排序方式： 共有16条查询结果，搜索用时 15 毫秒
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构皮滩水电站下游RCC围堰混凝土施工具有工期紧、强度大、施工质量要求高等特点。在充分考虑了施工现场的地形地貌基础上,采用自卸车直接入仓方案,通过对入仓道路及入仓口合理设计与施工,确保了混凝土顺利连续浇注,并且施工质量符合设计要求。 相似文献
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The transport characters of non-uniform sediment before and after the reservoir operation are compared and analyzed. Field
data from the Three Gorges Reservoir (TGR), Danjiangkou, and Sanmenxia reservoir indicate that the transport character of
coarse particle is various in different reaches. Before the reservoir operation, the dramatic decrease of the hydraulic condition
in some reaches is the main reason to cause the coarse particle deposited. After the reservoir operation, almost all grain
sized sediment may be eroded, when the reach is eroded seriously. However, the transport character of the coarse particle
will be consistent with what it was before, when the reach is not eroded seriously. The deposition amount will be less than
its pre-dam value, and it will tend to decrease with the time going on. Erosion of fine particle results from its unsaturation.
Long-distance erosion downstream from reservoir is caused by shortage of the supply from riverbed, especially the shortage
of fine particle.
Supported by the National Basic Research Program of China(“973” Program, No.2003CB415200).
LI Yitian, born in 1957, male, Prof. 相似文献
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黄建设 《邵阳学院学报(社会科学版)》2002,(6)
汽轮机快速冷却的几种方法及其优缺点 ,对设置快冷装置的汽轮机进行了热经济性和热冲击分析 ,说明了大型汽轮机采用快速冷却装置的必要性 . 相似文献
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普通高校本科校内专业评估体系研究 总被引：2，自引：0，他引：2
校内专业评估是高校发挥专业建设积极性、能动性,实施专业“自我诊断”,自觉推动专业发展的有效手段,是对教育部门组织的由外部专家实施的（校外）专业评估的重要补充。校内专业评估目的在于：通过校内专业评估实践,构建专业持续发展的促进机制;凸显专业评估“常态化”,构建“低重心、常态化、开放式”的内部教学质量保障机制;通过专业评估,构建“招生一培养一就业”联动机制。作为一个“立体”的运行机制,校内专业评估体系的设计和运行必须以“理念创新一一机制设计一一实践探索”为基本模式。在设计的理念层面应围绕“内涵建设”,立足“学生”与“专业”的共同发展;在具体的评估体系的设计上,应以专业特性为导向,凸显体系的科学性和可操作性;在具体的评估体系的运行上,应凸显评估体系与实践的互动（并通过互动完善评估体系）,实现“上行”与“下行”的有机结合。 相似文献
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综述了近年发展起来的发酵液后处理新技术,包括双水相萃取技术、超临界二氧化碳萃取技术、细胞过滤培养技术、反胶团提取分离技术,经过不断的研究、改进,已有些达到商业规模,有非常诱人的前景 相似文献
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曹小波 《南昌教育学院学报》2011,26(3):18-19
宋金绍兴和议后,地域上虽然人为的分裂了,但由于双方经济发展的不平衡性,经济交流却是十分密切,双方在边界建立了众多榷场进行贸易,互通有无。在这些众多的榷场中,位于淮河下游的盱眙、泗州场分别是双方最大的榷场,建置的时间也最早,其为双方经济交流作出巨大的贡献。 相似文献
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青藏高原及其周边地区是亚洲大河文明的重要水源地,被称为"亚洲水塔"。"亚洲水塔"变化引起的水资源连锁效应与下游几十亿人民生活和社会发展息息相关,是下游地区实现联合国可持续发展目标的重要影响因素之一。在全球变化背景下,"亚洲水塔"下游流域水资源开发利用强度不断提高,水安全问题日益复杂和突出,"亚洲水塔"变化给下游地区水治理带来新的挑战。"亚洲水塔"变化改变河源区下泄径流,导致冰湖溃决等极端水文事件频发,威胁到下游地区供水安全、防洪安全和生态安全。文章通过分析"亚洲水塔"变化对下游水资源影响及相关研究不足,提出应加强青藏高原环境变化与下游流域水资源研究的结合,发展全流域水循环过程综合集成与模拟技术,阐明流域上下游的关联机制与"亚洲水塔"变化对下游水资源的连锁效应,提出风险应对措施与方案。 相似文献
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Yunfei Fu Yaoming Ma Lei Zhong Yuanjian Yang Xueliang Guo Chenghai Wang Xiaofeng Xu Kun Yang Xiangde Xu Liping Liu Guangzhou Fan Yueqing Li Donghai Wang 《国家科学评论(英文版)》2020,7(3):500
Correct understanding of the land-surface processes and cloud-precipitation processes in the Tibetan Plateau (TP) is an important prerequisite for the study and forecast of the downstream activities of weather systems and one of the key points for understanding the global atmospheric movement. In order to show the achievements that have been made, this paper reviews the progress on the observations for the atmospheric boundary layer, land-surface heat fluxes, cloud-precipitation distributions and vertical structures by using ground- and space-based multiplatform, multisensor instruments and the effect of the cloud system in the TP on the downstream weather. The results show that the form drag related to the topography, land–atmosphere momentum and scalar fluxes is an important part of the parameterization process. The sensible heat flux decreased especially in the central and northern TP caused by the decrease in wind speeds and the differences in the ground-air temperatures. Observations show that the cloud and precipitation over the TP have a strong diurnal variation. Studies also show the compressed-air column in the troposphere by the higher-altitude terrain of the TP makes particles inside clouds vary at a shorter distance in the vertical direction than those in the non-plateau area so that precipitation intensity over the TP is usually small with short duration, and the vertical structure of the convective precipitation over the TP is obviously different from that in other regions. In addition, the influence of the TP on severe weather downstream is preliminarily understood from the mechanism. It is necessary to use model simulations and observation techniques to reveal the difference between cloud precipitation in the TP and non-plateau areas in order to understand the cloud microphysical parameters over the TP and the processes of the land boundary layer affecting cloud, precipitation and weather in the downstream regions. 相似文献
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Qiuwen Chen Wenqing Shi Jef Huisman Stephen C Maberly Jianyun Zhang Juhua Yu Yuchen Chen Daniele Tonina Qitao Yi 《国家科学评论(英文版)》2020,7(9):1449
Hydropower development is the key strategy in many developing countries for energy supply, climate-change mitigation and economic development. However, it is commonly assumed that river dams retain nutrients and therefore reduce downstream primary productivity and fishery catches, compromising food security and causing trans-boundary disputes. Contrary to expectation, here we found that a cascade of reservoirs along the upper Mekong River increased downstream bioavailability of nitrogen and phosphorus. The dams caused phytoplankton density to increase with hydraulic residence time and stratification of the stagnant reservoirs caused hypoxia at depth. This allowed the release of bioavailable phosphorus from the sediment and an increase in dissolved inorganic nitrogen as well as a shift in nitrogen species from nitrate to ammonium, which were transported downstream by the discharge of water from the base of the dam. Our findings provide a new perspective on the environmental impacts of river dams on nutrient cycling and ecosystem functioning, with potential implications for sustainable development of hydropower worldwide. 相似文献