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西北地区农村民房现状及抗震技术研究 总被引:2,自引:0,他引:2
在对西北地区农村民房实地调研的基础上,根据承重结构、建筑材料和工艺的不同,将其划归为生土墙体承重房屋、砖砌墙体承重房屋、木构架承重房屋和混合承重房屋.研究表明.不同类型房屋分布具有明显的区域性和年代特征,抗震性能差异较大,但均存在不同程度的地震安全问题;提高西北地区农村民房的抗震能力,需要加快实施农居地震安全工程,加快... 相似文献
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本文阐述了升钟水库右总干渠石爬明渠填方段滑坡的地质环境、规模及特征,分析了渗漏对填筑土、粉砂质泥岩C、值的影响,论述了红层丘陵区填方输水渠道滑坡形成的原因,计算了孔隙水压力、渗透压力对填方渠堤稳定性的影响,介绍了该区的防渗整治措施。 相似文献
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本文分析了两类(反)EINino年1949~1988年西北太平洋热带风暴活动的气候特点,包括热带风暴生成数和登陆数、风暴生成位置及路径,并讨论了其与太平洋副热带高压的关系。分析结果表明,在EINinoⅠ类年,105°~119.9°E经度范围内的热带风暴生成数偏多,而120°~179.9°E范围内的风暴生成数偏少;风暴生成位置偏西、偏北;移动趋势多转向路径而少西行路径;另外,登陆我国的热带风暴数也偏多,此时,副高脊线偏南,西伸脊点偏东,强度及面积指数均偏弱,Ⅱ类年则相反。同样,分析反EINinoⅠ、Ⅱ类年亦可得到类似的结果。 相似文献
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Porcelain crabs possess a ‘hair‐trigger’ propensity to autotomize their chelipeds (claws), and laboratory studies have demonstrated that this ability is highly effective in avoiding predation from other crabs. However, porcelain crabs are also subject to predation from fishes, which use a very different means of capture. In this study, we investigated whether autotomy in porcelain crabs is also effective against predation by fishes. To do this, we examined stomach‐contents data from four common species of kelp‐forest rockfishes and determined the frequency of disassociated chelipeds (those with no associated bodies) in porcelain crabs and in brachyuran crabs, which do not readily autotomize their chelipeds. We found that disassociated chelipeds of porcelain crabs were six times as common as those of brachyuran crabs (35% of the remains of all porcelain crabs versus 6% of the remains of all brachyuran crabs). We interpret this difference to be evidence that, through autotomy, porcelain crabs escaped ingestion of their entire bodies, and thus certain mortality, at a higher rate than did brachyuran crabs. We conclude that autotomy constituted an effective escape strategy from rockfish predation. This evidence, in conjunction with previous studies, suggests that autotomy of chelipeds in porcelain crabs is an effective anti‐predatory strategy against phylogenetically disparate predatory groups. 相似文献