The phase transfer catalytic (PTC) bis-Wittig reaction between substitutedbenzaldehyde and 1,2- and 1,3-bisylides in the presence of K2Co3 was discussed.
A convenient method for preparing unsaturated amides via telluro- nium salts employing solid potassium carbonate as a base with high stereo- selectivity in excellent yields has been developed.
Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(C...Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(CBI process)converges almost surely.If an x log(x)moment condition on the branching mechanism does not hold,then the limit is zero.If this x log(x)moment condition holds,then we prove L1 convergence as well.The projection of the limit on any left non-Perron eigenvector of the branching mean matrix is vanishing.If,in addition,a suitable extra power moment condition on the branching mechanism holds,then we provide the correct scaling for the projection of a CBI process on certain left non-Perron eigenvectors of the branching mean matrix in order to have almost sure and L1 limit.Moreover,under a second order moment condition on the branching and immigration mechanisms,we prove L2 convergence of an appropriately scaled process and the above-mentioned projections as well.A representation of the limits is also provided under the same moment conditions.展开更多
Two kinds of Nb-doped silica fibers, an NbCl5-doped fiber and an Nb205-doped fiber, are fabricated and char- acterized in this Letter. First, the refractive index profiles of both fibers are obtained, and then their R...Two kinds of Nb-doped silica fibers, an NbCl5-doped fiber and an Nb205-doped fiber, are fabricated and char- acterized in this Letter. First, the refractive index profiles of both fibers are obtained, and then their Raman spectra are measured with 785 nm exciting light. The Nb-doped fibers＇ Raman spectra are compared with a conventional GeO2-doped single-mode silica fiber that is prepared with the same method and under the same conditions. As a result, the Raman gain coefficients of the Nb-doped silica fiber core are obtained. The exper- imental results show that Nb2O5 doping can enhance the Raman scattering intensity of the optical fibers.展开更多
文摘The phase transfer catalytic (PTC) bis-Wittig reaction between substitutedbenzaldehyde and 1,2- and 1,3-bisylides in the presence of K2Co3 was discussed.
文摘A convenient method for preparing unsaturated amides via telluro- nium salts employing solid potassium carbonate as a base with high stereo- selectivity in excellent yields has been developed.
基金supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciencessupported by the Royal Society Newton International Fellowship and the EU-funded Hungarian(Grant No.EFOP-3.6.1-16-2016-00008)。
文摘Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(CBI process)converges almost surely.If an x log(x)moment condition on the branching mechanism does not hold,then the limit is zero.If this x log(x)moment condition holds,then we prove L1 convergence as well.The projection of the limit on any left non-Perron eigenvector of the branching mean matrix is vanishing.If,in addition,a suitable extra power moment condition on the branching mechanism holds,then we provide the correct scaling for the projection of a CBI process on certain left non-Perron eigenvectors of the branching mean matrix in order to have almost sure and L1 limit.Moreover,under a second order moment condition on the branching and immigration mechanisms,we prove L2 convergence of an appropriately scaled process and the above-mentioned projections as well.A representation of the limits is also provided under the same moment conditions.
基金supported by the National Natural Science Foundation of China(Nos.61027015,61177088,61475095,and 61575120)the National"973"Programof China(No.2012CB723405)the Key Laboratory of Specialty Fiber Optics and Optical Access Networks(Nos.SKLSFO2012-01,SKLSFO2013-02,and SKLSFO2015-01)
文摘Two kinds of Nb-doped silica fibers, an NbCl5-doped fiber and an Nb205-doped fiber, are fabricated and char- acterized in this Letter. First, the refractive index profiles of both fibers are obtained, and then their Raman spectra are measured with 785 nm exciting light. The Nb-doped fibers＇ Raman spectra are compared with a conventional GeO2-doped single-mode silica fiber that is prepared with the same method and under the same conditions. As a result, the Raman gain coefficients of the Nb-doped silica fiber core are obtained. The exper- imental results show that Nb2O5 doping can enhance the Raman scattering intensity of the optical fibers.
