排序方式: 共有78条查询结果,搜索用时 15 毫秒
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Marion Bowman 《Folklore》2013,124(1-2):164-167
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Characterization of a Historical Cannonball from the Fortress of San Juan De Ulúa Exposed to a Marine Environment 下载免费PDF全文
M. Hernandez M. Hernandez‐Escampa C. Abreu J. Uruchurtu M. Bethencourt A. Covelo 《Archaeometry》2016,58(4):610-623
Metallurgical analyses and chemical characterizations were carried out on historical cannonballs from the Fortress of San Juan de Ulúa, Veracruz, México. Cannonballs dating from the 18th and 19th centuries share metallurgical characteristics similar to those of material coming from a shipment of ammunition found in the wreck of a sunken French ship from the battle of Trafalgar. The analyses show that the base material is grey cast iron with a carbon equivalent of 4.94 and a ferritic–perlitic matrix, in which the high phosphorus content has led to the formation of iron phosphide compounds in conjunction with a homogeneous distribution of carbon graphite flakes of Type C. In addition, corrosion products from samples revealed the presence of various crystalline iron compounds (X‐ray diffraction), mostly highly chlorinated iron compounds identified as akaganeite. X‐ray fluorescence identified various characteristics of the corrosion products as a function of the sampling depth. FT–IR spectroscopy revealed that the main difference between the corrosion products (internal and external) is determined by the number of organic species. Differential scanning calorimetry corroborated that these corrosion products are thermally stable compounds at elevated temperatures. 相似文献
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Ruisinger MM 《Journal of the history of the neurosciences》2002,11(3):286-300
In the 18th century, medical practice was essentially based on communication. Cranial trepanation, however, was usually performed on an unconscious person. Here the dialogue ceased. It was the only operation which had to be attempted without the positive consent of the patient. Thus trepanation challenged the surgeon's skill not only with its intricate surgical practice, but also with its unusual social setting. The present paper illustrates possible ways out of the "trap of trepanation" by interweaving two points of view. On the one hand, a general account is given on the basis of surgical publications written by Lorenz Heister and his contemporaries. On the other, the unpublished sources of the Heister correspondence serve to reconstruct the case of Heinrich Wilhelm Bachmann, a German merchant who fell victim to a traffic accident and underwent trepanation in 1753. The case study shows how the physician in charge counterbalanced the patient's inability to communicate by strengthening the remaining network of professionals, and ultimately confirming his decisions by use of the post-mortem. 相似文献
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Image‐Based Modelling from Unmanned Aerial Vehicle (UAV) Photogrammetry: An Effective,Low‐Cost Tool for Archaeological Applications 下载免费PDF全文
J. Fernández‐Hernandez D. González‐Aguilera P. Rodríguez‐Gonzálvez J. Mancera‐Taboada 《Archaeometry》2015,57(1):128-145
The recording and 3D modelling of complex archaeological sites is usually associated with high capital and logistical costs, because the data acquisition must be performed by specialists using expensive surveying sensors (i.e., terrestrial laser scanners, robotic total stations and/or ground‐penetrating radar). This paper presents a novel, low‐cost, user‐friendly photogrammetric tool for generating high‐resolution and scaled 3D models of complex sites. The results obtained with unmanned aerial vehicle (UAV) photogrammetry of an archaeological site indicate that this approach is semi‐automatic, inexpensive and effective, and that it guarantees quality. 相似文献
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Over the last decade, the global value chain (GVC) approach, with its associated notions of chain governance and firm upgrading, has proliferated as a mode of analysis and of intervention amongst development institutions. This article examines the adoption and adaptation of GVCs at four multilateral agencies in order to understand the purchase of value chain approaches within the development field. Mixing GVC perspectives with other theoretical influences and applied practices, these institutions deploy value chain frameworks to signal a new generation of policies that promise both to consolidate, and to advance beyond, the market fundamentalism of the Washington Consensus. To achieve this, value chain development frameworks craft interventions directed toward various constellations of firm and non‐firm actors as a ‘third way’ between state‐minimalist and state‐coordinated approaches. The authors identify key adaptations of the GVC framework including an emphasis on value chain governance as an instrument to correct market failure in partnership with state and development agencies, and upgrading as a de facto tool for poverty reduction. They find that efforts are ongoing to construct a ‘post’ to the Washington Consensus and that the global value chain is enabling this process by providing a new language and new object of development intervention: ‘the chain’ and the local–global linkages that comprise it. 相似文献
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Mike Mccarthy Marion Archibald Colleen Batey Catherine Batt Catherine Brooks Jo Buckberry 《考古杂志》2014,171(1):185-257
Excavations in 1988 revealed a stratigraphic sequence extending from the later Roman period to the twelfth century. Of particular interest and importance is a collection of Viking-Age metalwork which, with other material, sheds light on settlement in Carlisle before the arrival of the Normans in 1092. 相似文献