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991.
992.
V. A. Dorokhov A. R. Amamchyan V. S. Bogdanov B. I. Ugrak 《Russian Chemical Bulletin》1991,40(1):222-224
A method is proposed for the synthesis of N-substituted 5-azaadenines. The condensation of N-(1,2,4-triazol-5-yl)amidines with trichloroacetonitrile gives trichloromethyl derivatives of 1,2,4-triazolo[1,5-a]-1,3,5-triazines, which are converted by the action of primary or secondary amines into N-alkylamino- or N,N-dialkylamino-1,2,4-triazolo-[1,5-a]-1,3,5-triazines (5-azaadenines).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 241–243, January, 1991. 相似文献
993.
The existence of a Nash equilibrium in the undiscounted repeated two-person game of incomplete information on one side is
established. The proof depends on a new topological result resembling in some respect the Borsuk-Ulam theorem. 相似文献
994.
A conjecture of Toft [17] asserts that any 4-critical graph (or equivalently, every 4-chromatic graph) contains a fully odd subdivision ofK
4. We show that if a graphG has a degree three nodev such thatG-v is 3-colourable, then eitherG is 3-colourable or it contains a fully oddK
4. This resolves Toft's conjecture in the special case where a 4-critical graph has a degree three node, which is in turn used to prove the conjecture for line-graphs. The proof is constructive and yields a polynomial algorithm which given a 3-degenerate graph either finds a 3-colouring or exhibits a subgraph that is a fully odd subdivision ofK
4. (A graph is 3-degenerate if every subgraph has some node of degree at most three.) 相似文献
995.
A time-dependent model corresponding to an Oldroyd-B viscoelastic fluid is considered, the convective terms being disregarded.
Global existence in time is proved in Banach spaces provided the data are small enough, using the implicit function theorem
and a maximum regularity property for a three fields Stokes problem. A finite element discretization in space is then proposed.
Existence of the numerical solution is proved for small data, so as a priori error estimates, using again an implicit function
theorem.
Supported by the Swiss National Science Foundation. Fellowship PBEL2–114311. 相似文献
996.
Anna Avallone 《Mathematica Slovaca》2007,57(2):129-140
We prove the existence of separating points for every countable family of nonatomic σ-additive modular measures on a σ-complete lattice ordered effect algebra.
相似文献
997.
Athanassios G. Bratsos 《Numerical Algorithms》2007,46(1):45-58
A predictor–corrector (P-C) scheme is applied successfully to a nonlinear method arising from the use of rational approximants
to the matrix-exponential term in a three-time level recurrence relation. The resulting nonlinear finite-difference scheme,
which is analyzed for local truncation error and stability, is solved using a P-C scheme, in which the predictor and the corrector
are explicit schemes of order 2. This scheme is accelerated by using a modification (MPC) in which the already evaluated values
are used for the corrector. The behaviour of the P-C/MPC schemes is tested numerically on the Boussinesq equation already
known from the bibliography free of boundary conditions. The numerical results are derived for both the bad and the good Boussinesq
equation and conclusions from the relevant known results are derived.
相似文献
998.
Guang-hua DONG~ Yan-pei LIU Department of Mathematics School of Science Beijing Jiaotong University Beijing China 《中国科学A辑(英文版)》2007,50(11):1563-1570
In this paper,we provide a new class of up-embeddable graphs,and obtain a tight lower bound on the maximum genus of a class of 2-connected pseudographs of diameter 2 and of a class of diameter 4 multi-graphs.This extends a result of Skoviera. 相似文献
999.
Yakov Varshavsky 《Geometric And Functional Analysis》2007,17(1):271-319
The goal of this paper is to generalize a theorem of Fujiwara (Deligne’s conjecture) to the situation appearing in a joint
work [KV] with David Kazhdan on the global Langlands correspondence over function fields. Moreover, our proof is more elementary
than the original one and stays in the realm of ordinary algebraic geometry, that is, does not use rigid geometry. We also
give a proof of the Lefschetz–Verdier trace formula and of the additivity of filtered trace maps, thus making the paper essentially
self-contained.
The work was supported by the Israel Science Foundation (Grant No. 555/04)
Received: May 2005 Accepted: August 2005 相似文献
1000.
Ji-hong SU & Yi-cai ZHAO LMAM Department of Mathematics Jinan University Guangzhou China 《中国科学A辑(英文版)》2007,50(4):495-502
Let X be a smooth projective variety of dimension 2k-1 (k≥3) over the complex number field. Assume that fR: X→Y is a small contraction such that every irreducible component Ei of the exceptional locus of fR is a smooth subvariety of dimension k. It is shown that each Ei is isomorphic to the k-dimensional projective space Pk, the k-dimensional hyperquadric surface Qk in Pk 1, or a linear Pk-1-bundle over a smooth curve. 相似文献