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21.
西安城墙东门箭楼砖坯墙体风化因素研究报告 总被引:2,自引:2,他引:0
论述了西安城墙东门箭楼的文化背景,实地考察了风化外状,并对风化外状进行了分类测试。通过对砖坯墙体材料进行化学全分析、X-射线衍射分析、吸水率测定(含他和系数)、冻融实验、泛霜实验、环境污染与水文气象监测资料的分析,研究了东门箭楼砖坯墙体不同风化外状的风化因素,同时对现代修缮用砖的理化性能及质量进行了评估。结果表明,温度的交替变化、水的冻结与融化使得砖坯裂解成碎块;干湿引起可溶盐的结晶与潮解以及自然界中的雨水、地面水或地下水、污染气体等通过溶解、水化、水解、碳酸化、氧化等方式,使得砖坯墙体表面酥碱粉化。同时说明研究适用于古建筑修缮使用的抗风化仿古青砖是当务之急。 相似文献
22.
浑仪、简仪(以下简称两仪)在高PH、大气污染和日晒雨淋环境中的腐蚀是一种动态加速腐蚀过程。采用合成的双唑胺铜缓蚀剂和有机硅改性的甲基丙烯酸树脂,并分别复配成协同缓蚀剂群和含有增效稳定剂的封护剂。采用这两种材料和脱水后再防护的工艺,使带锈防护后的浑仪、简仪的腐蚀低于无污染大气中的速率。用电化学方法评价了防护技术的可行性,根据腐蚀与人工老化试验结果讨论了防护材料性能与腐蚀环境和带锈防护的关系,采用XPS分析方法探索了双唑胺比BTA更适用于两仪防护的原因。 相似文献
23.
Stephen J. Shennan 《Journal of World Prehistory》1993,7(2):121-161
The chronology of the period is briefly considered in the light of the dendrochronological results which have appeared in recent years. Patterns of settlement history in different parts of the area are then examined, and it is suggested that in some of them the late fourth millennium was a period of population decline which was not reversed until the Early Bronze Age, 1000 years later. Detailed information about specific local occupation patterns is provided by recent work on the circum-Alpine lake villages. Changes in cultural patterns during the period, especially the appearance of the Corded Ware, are discussed and explanations of them reviewed. It is argued that changing patterns of gender relations were a major feature of the period, linked to processes which eventually led to the development of small-scale chiefdoms. The development of copper and bronze metallurgy and its connection to these processes are discussed. 相似文献
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M. L. Ryder 《Journal of archaeological science》1983,10(6):541-545
Wool fibre measurements defining fleece type are described from the cloth in the Bocksten costume dated about 1350 and kept in the Varbergs Museum, Sweden. Over 80% belonged to hairy types, the remainder coming from the modern true medium or primitive generalised medium types. Three quarters of the wools had natural pigment giving a grey colour.The findings accord with the fleece of the native Swedish Landrace sheep, but fibre diameter measurements were closer to those of the 17th century Wasa textiles, than to fleece measurements of the surviving Goth remnant of the Swedish Landrace. 相似文献
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Jen Jack Gieseking 《The Canadian geographer》2018,62(1):55-66
In the last decade, conversations around queering of GIScience emerged. Drawing on literature from feminist and queer critical GIS, with special attention to the under‐examined political economy of GIS, I suggest that the critical project of queering all of GIS, both GIScience and GISystems, requires not just recognition of the labour and lives of queers and research in geographies of sexualities. Based upon a queer feminist political economic critique and evidenced in my teaching critical GIS at two elite liberal arts colleges, I argue that the “status quo” between ESRI and geography as a field must be interrupted. Extending a critical GIS focus beyond data structures and data ethics, I argue that geographic researchers and instructors have a responsibility in queering our choice and production of software, algorithms, and code alike. I call this production and choice of democratic, accessible, and useful software by, for, and about the needs of its users, good enough software. 相似文献
28.
Determination of the Fineness of Medieval Coins—Evaluation of Methods in a Case Study of a Medieval Pfennig
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The original fineness of coins is very important information that can help us to understand the commercial situation in a wide historical context. This paper deals with a comparison of analytical methods suitable for the evaluation of the actual and original fineness of coins based on a detailed case study of a medieval coin sample. Both non‐destructive (i.e., scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, X‐ray fluorescence, atomic force microscopy and hydrostatic weighing) and destructive (i.e., inductively coupled plasma – mass spectrometry and the Volhard titration method) techniques were used. The original fineness can be also deduced from knowledge of the internal structure of the coin (limited miscibility of copper and silver). A new analytical method based on a combination of a micrograph of the metallographic cross‐section with consequent image analysis was developed for determination of the original fineness. The proposed approach is relatively simple and provides reliable values. Sample heterogeneity and its impact on the determination of fineness are also discussed. 相似文献
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30.
Kate Stevens 《The Journal of Pacific history》2018,53(4):478-501
ABSTRACTEarly colonial officials and other newcomers frequently lamented the poor copra production in Wallis and Futuna, positioning the continued consumption of coconuts by Islanders as a waste. This article explores the contested uses of coconuts and the divergent visions of the islands’ landscape and future held by Islanders, officials, missionaries and traders during opening decades of French colony rule. In particular, a variety of incidents in the 1920s – from an indigenous co-operative to French expulsions – highlight the centrality of the emergent copra trade to the social and political status of these different groups. More broadly, however, the article demonstrates the failure of elites – both indigenous and newcomer – to substantially increase copra exports prior to the Depression in 1930, indicative of the limits of their ability to demand labour and transform the lifeways of the wider population. 相似文献