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排序方式: 共有4649条查询结果,搜索用时 31 毫秒
991.
OPTIMALQUADRATUREOFTHESOBOLEVCLASSW_1~r(R)DEFINEDONWHOLEREALAXIS(房艮孙,刘永平)¥FangGensun;LiuYongping(Dept.ofMath.,BeijingNormalUni... 相似文献
992.
Yoonweon Lee 《Transactions of the American Mathematical Society》2003,355(10):4093-4110
The gluing formula of the zeta-determinant of a Laplacian given by Burghelea, Friedlander and Kappeler contains an unknown constant. In this paper we compute this constant to complete the formula under an assumption that the product structure is given near the boundary. As applications of this result, we prove the adiabatic decomposition theorems of the zeta-determinant of a Laplacian with respect to the Dirichlet and Neumann boundary conditions and of the analytic torsion with respect to the absolute and relative boundary conditions.
993.
Sheng‐Huei Hsiao Yu‐Hui Chang 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1255-1271
A new fluorinated diamine monomer, 2′,5′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐p‐terphenyl, was synthesized from the chloro‐displacement of 2‐chloro‐5‐nitrobenzotrifluoride with the potassium phenolate of 2,5‐diphenylhydroquinone, followed by hydrazine palladium‐catalyzed reduction. A series of trifluoromethyl‐substituted polyimides containing flexible ether linkages and laterally attached side rods were synthesized from the diamine with various aromatic dianhydrides via a conventional two‐step process. The inherent viscosities of the poly(amic acid) precursors were 0.84–1.26 dL/g. All the polyimides afforded flexible and tough films. The use of 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride produced essentially colorless polyimide films. Most of the polyimides revealed an excellent solubility in many organic solvents. The glass‐transition temperatures of these polyimides were recorded between 254 and 299 °C by differential scanning calorimetry, and the softening temperatures of the polymer films stayed in the range of 253–300 °C according to thermomechanical analysis. The polyimides did not show significant decomposition before 500 °C in air or under nitrogen. These polyimides also showed low dielectric constants (2.83–3.34 at 1 MHz) and low moisture absorption (0.4–2.2%). For a comparative study, a series of analogous polyimides based on the nonfluorinated diamine 2′,5′‐bis(4‐aminophenoxy)‐p‐terphenyl were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1255–1271, 2004 相似文献
994.
We prove a general integration by parts formula for first‐order differential operators on submanifolds of arbitrary codimension of a given Riemannian manifold. The differential operators in question are assumed to satisfy a suitable tangentiality condition. Several particular cases, particularly relevant to applications to PDE arising in mathematical physics are discussed. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
995.
实二次代数整数环上的单位格的类数 总被引:2,自引:0,他引:2
用邻格方法及Siegelmass公式证明了实二次代数域Q(√d)上单位格种gen(In)n≥4)的类数h(In)=3当且仅当Q(√3):n=4;Q(√5);n=6;Q(√3);n=4;Q(√17):n=4. 相似文献
996.
P. J. Fitzsimmons 《Journal of Theoretical Probability》1989,2(4):487-501
We prove a Feynman-Kac formula in the context of symmetric Markov processes and Dirichlet spaces. This result is used to characterize the Dirichlet space of the time change of an arbitrary symmetric Markov process, completing work of Silverstein and Fukushima. 相似文献
997.
5l.TheMedianFormulaAseveryoneknows:in6ABC,letal=BC,a2=CA,a3=AB,;)11,)n2,n13aremedian1inesseparatelyonthethreeedgesBC,CA,AB,tI1entheequalityistrueasfollowsTheequality(l)iscalledmedianformulaofQABC,andwecanobtainfrom(l)Inthispaper,wesha1lextendtheequality(l)and(2)to,l-simplexin)l-EuclideanspaceH.Itisobtainedthemedianformulaof)I-simplex,andusingthisformula.wegetsomein-equalities.Themedianformulaofn-simp1exisobtainedasfollows:TheoremlFork=1,2,--',It 1andl相似文献
998.
分别从光线方程,程函方程,折射定射的矢量表示,哈密顿混合特征函数和球面折射矩阵出发导出近轴光线条件下球折射的物象公式。 相似文献
999.
1000.
We present an extrapolation type algorithm for the numerical solution of fractional order differential equations. It is based
on the new result that the sequence of approximate solutions of these equations, computed by means of a recently published
algorithm by Diethelm [6], possesses an asymptotic expansion with respect to the stepsize. From this we conclude that the
application of extrapolation is justified, and we obtain a very efficient differential equation solver with practically no
additional numerical costs. This is also illustrated by a number of numerical examples.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献