With the frequent fluctuations of international crude oil prices and China＇s increasing dependence on foreign oil in recent years, the volatility of international oil prices has significantly influenced China domesti...With the frequent fluctuations of international crude oil prices and China＇s increasing dependence on foreign oil in recent years, the volatility of international oil prices has significantly influenced China domestic refined oil price. This paper aims to investigate the transmission and feedback mechanism between international crude oil prices and China＇s refined oil prices for the time span from January 2011 to November 2015 by using the Granger causality test, vector autoregression model, impulse response function and variance decomposition methods. It is demonstrated that variation of international crude oil prices can cause China domestic refined oil price to change with a weak feedback effect. Moreover, international crude oil prices and China domestic refined oil prices are affected by their lag terms in positive and negative directions in different degrees. Besides, an international crude oil price shock has a signif- icant positive impact on domestic refined oil prices while the impulse response of the international crude oil price variable to the domestic refined oil price shock is negatively insignificant. Furthermore, international crude oil prices and domestic refined oil prices have strong historical inheri- tance. According to the variance decomposition analysis, the international crude oil price is significantly affected by its own disturbance influence, and a domestic refined oil price shock has a slight impact on international crude oil price changes. The domestic refined oil price variance is mainly caused by international crude oil price disturbance, while the domestic refined oil price is slightly affected by its own disturbance. Generally, domestic refined oil prices do not immediately respond to an international crude oil price change, that is, there is a time lag.展开更多
The aim of this study was to investigate the effects of concentration of different growth regulators (auxins and cytokinins) on growth and development of banana shoot tips cultured in vitro. Explants were taken from y...The aim of this study was to investigate the effects of concentration of different growth regulators (auxins and cytokinins) on growth and development of banana shoot tips cultured in vitro. Explants were taken from young suckers of field grown plants of var. “Yangambi”. The shoot tips were cultured on MS media supplemented with different concentrations of BAP (0, 2, 4, 6 and 8 mg/l) with or without IAA at concentration of 0.34 mg/l. At the rooting phase, the media was supplemented with different concentrations of IBA (0.1, 0.5, 1.0, 1.5 and 2.0 mg/l) with or without BAP at concentration of 0.2 mg/l. The results indicated that 6.0 mg/l BAP significantly increased the number of shoots formed and the interaction of 6 mg/l BAP with 0.35 mg/l IAA significantly increased the fresh weight. For rooting, 2.0 mg/l IBA was more efficient in number and length of roots produced than all other treatments.展开更多
From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Symplocos cochinchinensis var. philippinensis, 12 compounds were isolated. Spectroscopic analyses of compounds 1 - 3 established their structures to ...From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Symplocos cochinchinensis var. philippinensis, 12 compounds were isolated. Spectroscopic analyses of compounds 1 - 3 established their structures to be megastig-mane glycosides, named symplocosionosides A-C. The absolute structure of 1 was determined by the modified Mosher’s method. Compound 4 was found to be a neolignan glucoside and named symplocosneolignan. The structures of com-pounds 5 and 6, named symplocosins A and B, were elucidated to be the saponins of hederagenin sugar esters. The structures of the remaining known compounds (7 - 12) were identified by comparison of spectroscopic data with those reported in the literature.展开更多
A new diterpenoid was isolated from the bark of Larix olgensis Henry var. koreana Nakai. Its structure was elucidated as 5S, 9S, 10R-labda-8 (17), 13-diene-6a, 15-diol l by spectroscopic methods.
Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.for...Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.fortunei S.Y.Hu transplanting and greening,and has the advantages of no time limit for planting and saving management costs.Based on this,this paper introduced the container seedling double-covering cutting technology for L.cornut a var.fortunei,to provide a reference for the propagation of L.cornut a var.fortunei.展开更多
基金support from the Key Project of National Social Science Foundation of China (NO. 13&ZD159)
文摘With the frequent fluctuations of international crude oil prices and China＇s increasing dependence on foreign oil in recent years, the volatility of international oil prices has significantly influenced China domestic refined oil price. This paper aims to investigate the transmission and feedback mechanism between international crude oil prices and China＇s refined oil prices for the time span from January 2011 to November 2015 by using the Granger causality test, vector autoregression model, impulse response function and variance decomposition methods. It is demonstrated that variation of international crude oil prices can cause China domestic refined oil price to change with a weak feedback effect. Moreover, international crude oil prices and China domestic refined oil prices are affected by their lag terms in positive and negative directions in different degrees. Besides, an international crude oil price shock has a signif- icant positive impact on domestic refined oil prices while the impulse response of the international crude oil price variable to the domestic refined oil price shock is negatively insignificant. Furthermore, international crude oil prices and domestic refined oil prices have strong historical inheri- tance. According to the variance decomposition analysis, the international crude oil price is significantly affected by its own disturbance influence, and a domestic refined oil price shock has a slight impact on international crude oil price changes. The domestic refined oil price variance is mainly caused by international crude oil price disturbance, while the domestic refined oil price is slightly affected by its own disturbance. Generally, domestic refined oil prices do not immediately respond to an international crude oil price change, that is, there is a time lag.
文摘The aim of this study was to investigate the effects of concentration of different growth regulators (auxins and cytokinins) on growth and development of banana shoot tips cultured in vitro. Explants were taken from young suckers of field grown plants of var. “Yangambi”. The shoot tips were cultured on MS media supplemented with different concentrations of BAP (0, 2, 4, 6 and 8 mg/l) with or without IAA at concentration of 0.34 mg/l. At the rooting phase, the media was supplemented with different concentrations of IBA (0.1, 0.5, 1.0, 1.5 and 2.0 mg/l) with or without BAP at concentration of 0.2 mg/l. The results indicated that 6.0 mg/l BAP significantly increased the number of shoots formed and the interaction of 6 mg/l BAP with 0.35 mg/l IAA significantly increased the fresh weight. For rooting, 2.0 mg/l IBA was more efficient in number and length of roots produced than all other treatments.
文摘From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Symplocos cochinchinensis var. philippinensis, 12 compounds were isolated. Spectroscopic analyses of compounds 1 - 3 established their structures to be megastig-mane glycosides, named symplocosionosides A-C. The absolute structure of 1 was determined by the modified Mosher’s method. Compound 4 was found to be a neolignan glucoside and named symplocosneolignan. The structures of com-pounds 5 and 6, named symplocosins A and B, were elucidated to be the saponins of hederagenin sugar esters. The structures of the remaining known compounds (7 - 12) were identified by comparison of spectroscopic data with those reported in the literature.
文摘A new diterpenoid was isolated from the bark of Larix olgensis Henry var. koreana Nakai. Its structure was elucidated as 5S, 9S, 10R-labda-8 (17), 13-diene-6a, 15-diol l by spectroscopic methods.
文摘Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.fortunei S.Y.Hu transplanting and greening,and has the advantages of no time limit for planting and saving management costs.Based on this,this paper introduced the container seedling double-covering cutting technology for L.cornut a var.fortunei,to provide a reference for the propagation of L.cornut a var.fortunei.
