Results 71 to 80 of about 3,307 (154)
, 2003 虽然防护林用于减小风速、控制热量和水汽传递及污染物扩散、改善气候与环境、增加作物产量等已经有几百年了,但直到近几十年,人们才开始系统地研究防护林空气动力学的遮蔽机制.在本综述中,我们考察了绕防护林带的流动与湍流控制机制,最新的模型与数值模拟研究情况;通过数值模拟与实验数据的比较,来了解防护林带结构与防风效果之间的关系;讨论数值分析如何及为什么能够得到所需要的结果.本文将从多孔隙防护林带流动基本方程组的推导开始,讨论数值模型及模拟过程,对附体与分离流动进行预测;分析了遮蔽机制与动量交换;对风向、防护林密度、
Shen JM +4 more
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Zhongguo shiyan zhenduanxue, 2006 目的应用视网膜厚度分析仪鉴别黄斑裂孔与黄斑囊样水肿。方法采用Tilia公司的视网膜厚度分析仪对怀疑黄斑裂孔及黄斑囊样水肿的患者进行分析。结果正常人的黄斑区裂隙光带平滑,中心凹清晰可见;黄斑裂孔患者黄斑区裂隙光带前部连续性中断,视网膜水肿明显;黄斑囊样水肿患者黄斑区裂隙光带前部连续性存在,其后囊样水肿影像清晰,视网膜水肿明显。结论视网膜厚度分析仪灵敏度高,利用RTA可以确诊黄斑裂孔及黄斑囊样水肿。
吴荒, 孙莹, 吴雅臻, 周跃理
doaj
Experimental method for optimizing the molding conditions of hot-pressed briquette [PDF]
In response to the problems of low strength and high permeability of coal materials in the current physical simulation test of coal mine gas dynamics, a set of experimental research methods for optimizing the molding conditions of hot-pressed briquette ...
Fazhi YAN +9 more
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Shuitu Baochi Xuebao, 2005 运用土壤粒径质量分布原理与分形理论,对淄川峨庄流域内7种林分和对照荒草地的土壤结构特征进行研究。结果表明:①各种林分的土壤结构明显好于荒草地,不同林分类型中混交林分明显优于单纯林。良好的林分结构能明显提高土壤粒径的分布均匀程度与范围,改善土壤孔隙状况;②分形维数和重量平均直径能比较客观地表征土壤结构特征,是较为理想的土壤结构测定指标。混交林分分形维数均低于单纯林与荒草地,土壤重量平均直径均高于单纯林与荒草坡,说明混交林土壤结构稳定性最好,土壤通透性较好,具有较高的水土保持功能;③不同林分类型之间 ...
刘霞 王丽 张光灿 刘信儒 梁华
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Shuitu Baochi Xuebao目的冻融循环是高寒地区重要的物理过程，为明确冻融作用对不同退化程度高寒草甸土体微观结构的影响。方法以青海门源地区不同退化程度高寒草甸土为研究对象，以不同含根量表征不同退化程度，对重塑试样进行冻融循环试验和SEM电镜扫描，分析不同冻融次数及冻融条件下不同质量含水率和含根量对草甸土微观结构的影响。结果随冻融次数增加，高寒草甸土体孔隙分形维数持续增大，平均直径呈减少趋势，在7次冻融后趋于稳定，孔隙度增长集中于前4次冻融中。草甸土体质量含水率越高，冻融后孔隙度增长幅度越大。当质量含水率>40%时 ...
洪晨泽 +6 more
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A Numerical Simulation Study on Natural Gas Hydrate Reservoir Exploitation [PDF]
, 2015 The TOUGH2 is a set of seepage simulation software developed by the Lawrence Berkeley National Laboratory; its function has many common grounds with aspects of gas hydrate reservoir exploitation including gas and fluid seepage, mass and heat ...
孙福街 +4 more
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Characteristics of water absorption capacity of weathered sandstone based on nuclear magnetic resonance and wave velocity testing [PDF]
Water is a key factor in the weathering and erosion of rocks, and highly porous rocks are generally more susceptible to weathering. However, there has been a lack of in-situ methods for assessing the water absorption capacity of rocks. To investigate the
Hongbin YAN +6 more
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Logging Response Characteristics of Gas Hydrate Formation in Shenhu Area of the South China Sea [PDF]
, 2010 分析了南海北部神狐海域含天然气水合物沉积层声波速度及密度的分布特征和变化规律,并通过对比dSdP 84航次570号钻孔含天然气水合物层段测井资料,总结出神狐海域含水合物地层的测井响应规律特征:神狐海域含水合物地层存在着明显的高声波速度、低密度特征,地层密度随声波速度的变化并不是单一的反比例关系,总体趋势上随声波速度的升高而降低;含水合物地层高声波速度值主要集中在197--220 M段,饱和度值在15%--47%之间,低密度值集中在200--212 M段,分布在水合物饱和度大于20%的地层内 ...
梁劲 +5 more
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Shuitu Baochi Xuebao, 2011 对大兴安岭山地樟子松天然林土壤水分物理性质及水源涵养能力进行研究,结果表明,0-20 cm土层土壤含水量、土壤毛管孔隙度、总孔隙度、枯落物蓄积量和蓄水量均表现为:坡下>坡中>坡上,土壤含水量变化范围为278.71~377.98 g/kg,平均值为327.67 g/kg;整个坡面土壤毛管孔隙和总孔隙度平均值分别为29.08%和53.15%;枯落物蓄积量和最大蓄水量分别为16.72,53.24 t/hm2。0-20 cm土层土壤容重随坡位降低有减小趋势,其平均值为0.84 g/cm3。土壤非毛管孔隙 ...
李奕, 满秀玲, 蔡体久, 盛后财
doaj
Research on soil improvement and engineering application under mixed application of environmental materials in alpine mining areas [PDF]
To address the issues of inadequate topsoil structure, soil erosion, and low soil fertility in the reclamation of alpine mining areas. Taking Qinghai West Copper Mine as an example, this study investigates the impact of three materials—sheep manure(A ...
Jie REN +4 more
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