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991.
从纵波传播过程的反射和透射的基本原理出发,介绍了反射波法桩身完整性检测数据在频率域中定量确定视反射系数和反射波往返时间的一种新的理论和方法. 相似文献
992.
贵池铜山岩体演化与成矿的关系 总被引:15,自引:1,他引:14
铜山岩体是在同一岩浆源,同一时期内由岩浆演化形成的石英闪长岩、花岗闪长岩和二长花岗岩组成的复式岩体。铜山铜矿床的成矿物质和热液主要来源于铜山岩体。随着岩浆长期的演化分异和侵入活动,成矿物质不断富集在岩浆热液中,在有利成矿空间形成了层状黄铁矿型、角砾岩型、矽卡岩型和斑岩型铜矿床 相似文献
993.
INTRODUCTIONThemiddleandlowerreachesofChangjiangRiverareoneofthemainregionsinChinawhichischaracteristicofthewidespreaddistrib... 相似文献
994.
运用三维有限单元法,探索地壳结构的非均匀性对地壳应力场的影响.假定分层地壳结构中镶嵌高速块体,低速块体,高、低速块体3种情况,分别计算壳内平均应力与水平剪应力的变化图像.结果表明:高速块体单独存在可导致高应力在高速体内的局部集中,并在其边缘和四个角区形成应力的高度集中,有利于强震的孕育和发生;低速体单独存在时,由于低速体本身不能积累应力,而其上部的应力集中程度不大,难以形成强震;高、低速体的同时存在则有利于高应力在高速体内的高度集中和在高速体外的地壳上、下部的相对集中,形成对大地震孕育、发生更加有利的条件.本文结果与邢台地震序列的空间分布图像吻合甚好. 相似文献
995.
Life-stage differences in the diet of Parabroteas sarsi (Daday) (Copepoda, Calanoida): A field study
The diet of P. sarsi in different life-stages from copepodid I to adult was investigated. Gut contents of copepodid I to II consisted mainly of algae such as diatoms and dinoflagellates. From copepodid III to adult stages the composition of the diet changed towards the inclusion of nauplii, cladocerans and copepods. The importance of the algae on the diet decreased with the inclusion of the prey items. Copepods were the most important components of the diet from C V to adult. Differences in the capture and ingestion of cladocerans and copepods were found. Diet of P. sarsi can be characterized as diverse consisting of diatoms, phagotrophic algae, protozoans, rotifers and nauplii from C I to C III and consisting mainly of carnivorous items from C IV to adult. The ability to eat a variety of food allows the copepods to modify their diet with varying conditions in the food environment. The effect of these diversity in the diet seems to be advantageous, specially in stressed environments imposed by episodes of drying. 相似文献
996.
The paper provides a detailed analysis for the second-order diffraction of monochromatic waves. For the second-order potential on the free surface, the paper proposed a forward prediction method for computing the integration on the free surface. By this method we only need to run the infinity integration on the free surface directly for a few points; a one-step quadrature can then be applied successively outward from the body for potentials at other points. For wave diffraction from a body of revolution with a vertical axis, the paper derives a new integral equation, which can cancel the leading singularity in the derivative of ring Green's functions automatically. To obtain accurate results, different approaches are also used to deal with singularities in the ring Green's functions in the integration on both the body surface and free surface. The method has been implemented for bodies of revolution with vertical axes, but the theory is also available for arbitrary bodies.A numerical examination is made to validate the numerical code by comparing the second-order forces and moments on uniform and truncated cylinders and second-order diffraction potentials on the free surface with some published results. The comparison shows that the present results are in good agreement with those published. The method is also used to compute the second-order wave elevation around uniform and truncated cylinders. 相似文献
997.
按河道形态,河流分为4类:(1)顺直河;(2)曲流河;(3)辫状河;(4)网状河。根据河道砂岩体主体的宽(w)与(h)高之比,河道砂岩体分为带状砂岩体(w∶h小于15)和席状砂岩体(w∶h大于15)。在参考前人资料的基础上,总结了在横切河道的地震剖面上河道砂岩体的反射形态、结构及振幅变化。重点介绍了曲流河内侧沙洲地震勘探,以及三维地震勘探技术在寻找河道砂岩体方面的应用。并强调指出,在河道砂岩体地震勘探中,应当加强地震资料与钻井资料、测井资料的结合。 相似文献
998.
E. Piña 《Celestial Mechanics and Dynamical Astronomy》1999,74(3):163-174
The motion of three particles, interacting by gravitational forces, is studied in a new coordinate system given by the principal
axes of inertia, as determined by Euler angles, and using the inertia principal moments and an auxiliar angle as coordinates.
The solution to the particular Lagrange case of the three‐body problem is reviewed and solved in these new coordinates.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
999.
This paper presents reflections on a research project in women's health, providing both substantive findings surrounding tanning and social status and methodological recommendations for future research. The project under review utilized a picture-elicited storytelling method to: a) understand how women link tanned, bronzed skin to health, status, and attractiveness; and b) test the effectiveness of picture-elicited storytelling as a research method. The project found that, when tanning, women use their bodies to inscribe the social norm of the bronzed aesthetic. While women indicate considerable knowledge of the health dangers of tanning, they continue to link tanned skin to beauty, status, and attractiveness. Further, the research project found that the use of picture-elicited storytelling as a method is potentially powerful but requires considerable attention to concerns of power and representation on the part of the research team. 相似文献
1000.
Ralph H. Saunders 《The Professional geographer》1999,51(1):135-146
This paper examines the ways that community policing organizes urban space in order to increase the police's ability to observe and to enforce. The logic of that organization, I argue, rests in the particular way that police are integrating civilians into police practice as part of community policing's police-community partnership, a partnership that is characterized by the concrete metaphor of a policing body. This paper presents the results of twenty months of field research with the Boston Police Department whose community policing program, Neighborhood Policing, is being hailed as a national model. 相似文献