This study was conducted to explore the individual uses of formulaic sequence(FS)frequency and their effects on complexity,accuracy,and fluency(CAF)in academic writing.Data was collected from the conclusion sections o...This study was conducted to explore the individual uses of formulaic sequence(FS)frequency and their effects on complexity,accuracy,and fluency(CAF)in academic writing.Data was collected from the conclusion sections of a self-compiled corpus of 30 L2 master’s theses.Statistical analysis revealed several notable conclusions.1)Student writers tend to make repetitive use of particular FSs in single texts.2)FS use has a significant frequency effect on fluency,and the high-frequency group slightly outperforms the low-frequency group.3)FS use has a certain frequency effect on accuracy,and the high-frequency group demonstrates the strongest correlation between FS frequency and accuracy.4)FS use has a significant frequency effect on lexical complexity,and the low-frequency group slightly outperforms the high-frequency group.In the low-frequency group,FS use has a significant frequency effect on syntactic complexity as well.Finally,5)The results support Skehan’s trade-off effect,a competition between CAF,which,to a certain degree,is affected by individual uses of FS frequency.The low-frequency group displays a greater trade-off effect than the high-frequency group.展开更多
所谓有标记主位(marked theme),即一个句子的主位不由逻辑主语充当,而是由句子的其它成分充当。如: (1)Little we see in nature that isours. 从语义——句法角度看,有标记主位是一种倒装,"是一种调整语义核心的方法"(秦秀白...所谓有标记主位(marked theme),即一个句子的主位不由逻辑主语充当,而是由句子的其它成分充当。如: (1)Little we see in nature that isours. 从语义——句法角度看,有标记主位是一种倒装,"是一种调整语义核心的方法"(秦秀白1988:77)。与此有关的文体学认为这是一种句法变异(syntactic deviation),具有突出语义、增强表达效果和艺术感染力的作用。而从语篇角度看,它具有承上启下和进一步扩展语篇的功能(Brown & Yule1987:133)。汉语中也存在着这种有标记主位。如:展开更多
Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described ...Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.展开更多
The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the ...The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the framework of the polarization continuum model. Particular emphasis was put on the characterization of solvent effects on the molecular geometrical structures and geometric distortion, which were measured by the bond-length-alternation parameter. The π centres in the compounds are seen to play a decisive role in increasing the TPA cross section and nonlinear optical properties. All studied molecules have relatively strong TPA characteristics, while the alkyne π-bridging ones yield larger TPA cross sections.展开更多
First,an explicit representation A(2)T,S=(GA+E)^-1G of the outer invers A(2)T,S for a matrix A∈Cm×n with the prescribed range T and null space S is derived,which is simpler than A(2)T,S=(GA+E)^-1G-V(UV)-2UG prop...First,an explicit representation A(2)T,S=(GA+E)^-1G of the outer invers A(2)T,S for a matrix A∈Cm×n with the prescribed range T and null space S is derived,which is simpler than A(2)T,S=(GA+E)^-1G-V(UV)-2UG proposed by Ji in 2005.Next,a new algorithm for computing the outer inverse A(2)T,S based on the improved representation A(2)T,S=(GA+E)^-1G through elementary operations on an appropriate partitioned matrix GAInIn0 is proposed and investigated.Then,the computational complexity of the introduced algorithm is also analyzed in detail.Finally,two numerical examples are shown to illustrate that this method is correct.展开更多
基金This project was supported by China National Social Science Funding(No.18BYY107).
文摘This study was conducted to explore the individual uses of formulaic sequence(FS)frequency and their effects on complexity,accuracy,and fluency(CAF)in academic writing.Data was collected from the conclusion sections of a self-compiled corpus of 30 L2 master’s theses.Statistical analysis revealed several notable conclusions.1)Student writers tend to make repetitive use of particular FSs in single texts.2)FS use has a significant frequency effect on fluency,and the high-frequency group slightly outperforms the low-frequency group.3)FS use has a certain frequency effect on accuracy,and the high-frequency group demonstrates the strongest correlation between FS frequency and accuracy.4)FS use has a significant frequency effect on lexical complexity,and the low-frequency group slightly outperforms the high-frequency group.In the low-frequency group,FS use has a significant frequency effect on syntactic complexity as well.Finally,5)The results support Skehan’s trade-off effect,a competition between CAF,which,to a certain degree,is affected by individual uses of FS frequency.The low-frequency group displays a greater trade-off effect than the high-frequency group.
文摘所谓有标记主位(marked theme),即一个句子的主位不由逻辑主语充当,而是由句子的其它成分充当。如: (1)Little we see in nature that isours. 从语义——句法角度看,有标记主位是一种倒装,"是一种调整语义核心的方法"(秦秀白1988:77)。与此有关的文体学认为这是一种句法变异(syntactic deviation),具有突出语义、增强表达效果和艺术感染力的作用。而从语篇角度看,它具有承上启下和进一步扩展语篇的功能(Brown & Yule1987:133)。汉语中也存在着这种有标记主位。如:
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (NSFC Center for Chemical Dynamics (No.21688102)+4 种基金the National Natural Science Foundation of China (No.21673232, No.21873099, No.21922306)the International Partnership Program of Chinese Academy of Sci-ences (No.121421KYSB20170012)supported by the National Natural Science Foundation of China (No.21973010)supported by the National Natural Science Foundation of China (No.21773236)supported by the Natural Science Research Project of Education Department of Anhui Province (No.KJ2019A0521).
文摘Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.
文摘The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the framework of the polarization continuum model. Particular emphasis was put on the characterization of solvent effects on the molecular geometrical structures and geometric distortion, which were measured by the bond-length-alternation parameter. The π centres in the compounds are seen to play a decisive role in increasing the TPA cross section and nonlinear optical properties. All studied molecules have relatively strong TPA characteristics, while the alkyne π-bridging ones yield larger TPA cross sections.
基金The National Natural Science Foundation of China(No.11771076).
文摘First,an explicit representation A(2)T,S=(GA+E)^-1G of the outer invers A(2)T,S for a matrix A∈Cm×n with the prescribed range T and null space S is derived,which is simpler than A(2)T,S=(GA+E)^-1G-V(UV)-2UG proposed by Ji in 2005.Next,a new algorithm for computing the outer inverse A(2)T,S based on the improved representation A(2)T,S=(GA+E)^-1G through elementary operations on an appropriate partitioned matrix GAInIn0 is proposed and investigated.Then,the computational complexity of the introduced algorithm is also analyzed in detail.Finally,two numerical examples are shown to illustrate that this method is correct.
