Isovaleraldehyde possesses malty, fruity, cocoa-like odor and is widely used in fruit, chocolate, coffee flavors. The preparation of natural isovaleraldehyde by the Maillard model reaction was studied in this paper. T...Isovaleraldehyde possesses malty, fruity, cocoa-like odor and is widely used in fruit, chocolate, coffee flavors. The preparation of natural isovaleraldehyde by the Maillard model reaction was studied in this paper. The effects of the ratio of d-glucose/l-leucine, reaction temperature and pH value on the yield of isovaleraldehyde were explored. The optimum conditions were as follows: n(d-glucose):n(l-leucine) = 4, temperature 150 °C, reaction time 3 h, pH 5. The highest yield of isovaleraldehyde obtained was about 32%.展开更多
The effect of rare earths （Sm, Pr, Ce, Nd and La） on the hydrogenation properties ofp-chloronitrobenzene （CNB） over Pt/CNTs catalyst was studied in ethanol at 303 K and normal pressure. The results exhibited that ...The effect of rare earths （Sm, Pr, Ce, Nd and La） on the hydrogenation properties ofp-chloronitrobenzene （CNB） over Pt/CNTs catalyst was studied in ethanol at 303 K and normal pressure. The results exhibited that the hydrogenation of p-CNB could be carried out over PtMOx/CNTs catalysts. Both catalytic activities and yields ofp-chloroaniline （CAN） were all improved. PtCeOx/ CNTs catalyst exhibited the best catalytic activity （TOF was 0.47 s^-1） and the highest yield of p-CAN （97.5 mol%）. PtCeOx/CNTs （1.0 wt%） catalyst exhibited good stability on the hydrogenation of p-CNB.展开更多
Let X＊ be a free monoid over an alphabet X and W be a finite language over X. Let S（W） be the Rees quotient X＊/I（W）, where I（W） is the ideal of X＊ consisting of all elements of X＊ that are not subwords of W....Let X＊ be a free monoid over an alphabet X and W be a finite language over X. Let S（W） be the Rees quotient X＊/I（W）, where I（W） is the ideal of X＊ consisting of all elements of X＊ that are not subwords of W. Then S（W） is a finite monoid with zero and is called the discrete syntactic monoid of W. W is called finitely based if the monoid S（W） is finitely based. In this paper, we give some sufficient conditions for a monoid to be non-finitely based. Using these conditions and other results, we describe all finitely based 2-limited words over a three-element alphabet. Furthermore, an explicit algorithm is given to decide that whether or not a 2-limited word in which there are exactly two non-linear letters is finitely based.展开更多
文摘Isovaleraldehyde possesses malty, fruity, cocoa-like odor and is widely used in fruit, chocolate, coffee flavors. The preparation of natural isovaleraldehyde by the Maillard model reaction was studied in this paper. The effects of the ratio of d-glucose/l-leucine, reaction temperature and pH value on the yield of isovaleraldehyde were explored. The optimum conditions were as follows: n(d-glucose):n(l-leucine) = 4, temperature 150 °C, reaction time 3 h, pH 5. The highest yield of isovaleraldehyde obtained was about 32%.
文摘The effect of rare earths （Sm, Pr, Ce, Nd and La） on the hydrogenation properties ofp-chloronitrobenzene （CNB） over Pt/CNTs catalyst was studied in ethanol at 303 K and normal pressure. The results exhibited that the hydrogenation of p-CNB could be carried out over PtMOx/CNTs catalysts. Both catalytic activities and yields ofp-chloroaniline （CAN） were all improved. PtCeOx/ CNTs catalyst exhibited the best catalytic activity （TOF was 0.47 s^-1） and the highest yield of p-CAN （97.5 mol%）. PtCeOx/CNTs （1.0 wt%） catalyst exhibited good stability on the hydrogenation of p-CNB.
基金Supported by National Natural Science Foundation of China (Grant No. 10971086)Mathematical Tianyuan Foundation of China (Grant No. 11126186)+1 种基金Natural Science Foundation of Gansu Province (Grant No.1107RJZA218)Fundamental Research Funds for Central Universities (Grant No. lzujbky-2012-12)
文摘Let X＊ be a free monoid over an alphabet X and W be a finite language over X. Let S（W） be the Rees quotient X＊/I（W）, where I（W） is the ideal of X＊ consisting of all elements of X＊ that are not subwords of W. Then S（W） is a finite monoid with zero and is called the discrete syntactic monoid of W. W is called finitely based if the monoid S（W） is finitely based. In this paper, we give some sufficient conditions for a monoid to be non-finitely based. Using these conditions and other results, we describe all finitely based 2-limited words over a three-element alphabet. Furthermore, an explicit algorithm is given to decide that whether or not a 2-limited word in which there are exactly two non-linear letters is finitely based.
