公用微机硬盘信息保护的一种有效方法

介绍一种保护公用微机硬盘信息的有效方法．不仅可以预防各种计算机病毒，更重要的是可以防止人为操作对硬盘信息的破坏。适用于学校等开放性微机实验室的信息安全与保护．     

台湾海峡西部柱状沉积物粘土矿物的分析

根据台湾海峡西部10个柱102个样品的X 射线衍射等分析,鉴定了该区粘土矿物组合与含量变化,分析了其与沉积环境的关系.结果表明,该区粘土矿物组合大多数站位以伊利石含量占首位,绿泥石和高岭石次之,且含少量蒙脱石;伊利石含量随距岸、水深的增加而递增,高岭石则反之;蒙脱石含量与火山活动密切相关,绿泥石含量呈斑块状分布;775和819号站有典型的陆相层,为早玉木冰期的“台湾陆桥”或“东山陆桥”提供有力证据.     

黄河三角洲沿岸及邻近海区细粒沉积物中的碳酸盐

本文用X-射线衍射法直接计算了来自黄河三角洲沿岸及邻近海区80个沉积样的细粒组分(<2μm)中的碳酸盐含量。计算结果与全样的容量法分析结果基本一致。研究结果表明,本区细粒沉积物中碳酸盐含量变化受沉积物来源、海区水动力作用、海底地貌特征和碳酸盐的地球化学行为等因素所影响。     

Seismic structure and tectonics of the Shackleton Fracture Zone (Drake Passage,Scotia Sea)

The structural framework of the southern part of the Shackleton Fracture Zone has been investigated through the analysis of a 130-km-long multichannel seismic reflection profile acquired orthogonally to the fracture zone near 60° S. The Shackleton Fracture Zone is a 800-km-long, mostly rectilinear and pronounced bathymetric lineation joining the westernmost South Scotia Ridge to southern South America south of Cape Horn, separating the western Scotia Sea plate from the Antarctic plate. Conventional processing applied to the seismic data outlines the main structures of the Shackleton Fracture Zone, but only the use of enhanced techniques, such as accurate velocity analyses and pre-stack depth migration, provides a good definition of the acoustic basement and the architecture of the sedimentary sequences. In particular, a strong and mostly continuous reflector found at about 8.0 s two-way traveltime is very clear across the entire section and is interpreted as the Moho discontinuity. Data show a complex system of troughs developed along the eastern flank of the crustal ridge, containing tilted and rotated blocks, and the presence of a prominent listric normal fault developed within the oceanic crust. Positive flower structures developed within the oceanic basement indicate strike-slip tectonism and partial reactivation of pre-existing faults. Present-day tectonic activity is found mostly in correspondence to the relief, whereas fault-induced deformation is negligible across the entire trough system. This indicates that the E–W-directed stress regime present in the Drake Passage region is mainly dissipated along a narrow zone within the Shackleton Ridge axis. A reappraisal of all available magnetic anomaly identifications in the western Scotia Sea and in the former Phoenix plate, in conjunction with new magnetic profiles acquired to the east of the Shackleton Fracture Zone off the Tierra del Fuego continental margin, has allowed us to propose a simple reconstruction of Shackleton Fracture Zone development in the general context of the Drake Passage opening.     

海洋沉积物中石英单矿物的化学分离

海洋沉积物中的石英作为陆源物质的标志性矿物,是古环境和古气候演化的信息载体,已成为古环境和古气候演化研究的重要替代指标.提供了改进了的化学分离海洋沉积物中石英单矿物的方法流程.在流程中的不同阶段可有效去掉全样中的生物组分、粘土矿物和长石等,取得海洋沉积物全样的总陆源矿物、石英+长石、石英的相对和绝对含量,通过计算可获得各种组分的通量,通过粒度分析可获得粒度数据.同一样品的17次重复实验表明,含量结果的平均相对误差仅为2.36%;显微镜和X射线衍射分析检查所分离出的石英纯度可达98%以上;激光粒度分析表明,化学试剂对石英的溶蚀作用不明显,不影响粒度分析结果.     

冰心中的气候环境记录与全球变化研究

冰心是高分辨地记录全球变化的主要信息载体之一。本文总结了冰心中提取古气候和古环境信息的系列记录，包括同位素、微量气体、阴阳离子、微粒、生物和有机质等。着重讨论了由这些记录提取的古气候和古环境变化方面的研究进展，并提出了今后的研究重点。     

The status of geological dredging techniques

Scientific sea-floor dredging is currently used in marine geology primarily by the hard-rock community interested in the recovery of basement rock samples from the unsedimented deep ocean floor. The technique has generally been eclipsed by ocean drilling for recovery of sedimentary rocks, because of perceived uncertainties in the location of sampling and in the representativeness of recovered material. This contribution reviews dredging equipment currently in use by marine geological institutions and refers to pinger attachments that allow precise information on the behaviour of the dredge to be telemetered back to the ship. We argue that improvements in ship navigation and transponder navigation at the seafloor, when used in conjunction with surface and/or deeply towed sidescan and swathemapping surveys, now allow for considerably less uncertainty on the location of dredge sampling. Refined sorting criteria for dredge hauls are now also available. Recent comparisons of regional sample recovery by ocean drilling and by dredge sampling indicate that the dredge hauls can usefully supplement the drilling data in the construction of sedimentary and tectonic histories of seafloor areas.     

黄河三角洲桩西101站潮沟地貌形态及其水动力学研究

在潮沟下游，横跨且生趣与潮沟的横断面设了５个观测站，进行了２４ｈ的水动力测量。结果表明，涨落潮流速流向不对称，在潮沟内，涨落潮流流速差别很大，涨潮流流速最大为９ｃｍ／２，而落潮流流速最大可达３８ｃｍ／ｓ。据推测，潮沟内之所以落潮流流速明显大于涨潮流流速，可能是由于潮沟与岸线斜交有关。     

互花米草及其对海岸的防护作用

本文论述了互花米草在滩涂中种植的时间、种植的方法及其生长的适应性。文中着重讨论互花米草在海岸工程中防浪和消浪能力。与工程护岸比较，互花米草护岸是最经济、合理和有效的。通过本文的讨论为今后利用互花米草进行海岸防护提供依据     

Three-dimensional Layer-integrated Modelling of Estuarine Flows with Flooding and Drying

Details are given of the refinement and application of a thee-dimensional (3-D) layer-integrated numerical model of tidal circulation, with the aim of simulating severe tidal conditions for practical engineering applications. The mode splitting strategy has been used in the model. A set of depth-integrated 2-D equations are first solved to give the pressure gradient, and the layer-integrated 3-D equations are then solved to obtain the vertical distributions of the flow velocities. Attention has been given to maintaining consistency of the physical quantities derived from the 2-D and 3-D equations. A TWO=layer mixing length turbulence model for the vertical shear stress distribution has been included in the model. Emphasis has been focused on applying the model to a real estuary, which is geometrically complicated and has large tidal ranges giving rise to extensive flooding and drying. The model has been applied to three examples, including: wind-driven flow in a rectangular lake, tidal circulation in a model rectangular harbour, and tidal circulation in a large estuary. Favourable results have been obtained for both the simple and complex flow beds.