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191.
Effects of the grain-for-green program on soil erosion in China 总被引:1,自引:0,他引:1
Severe soil erosion is a serious environmental problem in China.In 1999 the Chinese government implemented the Grain-for-Green Program (herein referred to as the Program),a well rounded program of ecol... 相似文献
192.
IODP中的海陆对比和海陆相互作用 总被引:4,自引:0,他引:4
综合大洋钻探计划(IODP)将于2003年10月启动。与大洋钻探计划(ODP)相比,IODP规模更大,钻探和研究范围更宽,囊括地球科学的诸多领域,涉及海底生物圈、地球壳幔结构、俯冲工厂和地震活动、古环境记录和海底资源等。从海陆对比和海陆相互作用的角度,分析我国地球科学,尤其是新生代地质学研究中的一些特点和优势。中国新生代地质演化历史别具特色,如宏观地形格局的变化,喜马拉雅山和青藏高原的隆升,西太平洋边缘海的扩张,亚洲季风系统的形成等,这些特色成为中国科学家参与IODP科学研究计划的优势。 相似文献
193.
The first 7 years of the National Tsunami Hazard Mitigation Program (NTHMP) have had a significant positive impact on operations of the Richard H. Hagemeyer Pacific Tsunami Warning Center (PTWC). As a result of its seismic project, the amount and quality of real-time seismic data flowing into PTWC has increased dramatically, enabling more rapid, accurate, and detailed analyses of seismic events with tsunamigenic potential. Its tsunameter project is now providing real-time tsunameter data from seven strategic locations in the deep ocean to more accurately measure tsunami waves as they propagate from likely source regions toward shorelines at risk. These data have already been used operationally to help evaluate potential tsunami threats. A new type of tsunami run-up gauge has been deployed in Hawaii to more rapidly assess local tsunamis. Lastly, numerical modeling of tsunamis done with support from the NTHMP is beginning to provide tools for real-time tsunami forecasting that should reduce the incidence of unnecessary warnings and provide more accurate forecasts for destructive tsunamis. 相似文献
194.
本文是使用计算机绘制的地层柱状剖面图和柱状剖面对比图的尝试。分析认为,表示各种岩石类型的花纹图式都是由简单的几何图形或符号组成,而这些图形、符号均可用一些简单的数学式子表述。因此,完全可以用计算机输出。文中讨论了岩石花纹符号的设计方法和输出步骤,并附有输出的柱状剖面图和剖面对比图实例。结果表明,使用本方法不仅方便可行,而且速度快、精度高、质量好。 相似文献
195.
196.
Urban resilience, a new urban development and governance agenda, is being rolled out from the top down by a network of public, private, non-profit sector actors forming a global urban resilience complex: producing norms that circulate globally, creating assessment tools rendering urban resilience technical and managerial, and commodifying urban resilience such that private sector involvement becomes integral to urban development planning and governance. The Rockefeller Foundation's 100 Resilience Cities Program is at the center of this complex, working with the World Bank, global consultants, NGOs, and private sector service providers to enroll cities, develop and circulate urban resilience assessment tools, and create a market catalyzed by the notion of a resilience dividend. Notwithstanding the claim of this program being open and inclusive, aspects of its initial operationalization in Jakarta suggest that urban resilience assessment tools preempt alternative understandings of urban resilience and marginalizing voices of the city's most vulnerable populations. 相似文献
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198.
SAVOV IVAN P.; HICKEY-VARGAS ROSEMARY; D'ANTONIO MASSIMO; RYAN JEFFREY G.; SPADEA PIERA 《Journal of Petrology》2006,47(2):277-299
Site 1201D of Ocean Drilling Program Leg 195 recovered basalticand volcaniclastic units from the West Philippine Basin thatdocument the earliest history of the IzuBoninMarianaconvergent margin. The stratigraphic section recovered at Site1201D includes 90 m of pillow basalts, representing the WestPhilippine Basin basement, overlain by 459 m of volcaniclasticturbidites that formed from detritus shed from the EoceneOligoceneproto-IzuBoninMariana island arc. Basement basaltsare normal mid-ocean ridge basalt (N-MORB), based on their abundancesof immobile trace elements, although fluid-mobile elements areenriched, similar to back-arc basin basalts (BABB). Sr, Nd,Pb and Hf isotopic compositions of the basement basalts aresimilar to those of basalts from other West Philippine Basinlocations, and show an overall Indian Ocean MORB signature,marked by high 208Pb/204Pb for a given 206Pb/204Pb and high176Hf/177Hf for a given 143Nd/144Nd. Trace element and isotopicdifferences between the basement and overlying arc-derived volcaniclasticsare best explained by the addition of subducted sediment orsediment melt, together with hydrous fluids from subducted oceaniccrust, into the mantle source of the arc lavas. In contrastto tectonic models suggesting that a mantle hotspot was a sourceof heat for the early IzuBoninMariana arc magmatism,the geochemical data do not support an enriched, ocean islandbasalt (OIB)-like source for either the basement basalts orthe arc volcanic section. KEY WORDS: back-arc basalts; IzuBoninMarianas; Philippine Sea; subduction initiation; Ocean Drilling Program Leg 195 相似文献
199.
微波穿透雷达对月球的观测方式可以分为地基、星载环绕、星地联合以及就位探测等。对比其他探测手段,微波雷达在探测范围和空间分辨率上有很明显的优势,因此在月球和其他行星探测中起着重要的作用。国内外越来越多的深空探测任务已经或准备携带微波雷达,用于探索地外天体的浅表层地质结构,以了解行星地质过程和演化历史。本文综述了我国嫦娥三号和四号月球车玉兔号和玉兔2号在就位微波雷达(测月雷达)探测月球浅表层地质结构方面所取得的新进展,重点阐述了测月雷达在揭示月壤内部的精细结构、表层与次表层地质结构探测等方面的应用。最后,展望了我国月球微波雷达的发展趋势。 相似文献
200.