994 resultados para 7136-401
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Linxia Basin, situated in the northeast belt of the Tibetan Plateau, is a late Cenozoic depression basin bounded by the Tibetan Plateau and the Chinese Loess Plateau. The Cenozoic deposition, spanning over 30Ma, in which very abundant mammal fossils were discovered, is very suitable for study of uplift processes and geo-morphological evolution of the Tibetan Plateau. The Longdan section (35°31′31.6″N,103°29′0.6″E) is famous for the middle Miocene Platybelodon fauna and the late Miocene Hipparion fauna for a long time and is also one of the earliest known places for wooly rhino, which lies on the east slope of Longdan, a small village of township Nalesi in the south of the Dongxiang Autonomous County, Linxia Hui Nationallity Autonomous Prefecture. The Longdan mammal fauna was discovered at the base of the Early Pleistocene loess deposits at Dongxiang, where the lithology is different from the typical Wucheng Loess on the Chinese Loess Plateau. The rich fossils contain many new species and the major two layers of fossils are in the loess beds. Geologically the fossiliferous area is located in the central part of the Linxia Cenozoic sedimentary basin. Tectonically the Linxia Basin is an intermountain fault basin, bordered by the Leijishan major fault in the south and the north Qinling and Qilianshan major faults in the north. The section is 51.6m thick above the gravel layer, including the 1.6m Late Pleistocene Malan Loess on the top and the other loess-paleosol sequences in the middle of the section. The base of the section is the Jishi Formation, consisting of gravel layer of 13 ~ 17m thick. In this study, 972 bulk samples were collected with an interval of 5cm and other 401 orientied samples were taken with a magnetic compass. In the laboratory, the paleomagnetism, medium grain size, susceptibility, color, micromorphology, anisotropy of magnetic susceptibility were analyzed. From the stratigraphic analysis, the Longdan section from the top 0.3m to the bottom 51.6m, containing 5 normal polarities (N1-N5) and 5 reversal polarities (R1-R5). The paleomagnetic results show N3 is the Olduvai subchron in the middle of the Matuyama chron, and then the chronology of the Longdan mammal fauna is constructed along the section. The Matuyama-Gauss boundary is 45m and N5 enters Gauss chron. The Olduvai subchron with the age of 1.77 ~ 1.95Ma is found just in the upper fossiliferous level of Longdan mammal fauna. Taking the deposit rate of the section into account, the geological age of the upper fossiliferous level of Longdan mammal fauna is estimated to be about 1.9Ma. The lower fossiliferous level is just below the Reunion subchron and its age is estimated to be 2.25Ma. In addition, anisotropy of magnetic susceptibility of the loess-paleosol and other climatic indexes were used for discussing the late Cenozoic paleoenvironmental changes at Longdan, from which the Longdan area should have been an area of predominantly steppe the same as the Longdan mammal fauna.
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在全球变化研究领域,高分辨率重建2 000年来的气候环境变化是近期工作的主要内容之一。石笋微层由于其沉积界面完整,微层明显和组分构造有序,从而成为综合研究气候环境变化的理想载体。本文详细分析了石笋微层灰度和石笋微层厚度的成因、类型和影响因素,对石笋微层在高分辨率气候环境变化研究中的应用现状及目前所存在的问题作了简要介绍,并对该领域今后的发展方向提出了一些看法。
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以华南两个复式岩体中的中生代(主要是燕山期)花岗岩为例,通过对石英中原生流体包裹体类型、分布特征、均一温度、盐度、压力、形成深度的确定,结构包裹体成分分析,并与华南部分铀矿床成矿流体进行对比,认为高温高压、低CO2和HCO3^-,低fo2,是制约华南含铀花岗岩体在成岩过程中分异出的岩浆流体不能活化自身携带的铀,而形成与花岗岩侵入同期铀矿的主要原因。
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以中国西南“三江”(澜沧江-金沙江-怒江)地区西范坪铜矿床、玉龙铜矿床和北衙金矿床为例说明了该地区斑岩型铜或金矿床的次生分带特征,概述了青藏高原、滇川西部高原的隆升,以及新生代构造抬升对地表化学风化的影响;指出西范坪铜矿床、玉龙铜矿床和北衙金矿床等明显经历过表生成矿作用的典型斑岩型矿床均位干青藏高原强烈隆升区的边部或边缘地带,新生代构造抬升对这些地段气候、地形的影响大大促进了地表的化学风化作用;认为新生代强烈隆升可能是导致这些矿床发生强烈次生富集作用的深层次原因。
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位于扬子地块西南缘川、黔、滇铅锌多金属成矿区的中南部的云南会泽铅锌矿床是我国著名的Pb、Zn、Ge生产基地之一,近年来受到很多地质学家和地学工作者的关注。本文在自己研究成果和前人资料的基础上,以云南省会泽铅锌矿床为研究对象,从脉石矿物方解石和脉石矿物热液白云石中的流体包裹体入手,详细研究矿床成矿流体的物理化学条件变化;并结合高温高压实验和前人研究成果(成矿元素分析、同位素等),详细分析该矿床的成矿流体来源、迁移机制与成矿机制,解决矿床成矿流体与围岩、基底、峨眉山玄武岩三者之间的关系,并提出合理的矿床的成因模式;并通过该课题研究,揭示成矿流体随温度、压力变化而变化的规律,了解矿床成矿元素迁移、富集和沉淀的热力学、动力学作用机制,为区域内其他铅锌矿床的找矿和研究提供理论依据。通过系统的研究,获得以下结论和成果: ⑴矿物流体包裹体均一温度主要变化于150~250℃之间,部分包裹体大于300℃;矿床矿物包裹体的形成存在两个高峰期:第一个高峰期包裹体均一温度主要集中于150~220℃,第二个高峰期包裹体均一温度主要集中于300~350℃;包裹体的捕获温度位于150℃~401℃之间,其中大部分高于200℃;盐度变化范围5~21wt% NaCl,平均值为13.24wt% NaCl;密度0.546~1.129 g/cm3;均一瞬间压力145×105Pa ~754×105Pa;成矿过程中流体曾存在沸腾作用和不混溶现象;沸腾包裹体的证据表明,成矿的深度为当时地表以下2200~2450米。因此,矿床成矿流体总体属中温-中压-中等盐度性质。 ⑵H、O同位素计算、流体包裹体、Sr同位素和水-岩反应实验结果表明,矿床成矿流体为不同来源流体混合的产物,具有多源性。而地层成矿元素含量、Pb同位素和水-岩反应实验结果证明成矿物质同样也具有多源性。因此,会泽铅锌矿床的成矿流体、成矿物质都具有多种来源。 ⑶矿床成矿条件:成矿温度为131℃~491℃,平均值为260℃;矿化时间与峨眉山玄武岩岩浆活动的时代较为相近;成矿时流体pH值为4.2~7.5,呈中性~弱碱性;金属矿物的氧逸度主要变化范围为10-55—10-20,硫逸度主要变化范围为10-30—10-10。矿石的品位主要跟流体混合、沸腾作用和断裂带宽度受到限制有关。 ⑷在该矿床,中低温(100~250℃)环境下的铅锌迁移形式有所不同,锌主要以硫氢化物络合物形式进行迁移,兼有少量氯化物络合物;而铅主要以氯化物络合物形式进行迁移,但有部分硫氢化物络合物。而在中高温条件下铅、锌基本都以氯化物络合物的形式进行迁移。影响矿物沉淀的因素很多,但流体混合作用和沸腾作用是引起会泽铅锌矿床金属矿物沉淀的主要原因。 ⑸肉红色白云岩形成的原因可能跟较为封闭的潮坪—泻湖的原始蒸发环境有关;而灰色白云岩则可能来自肉红色白云岩的淋滤交代;白色白云岩的形成则与灰岩、白云质灰岩的热液交代有关。
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The surface sites of sulfated zirconia were investigated in situ by laser-induced fluorescence spectroscopy using aniline as the probe molecule. Different from the cases for many other oxides, the aniline adsorbed on the unique active sites of sulfated zirconia at r.t. is changed into another species, which emits a characteristic fluorescence band at 422 nm. The results illustrate that the sulfate groups in sulfated zirconia are favorable for the generation of these unique active sites, which also rarely exist on pure zirconia composed of tetragonal and monoclinic phases but do not exist on pure zirconia composed of monoclinic phase. (C) 2004 Elsevier B.V. All rights reserved.
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This paper begins by defining the meaning of the term `maritime policy'. Since devolution in the UK, the opening of the new Scottish parliament in 1998 and the creation of the Scottish Executive, little effort has been made to establish a distinct maritime policy for Scotland. As was evident prior to devolution, the primary emphasis from any maritime policy perspective has continued to be a focus on lifeline island ferry services. This ignores significant developments in several other key maritime transport sectors, and this paper provides examples of areas that require some form of policy response, including intra-European short sea shipping, UK coastal shipping, urban/river transport and global container shipping. Long-standing institutional bias against maritime transport coupled with subsidy devoted almost entirely to land transport systems has resulted in a quite distorted marketplace. This suggests that a maritime policy is now imperative if maritime transport is to play a more significant role in the overall transport system. Further discussion centres on the need to consider, from a Scottish policy perspective, the role of various state-sponsored maritime service providers and how these bodies might fit better within evolving policy. The conclusion is that formulation of a maritime policy by the Scottish Executive is overdue and that a degree of restructuring of transport responsibilities within the Executive, combined with adequate resource allocation towards the maritime industry, will be necessary in order that market distortions can be overcome, so enabling Scotland to fully exploit the competitive and environmental advantages that maritime transport can provide.
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Bullying incidents in traditional and online settings are a cause for concern to many parties. The goal of the current study was to explore the extent to which a bystander would intervene in a bullying incident and the degree to which this behavior is influenced by group size (the number of other witnesses), the setting (traditional or cyberbullying), and gender of the victim. Using an online survey method, participants were presented with eight bullying scenarios, each of which involved verbal bullying of a victim. Participants (N = 82) were asked to report how likely they would be to intervene in each of these scenarios. Results showed that female victims were more likely to be helped than male victims. Furthermore, female participants were more willing to intervene than the male participants in the cyberbullying scenarios. Altruism was a positive predictor of participants’ willingness to intervene. The present findings suggest that certain gender differences in helping behavior may depend on the context in which bullying is observed (traditional or cyberbullying).
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X. Fu and Q. Shen. 'Knowledge representation for fuzzy model composition', in Proceedings of the 21st International Workshop on Qualitative Reasoning, 2007, pp. 47-54. Sponsorship: EPSRC
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Vincentelli, Moira, Women Potters: Transforming Traditions (London: A and C Black, 2003) RAE2008
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Previous research argues that large non-controlling shareholders enhance firm value because they deter expropriation by the controlling shareholder. We propose that the conflicting incentives faced by large shareholders may induce a nonlinear relationship between the relative size of large shareholdings and firm value. Consistent with this prediction, we present evidence that there are costs of having a second (and third) largest shareholder, especially when the largest shareholdings are similar in size. Our results are robust to various relative size proxies, firm performance measures, model specifications, and potential endogeneity issues.
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Der vorliegende Aufsatz ist ein Versuch, den Erziehungs- und Fürsorgestand in bezug auf die moderne polnische Gesellschaft festzustellen, wobei in erster Linie diejenigen Umwandlungen berücksichtigt werden, die sich in dieser Hinsicht in der Geschichte der Volksrepublik Polen vollzogen. Der Aufsatz stützt sich auf eine Reihe von Studien und Analysen, die von mehreren Autoren durchgeführt wurden. Die Untersuchungsergebnisse wurden jedoch synthetisch aufgefaßt, ohne auf die einzelnen Feststellungen und Angaben näher einzugehen. Die Hauptthese des vorliegenden Aufsatzes ist, daß das soziale Bewußtsein der polnischen Gesellschaft in den letzten Jahren einen totalen Wandel erfuhr, der sich grundlegend auf ihre Erziehung auswirkte. Dieser Wandel folgte aus den Prozessen, die mit der Funktionierung des Staatssystems sowie deren Ergebnis, d.h. der gesamten sozialen Erfahrung der Menschen zusammenhingen. Es wurde auf die wichtigsten Richtungen dieses Wandels sowie dessen soziopolitische Voraussetzungen hingewiesen.
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31 hojas.