关于网络用户经济效益评测模型的研究     

岳正华  李黎 《成都信息工程学院学报》2001,16(2):141-144

着重讨论了网络用户经济效益的内涵以及用户的投入量和产出量，并提出了评价网络用户经济效益的指标体系，包括成本降低率，成本利润增长率、产品开发时间约率、市场占有增长率等系列指标。  相似文献   

山东省区域地质构造演化探讨   总被引：13，自引：0，他引：13       下载免费PDF全文

宋明春  李洪奎 《山东国土资源》2001,17(6):12-21

山东省区域地质构造演化分为5个阶段.①陆核形成阶段形成太古宙高级区,地壳分异成稳定的花岗岩穹窿和活动的绿岩带,第一次克拉通化完成.②陆块发生形成阶段地壳向刚性发展,在华北陆核硅铝壳的基础上先后有3次张开、闭合裂谷作用,第二次克拉通化完成.这一阶段演化在鲁西地区主要表现为挤压作用,形成大量造山花岗岩;鲁东地区则以拉张作用为主,形成海槽,产生沉积.③秦昆洋形成演化阶段四堡期沿鲁东南部地壳拉张,在华北板块与扬子板块间形成秦昆洋.晋宁期秦昆洋关闭,华北板块与扬子板块对接碰撞,沿胶南造山带产生大量同碰撞花岗岩,同时产生超高压变质作用及形成丰富多彩的碰撞构造.晋宁运动最终形成统一的原始中国古陆,第三次克拉通化完成.④陆块发展阶段鲁西地区地壳频繁升降,形成广泛的海相及海陆交互相沉积;鲁东地区则以造山抬升为主,地层沉积较少.⑤滨太平洋发展阶段该阶段的主要特征是断块构造发育,形成盆岭构造格局,产生大陆边缘花岗岩,构造体系由古亚洲构造域转向滨太平洋构造域.  相似文献   

Paleoproterozoic Extensional Structure and Its Controlling on Mineralization in the East of Liaoning Province     

Yang Zhongzhu  Chen Shuliang  Li Xiandong  Wang Zhongjiang  Qu Hongxiang  Gang Jiang 《东北亚地学研究》2001,(1)

IntroductionThe area of eastern Liaoning is an importantmetal and nonmetal metallogenetic district in China,and the Liaohe group is one of the most importantstrata that hosts Pb, Zn, Au, B and Mg etcstratabound deposits. Up to now many geo1ogistssuch as Z…  相似文献   

    

Huang Ronghui  Zhang Renhe 《大气科学进展》1993,10(1):133

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平阳矾山明矾石矿床岩石学特征及其成因浅析     

王福生  兰翔  梁祥济 《浙江国土资源》1997,(1)

在野外地质工作的基础上，通过对浙江平阳研山明矾石矿床的岩石学及地球化学特征进行认真的研究，进一步证实了矾山明矾山矿床是酸性火山气热液与中酸性火山碎屑岩内的碱性长石的交代中形成的。为了解释矿床的均一性，成矿的周期性和矿床单向依变分带等重要特征，我们重点研究了矿床中明矾石化和叶蜡石化的热力学性质，得出了K 活度和pH值是控制交代产物的重要因素的新结论，提出了该矿床交代成矿作用的新模型，并据此成功地解释了矿床的一些重要特征。  相似文献   

河西走廊东部地区早二叠世地层研究的新认识     

罗桂昌  汪明洲 《地球科学与环境学报》1992,(2)

本文讨论了河西走廊东部地区早二叠世地层研究的有关问题,认为甘肃山丹青羊泉下二叠统剖面是北祁连山—河西走廊地区的重要代表剖面之一。以该剖面研究为依据,提出走廊东部地区下二叠统的进一步划分方案,分析该区早二叠世地层岩性特征差异的原因,并与走廊西部地区同期地层进行对比,进一步明确了大黄沟组的含意。  相似文献   

滇西北和邻区均衡重力异常特征及其壳内构造     

袁果田  项爱民 《大地测量与地球动力学》1992,(2)

本文以爱黎-海斯卡宁均衡补偿假设模式为基础,利用圆模板编制了滇西北及邻区均衡重力异常图。分析了异常的基本特征与壳内构造的关系,并初步探讨了均衡重力异常和强震活动的相关性。  相似文献   

Formation of saline groundwaters in the Baltic region through freezing of seawater during glacial periods   总被引：1，自引：0，他引：1  

Amos Bein  Arnon Arad 《Journal of Hydrology》1992,140(1-4):75-87

Typical Ca---Cl brines occur in crystalline and metamorphic rocks below freshwater horizons at various localities in Sweden and Finland. Total dissolved solids (TDS) range in concentration between 2 and 120 gl⁻¹ and have long been thought to derive from water-rock interactions. The relationships between Na, Cl and Br in these brines suggest, however, that they were derived from freezing of seawater during glacial periods. The brines were subsequently diluted by meteoric waters and their Ca/Mg ratio was increased through water-rock interactions in the subsurface. The hydrogeological model for both the formation of freeze-derived marine brines and their lateral intrusion involves restricted inland marine basins in recent and subrecent polar climatic belts. Seawater in such basins gradually freezes in response to glaciation. The solutes which concentrate in the remaining water body are residual after precipitation of a sequence of minerals which include carbonates, mirabilite and hydrohalite. Hydraulic pressure of the growing ice sheet over the frozen seas is gradually added to the ambient hydrostatic pressure exerted on the brines. This, together with their increased density, increases the intrusional potential of the brines. As the land ice cannot exert hydraulic pressure on continental groundwater in the aquifers, the balance of pressure favours deep landward intrusion of brines. Post-glacial processes cause the subsurface dilution and replacement of the brines both by seawater and fresh waters. The presence of such brines also far from present-day coastal settings reflects the shifting of coastlines as a result of isostatic movements and eustatic sea-level changes associated with glaciation and deglaciation.  相似文献   

On the calculation of perturbations in the radial position of satellites     

Lin Liu 《Chinese Astronomy and Astrophysics》1997,21(4):488-500

With the aim of analyzing the errors in the radial position of satellites, we give in this paper the expressions for the radial perturbation which include the complete zeroth- and first-order terms in the orbital eccentricity. A simpler and faster method of calculating the perturbation is given.  相似文献   

THE SIMULATED STORAGE CAPACITY OF FLOOD AND WATERLOGGING IN THE TYPICAL AGRICULTURAL REGION IN JIANGHAN PLAIN   总被引：2，自引：0，他引：2  

WANG Xue-lei    LIU Xing-tu  HU Wang-bing 《中国地理科学(英文版)》2001,11(3):259-263

１ＩＮＴＲＯＤＵＣＴＩＯＮＪｉａｎｇｈａｎＰｌａｉｎｉｓｏｎｅｏｆｔｈｅｉｍｐｏｒｔａｎｔｂａｓｅｓｏｆＣｈｉｎａ′ｓａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｉｖｉｔｙｌｏｃａｔｅｄｉｎｔｈｅｍｉｄｄｌｅＣｈａｎｇｊｉａｎｇＲｉｖｅｒｖａｌｌｅｙｏｆｃｅｎｔｒａｌＣｈｉｎａ．ＴｈｅＪｉａｎｇｈａｎｐｌａｉｎａｐｐｒｏｘｉｍａｔｅｌｙ６．６×１０４ｋｍ２ｉｎａｒｅａａｎｄｏｖｅｒ３０ｍｉｌｌｉｏｎｉｎｐｏｐｕｌａｔｉｏｎｉｓｔｈｅｒｅｎｏｗｎｅｄ“ｃｏｕｎｔｒｙｏｆｆｉｓｈａｎｄｒｉｃｅ＂ｉｎ…  相似文献