Environmentally-induced stone decay: the cumulative effects of crystallization–hydration cycles on a Lincolnshire oopelsparite limestone     

Belinda J. Colston  David S. Watt  Helen L. Munro   《Journal of Cultural Heritage》2001,2(4)

An investigation has been undertaken at St Andrew’s church, Walpole St Andrew, Norfolk, to establish the underlying causes of the observed stone decay to the upper parts of the six stone piers. The stone decay was first recorded in the early 1930s. The salt-contaminated masonry within the church has been shown to undergo severe salt decay during the summer, with little damage occurring over the winter months. The south aisle piers have been shown to decay 2.5 times faster than the north aisle piers. Although crystallization–hydration cycles have been identified, the rate of decay is at its greatest when the cycling is relatively infrequent. This was not the expected trend. Furthermore, it has been shown that during extended periods where the ambient relative humidity is less than 75%, the rate of decay reaches a maximum. It is the length of this ‘drying’ period that apparently has the greatest influence on the rate of decay and could explain the significant difference in the rate of decay between the south and north aisle piers. The results have serious implications for passive conservation, where it is often recommended to lower the ambient relative humidity to well below the equilibrium relative humidity of the salt contaminant, to avoid crystallization–hydration cycles. Since, at the time of building, the church was situated on the coast, it is possible that the sodium chloride contamination occurred during the building process (1440–1520), particularly since the area was prone to sea-flooding at this time. Alternatively, the salt could have been applied as a treatment during the general restoration of 1897. Whatever the source of the salt, it seems likely that the ambient environment was changed by the insertion of a sealed floor in 1897, which could account for the onset of the salt decay.  相似文献   

体育教师继续教育问题刍议   总被引：8，自引：0，他引：8  

谢翔 《体育科技》2001,22(2):1-4

阐明体育教师继续教育的必要性,分析研究了体育教师继续教育中存在的若干问题,从转变观念、建立制度、探索有效的培训模式和构建适宜的课程体系等方面,提出了改进体育教师继续教育的途径和方法.  相似文献   

Response to Kronick     

L Heshusius 《Journal of learning disabilities》1990,23(8):458-459

  相似文献   

一种有限非交换环的构造方法     

谢保利  侯维民 《天水师范学院学报》2006,26(5):26-27

先分别对高斯整环Z(i)=｛a bi｜a,b∈Z｝的元素a bi的实、虚部a,b按模n同余分类得到Zn(i)=｛[a] [b]i｜a,b∈Z｝,再利用两个的直积构造了一类有限非交换环。  相似文献   

Cycles, a crystal ball, and the telecommunications- act of 1996—Been there, done that     

Robert E. Dugan  Jennifer L. Souza  Timothy V. Cash 《The Journal of Academic Librarianship》1996,22(6):457-461

  相似文献   

联机公共检索目录系统的发展   总被引：2，自引：0，他引：2  

谢新洲 《中国图书馆学报》1992,18(2)

Since the development of the Online Public Access Catalogues in the 1970s, libraries in Europe and America have devoted more and more attention to it. To date, it has already developed to the third generation. The OPAC System makes those users who lack training and experience be able to use it directly. It provides the users a kind of capability to access, which is neither like the order language with a very complex function, nor is it like the "menu" one with a very simple function. The interface design of it is an important phase of OPAC device,the study of which falls into the following categories;1)the matching aid.2)the retrieval aid.and 3)the semantic/contextual aid.The successful practice of the development and services of OPAC opens up a wide range of prospect for readers to use library materials directly.  相似文献   

The Buffalo Medical Journal: 1845-1919     

L Sentz 《Bulletin of the Medical Library Association》1985,73(3):278-282

Fielding H. Garrison's paper "The medical periodical and the scientific society" cited the Buffalo Medical Journal in the company of eminent periodicals published in Berlin, Boston, and Edinburgh. This article provides an overview of the Journal and places it in context of 19th-century medical journalism. The Journal is assessed in terms of original scientific contributions and as a source of social and local history.  相似文献   

The statistician's role in society: The institutional establishment of statistics in France     

Lécuyer BP 《Minerva》1987,25(1-2):35-55

  相似文献   

科技文献信息抽取方法浅析SSCI     

敖龙  谢海先 《高校图书馆工作》2022,42(2):24-27

文章在Web of Science等影响力较大的国际数据库中检索内容与“科技文献”和“信息抽取”相关的文献,经设定条件筛选后获得63篇相关文献。回顾相关文献,从抽取的信息与抽取的方法两个角度进行分类与分析,总结该领域已有的研究成果和存在的不足。从科技文献中抽取的信息主要为结构化信息、显式信息和隐式信息,最新最先进的抽取方法主要集中在机器学习、自然语言处理和统计学中。语义信息的抽取有一定的进步空间及挑战性,灵活结合机器学习和自然语言处理方法是处理此领域问题的未来趋势。  相似文献   

中国共产党互联网思想的形成与发展     

谢建东  郑保卫 《传媒观察》2022,(1)

在我国互联网从无到有、快速发展,向世界网络强国迈进的过程中,几代中国共产党主要领导人根据所处时代背景和现实需要,提出一系列有关论述,推动我国互联网快速健康发展,逐渐形成一套立足中国实际的网信事业发展规范和原则,构建起中国共产党互联网思想的知识与理论体系。中国共产党互联网思想在改革开放初期科学技术快速发展浪潮中萌芽,在推进跨世纪发展战略实践中逐渐形成与发展,在科学发展观理念指导下与时俱进地加以调整和巩固,在新时代建设网络强国战略指引下不断创新突破。  相似文献