排序方式: 共有42条查询结果,搜索用时 15 毫秒
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HUANG Qing-Ming 《结构化学》2007,26(8):902-906
Fluorescence material of Sm doped Si-Ca-Mg system was synthesized by using the method of solid phase reaction at high temperature. The phase composition and crystal structure of this material were analyzed with XRD method for its composition and the existence form of Sm atom. We aimed to exactly determine the phase composition of this fluorescence material and the doping position and environment of rare-earth Sm atom in the system because these factors have significant effects on the properties. The analytical results show that the Sm atoms dope in Ca2O26Si6Sm8 lattice in the form of atomic site-occupation in three different space positions with different occupancy rates. Therefore, based on the XRD analytical results, the fluorescence material of Sm doped Si-Ca-Mg system with high performance can be synthesized. 相似文献
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A.Al-Shuaibi F.Al-Rawjih 《分析论及其应用》2004,20(1):28-34
Given the Laplace transform F(s) of a function f(t), we develop a new algorithm to find an approximation to f(t) by the use of the classical Jacobi polynomials. The main contribution of our work is the development of a new and very effective method to determine the coefficients in the finite series expansion that approximation f(t) in terms of Jacobi polynomials. Some numerical examples are illustrated. 相似文献
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计量是保证产品质量提高的技术基础,是企业提高经济效益的有效手段.本文从建立和完善计量管理体系、加强产品计量保证和计量基础管理、更新计量管理观念等方面,阐述了计量对企业科研、生产、经营的监督、保障作用. 相似文献
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Equations describing gradient elution in TLC, with a mobile phase of a constant composition in each step, have been derived. These equations are useful for calculating retention volumes from isocratic TLC data. Equations originally derived for gradient HPLC were adapted for TLC. The validity of the equations has been experimentally verified. The satisfactory agreement between experiment and theory for binary mobile phase composed of methyl ethyl ketone and n-heptane suggests that TLC can be used as a pilot technique for gradient HPLC. 相似文献
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微波消解优化-原子荧光光谱法测定了山茶油中痕量砷;在多组实验研究的基础上,研究了不同消解酸配比条件下,微波消解方法对测定结果的影响.试验结果表明:微波消解0.3g茶叶对照品和0.3g山茶油样品过程中,消解酸为6mL硝酸+4mL过氧化氢的平行性和回收率最好.山茶油样品回收率为92%-102%;RSD为5.06% 。该法适用于山茶油中痕量砷的测定。 相似文献
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大学微积分的教学内容是在实数集合上展开的.存在性问题贯穿微积分教学的始终.从深入讨论实数的基本性质开始,引入了求解存在性问题的一般思路.希望从微积分教学的一开始,就让学生深刻体会到数学思想方法的无穷魅力. 相似文献
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