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11.
The reactions of IO radicals with CH3SCH3, CH3SH, C2H4, and C3H6 have been studied using the discharge flow method with direct detection of IO radicals by mass spectrometry. The absolute rate constants obtained at 298 K are the following: IO + CH3SCH3 → products (1): k1 = (1.5 ± 0.2) × 10?14; IO + CH3SH → products (2): k2 = (6.6 ± 1.3) × 10?16; IO + C2H4 →products (3): k3 < 2 × 10?16; IO + C3H6 → products (4): k4 < 2 × 10?16 (units are cm3 molecule?1 s?1). CH3S(O)CH3 and HOI were found as products of reactions (1) and (2), respectively. The present lower value of k1 compared to our previous determination is discussed. 相似文献
12.
The International Telecommunication Union (ITU) has completed work on a series of standards on asynchronous transfer mode (ATM) equipment functional operations and network element management. The objective of these standards is to enable flexible design and interoperability of network elements for use in a global ATM network, independent of any specific implementation. This article discusses these standards with respect to their development and application in planning ATM networks. Specifically, it addresses the following: the modeling approach taken in the development of the ITU standards, key operational features specified in the ATM network element functional model, and the capabilities of the ATM network element management interface. Examples of ATM equipment are provided to illustrate how the functional models specified in the ITU standards may be used by network planners and equipment manufacturers to specify and develop ATM equipment tailored to specific needs, while ensuring network interoperability. The article concludes with some points on the future enhancement of these and related ATM equipment operations standards 相似文献
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The thiochlorides Mo6Cl10Y (Y = S, Se, Te) have been prepared; they are isostructural with Nb6I11, space group Pccn, and have four formula units per unit cell. The X-ray structure of Mo6Cl10Se has been determined from three-dimensional single-crystal counter data and refined to a final R value of 0.053 for 3350 independent reflections. The most important result concerning this structure is a statistical distribution of the Se atom on the unit (Mo6X′8) with : so the compound Mo6Cl10Se must be formulated . The diamagnetic and dielectric behavior of these new thiochlorides is discussed. 相似文献
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Summary The existence of a joint asymptotic distribution for the windings of a three-dimensional Brownian motion around a finite number of straight lines is obtained. This complements the recent studies, by Pitman- Yor, and the authors, of the joint asymptotic distribution for the windings of planar Brownian motion around a finite number of points.The following principle governs the passage from results in the plane to results in space:Let B be a three-dimensional Brownian motion, and P
1, ..., P
k, k planes which intersect two by two. Then, the convergences in distribution concerning the planar Brownian motions B
i (1ik), defined respectively as the orthogonal projections of B on P
i (1ik), take place jointly, and the corresponding limit variables are independent. 相似文献
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The examination of 19F chemical shifts for ca. 650 F-alkylated compounds of general formula CF3(CF2)nCF2X led to the following conclusions: the CF2 groups α to X are very sensitive to the nature of X, and are spread over a range of 85 ppm. The effect of the length of the F-alkyl chain decreases rapidly, so that δCF2(α) can already be considered as characteristic of X for n = 1 or 2 for most practical purposes. Solvent effects (in 9 different solvents having ε = 1.8 to 52.1) were found to be rather small except for the F-alkyl iodides. A chart which indicates the domain in which the CF2(α) resonance signal is to be expected is given for 42 different series of F-alkylated compounds; it is expected to provide the synthetic chemist with a useful tool for the identification and characterization of such compounds. 相似文献
19.
Patrice Le Boudec François Sanchez Pierre-Luc FranÇois Jean-François Bayon Guy Michel StÉphan 《电信纪事》1994,49(3-4):178-192
The dynamics of the erbium doped fiber laser is analysed both experimentally and theoretically. This laser operates spontaneously in self-pulsing, in sinusoidal or in CW regime. Experiments have allowed to determine the control parameters : the cavity losses, the pumping rate and the ion pairs concentration. An antiphase dynamics is observed when the laser operates simultaneously at 1.55 µn and 1.536 µm. The self-pulsing behavior is attributed to a fast energy transfer which occurs between two neighboring ions (pair induced quenching). A simple model considering the active medium as a mixture of isolated ions and ions pairs is developped and leads to a good qualitative agreement with the experimental results. 相似文献
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