994 resultados para 7038-401
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调查草毡寒冻雏形土生物量及土壤有机质,利用涡度相关技术观测该区域作用层与大气CO2通量.结果表明:地下90%生物量集中于0~10 cm的表土层,年总净初级生产量约935.0 g/m2;土壤有机质含量在6.401~7.060%之间;净CO2通量呈明显的日变化和季节变化规律;5月中旬到9月底为CO2的净吸收(780 g CO2/m2),其中以7月最高,净吸收量明显高于非生长季的,10月到翌年5月初CO2的净排放量(383 g CO2/m2);全年固定碳高达397 g/m2.
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于1990-2004年的繁殖季节,在青藏高原北部地区收集了12种常见的雀形目鸟类的巢,并且对这些鸟巢的分布格局和结构特征进行了比较研究。所有鸟巢分布表现出草地、灌木丛和沼泽的水平分割和地上、地面及地下的垂直分割的空间分布模式,其中地面杯状巢最普遍。巢结构特征,存在从简单到复杂的系列谱变化,主要表现:巢形状从浅到深,从开放到封闭;巢材性质从单一的植物性到复合的动植物性;巢材重从少到多。不管这些变化有多大,都反映了所有鸟种选择巢址是在安全和隔热两种基本条件之间权衡。在变化谱上的每种鸟巢都有自己的利弊,选择哪种类型的巢是由鸟本身的遗传和环境特征两方面的因素决定的。另外,巢材的运输反映了亲鸟对筑巢活动的投资,是繁殖投入的重要组成部分。因此,巢材重与亲鸟体重之比可以反映出筑巢活动投资的高低。百灵科鸟的开放式地面巢材重大约是亲鸟体重的1/21而褐背拟地鸦的地下封闭巢的巢材重约为亲鸟体重的5倍以上。其余种类都在两者之间变化。总之,如此不同的投资差异是在捕食压力和种间竞争作用下以及亲鸟为满足鸟卵胚胎和雏鸟迅速生长发育的必要条件下,各种生物学特征协调的结果。
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2002年4~8月,在中国科学院海北高寒草甸生态系统定位站对高原鼠免的种群进行标志重捕,用眶下取血法对樗的鼠免各取血样100μL,使用8对引物对血样中的DNA微卫星序列进行扩增。结果每对引物所扩增的产物都具有明显的多态性;结合野外行为观察对这些多态性位点进行分析,基本上对当年出生幼体的父权进行了准确的确定;从中发现高原鼠免的交配体制为多配制,其家庭中存在等级制度,处于统治地位的雄性的繁殖成功率明显高于处于从属地位的雄性个体。上述工作表明微卫星技术在动物行保具有很高的优越性,在高原鼠兔社会动态、亲缘关系和行为进行等研究领域具有广阔的应用前景。
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根据应用对象的不同,结构光测量路径规划分为基于CAD模型的测量路径规划和无模型的测量路径规划。本文针对无模型的测量路径规划问题,提出了一种基于机器人特征点示教和准均匀B样条插值的半自动自由曲面测量路径规划策略。该策略充分考虑了自由曲面的特征及结构光测量路径的特殊要求,通过少量特征点的示教和准均匀B样条插值,半自动的规划出测量路径。实验证明,该规划策略能提高无模型工件测量的效率,且该策略已在智能测量建模加工一体化装备中得到了应用。
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随着MEMS、无线通信、自动控制和人工智能等技术的快速发展,无线传感器网络引起了学术界的极大关注。它的出现改变了人与自然界的交互方式,其应用领域将会深入到社会生活的各个方面。 节点部署问题是无线传感器网络研究的基本问题之一。在无线传感器网络的某些实际应用中,节点部署通常采用人工部署方式,为满足网络的节能性、可靠性、实时性等性能需求,需要额外部署一些节点。为限制网络布设成本,要对这些新增加的节点进行有针对性地部署。基于这种应用环境,论文对面向数据收集的无线传感器网络节点部署问题展开研究工作,主要的研究内容与成果包括以下几个方面。 论述了无线传感器网络节点部署问题的研究内容、分类和评价体系,系统地总结了前人的研究成果和不足。 为改善网络的连通性和满足网络生命期需求,提出了一种启发式的两阶段中继节点部署策略。第一阶段的部署确保了网络连通性;第二阶段部署,结合负载平衡的路由协议,满足了网络的生命期需求。仿真结果表明该方法在满足上述性能需求的前提下,最大限度地减少了需要部署的中继节点数目。 针对网络中簇首选择不合理导致数据收集成本过高的问题,提出了面向数据收集成本最优化的簇首节点选择算法。当网络状态一定时,簇首节点的优化选择问题是一类组合优化问题。论文首先提出了基于小规模网络的全局最优化的簇首节点选择算法(BFM)。针对BFM算法复杂度高的缺点,进而提出了基于大规模网络的启发式的簇首节点选择算法,该算法可以在较短时间内得到问题的次优解。 考虑网络簇首的容量限制和最大簇半径限制,把簇首节点的优化部署问题形式化为整数规划问题。提出两种启发式的簇首优化部署策略:基于K-平均的簇首部署策略和基于K-平均与模拟退火混合算法的簇首部署策略。前者适用于网络运行时的动态部署,后者适用于网络投入使用前的规划部署。仿真结果表明,分簇后的网络在满足上述限制的情况下,最大限度地延长了网络生命期。 有针对性的节点部署离不开网络状态监测,为使网络状态监测不过多占用网络资源,提出了一种高效的网络状态监测机制。通过对节点编码并在节点间建立起一个逻辑层次簇结构,利用各个子簇状态数据的相似性和编码的连续性,实现了网内无损聚合。该监测机制使得网络状态信息的收集,在不丢失数据细节信息的情况下,数据通信量大大减少。 本论文的研究仅为无线传感器网络中的规划部署问题提供了一个框架,尚未形成一个完整可行的网络规划部署系统。各项研究成果可以为无线传感器网络设计者、方案提供者以及无线传感器网络应用的系统集成,提供一些有益的指导。
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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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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