日受青睐的被叫集中付费业务

本文介绍了被叫集中付费业务的定义及其在美国和欧洲的开展情况，在分析其大受欢迎的原因的同时也指出其存在的问题。     

The chemistry of sulfines. 9. A novel synthesis of α-chloroalkyl alkanethiosulfonate esters

Sulfines react with sulfinyl chlorides giving α-chloroalkyl alkanethiosulfonate esters and with thionyl chloride giving α-chloroalkanesulfenyl chlorides, both in good yields.     

Thermally stimulated luminescence and infrared studies of CaS : Bi,Tm phosphors

Calcium sulphide phosphors doped with bismuth and thulium are prepared from Indian minerals. The glow curves are recorded in the temperature range of 96–320 °K. The activation energies are determined by analyzing the glow peaks after thermal cleaning, using different methods. The results show that, in these phosphors, the electron traps responsible for thermoluminescence are present prior to irradiation. The infrared absorption spectra are recorded in the range of 4000-250 cm^-1. It is concluded that the traps are due to host lattice defects which may arise from S^-2 ion vacancies, created during phosphor preparation.     

Minimal graphs with cyclic color group

We determine the minimum number of vertices an edge-colored graph must have, if its group of color preserving automorphisms is the cyclic group of order n.     

微蜂窝型导管和气吹集束型光缆系统的技术介绍

针对目前光缆网建设存在的光纤利用率不高、投资不经济的基本问题，通过对目前国内外使用或出现的“微管”、“微缆”、“Fibreflow”导管、“JETnet”等使用技术特点的介绍与研究，提出了微蜂窝型导管和气吹集束型光缆的概念并探索性地论述其解决光缆网建设存在基本问题的若干应用方式、经济性及技术优越性。     

A partial model of NF with ZF

The theory New Foundations (NF) of Quine was introduced in [14]. This theory is finitely axiomatizable as it has been proved in [9]. A similar result is shown in [8] using a system called K. Particular subsystems of NF, inspired by [8] and [9], have models in ZF. Very little is known about subsystems of NF satisfying typical properties of ZF; for example in [11] it is shown that the existence of some sets which appear naturally in ZF is an axiom independent from NF (see also [12]). Here we discuss a model of subsystems of NF in which there is a set which is a model of ZF. MSC: 03E70.     

Hybridization in propellanes

Using the Maximum Overlap Approximation, the hybridization of a series of small ring propellanes is studied in order to arrive at a measure of the strain in these compounds     

Gas chromatographic resolution of carbohydrate enantiomers. A new chiral phase for pentoses

New chiral polymers have been prepared by conversion of cyano groups of polysiloxanes XE-60 and OV-225 into carboxylic groups and subsequent coupling to give the respective S-valine-R-α-phenyl-ethyl amide. In contrast to the corresponding stationary phases with S-α-phenylethyl amide groups, which have been used for the resoultion of trifluoroacetylated hexose derivatives, the new phase show high enantioselectivity for pentose and 6-deoxyhexose derivatives.     

Dihydridoiridium diolefin complexes as intermediates in homogeneous hydrogenation

Two isomeric series of dihydrido-diolefin complex cations, cis- and cis-trans- [IrH₂(cod)L₂]PF₆ (cod = 1,5-cyclooctadiene; L = tertiary phosphine)have been observed directly by PMR spectroscopy and in some cases have been isolated as crystalline solids. They are prepared by H₂ addition to a diolefin complex (unsaturated route) or by diolefin addition to a hydrido complex (hydride route), respectively. These complexes appear to be important intermediates in the catalytic hydrogenation of (cod) by the catalysts [Ir(cod)L₂]PF₆. The cis- isomers transfer hydrogen to the coordinated (cod) much more rapidly than the cis, trans isomers; the hydrogen transfer to the olefin seems to require a coplanar M(CC)H system. H₂ addition to [Ir(cod)₂]⁺ at ?80° C gives [IrH₂(cod)₂]⁺; electron-withdrawing substituents therefore do not deactivate the metal center with respect to oxidative addition.