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存在于数学知识中的“特殊”情形,例如数学知识中一些特殊的存在形式、特殊的表达方式,某些定理或性质存在的一些特殊条件以及解决问题过程中的一些特殊方法等等,在学生的数学学习中都起到了重要的教育作用,不少“特殊”甚至还是理解数学知识,乃至最终解决问题的关键所在.1. 数学认识过程的切入点我们可以看到,在数学学习中,一个概念的产生、某一规律的形成,经常是从一些特殊的情形开始,通过分析、归纳、猜想与演绎等各种方法得到完成的,这是数学重要的思想方法———归纳推理,著名数学家高斯就曾说过,他的许多结论都是依赖归纳法而发现… 相似文献
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催化裂化轻汽油及醚化产品的气相色谱分析 总被引:1,自引:0,他引:1
1引言催化裂化轻汽油醚化工艺将催化裂化汽油中的叔碳烯烃转化为甲基叔烷基醚,不但可以提高辛烷值,增加含氧量,还可以降低蒸汽压和烯烃含量,因而是生产环境友好汽油的理想工艺。在催化裂化轻汽油醚化工艺的研究过程中,原料与产品需要快速准确的分析手段。本文采用气相色谱/质谱法(GC/MS)结合标准样对照法进行定性,根据采用自制的标准样测定的甲醇和醚类的相对重量校正因子进行定量分析,取得了满意的结果,为试验研究和工业生产提供了一种快速准确的分析方法。2实验部分2.1仪器与试剂MAT90型GC/MS联用仪(德国菲尼根公司)… 相似文献
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One binuclear sodium(Ⅰ) complex [Na2(2-benzoylbenzoato)4(Phen)2(H2O)2]·H2O has been synthesized with 2-benzoylbenzoic acid and 1,10-henanthroline as ligands. The crystal structure was determined by X-ray diffraction. The crystal belongs to the triclinic system with space group P , a = 1.08096(8), b = 1.09619(8), c = 1.09740(8) nm, α = 79.0600(1), β = 71.0450(1), γ = 62.0540(1)o, V = 1.08533(1) nm3, Dc = 1.421 g/cm3, Z = 2, F(000) = 484, GOOF = 1.036, the final R = 0.0363 and wR = 0.0961. The crystal structure shows that two neighboring sodium(Ⅰ) ions are linked together by two bridging water molecules, and each end position is coordinated with one 1,10-phenanthroline molecule and one 2-benzoylbenzoato to form a binuclear structure. Each sodium(Ⅰ) ion in the molecule is coordinated with five atoms to give a distorted trigonal bipyramid. The fluorescence property of the title complex is also discussed. 相似文献
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<正> 设X_1,X_2是Banach空间.对A∈B(X_1),B∈B(X_2),定义广义导算子:δ_(AB)|T→AT-TB,T∈B(X_2,X_1). 当X_1=X_2=X时,设A=B,则称δ_(AA)(≡δ_A)为内导算子,简称导算子. 本文分两部分.前一部分讨论几个有关导算子值域的未解决问题;后一部分讨论刻 相似文献
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The main purpose of this paper is to study the lower order and type of second order differential equation w"(z)-A(z)w=0,where A(z)is a polynomial.In the case of A(z)=a_dz~d,the authors prove that the lower order and the type of all non-trivial solutions w of w"(z)-A(z)w=0 are equal to(d+2)/2 and(2(|a_d|)~(1/2))/(d+2)respectively.In the case of A(z)=a_dz~d+a_(d-1)z~(d-1)+…a_1z+a_0,a_d0,a_(d-1)0,…,a_1≥0,a_0≥0,the authors prove that the lower order of all non-trivial solutions w of w"(z)-A(z)w=0 is(d+2)/2. 相似文献
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THE UNCONDITIONAL STABILITY FOR THE HYPERNEUTRAL TYPE CONSTANT LINEAR CONTROL SYSTEM WITH DELAYS 总被引:3,自引:0,他引:3
With great developments of 8cience and technology exten8ion of system scale and variousapplication of computer, control 8ystem become expansive and sophisticated in the structureproperty About the stable questions of the delny type and the delay neutral type continuouscontrol sy8tem, many good result8 bave been establi8hed by many authors, but we seldom 8eethe studying of the unconditional stability problem for the hyperneutral type. In this paper,applying to the frequency domain method and th… 相似文献
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