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991.
Giorgio Peyronel Anna Pignedoli Wanda Malavasi 《Journal of chemical crystallography》1982,12(6):481-488
The crystal and molecular structure of 3,5-diamino-1,2,4-dithiazolium bromide has been refined from three-dimensional counter data (856 reflections) by least-squares methods, anisotropically for the nonhydrogen and isotropically for the hydrogen atoms, to a finalR=0.036:a=9.948(1),b=12.731(1),c=5.098(1) Å, B=98.70(1)° at 18°C,Z=4,P21/n. The S-S (2.075 Å) distance is intermediate between those of the thiouret hydrochloride and hydroiodide. The C-N(terminal) and C-N(bridging) distances are close to their average value (1.322 Å) within their standard deviations. Thev(NH2) and (NH2) frequencies of the thiouret hydrohalides are close to those of dithiobiuret while thev(NH) and (NH) bands are, as expected, absent. Thev(CN) andv(CS) bands are shifted to higher and lower frequencies, respectively, while a newv(SS) broad band is observed in the 430–410 cm–1 region. 相似文献
992.
993.
Anna Maria Venezia Ronald G. Cavell 《Journal of Electron Spectroscopy and Related Phenomena》1985,36(3):281-296
Photoelectron and Auger (MNN) spectra of tetramethyltin and hexamethylditin have been measured and the results compared to those of metallic tin. Energies and intensities of the Auger lines are in agreement with theory based on an Intermediate Coupling scheme since LS coupling theory was inadequate. Relaxation contributions have been evaluated. 相似文献
994.
Using light-front dynamics, and the notion of the running effective quark mass, we propose a model of the three-quark nucleon wave function, which accounts simultaneously both for the low and the high energy experimental data. Our wave function is a product of a spinor part, inferred from the QCD sum rules, and a gaussian scalar factor, taken for simplicity. Including all three Ioffe currents we get from one wave function both the negative neutron charge radius 〈r2〉neutron=-0.108 fm2 and the decreasing d/u ratio in the proton for xBj increasing from 0.5 to 1. 相似文献
995.
The influence of silica addition and of the annealing on the structure and properties of phosphate coatings are investigated. It has been observed that silica stabilizes phosphates and reduces the transport of iron towards the surface. 相似文献
996.
997.
Anna Tozzi 《Topology and its Applications》1983,16(1):69-80
Characterizations of epidense subcategories of topological categories and of existence of epidense hulls have been described in [2, 3, 4]. In this paper a similar characterization is given in a much more general setting; for example the category need not have products. The relationship between finite factorization structures and existence of epidense hulls is investigated. It is found to be analogous to the relationship between general factorization structures and epireflective hulls. 相似文献
998.
Luigi P. Battaglia Anna Bonamartini Corradi Francesco A. Devillanova Gaetano Verani 《Transition Metal Chemistry》1979,4(4):264-266
Summary The crystal structure of the title compound has been determined from x-ray diffractometer data by the heavy-atom method and refined anisotropically by least-squares calculations. Crystals are monoclinic, space groupP 21/c, with unit cell dimensions:a=7.321(1),b=14.622(2),c=14.827(2) Å,=92.95(2), Z=4. The finalR index is 4.6%. The copper coordination is trigonal, involving the sulphur atoms of twoN-ethyl-1,3-imidazolidine-2-thione molecules and one chlorine atom. The structure is held together by two intramolecular N-HCl hydrogen bonds and by normal van der Waals interactions. 相似文献
999.
Anna Maria Ghirlanda 《Annali dell'Universita di Ferrara》1962,11(1):93-106
Riassunto Si introducono certi gruppi di numeri associati ad un grafo o singrammaG che vengono chiamati caratteristiche diG. Si studiano alcune proprietà delle caratteristiche e se ne fanno applicazioni a vari problemi sui grafi.
Lavoro eseguito nell’ambito del Gruppo N. 26 del Comitato Naz. per la Mat. del C.N.R. 相似文献
Résumé On introduit certains groupes de nombres qui sont associés à un grapheG et qu’on appelle caractéristiques deG. Ou étudie quelques proprietés des caractéristiques et on en fait des applications a divers problèmes sur les graphes.
Lavoro eseguito nell’ambito del Gruppo N. 26 del Comitato Naz. per la Mat. del C.N.R. 相似文献
1000.
Dr. Anna Klingst 《Mathematical Methods of Operations Research》1959,3(2):81-87
Zusammenfassung Ermittlung des günstigsten Bestellzeitpunktes, wenn die Zeitspanne zwischen der Bestellung und der Lieferung eine Zufallsveränderliche mit bekannter Verteilung ist.
Summary Determination of the optimal time for placing orders in those cases where the time interval between order and supply is a random variable with known distribution.相似文献