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61.
青铜古镜表面层富硅的考察   总被引:1,自引:0,他引:1  
运用扫描电子显微镜、电子探针微量分析、X射线衍射、原子力显微镜和红外反射光谱等分析手段对16块古青铜镜残片的合金基体及表面层进行了分析比较,结果发现表面层内Cu含量低于基体,而Sn.O的含量则明显增高;表面层内有Si元素的富集,并且是以SiO_2非晶形态存在;对于不同种类的青铜镜,表面层深度不同,含Si量有差异,其表面光亮度和釉质感亦有区别。对古铜镜颜色的变化,SiO_2的保护作用及铜镜表面的加工工艺进行了分析探讨。  相似文献   
62.
Tourism produces an increasing share in global greenhouse gas (GHG) emissions. These are mostly derived from transport emissions, and long-haul air travel in particular. Short-haul domestic tourism is believed by some to be a potential substitute for long-haul tourism. Using the example of Finland this paper examines the extent to which domestic second home tourism can substitute for other leisure trips and therefore contribute to reductions of travel-generated GHG emissions. Survey data are used to evaluate the CO2 emissions caused by travel to domestic second homes, and to create statistical models that verify if the owners of domestic second homes travel to other leisure destinations less frequently than others, and if they cause less emissions by their leisure mobility than others with comparable economic and demographic background. We find that although the owners and users of domestic second homes travel for other leisure purposes less frequently than others, this does not mean their leisure mobility generates less emissions. Overall, owners of second homes produce significantly more CO2 by their leisure mobility than non-owners. The use of second homes does not seem to be a substitute for high emission long-haul travels, but rather a part of an overall highly mobile leisure lifestyle. It is therefore necessary to better understand and influence the entire range of individual mobility behaviours in order to reduce travel-related GHG emissions.  相似文献   
63.
Water acidification follows CO2 injection and leads to reactive fluid transport through pores and rock fractures, with potential implications to reservoirs and wells in CO2 geologic storage and enhanced oil recovery. Kinetic rate laws for dissolution reactions in calcite and anorthite are combined with the Navier‐Stokes law and advection–diffusion transport to perform geometry‐coupled numerical simulations in order to study the evolution of chemical reactions, species concentration, and fracture morphology. Results are summarized as a function of two dimensionless parameters: the Damköhler number Da which is the ratio between advection and reaction times, and the transverse Peclet number Pe defined as the ratio between the time for diffusion across the fracture and the time for advection along the fracture. Reactant species are readily consumed near the inlet in a carbonate reservoir when the flow velocity is low (low transverse Peclet number and Da > 10?1). At high flow velocities, diffusion fails to homogenize the concentration field across the fracture (high transverse Peclet number Pe > 10?1). When the reaction rate is low as in anorthite reservoirs (Da < 10?1), reactant species are more readily transported toward the outlet. At a given Peclet number, a lower Damköhler number causes the flow channel to experience a more uniform aperture enlargement along the length of the fracture. When the length‐to‐aperture ratio is sufficiently large, say l/d > 30, the system response resembles the solution for 1D reactive fluid transport. A decreased length‐to‐aperture ratio slows the diffusive transport of reactant species to the mineral fracture surface, and analyses of fracture networks must take into consideration both the length and slenderness of individual fractures in addition to Pe and Da numbers.  相似文献   
64.
X. R. Ming  L. Liu  M. Yu  H. G. Bai  L. Yu  X. L. Peng  T. H. Yang 《Geofluids》2016,16(5):1017-1042
This study investigates the Wangfu Depression of the Songliao Basin, China, as a natural analogue site for Fe migration (bleaching) and mineralization (formation of iron concretions) caused by reducing CO2‐bearing fluids that leak along fractures after carbon capture, utilization, and storage. We also examined the origin of fracture‐filling calcite veins, the properties of self‐sealing fluids, the influence of fluids on the compositions of mudstone and established a bleaching model for the study area. Our results show that iron concretions are the oxidative products of precursor minerals (pyrite and siderite) during uplift and are linked to H2S and CO2 present in early stage fluids. The precipitation of calcite veins is the result of CO2 degassing and is related to CO2, CH4, and minor heavy hydrocarbons in the main bleaching fluids. In our model, fluids preferentially enter high‐permeability fracture systems and result in the bleaching of surrounding rocks and precipitation of calcite veins. The infilling of calcite veins significantly decreases the permeability of fractures and forces the fluids to slowly enter and bleach the mudstone rocks. The Fe2+ released during bleaching migrates to elsewhere with the solutions or is reprecipitated in the calcite veins and iron concretions. The formation of calcite veins reduces the fracture space and effectively prevents fluid flow. The fluids have an insignificant effect on minerals within the mudstone. In terms of the chemistry of the mudstone, only the contents of Fe2O3, U, and Mo change significantly, with the content of U increasing in the mudstone and the contents of Fe2O3 and Mo decreasing during bleaching.  相似文献   
65.
This article discusses the pilgrimage of the nations to Zion described in Isa 2,2-5, focusing on Isaiah’s attitude to their future faith in the God of Israel. A number of ways of understanding Isaiah’s view are proposed on the basis of a series of ever-widening interpretive circles. These are determined by their linguistic and/or substantive and/or cognitive affinities with the vision, influencing the exegesis of the vision either through their content or the worldview they reflect. None of the circles entails a reading of the vision as a closed unit isolated from its context.  相似文献   
66.
67.
甘肃出土木器依据形态与结构划分,属于典型的糟朽木器类型,材质外观特征与特性明显。制作材质鉴定表明,基本类型有①松科云杉;②松科冷杉;③柏科圆柏。通过对糟朽木器形态类型、结构属性、影响因素及发生改变原因剖析,指出了糟朽木器材质在经历了第一阶段的转折性根本改变后(含水率远低于纤维饱和点),即将面临第二阶段的转折性根本变化(含水率略高或接近于平衡含水率),而这一阶段的改变结果对器物将是毁灭性的;为了避免出土器物在短期内形态发生剧变,运用生物切片、扫描电镜分析技术对木质纤维显微结构进行了观察和研究,研究结果与结构病害腐变结果相吻合。选取与糟朽器物同期考古出土的糟朽棺板木作为分析对象,分别对其化学成分、容积重、含水率以及力学性能进行了实验测试,测得糟朽木器降解损失超过50%,含水率约为10.5%,力学强度指标与正常材质相比,均有明显的下降,且相对差异较大,最大约为正常木材强度的60%。对比分析结果,得出了结论:①糟朽木器的形态与结构状况与实验生物切片分析、电镜显微结构观察和研究结果相吻合,同时材质成分、容积重与力学性能测定结果为上述分析结果提供了有力的数据支撑;②致使糟朽木器形态和结构发生改变的主要因素是胎木含水率,其值是非恒定的并随外部环境而改变,因此含水率可用于反映糟朽木器的材质特性;③纤维饱和点与平衡含水率是影响、衡量和评估糟朽木器形态与结构的两个重要的物理参数;④鉴于糟朽木器的材质特性,后期保存应尽量避免与水分的直接接触,需要严格控制其胎木的含水率,且维持恒定、稳定的保存环境,这点对后期糟朽木器的保存是非常重要的  相似文献   
68.
The Jian copper deposit, located on the eastern edge of the Sanandaj–Sirjan metamorphic zone, southwest of Iran, is contained within the Surian Permo‐Triassic volcano‐sedimentary complex. Retrograde metamorphism resulted in three stages of mineralization (quartz ± sulfide veins) during exhumation of the Surian metamorphic complex (Middle Jurassic time; 159–167 Ma), and after the peak of the metamorphism (Middle to Late Triassic time; approximately 187 Ma). The early stage of mineralization (stage 1) is related to a homogeneous H2O–CO2 (XCO2 > 0.1) fluid characterized by moderate salinity (<10 wt.% NaCl equivalent) at high temperature and pressure (>370°C, >3 kbar). Early quartz was followed by small amounts of disseminated fine‐grained pyrite and chalcopyrite. Most of the main‐ore‐stage (stage 2) minerals, including chalcopyrite, pyrite and minor sphalerite, pyrrhotite, and galena, precipitated from an aqueous‐carbonic fluid (8–18 wt.% NaCl equivalent) at temperatures ranging between 241 and 388°C during fluid unmixing process (CO2 effervescence). Fluid unmixing in the primary carbonaceous fluid at pressures of 1.5–3 kbar produced a high XCO2 (>0.05) and a low XCO2 (<0.01) aqueous fluid in ore‐bearing quartz veins. Oxygen and hydrogen isotope compositions suggest mineralization by fluids derived from metamorphic dehydration (δ18Ofluid = +7.6 to +10.7‰ and δD = ?33.1 to ?38.5‰) during stage 2. The late stage (stage 3) is related to a distinct low salinity (1.5–8 wt.% NaCl equivalent) and temperatures of (120–230°C) aqueous fluid at pressures below 1.5 kbar and the deposition of post‐ore barren quartz veins. These fluids probably derived from meteoric waters, which circulated through the metamorphic pile at sufficiently high temperatures and acquire the characteristics of metamorphic fluids (δ18Ofluid = +4.7 to +5.1‰ and δD = ?52.3 to ?53.9‰) during waning stages of the postearly Cimmerian orogeny in Surian complex. The sulfide‐bearing quartz veins are interpreted as a small‐scale example of redistribution of mineral deposits by metamorphic fluids. This study suggests that mineralization at the Jian deposit is metamorphogenic in style, probably related to a deep‐seated mesothermal system.  相似文献   
69.
A noted British specialist in Russia's economic geography and the Far East region presents a comprehensive account of the development of the onshore and offshore oil and gas deposits of Sakhalin. Following a review of early multinational activity in geological surveying and exploration during the 1970s, he charts subsequent changes in the entities formed to develop and exploit the deposits (Sakhalin-I and -II) later in the Soviet period and during the first two decades of Russian independence. These changes have responded to improved knowledge of the geology of the deposits and changing relations between the Russian central government and Sakhalin regional authorities. Also analyzed are efforts by the Russian side to overturn or otherwise modify terms of previous agreements deemed unfavorable, and maneuvering by China and Japan to secure increasing sources of supply for their markets. With Sakhalin's two core projects now entering the active production phase, the author distills a number of key issues that have shaped the development of the island's offshore hydrocarbon resources and will have a bearing on prospects for a future generation of less spectacular new projects (incremental development); he also outlines wider lessons that have been learned over the life of Sakhalin's projects. Journal of Economic Literature, Classification Numbers: F210, L710, L950, P330, Q400. 4 figures, 2 tables, 45 references.  相似文献   
70.
This paper studies an attempt to replicate the Earth’s biosphere in the second half of the twentieth century with the aim of preserving and refashioning the environment as a self‐reproducing ecological system. Ecosystems dynamics framed the planet Earth as a closed system and directed scientific attention to questions of global environmental management. The image of the Earth as a spacecraft and operable in a similar way supported ideas of placing the environment in a laboratory setting. Using the case of Biosphere 2, launched in the Arizona desert in 1983, this paper studies the images of nature and environment contained in this quest to create an ecosystem and human habitat as good as, or superior to nature on Earth (known in this context as Biosphere 1). The second biosphere was designed as ‘a prototype for a space colony’ that would eventually enable its deteriorating predecessor, the Earthly biosphere, to reproduce and allow human settler societies to migrate to other planets. The paper draws on the cultural history of the ship in Western culture and on ships and spaceships as archetypes of autarkic enclosures set apart from nature. It argues that Biosphere 2 as an example of a technologically controlled endosphere advanced an understanding of the environment as a ‘life support system’ that emphasized not completeness but systems integrity, and was based on principles of functionality and replaceability. The paper will explore how notions of biospheric life support shaped demands on the natural and social environments in Biosphere 2 and Biosphere 1.  相似文献   
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