利用控制的断层破裂模型分析台湾地区地震危险性     

Loh.  CH 陈时军 《地震地质译丛》1993,15(5):46-50

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地下水中砷元素的形成及其控制因素   总被引：3，自引：0，他引：3  

曾昭华  张志良 《上海国土资源》2003,(3):11-15

研究了长江中下游地区和吉林省地区地下水中砷元素形成和主要控制因素及其分布规律。结果表明,地下水中砷主要以H_3ASO_3、H_2AsO_4~-、HA_3O_4~(2-)等形式存在。它的形成和分布与含水介质及其上覆土层的砷含量、地下水的酸碱度、地下水的迳流条件、氧化还原环境、有机物质及铁锰等有密切的关系。  相似文献   

美国加州帕克菲尔德附近的土耳基平地场地效应试验区的弱运动观测和…     

Cram.  CH 杨宝仁 《世界地震译丛》1996,(3):63-73

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Compound-specific isotopic analyses: a novel tool for reconstruction of ancient biogeochemical processes   总被引：10，自引：0，他引：10  

Hayes JM  Freeman KH  Popp BN  Hoham CH 《Organic Geochemistry》1990,16(4-6):1115-1128

Patterns of isotopic fractionation in biogeochemical processes are reviewed and it is suggested that isotopic fractionations will be small when substrates are large. If so, isotopic compositions of biomarkers will reflect those of their biosynthetic precursors. This prediction is tested by consideration of results of analyses of geoporphyrins and geolipids from the Greenhorn Formation (Cretaceous, Western Interior Seaway of North America) and the Messel Shale (Eocene, lacustrine, southern Germany). It is shown (i) that isotopic compositions of porphyrins that are related to a common source, but which have been altered structurally, cluster tightly and (ii) that isotopic differences between geolipids and porphyrins related to a common source are equal to those observed in modern biosynthetic products. Both of these observations are consistent with preservation of biologically controlled isotopic compositions during diagenesis. Isotopic compositions of individual compounds can thus be interpreted in terms of biogeochemical processes in ancient depositional environments. In the Cretaceous samples, isotopic compositions of n-alkanes are covariant with those of total organic carbon, while delta values for pristane and phytane are covariant with those of porphyrins. In this unit representing an open marine environment, the preserved acyclic polyisoprenoids apparently derive mainly from primary material, while the extractable, n-alkanes derive mainly from lower levels of the food chain. In the Messel Shale, isotopic compositions of individual biomarkers range from -20.9 to -73.4% vs PDB. Isotopic compositions of specific compounds can be interpreted in terms of origin from methylotrophic, chemautotrophic, and chemolithotrophic microorganisms as well as from primary producers that lived in the water column and sediments of this ancient lake.  相似文献   

钻探用金刚石强度的初步研究          下载免费PDF全文

张荣清  张志良  陶志新  王祖祥 《探矿工程》1983,(6):18-21,27

随着近代钻探技术的发展,金刚石作为一种主要钻探磨料,已越来越广泛地应用于地质、冶金、煤炭、石油等钻探工程。  相似文献   

解释湖成和海成沉积物磁性记录的一种简单模式     

Hilton  J  张志良 《国外第四纪地质》1989,(1):53-60

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青海省土地承载力的系统动力学研究     

杨晓鹏  张志良 《地理与地理信息科学》1992,(4)

以资源——资源生态——资源经济科学的理论为基础,对青海省土地资源人口承载力系统条件的综合分析,针对各类资源之间的平衡关系、农业结构与资源结构的匹配关系、单产潜力的预测与总生产潜力的仿真,进行人口与资源关系的综合研究,建立该地区土地资源人口承载力的动态模型。  相似文献   

应用正交偶极子测井资料测量EDA地层的横波各向异性   总被引：17，自引：4，他引：13       下载免费PDF全文

陶果 Cheng  CH 《地球物理学报》1999,42(2):277-286

采用３种分析ＥＤＡ地层横波各向异性的技术处理了从ＷｙｏｍｉｎｇＰｏｗｄｅｒ河谷用正交偶极子测井取得的数据资料。这些处理技术基于挠曲波在各向异性介质中发生分裂的现象而模拟ＶＳＰ中的横波数据处理。四组分的正交偶极子测井数据是用Ｓｃｈｌｕｍｂｅｒｇｅｒ公司的测井仪从井深３５５０ｍ的一段长为５６ｍ的垂向裂缝发育的地层中采集的。根据对各发射－接收器组记录数据处理结果的一致性与方差来看,非正交旋转法效果最好。但线性变换法的结果也是可以接受的。线性变换法的优点是节省机时。从这组数据处理的结果来看,极化能谱法计算量相对较大并且对噪音的影响较敏感。  相似文献   

Cloning of the HSP70 gene in barnacle larvae and its expression under hypoxic conditions     

Cheng SH  So CH  Chan PK  Cheng CW  Wu RS 《Marine pollution bulletin》2003,46(5):665-671

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The formation mechanisms of turbidity maximum in the Pearl River estuary, China   总被引：7，自引：0，他引：7  

Wai OW  Wang CH  Li YS  Li XD 《Marine pollution bulletin》2004,48(5-6):441-448

The formation and dynamics of turbidity maxima (TM) in the Pearl River estuary (PRE) are not well understood but the existence of TM in the estuary have great potential engineering and environmental impacts. Based on the measurements of two large-scale field surveys conducted in the wet season of 1978 (July of 1978) and the dry season of 1979 (March of 1979), the existence and seasonal variations of TM in the PRE focusing on the two major natural navigation channels have been studied. The sediment transport fluxes over two consecutive tidal cycles have been analyzed in detail. The analysis results reveal that the formation mechanisms of TM in the estuary are rather complex. In general, gravitational circulation, tidal trapping, and sediment resuspension and deposition processes are the primary TM formation mechanisms in the PRE. The clockwise back flow pattern around Lingding Island also leads to the formation of TM in the West channel of the PRE. The occurrence of TM far upstream of the salt water wedge is the result of the complex hydrodynamic and sediment transport processes generated by the runoff of the major rivers.  相似文献