The adsorption of low-coverage of F and Cl adatoms on the Mg（0001） surface was investigated using first-principles calculations based on the density functional theory（DFT）.The stability of the（2×2） structur...The adsorption of low-coverage of F and Cl adatoms on the Mg（0001） surface was investigated using first-principles calculations based on the density functional theory（DFT）.The stability of the（2×2） structures formed by halogen atoms adsorbed at different sites was determined.The difference between the adsorption of F and Cl on Mg（0001） surface was also discussed.The calculation results show that hollow sites are the energetically most favorable at the low-coverage.It can be concluded from the Mulliken charges and density of states that electrons transfer from the substrate Mg atoms to the adatoms,which leads to the formation of adsorbate bond and further causes the stronger interaction between Mg atom and adatom.The interaction between Cl and Mg atoms is weaker than the interaction between F and Mg.展开更多
目的研究苦瓜的化学成分。方法采用乙醇提取、氯仿萃取和硅胶柱色谱分离,通过理化常数和光谱分析鉴定化合物的结构。结果从苦瓜的氯仿萃取物中分离并鉴定了5个化合物,化学结构分别为苦瓜皂苷元F1(aglycone of momordicoside F1,Ⅰ)、5,...目的研究苦瓜的化学成分。方法采用乙醇提取、氯仿萃取和硅胶柱色谱分离,通过理化常数和光谱分析鉴定化合物的结构。结果从苦瓜的氯仿萃取物中分离并鉴定了5个化合物,化学结构分别为苦瓜皂苷元F1(aglycone of momordicoside F1,Ⅰ)、5,25-豆甾二烯醇(5,25-stigmastadien-3-ol,Ⅱ)、苦瓜皂苷元Ⅰ(aglycone of momordicoside,Ⅰ,Ⅲ)、苦瓜苷(charantin,Ⅳ)、β-谷甾醇(β-sitosterol,Ⅴ)。结论化合物和为首次从苦瓜中分离得到。展开更多
基金Project (51201079) supported by the National Natural Science Foundation of ChinaProject (2012Z099) supported by the Scientific Research Fund of Department of Education of Yunnan Province,ChinaProject (KKSY201251033) supported by the Scientific Research Foundation for Introduced Talents of KMUST,China
文摘The adsorption of low-coverage of F and Cl adatoms on the Mg（0001） surface was investigated using first-principles calculations based on the density functional theory（DFT）.The stability of the（2×2） structures formed by halogen atoms adsorbed at different sites was determined.The difference between the adsorption of F and Cl on Mg（0001） surface was also discussed.The calculation results show that hollow sites are the energetically most favorable at the low-coverage.It can be concluded from the Mulliken charges and density of states that electrons transfer from the substrate Mg atoms to the adatoms,which leads to the formation of adsorbate bond and further causes the stronger interaction between Mg atom and adatom.The interaction between Cl and Mg atoms is weaker than the interaction between F and Mg.
文摘In this paper, we introduce O-F-inverse semigroups and characterize O-F-inverse categorical semigroups by using their minimal primitive congruence β.
文摘目的研究苦瓜的化学成分。方法采用乙醇提取、氯仿萃取和硅胶柱色谱分离,通过理化常数和光谱分析鉴定化合物的结构。结果从苦瓜的氯仿萃取物中分离并鉴定了5个化合物,化学结构分别为苦瓜皂苷元F1(aglycone of momordicoside F1,Ⅰ)、5,25-豆甾二烯醇(5,25-stigmastadien-3-ol,Ⅱ)、苦瓜皂苷元Ⅰ(aglycone of momordicoside,Ⅰ,Ⅲ)、苦瓜苷(charantin,Ⅳ)、β-谷甾醇(β-sitosterol,Ⅴ)。结论化合物和为首次从苦瓜中分离得到。
