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1.
Times of longitudinal T
1b
and transverse T
2b
magnetic relaxation of hexane and decane molecules in micropores of ZSM-5 silicalite were measured as functions of the content of these liquid n-alkanes in zeolite and of temperature. The stepwise changes in the T
1b
and T
2b
times were revealed in the region of 8% content of hydrocarbons. The observed changes in the concentration and temperature dependences of T
1b
and T
2b
times are explained by the rearrangement of silicalite crystal lattice under the action of adsorbed molecules. 相似文献
2.
3.
We give cogenerators for the categories of convex (= finitely superconvex), finitely positively convex, and absolute convex (= finitely totally convex) spaces introduced by Pumplün and Röhrl.Dedicated to our academic teacher Dieter Pumplün on the occasion of his sixtieth birthday. 相似文献
4.
5.
Gerd Bürger 《Archive for Mathematical Logic》1989,28(3):155-166
For the classA of uncountable Archimedian real closed fields we show that the statement TheL
<-theory ofA is complete is independent of ZFC. In particular we have the following results:Assuming the Continuum-Hypothesis (CH) is incomplete. Conversely it is possible to build a model of set theory in which is complete and decidable. The latter can also be deduced from the Proper Forcing Axiom (PFA). In this case turns out to be equivalent to the elementary theory of the real numbers (by a quantifier-elimination procedure).Formally: is incomplete. is complete and decidable. 相似文献
6.
7.
We study the capillary forces arising from charged colloidal particles trapped at an oil-water interface. Since it is quadratic in the electric field, the electric stress acting on the interface cannot be written as the superposition of one-particle terms. Indeed, we find that the interfacial pressure is dominated by two-particle terms, which induce capillary forces involving one, two, three, or four particles. The dominant interaction is attractive and varies with the inverse cube of the particle distance. 相似文献
8.
Hans Bürger 《Angewandte Chemie (International ed. in English)》1973,12(6):474-486
In contrast to carbon, silicon fails to form multiple bonds that are stable at room temperature. Consequently molecules in which silicon exhibits coordination numbers (CN) of 1, 2, and 3 may only be obtained at very high or low temperatures. Under these conditions their structural features, including multiple bonds, resemble those of carbon. On the other hand, silicon is capable of forming various hexacoordinated compounds making use of its d orbitals. Nitrogen and oxygen bonded to silicon develop an unusual stereochemistry: planar nitrogen, nearly or completely linear oxygen, and considerable shortening of SiN, SiO, and SiF bonds are specific examples. N(SiR3)2 and CH2SiR3 ligands permit stabilization of unusually low CNs of many metals and give rise to amino and alkyl derivatives of unexpectedly high stability due to the particular electronic, the R3Si group. 相似文献
9.
Zusammenfassung Die Infrarot-und Raman-Spektren folgender Hydroxylamin-Derivate wurden registriert und zugeordnet: (CH3)3SiONH2 (1), (CH3)3SiONHSi(CH3)3, (CH3)3SiON[Si(CH3)3]2 (3), CH3ONH2 (4), CH3ON[Si(CH3)3]2 (5), CH3NHOCH3, CH3N[Si(CH3)3]OCH3, (C2H5)2NOH und (C2H5)2NOSi(CH3)3. Eine Normalkoordinatenanalyse für NH2OH,1, 3, 4 und5 zeigt, daß sich die Spektren durch Übertragung gleichbleibender Kraftkonstanten der Molekülfragmente wiedergeben lassen. O-und N-Substituenten beeinflussen die NO-Kraftkonstante nicht; die SiO-und SiN-Valenzkraftkonstanten sind mit 3,3 mdyn/Å bemerkenswert niedrig.
Mit 4 Abbildungen 相似文献
Vibrational spectra and normal coordinate analysis of some methyl-and trimethylsilylhydroxylamines
The infrared and Raman spectra of the hydroxylamine derivatives quoted above were recorded and frequencies assigned. A normal coordinate treatment of NH2OH,1, 3, 4 and5 showed that the spectra can be explained by a single force field set up by transferring force constants from the different fragments of the molecules. The NO stretching force constant remains unaffected by different substituents. The SiO and SiN stretching force constants are remarkably small (c. 3.3 mdyn/Å).
Mit 4 Abbildungen 相似文献
10.
Jörg Kärger 《Adsorption》2003,9(1):29-35
A review is given on the main problems associated with the determination and interpretation of molecular diffusion in zeolites. It is shown that the diffusivities may most decisively depend on the relevant space and time scales of observation, as well as on the physical state under which the measurements are carried out. Special emphasis is given to the microscopic techniques and their most recent evidence on the existence of transport resistances distributed over the intracrystalline space. 相似文献