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在各种地形变的异常中,有些异常不能只归属于一次地震,而是一组地震的共同反映,我们称之为”地震组异常”。本文着重介绍了我国华北和西南地区三组强震的地形变异常。地震组的地形变异常曲基本特征是:异常的时间跨度大,分布范围广,群体出现。异常的种类有两种:一种是速率异常,另一种是形态异常。地震组的地形变异常,可以作为地震组预测的重要依据。 相似文献
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乌什台两次地震钻孔应变异常的对比研究 总被引：3，自引：1，他引：2
2003年2月24日至12月1日先后在伽师和昭苏县境内发生了Ms6．8与Ms6．0两次地震,新疆乌什台距两次地震震中200多千米,震前钻孔应变仪均记录到异常。其异常的不同点是;伽师地震前有趋势异常,昭苏地震前则无;伽师地震的应变异常量级大于昭苏地震异常一个数量级;伽师地震异常类型齐全（趋势、短期、临震异常、指数型异常）,昭苏地震只有短期和临震异常。其异常的相同点是：短期异常形态、应变性质、异常出现时间基本相当;临震异常的出现时间及波动性基本相同。 相似文献
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为了检测动态导航观测异常和动力学模型异常,采用预测残差构造观测误差和动力学模型误差整体检验法,对观测异常可分别采用以模型为准的观测异常检验、以当前历元可靠观测为基准的异常检验或以Kalman滤波估值为基础的异常检验的方法;对于动力学模型异常检验,可以分别采用状态不符值检验法、以状态参数Kalman滤波估值为基础的动力学模型异常检验或以可靠观测为基础的动力学模型误差整体检验的方法.分析了以上几种检验方法的特点,并用实测数据进行了检验.结果表明:在观测异常或动力学模型异常处,异常检验对导航数据精度有一定程度地提高. 相似文献
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讨论了潮汐振幅因子γ值的变化幅度和频度异常的特征及含义。借助Ｆ统计检验理论研究了潮汐因子γ值的合成和异常定量化方法,提出了可用于定量描述异常程度的“异常指数”和异常检验准则。异常定量化研究的结果表明,震前异常呈有序迁移特征,并在异常时间和空间上与地震相关。研究结果与该区域现今大地测量结果相一致。 相似文献
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一、地球化学勘查（简称化探）异常筛选取的理论与方法
化探异常筛选取思路起初有两种不同的基础,一种是强调成矿地质条件,凡与地质成矿理论推断的找矿靶区一致的异常为有评价意义的异常,否则为无评价意义的异常;另一种是强调地球化学异常特征,对异常的找矿前景进行评序与筛选。以上两种化探异常筛选方法都取得了一定的找矿成效。 相似文献
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化探异常是重要的矿化信息和预测找矿标志。从元素的丰度、异常本身的分析研究及异常所处地质背景三个方面分析了化探异常在地质找矿方面的作用,并说明了化探异常的研究评价必须与异常所处地质背景有机结合起来,才能发挥化探在地质找矿中的作用。 相似文献
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利用EGM2008计算重力场模型高程异常,结合SRTM和DTM2006.0计算剩余地形模型,进而计算RTM高程异常,以弥补EGM2008重力场模型短波信号缺失的不足。从实测高程异常中减去重力场模型高程异常以及RTM高程异常,得到残余高程异常。利用曲面拟合方法拟合残余高程异常模型,解决高程基准系统偏差问题。通过实际GPS/水准数据计算证明,该方法能显著提高GPS点的高程异常计算精度,达到精化区域似大地水准面的目的。 相似文献
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根据南部非洲CMB上存在一尖锐边界S波低速异常体(超级地幔柱)的最新研究成果,利用地震层析成像及重力场理论,对该异常体的结构进行了探讨。通过建立模型,计算了该模型S波低速异常体所对应的密度异常产生的区域大地水准面异常,并将其和观测大地水准面异常进行对比。通过调整模型的几何构架、物理参数和力学平衡效应(流体静力学平衡及对流动力学效应所引起的核幔边界地形的起伏),寻找能够符合实际观测大地水准面异常的模型参数,最终得到非洲底部异常体的结构。单一的异常体模型计算结果表明,只有在选取低S波速度高密度异常时,模型预测大地水准面异常才能较好地吻合实际观测(EGM96)分布,由此可以推断,该异常体可能是高密度、低S波速的化学成分不同的异常体。但是当考虑全部地幔地震层析成像的数据,将其引入模型大地水准面异常的预测并且尝试一系列模型之后发现如果用简单叠加地幔地震层析成像数据和模型异常体对大地水准面的影响来预测该地区大地水准面异常,无法获得与观测大地水准面相吻合的结果。因而考虑更为复杂的动力学模型将是很有必要的。 相似文献
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Phylogenetic analysis based on 16S rDNA of 8 strains of cultivable bacteria isolated from Arctic sea-ice was studied.The results showed that strain BJ1 belonged to genus Planococcus,which was a genus of low mole percent G C gram-positive bacteria;strain BJ6 belonged to genus Burkholderia of β-proteobacteria and the rest 6 strain all belonged to γ-proteobacteria,of which strain BJ8 was a species of Pseudoalteromonas,strain BJ2-BJ5 and BJ7 were members of genus Psychrobacter.Phylogenetic analysis also indicated that bacteria of genus Psychrobacter of the isolates formed a relatively independent phylogenetic cluster in comparison with other bacteria belonged to genus Psychrobacter. 相似文献
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西南喀斯特地区不同石漠化阶段土壤黏土矿物组成及其含量变异研究 总被引：1，自引：0，他引：1
为了探索西南喀斯特地区土壤中黏土矿物组成及其含量的变异规律,以贵州省普定县和荔波县不同石漠化阶段典型土壤的黏土矿物为例,采用X-射线衍射仪图谱分析方法,计算得到黏土矿物组成及其含量,探讨不同石漠化阶段黏土矿物组成变化规律及其含量之间的线性关系.结果表明:不同石漠化阶段黏土矿物的组成是相同的,均为高岭石、蒙脱石和伊利石;在未石漠化、轻度石漠化、中度石漠化阶段,蒙脱石在剖面表层的质量分数分别为27.82％、29.34％、58.32％,高岭石分别为21.39％、31.81％、36.93％,伊利石分别为50.79％、38.85％、4.75％;在西南喀斯特地区,各石漠化阶段伊利石与蒙脱石的含量之间以及伊利石和高岭石的含量之间都呈显著的线性相关,相关系数分别为-0.970 3、-0.945 6;西南喀斯特地区土壤相似的成土作用和成土环境造成了黏土矿物相同的组成,而黏土矿物含量的差异说明各成土作用的程度或阶段是不同的;粉粒中的黏土矿物主要为石英和白云母,而砂砾中的黏土矿物主要为石英. 相似文献
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Gold and tin of fluid-magmatic systems： causes of combination-separation of concentration elements 
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下载免费PDF全文 The aim of the investigation is to reveal possible causes of isolation and co-occurrence of the economically significant concentrations of gold and tin. Comparative analysis of the different-rank factors that influenced migration and concentration of these elements show that different geochemical properties of Au and Sn are responsible for isolation of their big concentrations giving rise to independent metallogenic provinces, zones, and ore nodes. These differences resulted in individualization of the element migration ways to the level of ore concentration within the fluid-magmatic columns. Three main factors influenced the Au and Sn migration activity: different patterns of metal connection with the melt structure, different relation with oxygen, and different relation with other strong oxidizers. By the moment when ore-bearing fluid became isolated from magmas, the metallogenic signature of the melts, contrasting in redox-potential, had already been defined that was confirmed by the fact that tin ores associate predominantly with the granitoids of ilmenite series and gold ores with those of magnetite series. The fluid-magmatic systemswith an intermediate degree of the melt reduction-oxidation may be considered the potential producers of the combined metal concentrations. In these cases, the combined concentrating of tin and gold is plagued by an opposite direction of the oxidation-reduction reactions when their most common minerals are formed: the main migration form of Sn+2 must be oxidized (with cassiterite portioning) , and the forms of Au+ or Au+3 must be reduced (with native gold portioning) . Probably, because of this the combined tin and gold concentrations are dominated by one of the metals with a tendency of accumulation in different-stage mineral complexes. 相似文献
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Himalayan rangelands, the crucial but by and large the neglected ecosystems, are an integral part of mountain farming systems. The present investigation is based on the extensive survey and collection of mid-altitude range plants from Almora and Champawat districts of Kumaun division in the Uttarakhand Himalaya in India, from September 2003 to June 2007. The rangelands studied were oak types, chirpine types, grass types and mixed ones. Some 300 species of grasses, other herbaceous plants, trees and shrubs were found in the mid-altitude rangelands. A sizeable number of species belonged to the family of Poaceae. The grass-dominated rangelands especially harboured a variety of grass species of good fodder value. The diversity of fodder plants is a proportion of the enormous biodiversity occurring in the parts of the Himalaya. A panorama of the biodiversity emerged in this study, which is of both intangible value and direct value for the livestock- and rangeland- dependent mountain communities, suggests a very high scope of the utilization of this natural and uncultivated biodiversity for supporting livestock- based livelihoods of the region. This biodiversity also has enormous bearing on the cultivated area of the region. 相似文献
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State and Development： Changes in Livelihood Strategies in Garhwal with Special Reference to Ecotourism in the Gangotri Region 总被引：1，自引：0，他引：1
GitanjaliChaturvedi 《山地科学学报》2004,1(3):223-238
The object of the paper is to provide an insight into the changes in livelihood strategies of the people in the Garhwal Himalayas over time. From sustaining an economy based on transit trade and subsistence agriculture, there has been a shift towards tourism in recent times. This shift has been due to the tradition of pilgrimage to the higher reaches and also due to promotion by the state by developing infrastructure and providing incentives. The paper is divided into four parts. In the first part, the policies of the colonial state and the events leading to the destruction of forests and the impoverishment of the self-sustaining semi-pastoral economy in the Garhwal Himalayas are outlined. It is argued that the destruction of forests and subsequently, the economy of the Himalayas were directly responsible for the large-scale migration to the plains. This also led to further exploitation of forests by the people who were unfamiliar with any other form of livelihood. The paper also discusses the policies of the newly independent Indian state and sees them as an extension of the British policy of large-scale exploitation of Himalayan forests for the purpose of development and economic growth. In the third section, the growth of ecotourism as a direct outcome of the orocess of deforestation and as resulting from the need of society to conserve and yet to earn a livelihood is discussed. The case study of the Gangotrir egion examines the dilemma faced by the people of Garhwal in sustaining their livelihood, income or the development in the area. In addition, tourism has fostered monopolies of groups external to the region thereby contributing neither to the income or the development in the area. In addition, there is an added threat to the environment-deforestation, and erosion-a direct outcome of increased and unplanned tourism. Such problems demand state intervention and management of t.ourism. The conclusion to the paper asserts that in order that the requirements of the society to progress and to sustain itself in its natural habitat are not compromised, it is essential to increase the process of democratization by strengthening local structures and by vesting the community with the autonomy to determine its future. The paper therefore argues that ecotourism in the Himalayas undertaken without local involvement is not desirable. The constant need for local monitoring of external agencies or even of the State‘s participation and the need for re-evaluation of environmental standards are cumbersome details that add to the costs of promoting low-impact tourism. To be viable, ecotourism should be community based and the needs of the community, their ideas of conservation should be given prime importance and local community must be encouraged to review the standards governing conservation. Local structures should thus receive patronage and promotion, so that ecotourism becomes a dynamic facet of economic development. 相似文献
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As an important component of the cryosphere,sea ice is very sensitive to the climate change.The study of the sea ice physics needs accurate sea ice thickness.This paper presents an electromagnetic-induction(EM) technique which can be used to measure the sea ice thickness distribution efficiently,and the successful application in Bothnian Bay.Based on the electromagnetic field theory and the electrical properties of sea ice and seawater,EM technique can detect the distance between the instrument and the ice/water interface accurately,than the sea ice thickness is obtained.Contrastive analysis of the apparent conductivity data obtained by EM and the value of drill-hole at same positions allows a construction of a transformable formula of the apparent conductivity to sea ice thickness.The verification of the sea ice thickness calculated by this formula indicates that EM technique is able to get reliable sea ice thickness with average relative error of only 12%.The statistic of all ice thickness profiles shows that the level ice distribution in Bothnian Bay was 0.4-0.6 m. 相似文献
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Results of a series of experiments(on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of different composition and block structure) conducted in this systematic study of the effects of the composition and structure of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of the M/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu~(2+) ion decrease with the increase of the G-block or the average length of the G-block ((?)_G) and the total adsorption capacity of alginic acid is found to vary in the same order as the F_(MM)(diad frequency) in alginate in 相似文献
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Results of a series of experiments (on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of
different composition and block structure) conducted in this systematic study of the effects of the composition and structure
of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption
to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of
the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity
coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of theM/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu2+ ion decrease with the increase of the G-block or the average length of the G-block
and the total adsorption capacity of alginic acid is found to vary in the same order as theF
MM(diad frequency) in alginate in the mixed solution of Sr2+, Ba2+ and Cd2+.
Contribution No. 2166 from the Institute of Oceanology, Chinese Academy of Sciences. 相似文献
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FAN Tingjun YU Miaomiao YANG Lingling SHI Zhenping SUN Wenjie CONG Rishan YANG Xiuxia JIANG Guojian 《中国海洋大学学报(英文版)》2009,8(3)
To investigate the stimulating effects of immunostimulants on the autogenous immunocompetence of crabs and the possible mechanisms involved, the immunostimulating effects of β-1,3-glucan, lipopolysaccharide (LPS), inactivated Vibrio harveyi and Vibrio anguillarum on phenoloxidase (PO) and hemocytes of Charybdis japonica were investigated in this study. It was found that the yields and the enzymatic activities of purified PO in C. japonica increased significantly after the crabs were treated with immunostimulants, while the unit enzymatic activities remained almost the same. After treatment with β-1,3-glucan and LPS, the amount of rough endoplasmic reticulum (RER) and the number of mitochondria in both semigranular cells and granular cells increased greatly, and the number of cytoplasmic granules decreased but with enlarged volume. However, the corresponding characteristics of hyaline cells remained almost the same. On the other hand, the number of granules in semigranular cells decreased greatly, and the number of mitochondria of hyaline cells increased greatly, after treatment with inactivated vibrios. It may be concluded that the effect of polysaccharide immunostimulants on the innate immune system of C. japonica is different from that of inactivated vibrio immunostimulants. The immunity-enhancing mechanism of polysaccharides in crab autogenous immunocompetence is probably accomplished by the increased yields of PO and total PO activities, while that of inactivated vibrios is probably accomplished by the partially increased yields of PO and total PO activities as well as the significantly improved phagocytotic abilities of semigranular cells and hyaline cells. 相似文献