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991.
合肥地区超压密粉土-砂层的性状与地基评价   总被引:1,自引:0,他引:1  
本文论述了合肥地区超压密粉土—砂层的分布及其物理力这性质。通过多种方法计算对比,综合确定了地基承载力与桩的端阻力。认为可以作为中高层建筑的桩基或箱(筏)基持力层。并对地层时代归属作了探讨。  相似文献   
992.
The objective of this paper is to develop a simple model of an encounter between a comet and a planet, with a subsequent capture or an escape, and to study the potential consequences. The hypothetical scenario is as follows: a comet with a conic orbit meets close to one of its vertices (located near the ecliptic plane), a jovian planet, and transforms its orbit. There are two hypotheses which are made for the shock: this vertex becomes one of the final vertices and the orbital plane of the comet is unchanged during the encounter as it was the case for Brooks 2 in 1886. In this model, it was able to find an equation which was then used to obtain the pre‐ and post‐encounter orbits elements and the kind of orbit (ellipse, hyperbola, parabola) with respect to the initial inclination. The numerical experiments with the observed comets often provide pre‐encounter orbits with an aphelion point located near another jovian planet farther from the Sun, and so on with sometimes several planets, or with an aphelion point located beyond the Pluto orbit. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
993.
High resolution sediment physical properties, measured on gravity and piston cores collected during cruises to Lake Winnipeg, include bulk density, acoustic velocity, magnetic susceptibility, shear strength and colour reflectance. The high resolution data are used here to construct complete stratigraphic (composite) sections of Lake Winnipeg sediments from a series of individual, discontinuous cores for the North and South Basins. These composite sections are used to evaluate basin-wide glacial and post-glacial depositional histories and to compare the northern and southern basin histories. In addition, these sections provide a baseline depth reference for interpretation of the biostratigraphy, paleomagnetic record and rock magnetic stratigraphy. Some of the data (density and shear strength) are also be used to estimate sediment stress history for the two major lithostratigraphic units and their variations across the basin.  相似文献   
994.
综合自然地理研究有关问题的探讨   总被引:6,自引:1,他引:5  
倪绍祥  查勇 《地理研究》1998,17(2):113-118
该文从进一步完善综合自然地理研究的角度出发,就与综合自然地理研究有关的几个问题如综合自然地理学的研究对象,综合研究的内涵,区域综合研究以及综合自然地理研究成果的应用作了剖析.  相似文献   
995.
一种测试岩石拉伸和压缩弹性模量的方法   总被引:1,自引:1,他引:0  
李炜  尹建国 《岩土力学》1998,19(3):93-96
介绍一种利用同一试件,在一次加载过程中就可获得岩石试件的拉伸和压缩弹性模量的方法,并对几种花岗岩进行了初步的测试研究,测试结果证明这种测试方法是可行的。  相似文献   
996.
Micro-fine disseminated gold deposits are hosted in the Triassic Baipeng Formation (argillaceous siltstone and arenaceous mudstone)in the Youjiang Rift,South China.Physical properties(grain size,specific surface,porosity and permeability)of the host rocks are studied with respect to ore-fluid cirulation,water-rock reaction and the effective volume from which ore-components could be extracted.On this basis,it is considered that the ore-fluid and oremetals were extracted mainly from the strata and hydrothermal solutions,tending to move to wards low-energy sites,depositing their gold in fault zones at the margins of the basin and in the circle fracture systems around underwater uplifts.The gold deposits resulted from the deepcirculation of hydrothermal solutions,Probably aided by multi-stage superimposition The quantites of ore-fluid necessary to form the deposits were estimated.  相似文献   
997.
In this paper, an explosive cyclone (EC) that occurred over Northeast China in the spring of 2016 is studied by using 6.7 μm FY satellite water vapor (WV) imagery and NCEP (1°×1°) reanalysis data. Moreover, the evolutions of the upper-level jet stream (ULJ), the vertical motions, and the potential vorticity (PV) are analyzed in detail. Results show that different shapes of the WV image dark zones could reflect different stages of the EC. At the pre-explosion stage, a small dark zone and an S-shaped baroclinic leaf cloud can be found on the WV imagery. Then the dark zone expands and the leaf cloud grows into a comma-shaped cloud at the explosively developing stage. At the post-explosion stage, the dark zone brightens, and the spiral cloud forms. The whole process can be well described by the WV imagery. The dynamic dry band associated with the sinking motion and the ULJ can develop into the dry intrusion later, which is an important signal in forecasting the EC and should be paid attention to when analyzing the WV imagery. Furthermore, the mechanism is also analyzed in detail in this article. EC usually occurs in the left-exit region of the 200-hPa jet and the region ahead of the 500-hPa trough where there is significant positive vorticity advection (PVA). When the EC moves onto the sea surface, the decreased friction would favour the development of the EC. The upper-level PVA, the strong convergence at low level, and the divergence at high levels can maintain the strong updraft. Meanwhile, the high PV zone from the upper levels extends downward, approaching the cyclone. Together, they keep the cyclone deepening continuously.  相似文献   
998.
郑倩  孙杭媛  潘欣  顾振海  黄亿  叶飞 《气象科学》2022,42(3):390-401
利用2008年9月—2016年8月的CloudSat卫星资料对发生在我国低纬度陆地区域(5°~36.5°N,78°~124°E)的卷云物理特征进行统计分析,并分别讨论东部沿海、中部、西部3个子区域的卷云物理特征的季节变化。结果表明:卷云的整层发生率西部地区整体低于中部与东部沿海地区。3个子区域整层发生率均在夏季最高、冬季最低。卷云的主要发生高度在5.04~18.71 km,垂直分布中卷云发生率的最大值出现在春季中部地区,为15.34%,高度为9.83 km。冰水路径最大值出现在夏季的东部沿海,液水路径最大值在秋季的西部地区。冰水含量、冰粒数浓度、冰粒有效半径的主要分布高度与卷云的发生高度一致,液水含量、液滴数浓度、液滴有效半径的主要分布高度在5.04~9.35 km。3个子区域卷云冰水含量、冰粒数浓度、冰粒有效半径垂直分布中大多集中在中上部;液水含量垂直分布主要集中在分布高度的中下部。四季卷云雷达反射率因子的最大值在-19.89~-16.78 dBZ,分布高度在7.19~10.55 km。  相似文献   
999.
郑振华  彭希哲 《地理研究》2019,38(6):1481-1496
居家养老是中国老年人最主要的养老模式,社区环境成为影响老年人健康的重要因素。基于复旦大学2014年“社区老年人健康邻里调查”数据,探讨了社区环境、步行行为与老年人健康的关系。研究发现:良好的社区休闲环境对所有老年人的健康均有显著正向影响,而从低龄到高龄,社区交往环境与步行对老年健康的影响路径呈现出从个体步行行为向社区人际交往转移的特征,社区交往环境对高龄老年人的健康具有极为重要的作用。步行的减少一定程度上降低了中龄老年人的健康水平,高龄老年人在较低的社区交往环境的压抑效应下进一步降低了健康水平。重视社区休闲环境与交往空间的优化建设,增加社区交往活动的组织等将对中国老年人健康起到极为重要的改善作用。  相似文献   
1000.
Nematode species composition, trophic structure and body size distributions were followed over an annual production cycle in the central North Sea; to test responses to temporally changing food quality and quantity in the sediment. Changes in the phytoplankton concentration in the water column were quantitatively reflected in the concentration of chlorophyll a and breakdown products in the sediment, with higher concentrations in spring and autumn following blooms, and lower concentrations in summer and winter. The taxonomic and trophic structure of nematode communities differed significantly among stations over relatively short distances, potentially masking some of the temporal dynamics. Spatio-temporal differences in nematode species composition were linked to changes in the quality and quantity of organic material reaching the seabed, reflecting a species-specific response to the nutritional quality of sedimenting organic material and the biochemical changes in the sediment associated with its decomposition. The size distributions of selected nematode species indicated that most species bred continuously throughout the sampling period, although one species, the epigrowth feeder Spilophorella paradoxa, had periods of increased growth following the deposition of the spring phytoplankton bloom. There was no consistent temporal relationship between the trophic composition of nematode communities and spring chlorophyll a or carbon sedimentation, most likely a result of the trophic plasticity of most feeding types and the capacity of the community to use both freshly sedimented material as well as the subsequent breakdown products and refractory organic matter. Community metrics implied that there were small responses to the seasonal production cycle, but these belied strong responses of a few species with life histories that allowed them to track the availability of suitable food resources.  相似文献   
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