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C12 H4 ,C18H6,C2 4 H8大环多炔化合物是以乙炔为基本单元 ,以乙烯为连接元构成 .利用量子化学PM 3方法进行分子构型的优化和频率分析 ,判断分子的稳定性 相似文献
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LIUChen MAXiu-jun XIEKun-qing LIUYu FENGXue-bing 《重庆邮电学院学报(自然科学版)》2004,16(5):161-164
Digital Orthographic Map (DOM) can be used in various applications because it contains both image features and terrain information. Spatial database management systems aim at the effective and efficient management of data related to a space, engineering design and so on. Thereby spatial database provides an efficient solution for managing DOM. According to large amounts of the DOM data in storage, a data compression based on wavelet is introduced into the storage. Another stratcgy to solve this problem is to decompose the raw image into tiles and store the tiles individually as separate tuples. The metadata of DOM can be used to organize and manage spatial information, especially for spatial data sharing and fast locating. A tool for browsing, zooming and querying the DOM data is also designed. We implemented these ideas in SISP (Spatial Information Sharing System) and applied the subsystem into the DOM management of Beiiing City, which is an component of the Beijing Spatial Information Infrastructure. 相似文献
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