary assessments of envi-ronmental impacts often lack the scientific robustness to procure substantive and transactive effectiveness.This review presents an examination of the established practices of screening and scoping while highlighting the foremost challenges to improve the technical grounds of the ELP.The analysis of screening and scoping practices stresses the need for novel methods that ensure the sequential reasoning between their criteria while improving the preliminary evaluation of impact significance.Reducing the inherent subjectivity of discretionary judgment requires scientific methodologies that acknowledge the interaction between the natural system and human interventions,which has been addressed by geomor-phological research.The knowledge consolidated in this review opens the gate to explore the compatibil-ity between the United Nations strategy of Ecosystem Approach(EA)with the ELP through a novel geomorphological interpretation of the EIA.Therefore,this diagnosis demonstrate that screening and scoping practices would benefit from reliable methods that balance the precautionary principle with the efficient character required in the ELP.  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