排序方式： 共有122条查询结果，搜索用时 740 毫秒
71.
Chen Tieyun Zhang Huiyuan Professor Shanghai Jiao Tong University Shanghai Engineer China State Shipbuilding Corp. Shenzhen Shipbuilding Trading Co. Ltd. 《中国海洋工程》1993,(2)
The local joint flexibility matrix of multibrace tubular joints (uniplanar and multiplanar joints) is defined. The formulation for computing the elements of local flexibility factor matrix of multibrace tubular joints by semi- analytic method is presented in this paper. The stiffening effect of unloaded braces and cross-flexibility between braces are discussed. Using the local flexibility of unibrace joints instead of that of multibrace joints in conventional structural analysis will lead the result to an unsafe side. 相似文献
72.
由国家科学技术部、国家测绘局、民政部、国家发展和改革委员会等部门主持编制、成都地图出版社出版的《汶川地震灾害地图集》已正式出版发行。徐冠华、马宗晋、 相似文献
73.
ZHANG Hua YU Zhiying JIN Liu
Graduate Student State Key Laboratory of Esturine Coastal Research East China Normal University Shanghai P. R. China
Professor State Key Laboratory of Esturine Coastal Research East China Normal University Shanghai P. R. China
Professor Yangtze Estuary Waterway Construction Co. Ltd. Shanghai P. R. China 《中国海洋工程》1999,(3)
—On the basis of a comparison of the field hydrological,sediment and topographic data observedbefore and after the completion of the West Breakwater in Lianyungang Harbor,which has led to the changeof topography from a strait to a bay,a synthetical analysis is conducted on the change of back siltation.Theresults show that it is the change of coast line and the consequent change of hydrological condition and sedi-ment movement that has led to the change of back siltation in the harbor.This phenomenon is caused by thelag effects of water current,sediment movement and local adjustment of topography after the construction,and it tends to be stable.The results of analysis provide not only a basis for extension of Lianyungang Harborinto a deep water harbor,but also propose a case for the study of the change of back siltation in a harbor onmuddy coast. 相似文献
74.
FENG Weiheng FENG Yun Shanghai Gamma Ray Technology Co. Ltd. Laohumin Rd. Shanghai 《《地质学报》英文版》2000,74(3):685-691
The main reason why the application of nuclear technology in petroleum exploration has not yet been accepted by most exploration workers is that they are not clear about the homologous distribution features of oil and gas fields and radioactive radiation. The authors hold that the disequilibrium of uranium, radium and radon as a natural radioactive series is the basic feature in the use of this technology in petroleum exploration. The invention Gamma-ray Spectral Measurement of the Equilibium Coefficient Kp and Its Embodiment of the senior author now can readily solve that problem and replace the impedient measure of normalization of uranium and potassium to thorium that had to be proposed before. Application of this impedient measure has some limitations. In areas where the surface is covered by beach or river sands, thorium minerals such as monazite may be concentrated by placering. This could result in local thorium highs that would yield local uranium and potassium lows after normalization to thoriu 相似文献
75.
广西昆仑关A型花岗岩地球化学特征及构造意义 总被引：12，自引：2，他引：10
昆仑关岩体位于广西南丹-昆仑关燕山期花岗岩带西南端, 岩石类型为黑云母花岗岩.岩相学及化学成分显示其属高钾钙碱性岩系, 具高硅、富碱和铝、低磷和钛的特点, SiO2含量为68.13~72.61, K2O/Na2O比值介于1.28~1.69之间, 铝指数A/CNK=0.72~1.28, 属准铝质一强过铝质岩石.富集Ga、Rb、Th、U、Pb等元素, 而强烈亏损13a、Nb、Sr、P和Ti.稀土元素具明显负Eu异常, 总体呈现轻稀土富集的右倾"V"形配分模式.昆仑关古民单元锆石LA-ICP-MSU-Pb定年结果为93±1Ma, 形成于晚白垩世.矿物组成及地球化学特征确定了南丹-昆仑关花岗岩带是华南西南端一条重要的铝质A型花岗岩带, 控岩断裂构造为NW向南丹一昆仑关深大断裂.岩石学及主量和微量元素(含稀土)特征表明岩体侵位于后碰撞阶段的张性构造环境.结合研究范围在晚白垩世的构造背景及区域应力场匹配组合关系, 认为其与印度板块在该时期北移所引起的古太平洋板块高角度俯冲所导致的弧后拉张有关, 与浙闽沿海A型花岗岩或碱性岩分别代表了匹配构造体制下的两条A型花岗岩带. 相似文献
76.
川南古叙矿区某矿在基建过程中多次揭露大型导水陷落柱或溶洞,导致突水事故。该矿煤系地层底板为茅口组灰岩,岩溶发育,富水性强,为煤层的直接充水含水层。依据地表水和地下水的水质特征,结合连通试验,分析了矿区地表水和地下水的补给关系,并讨论了地下水水质的成因及其对茅口组灰岩岩溶发育的影响。结果表明,地表水水质为含可溶性固体少的HCO3-Ca型水,呈中性—弱碱性;地下水水质以含可溶性固体少的SO4·HCO3-Ca型水为主,呈酸性—中性,次为含可溶性固体少的SO4-Ca型水。地表水与地下水相互补给,呈酸性的地下水水质源于硫铁矿层的溶解和氧化,对茅口组灰岩岩溶发育有强烈的促进作用。此结果对防治矿井水害具有一定的指导意义。 相似文献
77.
78.
本文以网上地理数据维护为主线,分析了目前WebGIS应用的优缺点,阐述了基于B/S结构的跨平台网上地理数据维护系统的开发思路和具体应用模式。 相似文献
79.
80.
基于可拓评判法的黑土肥力质量评价 总被引：1，自引：0，他引：1
根据黑土肥力的实验特点及前人研究成果,选取与养分和理化性质相关的10个评价指标,包括有机质(SOM)、全氮(TN)、速效磷(AP)、速效钾(AK)、阳离子交换量(CEC)、酸碱度(pH)、容重(BD)、黏粒(CP)、>0.25mm水稳性团聚体(WSA>0.25)和分散率(DR),通过这些指标建立了新的黑土肥力质量评价体系。以该评价体系为参照,采用主成分分析法确定权重,运用可拓学理论对吉林省农业黑土的肥力质量进行综合评判。结果表明:WSA>0.25、BD和AP 3项指标权重最大,说明黑土肥力的主要限制因子可能为土壤的物理性质及有效磷肥含量;吉林省农业黑土的肥力质量以中等为主,占整个样品数的73%。 相似文献