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本文阐述了数据库设计的一般理论。结合工程建设有关法规、程序及合同示范文本等,提出工程项目投标决策支持系统的数据库主要数据库组成:(1)政策法规、技术标准数据库;(2)工程项目信息数据库;(3)工程造价信息数据库;(4)投标人信息数据库;(5)评委专家数据库;(6)内部业务管理数据库。 相似文献
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在面向对象的方法和人工智能数据库这两种技术的基础上 ,分析了现代数据库的特点 .总结了面向对象的分析方法在数据库管理系统应用中的优点 .说明OODBMS是数据库智能化的一种很好的方法 .用OODBMS方法使数据库智能化是数据库发展的一个重要方向 .并用图形数据库实例说明了面向对象的方法在智能数据库中的具体应用 相似文献
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刘赪娜 《科技情报开发与经济》2011,21(20):105-106
科技的进步使数据库产业迅猛发展,各国现有立法对数据库保护极为苛刻,由于数据库自身的技术特点,导致数据库极易受到复制侵害,因此对数据库的立法保护极为必要和迫切。我国对具有独创性的数据库以著作权模式保护,对大量不具有独创性的数据库则辅以合同法、侵权法、反不正当竞争法保护,这样的保护力度不利于数据库产业的发展。德国数据库的邻接权保护是对非独创性数据库保护立法的一个有益尝试,我国应借鉴德国做法,对我国数据库保护立法加以修改和完善。 相似文献
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探讨了药学专业数据库《中外药品质量标准数据库》的建设意义、数据库内容与结构、数据库元数据分析、数据库平台选择等相关问题。 相似文献
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通过下载国际一级序列数据库GenBank的序列数据,开发研制了真核生物基因内含子数据库EID,该数据库由一个主数据库和多个子数据库组成,子数据库包括细胞核内含子数据库、细胞器内含子数据库,以及植物、无脊椎动物、灵长类、啮齿类、其他哺乳类和其他脊椎动物等不同类型生物内含子数据库.文中详细介绍了数据的获取和筛选方法,主数据库中dEID,pEID,hEID的文件格式和结构,EID数据库构建程序,以及EID的查询方式,提供的分析工具等.EID将建设成为研究内含子功能和进化起源的生物信息学平台. 相似文献
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生物入侵已经成为破环生态系统,导致生物多样性丧失的首要原因.为有效控制和预防生物入侵,构建入侵生物数据库十分必要.为建立完整、安全、实用的云南生物入侵网络数据库,本文结合云南省外来生物的基本情况,分析了数据库建立的软件环境,提出了用SQL结构化查询语言来构建云南省入侵生物数据库,该数据库包括基本信息数据库、网络管理数据库、辅助数据库3个库.其中基本信息数据库是数据库的主体部分,可为用户提供云南外来入侵生物的详细信息. 相似文献
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王睿 《辽宁师专学报(自然科学版)》2005,7(4):38-40
文档数据库的兴起是由于组织管理和搜索完整文档的需求.传统的关系数据库在Internet应用方面和处理多媒体信息方面有许多限制和不足,文档数据库因此应运而生.概要地讨论了文档数据库的基本概念,阐述了文档数据库在Internet数据库构建方面具有的优势,从数据格式、数据库结构和Interne数据库方案三个方面比较了文档数据库与关系数据库的异同. 相似文献
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郝振荣 《中国新技术新产品精选》2009,(17):26-27
本文介绍了信息管理数据库的开发与设计的方法,提出了系统的数据库开发流程图,从用户的需求出发,经过数据库概念结构设计,数据库的逻辑结构设计,最后到系统数据库结构的实现,从而完成了数据库的设计。 相似文献
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充分利用索引作用提高Oracle数据库的性能 总被引:1,自引:0,他引:1
李国伟 《科技情报开发与经济》2010,20(18):118-120
在Oracle数据库的运行中,数据库设计的好坏直接影响到了数据库的性能,索引是数据库设计的重要部分,合理、优化的索引能够提高Oracle数据库系统的运行效率。本文讨论了索引在Oracle数据库系统中的作用及其实现过程。 相似文献
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Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
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Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
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Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well. 相似文献
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The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation. 相似文献
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理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
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As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
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Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
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Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
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Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
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《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献