A now lignan, neoarctin A, has been isolated from the seeds of Arctium lappa L. and the structure elucidated on the basis of spectral analysis. In the previous paper([1]) we reported the isolation and identification o...A now lignan, neoarctin A, has been isolated from the seeds of Arctium lappa L. and the structure elucidated on the basis of spectral analysis. In the previous paper([1]) we reported the isolation and identification of chemical constituents from the roots of Arctium lappa collected from Akesu, the Xinjiang Autonomous Region. In the present paper,we report the structure elucidation of a new lignan from the roots of the same plant.展开更多
Using electrode as laser cladding materials, the microstructure and wear resistance of laser clad layer of ductile cast iron was studied. The laser clad layer can be subdivided into the melted zone where existed large...Using electrode as laser cladding materials, the microstructure and wear resistance of laser clad layer of ductile cast iron was studied. The laser clad layer can be subdivided into the melted zone where existed large amounts of austenite, graphite nodules and some carbides, and the solid state transformation zone which included martensite and austenite below the melted zone. The Ti combined with C to form TiC increasing the wear resistance; The Co significantly increased the wear resistance compared with Ti.展开更多
Deuterium isotope effects in the CO2-reforming of methane to syngas were firstinvestigated over SiO2-supported rhodium catalysts. Normal deuterium isotop effect was morenoticeable on the methane conversion reaction t...Deuterium isotope effects in the CO2-reforming of methane to syngas were firstinvestigated over SiO2-supported rhodium catalysts. Normal deuterium isotop effect was morenoticeable on the methane conversion reaction than on the CO formation reaction, while there wasno such effect on the CO2 conversion reaction. It can be concluded that the dissociation of the C-Hbond in methane is a key mp and some CO is formed by the reverse water-gas shift reaction.展开更多
In situ FTIR spectra have been used to characterize surface oxygen and adspccies on 20%SrF2/La2O3 catalyst and for the oxidative coupling of methane (OCM).The O2- sur face superoxide with characteristic vibration fre...In situ FTIR spectra have been used to characterize surface oxygen and adspccies on 20%SrF2/La2O3 catalyst and for the oxidative coupling of methane (OCM).The O2- sur face superoxide with characteristic vibration frequency at 1113-1123 cm-1 was formed on the sample after treatment with H2 at 700℃ following exposure to O2 at temperatures between 650℃ and 25℃,The O2 adspecies could also be detected on the working sample at 65O℃ and might play an important role in OCM reaction leading to the production of C2H4 from CH4. These results provide evidence that superoxide ions may be the active oxygen on 20%SrF2/La2O3 catalyst during the oxidative coupling of methane.展开更多
Connective tissue growth factor (CTGF) is thought to be a specific mediator of TGF-β profibrogenic effect, but the role of CTGF in the transformation of renal fibroblasts to myofibroblasts, which are the most importa...Connective tissue growth factor (CTGF) is thought to be a specific mediator of TGF-β profibrogenic effect, but the role of CTGF in the transformation of renal fibroblasts to myofibroblasts, which are the most important host cells in the renal chronic fibrosis, is still unknown. Aimed at observing the biological effect of CTGF, we set up a cell line overexpressing CTGF, and analyzed the amount of myofibroblast and the level of extracellular matrix Collagen Ⅲ mRNA in cultured cells. Our results show that CTGF can directly induce myofibroblasts formation, and increase the level of Collagen Ⅲ mRNA. This suggests that CTGF may be a novel pharmacotherapeutical target protein for the interference with renal fibrosis, thus providing useful theoretic possibility for clinical prevention of chronic progression of kidney disease.展开更多
文摘A now lignan, neoarctin A, has been isolated from the seeds of Arctium lappa L. and the structure elucidated on the basis of spectral analysis. In the previous paper([1]) we reported the isolation and identification of chemical constituents from the roots of Arctium lappa collected from Akesu, the Xinjiang Autonomous Region. In the present paper,we report the structure elucidation of a new lignan from the roots of the same plant.
文摘Using electrode as laser cladding materials, the microstructure and wear resistance of laser clad layer of ductile cast iron was studied. The laser clad layer can be subdivided into the melted zone where existed large amounts of austenite, graphite nodules and some carbides, and the solid state transformation zone which included martensite and austenite below the melted zone. The Ti combined with C to form TiC increasing the wear resistance; The Co significantly increased the wear resistance compared with Ti.
文摘Deuterium isotope effects in the CO2-reforming of methane to syngas were firstinvestigated over SiO2-supported rhodium catalysts. Normal deuterium isotop effect was morenoticeable on the methane conversion reaction than on the CO formation reaction, while there wasno such effect on the CO2 conversion reaction. It can be concluded that the dissociation of the C-Hbond in methane is a key mp and some CO is formed by the reverse water-gas shift reaction.
文摘In situ FTIR spectra have been used to characterize surface oxygen and adspccies on 20%SrF2/La2O3 catalyst and for the oxidative coupling of methane (OCM).The O2- sur face superoxide with characteristic vibration frequency at 1113-1123 cm-1 was formed on the sample after treatment with H2 at 700℃ following exposure to O2 at temperatures between 650℃ and 25℃,The O2 adspecies could also be detected on the working sample at 65O℃ and might play an important role in OCM reaction leading to the production of C2H4 from CH4. These results provide evidence that superoxide ions may be the active oxygen on 20%SrF2/La2O3 catalyst during the oxidative coupling of methane.
基金This work was supported by the Special-fund for Promotion of Education, Ministry of Education (Peking University), the Scientific Foundation for Returned Overseas Chinese Scholars, the Ministry of Educationthe Research Grund from Peking University Firs
文摘Connective tissue growth factor (CTGF) is thought to be a specific mediator of TGF-β profibrogenic effect, but the role of CTGF in the transformation of renal fibroblasts to myofibroblasts, which are the most important host cells in the renal chronic fibrosis, is still unknown. Aimed at observing the biological effect of CTGF, we set up a cell line overexpressing CTGF, and analyzed the amount of myofibroblast and the level of extracellular matrix Collagen Ⅲ mRNA in cultured cells. Our results show that CTGF can directly induce myofibroblasts formation, and increase the level of Collagen Ⅲ mRNA. This suggests that CTGF may be a novel pharmacotherapeutical target protein for the interference with renal fibrosis, thus providing useful theoretic possibility for clinical prevention of chronic progression of kidney disease.
