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91.
Xe(OTeF5)2 reacts with Sb(OTeF5)3 under the formation of [Xe2(OTeF5)3]+[Sb(OTeF5)6]-. From SO2ClF solution a yellow solvate [F5TeOXe]+·SO2ClF· [Sb(OTeF5)6]- is formed with the crystal data: a = 1028.1(1), b = 1040.9(1), c = 1780.2(3) pm, α = 98.07(1), β = 97.68(1), γ = 105.82(1)°, space group . The O-Xe···O fragment is essentially linear (176.1(2)°), and the two Xe-O distances are quite different 197.1(4) and 242.6(4) pm. 相似文献
92.
Summary Shearing at constant gradient of polyisobutylene (PIB) solutions in viscous polybutene oils results in time dependent changes
of their viscosities. Two PIB fractions (M=8·106 and 3.8·106) have been studied in a variety of solvents, covering the viscosity range from 5 to 0.5·10−2 poise. The overall phenomenon is similar to that already observed for polymethylmethacrylate, polystyrene, and polyethylene
oxide solutions in Aroclor.
Results have been discussed in terms of polymer molecular weight and concentration, solvent viscosity and gradient. The systems
investigated are free from strong polar interactions and tendency toward molecular aggregation; time dependent changes of
viscosity are therefore observable also for true molecularly dispersed solutions.
Zusammenfassung Scherung mit konstantem Geschwindigkeitsgradienten von Polyisobutylen (PIB)-L?sungen in viskosen Polybuten-?len ergibt zeitabh?ngige ?nderungen ihrer Viskosit?ten. Zwei PIB-Fraktionen (M=8·106 und 3,8·106) wurden in einer Vielzahl von L?sungsmitteln untersucht, die den Viskosit?tsbereich von 5 bis 0,5·10−2 Poise überdeckten. Das ph?nomenologische Erscheinungsbild ist ?hnlich dem schon beobachteten für Polymethylmethacrylat, Polystyrol und Poly?thylenoxid-L?sungen in Aroclor. Die Ergebnisse wurden hinsichtlich des Polymer-Molekulargewichts und der Konzentration, der L?sungsmittelviskosit?t und des Gradienten diskutiert. Die untersuchten Systeme sind frei von starken polaren Wechselwirkungen und von Tendenzen in Richtung auf molekulare Aggregation. Zeitabh?ngige ?nderungen der Viskosit?t sind deshalb auch für wahre molekulardisperse L?sungen beobachtbar.相似文献
93.
Contributions to the Chemistry of Transition Metal Alkyl Compounds. XLIII. Tetrakis(alkoxycarbonylmethyl)titanium Compounds Organotitanium(IV) compounds of the type (ROCOCH2)4Ti (R ? C2H5, i-C3H7, t-C4H9, C6H5, C6H5CH2) were obtained by reactions of ROCOCH2Li derivatives with TiCl4 at low temperature. The compounds which decompose only above 90°C were characterized by the hydrolysis products, anaerobic reactions with iodine, and the i.r. spectra. The bond conditions are discussed. 相似文献
94.
Empirical solvent parameters of silica surfaces are determined by means of solvatochromic dyes, e.g., Cu(tmen) (acac)+ ClO
4
–
/B(C6H5)
4
–
, Fe(phen)2(CN)2, and Michlers Ketone dissolved in 1,2-dichloroethane or cyclohexane. The values obtained by UV/VIS-measurements are compared with both the polarity scales of Kamlet and Taft and with Gutmann's donor and acceptor numbers. Kamlet and Taft's -parameter (the hydrogen-bond donation capacity of a solvent) is determined independently by means of salicylideneaniline. The * of silica is determined using 5-N,N-dimethylamino-5-nitro-2,2-bithiophene and the complex of tetracyanoethylene with Michlers Ketone, respectively. Further on the reliabilities of the obtained Kamlet-Taft parameters , , and * are checked by comparism with experimental and calculated values of theE
T(30)-parameter of silica by means of multi-parameter regression analysis. The surface properties of silica are influenced mainly by HBD-properties (75%) and dipolarity/polarizability * (20%), but hardly by the HBA-properties (<5%). UV/VIS-measurements were carried out in a special equipment with glass fiber optics, A drawing of the apparatus is given. 相似文献
95.
Thierry Boulanger Christine Evrard Daniel P. Vercauteren Guy Evrard François Durant 《Journal of chemical crystallography》1991,21(3):287-295
The crystal structures ofp-methoxyphenyl-3-triazolo [4,3-a] isoquinoline (SR95926),p-methoxyphenyl-3-triazolophtalazine (CMW1842), andp-methoxyphenyl-3-N-dimethoxyethylamino-6-triazolophtalazine (L16317) have been solved by direct methods from single-crystal X-ray diffraction data, and refined by full-matrix least squares. SR95926: monoclinic,P21/n,a=20.950(3),b=6.769(1),c=9.465(2) Å,=100.90(1)°. CMW1842: triclinic,P¯1,a=8.784(1),b=9.160(4),c=8.555(1) Å,=99.10(2),=93.90(1), =106.77(1)°. L16317: monoclinic,P21/n,a=20.124(3),b=9.586(1),c=10.788(1) Å,=91.91(1)°. FinalR factors are 0.034, 0.037, and 0.053, respectively. Experimental geometries were used to perform STO-3Gab initio molecular-orbital calculations. A relationship between the electronic pattern within the molecules and the affinity of the benzodiazepine receptor sites is pointed out. 相似文献
96.
Polyvinyl chloride (PVC) is widely used in industry, but it is difficult to find any extensive discussion of theological relations that describe it. The present paper discusses the behaviour of rigid PVC in extensional deformations at various temperatures. In the tests, a step elongation was applied at an initial time, then after a delay the specimen was cut, permitting recoil. Both linear and nonlinear strain regimes were studied; the linear relaxation properties (relaxation function, storage modulus) were cross-checked with eccentric-disk measurements. In the non-linear strain regime a single-integral constitutive equation of the KBKZ Wagner type was used. Separability of time and strain effects was demonstrated in our tests and so a damping function could be found which was only a function of strain. Video recordings of recoil were made, and detailed predictions of the strain-time behaviour were checked against experiments.Various constitutive equation proposals were used in the comparison, and the separated kernel integral irreversible model performed reasonably well; some other models of a differential type, and a Doi-Edwards model were not as accurate.Dedicated to Professor Arthur S. Lodge on the occasion of his 70th birthday and his retirement from the University of Wisconsin. 相似文献
97.
Prof. Dr. Z. S. Olesiak 《Archive of Applied Mechanics (Ingenieur Archiv)》1992,62(3):202-209
Summary The stress distributions in a matrix, generated by thermodiffusive fluxes, are determined for the case of a thin, inextensible membrane bonded to the bounding plane over the outer regionr (b>0, ). The problem has been reduced to solving a corresponding system of dual integral equations. There exist singularities in the distribution of contact shear stresses, namely one over square root type atr=b while a logarithmic one at the lines of jumps of temperature and/or mass diffusion.
Ablösung einer dünner Schicht infolge thermodiffusiver Flüsse
Übersicht Es wird die sich in einer Matrix infolge thermodiffusiver Flüsse einstellende Spannungsverteilung ermittelt wobei auf einen Teil der Grenzfläche (im Bereichr (b>0, )) eine dünne und unverschiebliche Membran aufgebracht ist. Zur Lösung wird das Problem auf ein System von dualen Integralgleichungen reduziert. Die in den Kontaktschubspannungen auftretenden Singularitäten sind einerseits vom reziproken Quadratwurzeltyp am Innenrand, andererseits vom logarithmischen Typ bei Sprüngen in der Temperatur und/oder Massendiffusion.相似文献
98.
Prof. Dr. Hans Sachs 《Journal of Geometry》1992,43(1-2):148-165
According to H. BRAUNER a flag space is a three-dimensional affine space with an absolute {,f,F}, wheref is a line in the plane of infinity andF a point onf. A cyclide is a surface of order 4 that intersects only atf. A STROMMER-cyclide is a cyclide generated by translation of a circle in an isotropic plane. In this paper we proof that all STROMMER-cyclides can be generated by translation of an isotropic circle along a divergent Newton-parabola or a conic in a full isotropic plane. We give normal-forms and CAD-pictures of these surfaces. Finaly some geometrical results about STROMMER-cyclides are developed.
Herrn o.Prof. Dr. Gy. Strommer zum 70. Geburtstag gewidmet. 相似文献
Herrn o.Prof. Dr. Gy. Strommer zum 70. Geburtstag gewidmet. 相似文献
99.
Thierry Coulhon 《Potential Analysis》1992,1(4):343-353
One shows the equivalence between an abstract form of a Gagliardo-Nirenberg inequality and an estimate of the decay of the L
1–L
norm of a semigroup of operators. This equivalence, contrary to the one with the classical Sobolev inequalities, allows the treatment of situations where the decay is exponential. Related results and applications are given.
Cet article a pu être terminé pendant un séjour de l'auteur à l'université d'Edimbourg. 相似文献
100.
Craig C. Martens 《Journal of statistical physics》1992,68(1-2):207-237
We describe our work on qualitative methods for visualizing the quantum eigenstates of systems with nonlinear classical dynamics. For two-degree-of-freedom systems, our approach is based on the use of generalized coherent states, and allows systems with nonoscillator kinematics to be investigated. The general approach is illustrated with two examples involving vibration-rotation interaction in polyatomic molecules. We apply the coherent states of the Lie groupH
4SU(2) to define quantum surfaces of section for a model involving centrifugal coupling of a harmonic bend with molecular rotation, andSU(2)SU(2) coherent states to study two harmonic normal modes coupled to overall molecular rotation through coriolis interaction. In both systems, quantum states are visualized on the rotational surface of section and compared with the corresponding classical phase space structure. Striking classical-quantum correspondence is observed. We then describe recent results on the quantum states of (N 3)-dimensional systems of coupled nonlinear oscillators, which reveal a quantum delocalization that is reminiscent of classical Arnold diffusion. 相似文献