Results 251 to 260 of about 359,833 (281)

Remarks on rings of constants of derivations II

Communications in Algebra, 1992
Let k be a field of characteristic p>0 and D≠0 a family of k-derivations of k[x,y]. It is proved in [1] that k[x,y]D, the ring of constants with respect to D, can be generated, as a k[x p,y p]-algebra, by p - 1 elements. In this note we prove that p - 1 is the sharp upper bound of numbers of generators.
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Molecular Orbital Calculations of Vibrational Force Constants. II. The Ring-Twisting Constants of Benzene

The Journal of Chemical Physics, 1949
Two out-of-plane bending force constants of the C6 framework of benzene are calculated by the method of antisymmetric molecular orbitals, and the values obtained compared with those previously determined by Miller and Crawford from spectroscopic data.
Bryce L. Crawford, Robert G. Parr
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Substituent and ring size dependence of the coupling constant

Magnetic Resonance in Chemistry, 1987
AbstractThe magnitude of the 4J proton‐proton coupling constant across the fragment CH3CCH (a probe of the bond order between the central sp2‐sp2 hybridized carbon atoms) has been found to be essentially independent of substitution on a toluene fragment and on the size of the ring containing the ortho‐allylic fragment.
M. J. Collins, P. M. Hatton, S. Sternhell, C. W. Tansey   +3 more
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Ring Signatures of Constant Size Without Random Oracles

2015
Ring signatures allow a signer to anonymously sign on behalf of a group of users, the so-called ring; the only condition is that the signer is a member of the ring. At PKC 2007, Shacham and Waters left an open problem, “obtain a ring signature secure without random oracles and its signature size is independent of the number of signers implicated in the
Fei Tang, Hongda Li
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Hammett constants of the pyrroline-2, 5-dione ring

Chemistry of Heterocyclic Compounds, 1976
The electronic effect of the pyrroline-2,5-dione ring on the benzene ring in the case of N-aryl compounds is close to the effect exerted by halogens. The overall electron-acceptor effect depends markedly on the nature of the solvent. The electron-donor effect of conjugation is small.
V. D. Romanenko, N. N. Kalibabchuk, A. A. Rositskii, V. G. Zalesskaya, V. E. Didkovskii, S. V. Iksanova   +5 more
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Slab Analysis of Ring Rolling Assuming Constant Shear Friction

Journal of Materials Engineering and Performance, 2011
In this article, an analytic solution for ring rolling process based on the slab method theory is presented, in which the non-uniformity of the normal and shear stresses across the section of the deforming material throughout the plastic region is considered.
A. Parvizi, K. Abrinia, M. Salimi
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Suspended Ring Resonator for Dielectric Constant Measurement of Foams

IEEE Microwave and Wireless Components Letters, 2006
The present study introduces a microstrip-based resonant device that is specifically intended for measurements of polymer foam permittivity at frequencies of 1 to 10 GHz. The device utilizes the standard microstrip ring resonator. However, the ring and the ground plane/feed network are physically located in separate planes, enabling the placement of an
I. Waldron, S.N. Makarov, S. Biederman, R. Ludwig   +3 more
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Measurement of dielectric constant using a microstrip ring resonator

IEEE Transactions on Microwave Theory and Techniques, 1991
An approach for measuring the permittivity of dielectric materials by means of a microstrip ring resonator is presented. The method is used in conjunction with the variational calculation of the line capacitance of a multilayer microstriplike transmission line to compute the effective permittivity and hence the resonant frequency of the ring.
P.A. Bernard, J.M. Gautray
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Locally nilpotent derivations and their rings of constants.

2009
Given a UFD R containing Q , we study R-elementary derivations of B = R[Y1,..., Ym], i.e., R-derivations satisfying D( Yi) ∈ R for all i; in the particular case of m = 3, we will show that if R is a polynomial ring in n variables over a field k (of characteristic zero), and a1, a3, a3 ∈ R are three monomials, then the kernel of the derivation i=13ai6 ...
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Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes

Chemical Reviews, 2021
Vincent Pirenne, Bastian Muriel, Jerome Waser   +2 more
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