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991.
992.
C. C. Wilson 《Journal of chemical crystallography》1994,24(6):371-373
The structures of the substituted nucleic acid base 3-deazauracil, elucidated from pulsed neutron single crystal diffraction, is presented. The improved definition of the hydrogen atom positions and the hydrogen bonding scheme are emphasized in this work. 相似文献
993.
994.
995.
A well-formed ordered space is a totally ordered set equipped with any topology which possesses a subbase consisting entirely of initial and final segments of the set. The well-formed ordered spaces are the structures obtained by repeatedly taking subspaces, quotient spaces and inverse limits, starting from a collection of totally ordered sets with the interval topology, and the paper studies their properties. 相似文献
996.
The study of the three-body problem with short-range attractive two-body forces has a rich history going back to the 1930s. Recent applications of effective field theory methods to atomic and nuclear physics have produced a much improved understanding of this problem, and we elucidate some of the issues using renormalization group ideas applied to precise nonperturbative calculations. These calculations provide 11-12 digits of precision for the binding energies in the infinite cutoff limit. The method starts with this limit as an approximation to an effective theory and allows cutoff dependence to be systematically computed as an expansion in powers of inverse cutoffs and logarithms of the cutoff. Renormalization of three-body bound states requires a short range three-body interaction, with a coupling that is governed by a precisely mapped limit cycle of the renormalization group. Additional three-body irrelevant interactions must be determined to control subleading dependence on the cutoff and this control is essential for an effective field theory since the continuum limit is not likely to match physical systems (e.g., few-nucleon bound and scattering states at low energy). Leading order calculations precise to 11-12 digits allow clear identification of subleading corrections, but these corrections have not been computed. 相似文献
997.
P Erdös Joel C Fowler Vera T Sós Richard M Wilson 《Journal of Combinatorial Theory, Series A》1985,38(2):131-142
Denote by Mv the set of integers b for which there exists a 2-design (linear space) with v points and b lines. Mv is determined as accurately as possible. On one hand, it is shown for v > v0 that Mv contains the interval [v + p + 1, v + p + q ? 1]. On the other hand for v of the form p2 + p + 1 it is shown that the interval [v + 1, v + p ? 1] is disjoint from Mv; and if v > v0 and p is of the form q2 + q, then an additional interval [v + p + 1, v + p + q ? 1] is disjoint from Mv. 相似文献
998.
999.
1000.
Morrison R Schmidt D Procario M Johnson DR Lingel K Rankin P Smith JG Alexander J Artuso M Bebek C Berkelman K Besson D Browder TE Cassel DG Cheu E Coffman DM Drell PS Ehrlich R Galik RS Garcia-Sciveres M Geiser B Gittelman B Gray SW Hartill DL Heltsley BK Honscheid K Kandaswamy J Katayama N Kreinick DL Lewis JD Ludwig GS Masui J Mevissen J Mistry NB Nandi S Ng CR Nordberg E O'Grady C Patterson JR Peterson D Pisharody M Riley D Sapper M Selen M Worden H Worris M Avery P Freyberger A Rodriguez J 《Physical review letters》1991,67(13):1696-1700