The non-toxic and magnetically separable nano-CuFeOcatalyzed synthesis of symmetrical aryl sulfides by the reaction of thiourea with a wide variety of aryl halides,including aryl chlorides has been reported.Excellent ...The non-toxic and magnetically separable nano-CuFeOcatalyzed synthesis of symmetrical aryl sulfides by the reaction of thiourea with a wide variety of aryl halides,including aryl chlorides has been reported.Excellent yields of products have been obtained under ligand-free conditions and without the use of any expensive catalyst,such as palladium.展开更多
关于对alkali lead borotellurite玻璃吸收光谱的研究具有重大的现实意义.采用点电荷模型,调节R1和R2的值,对alkali lead borotellurite玻璃中Cr5+的吸收光谱进行理论解释,计算了d-d跃迁,对实验结果的一些主要吸收峰进行识别,同时还计算...关于对alkali lead borotellurite玻璃吸收光谱的研究具有重大的现实意义.采用点电荷模型,调节R1和R2的值,对alkali lead borotellurite玻璃中Cr5+的吸收光谱进行理论解释,计算了d-d跃迁,对实验结果的一些主要吸收峰进行识别,同时还计算了g因子.计算结果表明能级的理论值与吸收光谱的实验值以及g因子的实验值和理论值都符合的比较好.由此确定了alkali lead borotellurite玻璃中键长R1和R2.展开更多
1.Introduction In recent decades,noncentrosymmetric(NCS)compounds have attracted a lot of attention due to their special physical properties,such as ferroelectric,piezoelectric,pyroelectric and especially nonlinear op...1.Introduction In recent decades,noncentrosymmetric(NCS)compounds have attracted a lot of attention due to their special physical properties,such as ferroelectric,piezoelectric,pyroelectric and especially nonlinear optical(NLO)properties[1-6].The NLO crystal is one of the key components for laser technology,which can widen the wavelength range of output radiations.Second harmonic generation(SHG)mate-rials,as the most representative NLO crystals,have received broad concern in the field of optoelectronic functional materials[7-10].The premise for a SHG material is crystallized in a non-centrosymmetric space group because the second order nonlinear coefficient is a triva-lent tensor,which can only exist in NCS point groups[11-13].展开更多
As it is known, the closed inexact exterior form and associated closed dual form make up a differential-geometrical structure. Such a differential-geometrical structure describes a physical structure, namely, a pseudo...As it is known, the closed inexact exterior form and associated closed dual form make up a differential-geometrical structure. Such a differential-geometrical structure describes a physical structure, namely, a pseudostructure on which conservation laws are fulfilled (A closed dual form describes a pseudostructure. And a closed exterior form, as it is known, describes a conservative quantity, since the differential of closed form is equal to zero). It has been shown that closed inexact exterior forms, which describe physical structures, are obtained from the equations of mathematical physics. This process proceeds spontaneously under realization of any degrees of freedom of the material medium described. Such a process describes an emergence of physical structures and this is accompanied by an appearance of observed formations such as fluctuations, waves, turbulent pulsations and so on.展开更多
基金the funding support received for this project from the Isfahan University of Technology(1UT),IR Iran (A.R.H.) and Grant GM 33138(A.E.R.)the National Institutes of Health,USA.Further financial support from the Center of Excellency in Chemistry Research(IUT)
文摘The non-toxic and magnetically separable nano-CuFeOcatalyzed synthesis of symmetrical aryl sulfides by the reaction of thiourea with a wide variety of aryl halides,including aryl chlorides has been reported.Excellent yields of products have been obtained under ligand-free conditions and without the use of any expensive catalyst,such as palladium.
文摘关于对alkali lead borotellurite玻璃吸收光谱的研究具有重大的现实意义.采用点电荷模型,调节R1和R2的值,对alkali lead borotellurite玻璃中Cr5+的吸收光谱进行理论解释,计算了d-d跃迁,对实验结果的一些主要吸收峰进行识别,同时还计算了g因子.计算结果表明能级的理论值与吸收光谱的实验值以及g因子的实验值和理论值都符合的比较好.由此确定了alkali lead borotellurite玻璃中键长R1和R2.
基金supported by the National Natural Science Foundation of China(Grant Nos:91963105,22031009 and 21921001)
文摘1.Introduction In recent decades,noncentrosymmetric(NCS)compounds have attracted a lot of attention due to their special physical properties,such as ferroelectric,piezoelectric,pyroelectric and especially nonlinear optical(NLO)properties[1-6].The NLO crystal is one of the key components for laser technology,which can widen the wavelength range of output radiations.Second harmonic generation(SHG)mate-rials,as the most representative NLO crystals,have received broad concern in the field of optoelectronic functional materials[7-10].The premise for a SHG material is crystallized in a non-centrosymmetric space group because the second order nonlinear coefficient is a triva-lent tensor,which can only exist in NCS point groups[11-13].
文摘As it is known, the closed inexact exterior form and associated closed dual form make up a differential-geometrical structure. Such a differential-geometrical structure describes a physical structure, namely, a pseudostructure on which conservation laws are fulfilled (A closed dual form describes a pseudostructure. And a closed exterior form, as it is known, describes a conservative quantity, since the differential of closed form is equal to zero). It has been shown that closed inexact exterior forms, which describe physical structures, are obtained from the equations of mathematical physics. This process proceeds spontaneously under realization of any degrees of freedom of the material medium described. Such a process describes an emergence of physical structures and this is accompanied by an appearance of observed formations such as fluctuations, waves, turbulent pulsations and so on.
