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示波极谱法测定地质样品中痕量碘的样品分解方法比较 总被引:2,自引:1,他引:2
分别用半熔法、热解法、碱熔法,酸蒸馏法分解地质样品,极谱法测定痕量碘。比较了4种分解方法的效果。指出了半熔法为最佳。 相似文献
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叠氮化氢二聚体的分子间相互作用 总被引:1,自引:0,他引:1
通过ab initioHF/6-31G*计算求得叠氮化氢二聚体(HN3)2势能面上四种优化结构型,经MP4SDTQ电子相关校正和基组叠加误差2校正求得这些构型下的分子间相互作用能。结果表明,在四种优化构型中N3H...NHN2最稳定,其分子间相互作用能为-16.07KJ.mol^-1。 相似文献
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This paper proposes an efficient ADER(Arbitrary DERivatives in space and time)discontinuous Galerkin(DG)scheme to directly solve the Hamilton-Jacobi equation.Unlike multi-stage Runge-Kutta methods used in the Runge-Kutta DG(RKDG)schemes,the ADER scheme is one-stage in time discretization,which is desirable in many applications.The ADER scheme used here relies on a local continuous spacetime Galerkin predictor instead of the usual Cauchy-Kovalewski procedure to achieve high order accuracy both in space and time.In such predictor step,a local Cauchy problem in each cell is solved based on a weak formulation of the original equations in spacetime.The resulting spacetime representation of the numerical solution provides the temporal accuracy that matches the spatial accuracy of the underlying DG solution.The scheme is formulated in the modal space and the volume integral and the numerical fluxes at the cell interfaces can be explicitly written.The explicit formulae of the scheme at third order is provided on two-dimensional structured meshes.The computational complexity of the ADER-DG scheme is compared to that of the RKDG scheme.Numerical experiments are also provided to demonstrate the accuracy and efficiency of our scheme. 相似文献
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史永东 《数学的实践与认识》2002,32(4):605-612
本文研究了半导体流的表面张力进行区域提纯问题中提出的两点边值问题解的存在性 ,我们用上、下解方法和 Schauder不动点定理证明了如果 Q=2 A3 Re,其中 A是表面速率 ,Re是 Reynolds数 ,则当 0 Q 1 3.2 1时 ,该问题有解 ,对最近的结果 ( 0 Q 1 2 .6 8时 ,此问题的解存在 )进行了重要的改进 相似文献