Results 311 to 320 of about 383,519 (362)

Numerical estimates for a Grötzsch ring constant

Constructive Approximation, 1988
The paper studies the behavior of the modulus \(M_ n(a)\) of the Grötzsch extremal ring \(R_{G,n}(a)\subset {\mathfrak R}^ n\) as a tends to 0. In the first two parts lower and upper estimates are obtained for \[ \lim_{a\to 0}(M_ n(a)+\log a). \] The lower estimates are given in terms of n; the upper estimates are obtained numerically for \(3\leq n\leq
G. D. Anderson, J. S. Frame
openaire   +2 more sources

The relationship between proton–proton NMR coupling constants and substituent electronegativities. II—conformational analysis of the sugar ring in nucleosides and nucleotides in solution using a generalized Karplus equation

, 1981
The relationship between vicinal NMR proton–proton coupling constants and the pseudorotational properties of the sugar ring in nucleosides and nucleotides is reinvestigated.
C. Haasnoot, F. de Leeuw, H. De Leeuw, C. Altona   +3 more
semanticscholar   +1 more source

Spectral properties and absolute rate constants for beta-scission of ring-substituted cumyloxyl radicals. A laser flash photolysis study.

Journal of Organic Chemistry, 2002
A laser flash photolysis study of the spectral properties and beta-scission reactions of a series of ring-substituted cumyloxyl radicals has been carried out.
E. Baciocchi*, M. Bietti, M. Salamone, S. Steenken   +3 more
semanticscholar   +1 more source

Conformational analysis of the deoxyribofuranose ring in DNA by means of sums of proton-proton coupling constants: a graphical method.

Journal of Biomolecular Structure and Dynamics, 1987
A graphical method is presented for the conformational analysis of the sugar ring in DNA fragments by means of proton-proton couplings. The coupling data required for this analysis consist of sums of couplings, which are referred to as sigma 1' (= J1'2' +
L. J. Rinkel, C. Altona
semanticscholar   +1 more source

Structural effects on the beta-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals.

Journal of Organic Chemistry, 2005
[reaction: see text] The absolute rate constants for beta-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis.
M. Bietti, O. Lanzalunga, M. Salamone
semanticscholar   +1 more source

Spring constants of capsular tension rings

Journal of Cataract and Refractive Surgery, 2004
To determine the spring constants of several types of capsular tension rings (CTRs).Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany.Fourteen models of CTRs provided by 9 companies were tested; all were 11.0 mm in diameter.
Sabine Kurz, H. Burkhard Dick
openaire   +3 more sources

On constant Armendariz rings

Asian-European Journal of Mathematics, 2016
Let [Formula: see text] be a ring equipped with an endomorphism [Formula: see text] and an [Formula: see text]-derivation [Formula: see text]. In this article, we study [Formula: see text]-constant Armendariz rings and radicals of the Ore extension [Formula: see text], in terms of a [Formula: see text]-constant Armendariz ring [Formula: see text] with
openaire   +2 more sources

Conformational analysis of six-membered rings in solution: ring puckering coordinates derived from vicinal NMR proton-proton coupling constants

, 1993
A new method for quantitative analysis of the conformation of six-membered ring compounds in solution is presented. The method uses as a probe the endocyclic vicinal NMR proton-proton coupling constants, which are translated into the relevant ...
C. Haasnoot
semanticscholar   +1 more source

CONSTANTS OF DERIVATIONS OF PRIME RINGS

Mathematics of the USSR-Izvestiya, 1982
A Galois correspondence theorem is proved for any finite-dimensional Lie -algebra of outer derivations of a prime ring of positive characteristic. A theorem is proved on the existence of a locally finite ideal, in the sense of Sirsov, over the ring of constants of such a Lie -algebra. Extension and rigidity theorems are also obtained.
openaire   +2 more sources

13C−1H Spin-Coupling Constants in the β-d-Ribofuranosyl Ring: Effect of Ring Conformation on Coupling Magnitudes

, 1996
Experimental and computational methods have been used to examine the behavior of one-, two-, and three-bond {sup 13}C-{sup 1}H spin-coupling constants ({sup 1}J{sub CH}, {sup 2}J{sub CH} and {sup 3}J{sub CH}, respectively) within the {beta}-D ...
C. Podlasek, Wayne A. Stripe, I. Carmichael, M. Shang, B. Basu, A. Serianni   +5 more
semanticscholar   +1 more source