The purpose of the present study was to use Coh-Metrix,a computational tool,to examine the relationship between discourse coherence and writing level,and analyze the coherence of high level writing and low level writi...The purpose of the present study was to use Coh-Metrix,a computational tool,to examine the relationship between discourse coherence and writing level,and analyze the coherence of high level writing and low level writing.The study uses 5 Coh-Metrix variables to analyze 40 college students'timed compositions from Chinese Learners English of Corpus(CLEC) and their corresponding readability scores.The study demonstrates that Coh-Metrix variables,number of words,words per sentences,the Flesch-Kincaid Grade Level,LSA sentence all,and argument overlap can contribute to text coherence.Findings of the study indicate:there is a relationship between discourse coherence and writing level,but there is no significant difference between high level group and low level group in discourse coherence(p=.409>.05),and writing level can not distinguish discourse coherence in EFL learners'writing.展开更多
GThe title compound was synthesized by reaction of Cu(ClO4)2, picolinic acid and carbamide in C2H5OH/CH3CN solution, and characterized by single crystal X ray diffraction. It crystallizes in the orthorhombic system, s...GThe title compound was synthesized by reaction of Cu(ClO4)2, picolinic acid and carbamide in C2H5OH/CH3CN solution, and characterized by single crystal X ray diffraction. It crystallizes in the orthorhombic system, space group Pbcawith a=14.0481(8), b=9.0130(5), c=18.626(1)?, V=2358.3(2)?3, Z=4, Dx=1.771g·cm-3, μ=1.235mm-1 and F(000)=1276. The final R factor is 0.0440 for 1434 observed reflections. The X ray analysis revealed that the copper?atom iscoordinated by two picolinic ligands in the equatorial plane, while the two oxygen atoms of perchlorate occupy the axial positions of octahedron with lengthened Cu O distances, resulting in a 4+2 elongated octahedral environment. In the compound, there also exist two protonated carbamide cations for charge balance. CCDC: 195354.展开更多
Within the framework of density functional theory, crystal structure parameters, physical properties, electronic structures and thermal stability of Mg2CoH5 complex hydride are comprehensively investigated. The optimi...Within the framework of density functional theory, crystal structure parameters, physical properties, electronic structures and thermal stability of Mg2CoH5 complex hydride are comprehensively investigated. The optimized structural parameters including lattice constants, atomic positions and bond lengths are well close to the experimental data determined from X-ray and neutron powder diffraction. A detailed study on the energy band, density of states (DOS) and charge density distribution shows the orbital hybridization and bonding characteristics of the complex hydride. It is found that Mg2CoH5 is a semiconductor with a pseudo-gap of about 1.638 1 eV, and there is a mixed ionic-covalent bonding between Co and H in CoH5 complexes embedded in the matrix Mg2+ cations. The calculated formation enthalpy of Mg2CoH5 is in good agreement with the experimentally determined value.展开更多
文摘The purpose of the present study was to use Coh-Metrix,a computational tool,to examine the relationship between discourse coherence and writing level,and analyze the coherence of high level writing and low level writing.The study uses 5 Coh-Metrix variables to analyze 40 college students'timed compositions from Chinese Learners English of Corpus(CLEC) and their corresponding readability scores.The study demonstrates that Coh-Metrix variables,number of words,words per sentences,the Flesch-Kincaid Grade Level,LSA sentence all,and argument overlap can contribute to text coherence.Findings of the study indicate:there is a relationship between discourse coherence and writing level,but there is no significant difference between high level group and low level group in discourse coherence(p=.409>.05),and writing level can not distinguish discourse coherence in EFL learners'writing.
文摘GThe title compound was synthesized by reaction of Cu(ClO4)2, picolinic acid and carbamide in C2H5OH/CH3CN solution, and characterized by single crystal X ray diffraction. It crystallizes in the orthorhombic system, space group Pbcawith a=14.0481(8), b=9.0130(5), c=18.626(1)?, V=2358.3(2)?3, Z=4, Dx=1.771g·cm-3, μ=1.235mm-1 and F(000)=1276. The final R factor is 0.0440 for 1434 observed reflections. The X ray analysis revealed that the copper?atom iscoordinated by two picolinic ligands in the equatorial plane, while the two oxygen atoms of perchlorate occupy the axial positions of octahedron with lengthened Cu O distances, resulting in a 4+2 elongated octahedral environment. In the compound, there also exist two protonated carbamide cations for charge balance. CCDC: 195354.
基金Project(531105050037) supported by the Program for Changjiang Scholars and the Innovative Research Team in University of ChinaProject(2006CB605104) supported by the Ministry of Science and Technology of China
文摘Within the framework of density functional theory, crystal structure parameters, physical properties, electronic structures and thermal stability of Mg2CoH5 complex hydride are comprehensively investigated. The optimized structural parameters including lattice constants, atomic positions and bond lengths are well close to the experimental data determined from X-ray and neutron powder diffraction. A detailed study on the energy band, density of states (DOS) and charge density distribution shows the orbital hybridization and bonding characteristics of the complex hydride. It is found that Mg2CoH5 is a semiconductor with a pseudo-gap of about 1.638 1 eV, and there is a mixed ionic-covalent bonding between Co and H in CoH5 complexes embedded in the matrix Mg2+ cations. The calculated formation enthalpy of Mg2CoH5 is in good agreement with the experimentally determined value.
