In recent years, college English teaching has been undergoing great reform. Ministry of National Euducation has extended more and more attention on students＇ speaking and listening ability. To master a language is ba...In recent years, college English teaching has been undergoing great reform. Ministry of National Euducation has extended more and more attention on students＇ speaking and listening ability. To master a language is based on what people hear and understand. Thus, listening comprehension is vital in the college language teaching. In this critical moment, there should be a pratical and effective theory to advance the quality and efficiency of listening teaching and contribute to the whole college language teaching reform. Thus, this experimental research is on the basis of metaphor theory to find a way to improve students＇listening comprehension.展开更多
Regulating Lewis acid sites with well-defined electronic state and steric environment is still challenging for achieving high catalytic efficiency.Here we show coordinating zirconium nodes in the typical metal-organic...Regulating Lewis acid sites with well-defined electronic state and steric environment is still challenging for achieving high catalytic efficiency.Here we show coordinating zirconium nodes in the typical metal-organic framework known as MOF-545 with the monocarboxylate modulators including trifluoroacetic acid(TFA)or benzoic acid(BA)over meso-tetra(4-carboxyphenyl)-porphine(H_(2)TCPP),denoted as MOF-545-TFA or MOF-545-BA.Impressively,MOF-545-TFA shows the significantly enhanced performance for the catalytic ring-opening reaction of various epoxides with alcohols and good recyclability at 40°C in respect with MOF-545-BA and ZrO_(2).This mainly originates from the stronger Lewis acidity and more active zirconium sites induced by the electron-withdrawing TFA,resulting in the increased ability for activation of epoxides.This modulation approach is promising for enlarging the toolbox to extend the MOFs-based Lewis acid catalysis.展开更多
文摘In recent years, college English teaching has been undergoing great reform. Ministry of National Euducation has extended more and more attention on students＇ speaking and listening ability. To master a language is based on what people hear and understand. Thus, listening comprehension is vital in the college language teaching. In this critical moment, there should be a pratical and effective theory to advance the quality and efficiency of listening teaching and contribute to the whole college language teaching reform. Thus, this experimental research is on the basis of metaphor theory to find a way to improve students＇listening comprehension.
基金National Key Research and Development Program of China(Nos.2021YFA1500403 and 2021YFA1200302)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)+2 种基金National Natural Science Foundation of China(Nos.92056204,21890381,21721002,22173024,21722102 and 51672053)Beijing Natural Science Foundation,China(No.2182087)Youth Innovation Promotion Association of CAS.
文摘Regulating Lewis acid sites with well-defined electronic state and steric environment is still challenging for achieving high catalytic efficiency.Here we show coordinating zirconium nodes in the typical metal-organic framework known as MOF-545 with the monocarboxylate modulators including trifluoroacetic acid(TFA)or benzoic acid(BA)over meso-tetra(4-carboxyphenyl)-porphine(H_(2)TCPP),denoted as MOF-545-TFA or MOF-545-BA.Impressively,MOF-545-TFA shows the significantly enhanced performance for the catalytic ring-opening reaction of various epoxides with alcohols and good recyclability at 40°C in respect with MOF-545-BA and ZrO_(2).This mainly originates from the stronger Lewis acidity and more active zirconium sites induced by the electron-withdrawing TFA,resulting in the increased ability for activation of epoxides.This modulation approach is promising for enlarging the toolbox to extend the MOFs-based Lewis acid catalysis.
