The localized differential quadrature (LDQ) method is a numerical technique with high accuracy for solving most kinds of nonlinear problems in engineering and can overcome the difficulties of other methods (such as di...The localized differential quadrature (LDQ) method is a numerical technique with high accuracy for solving most kinds of nonlinear problems in engineering and can overcome the difficulties of other methods (such as difference method) to numerically evaluate the derivatives of the functions.Its high efficiency and accuracy attract many engineers to apply the method to solve most of the numerical problems in engineering.However,difficulties can still be found in some particular problems.In the following study,the LDQ was applied to solve the Sod shock tube problem.This problem is a very particular kind of problem,which challenges many common numerical methods.Three different examples were given for testing the robustness and accuracy of the LDQ.In the first example,in which common initial conditions and solving methods were given,the numerical oscillations could be found dramatically;in the second example,the initial conditions were adjusted appropriately and the numerical oscillations were less dramatic than that in the first example;in the third example,the momentum equation of the Sod shock tube problem was corrected by adding artificial viscosity,causing the numerical oscillations to nearly disappear in the process of calculation.The numerical results presented demonstrate the detailed difficulties encountered in the calculations,which need to be improved in future work.However,in summary,the localized differential quadrature is shown to be a trustworthy method for solving most of the nonlinear problems in engineering.展开更多
The study on the behaviourof potassium, phosphate and trace elements, Fe, Mn, Cu and Zn, in the rhizosphere of different varieties of flue-cured tobacco (Nicotiana tabacum L.) with high and low potassium application r...The study on the behaviourof potassium, phosphate and trace elements, Fe, Mn, Cu and Zn, in the rhizosphere of different varieties of flue-cured tobacco (Nicotiana tabacum L.) with high and low potassium application rate with rhizobag technique showed that soil available K, soil available P, and slow available K was in depletion status, whereas DTPA extractable Fe, Mn, Zn and Cu accumulated obviously in rhizosphere. The depletion and accumulation rates of mineral nutrients differed in degree with K application rate, soil type, and tobacco variety. The content of a vailable K in both rhizosphere and bulk soil and K concentration in tobacco leaf increased significantly, and the available P in rhizosphere dropped with more K applicatin. The DTPA-Fe content of red soil much lower in pH was higher than that of calcareous soil in bulk soil. But the DTPA-Fe content of calcareous soil was much higher than that of red soil in rhizosphere, which was considered perhaps to be mainly related to releasing of Fe phytosiderophore. Nitrate could increase depletion of available K in rhizosphere and also soil pH in comparison with ammonium.展开更多
To solve the problem of lack of water in arid areas and barren soil in the process of ecological restoration, the growth and drought resistance of Sainfoin （Onobrychis vidifolia Scop.） was studied by inoculation of ...To solve the problem of lack of water in arid areas and barren soil in the process of ecological restoration, the growth and drought resistance of Sainfoin （Onobrychis vidifolia Scop.） was studied by inoculation of AMF （arbuscular rnycorrhizal fungi）, under drought stress. The results show that the inoculation of AMF can significantly improve the growth and mycorrhizal infection rate of Sainfoin and accelerate the absorption of water and nutrients by the roots compared with uninoculated plants. On the 40th day under drought stress, the relative water content, total nitrogen and total phosphorus content of the leaves of inoculated plants increased by 7.27%, 4.21% and 2.40%, respectively, the osmotic adjustment property in plant cells was improved, the protective enzyme system was improved and membrane lipid peroxida- tion was reduced. The inoculation of AMF can slow down the damage from drought, improve the drought resistance of Sainfoin, and will be of great significance to the ecologic restoration in arid areas.展开更多
We investigated the chemical constituents of the fibrous root of Ophiopogon japonicus and their cytotoxicities against Hela and Hep2 cells.Ten compounds were purified by various chromatographic techniques.Their struct...We investigated the chemical constituents of the fibrous root of Ophiopogon japonicus and their cytotoxicities against Hela and Hep2 cells.Ten compounds were purified by various chromatographic techniques.Their structures were identified as 2 - hydroxylophiopogonone A（1）,5,8-dimethoxy-6-methyl-7-hydroxy-3-（2 -hydroxy-4 -methoxybenzyl） chroman-4-one（2）,5,7- dihydroxy-6,8-dimethyl-3-（4 -hydroxybenzyl） chroman-4-one（3）,7,4 -dihydroxy-5-methoxyflavanone（4）,N-trans-coumaroyltyramine （5）,N-trans-coumaroyloctopamine（6）, N-trans-feruloyltyramine （7）, 4-hydroxycinnamic acid （8）, caffeic acid （9）, and ferulic acid （10） on the basis of spectroscopic analyses. Compounds 4, 6, 7, 9, 10 were obtained from this genus for the first time. The cytotoxic activities of 1, 2, 4, 5, 6, 7, 9 and 10 against Hela and Hep2 cells are described.展开更多
文摘The localized differential quadrature (LDQ) method is a numerical technique with high accuracy for solving most kinds of nonlinear problems in engineering and can overcome the difficulties of other methods (such as difference method) to numerically evaluate the derivatives of the functions.Its high efficiency and accuracy attract many engineers to apply the method to solve most of the numerical problems in engineering.However,difficulties can still be found in some particular problems.In the following study,the LDQ was applied to solve the Sod shock tube problem.This problem is a very particular kind of problem,which challenges many common numerical methods.Three different examples were given for testing the robustness and accuracy of the LDQ.In the first example,in which common initial conditions and solving methods were given,the numerical oscillations could be found dramatically;in the second example,the initial conditions were adjusted appropriately and the numerical oscillations were less dramatic than that in the first example;in the third example,the momentum equation of the Sod shock tube problem was corrected by adding artificial viscosity,causing the numerical oscillations to nearly disappear in the process of calculation.The numerical results presented demonstrate the detailed difficulties encountered in the calculations,which need to be improved in future work.However,in summary,the localized differential quadrature is shown to be a trustworthy method for solving most of the nonlinear problems in engineering.
基金Project supported by the National Natural Science Foundation of ChinaChina National Tobacco Corporation.
文摘The study on the behaviourof potassium, phosphate and trace elements, Fe, Mn, Cu and Zn, in the rhizosphere of different varieties of flue-cured tobacco (Nicotiana tabacum L.) with high and low potassium application rate with rhizobag technique showed that soil available K, soil available P, and slow available K was in depletion status, whereas DTPA extractable Fe, Mn, Zn and Cu accumulated obviously in rhizosphere. The depletion and accumulation rates of mineral nutrients differed in degree with K application rate, soil type, and tobacco variety. The content of a vailable K in both rhizosphere and bulk soil and K concentration in tobacco leaf increased significantly, and the available P in rhizosphere dropped with more K applicatin. The DTPA-Fe content of red soil much lower in pH was higher than that of calcareous soil in bulk soil. But the DTPA-Fe content of calcareous soil was much higher than that of red soil in rhizosphere, which was considered perhaps to be mainly related to releasing of Fe phytosiderophore. Nitrate could increase depletion of available K in rhizosphere and also soil pH in comparison with ammonium.
基金provided by the Science and Technology Major Project of Shanxi Province (No. 20121101008), is gratefully acknowledged
文摘To solve the problem of lack of water in arid areas and barren soil in the process of ecological restoration, the growth and drought resistance of Sainfoin （Onobrychis vidifolia Scop.） was studied by inoculation of AMF （arbuscular rnycorrhizal fungi）, under drought stress. The results show that the inoculation of AMF can significantly improve the growth and mycorrhizal infection rate of Sainfoin and accelerate the absorption of water and nutrients by the roots compared with uninoculated plants. On the 40th day under drought stress, the relative water content, total nitrogen and total phosphorus content of the leaves of inoculated plants increased by 7.27%, 4.21% and 2.40%, respectively, the osmotic adjustment property in plant cells was improved, the protective enzyme system was improved and membrane lipid peroxida- tion was reduced. The inoculation of AMF can slow down the damage from drought, improve the drought resistance of Sainfoin, and will be of great significance to the ecologic restoration in arid areas.
基金Program for Changjiang Scholar and Innovative Team in University(Grant No.985-2-063-112).
文摘We investigated the chemical constituents of the fibrous root of Ophiopogon japonicus and their cytotoxicities against Hela and Hep2 cells.Ten compounds were purified by various chromatographic techniques.Their structures were identified as 2 - hydroxylophiopogonone A（1）,5,8-dimethoxy-6-methyl-7-hydroxy-3-（2 -hydroxy-4 -methoxybenzyl） chroman-4-one（2）,5,7- dihydroxy-6,8-dimethyl-3-（4 -hydroxybenzyl） chroman-4-one（3）,7,4 -dihydroxy-5-methoxyflavanone（4）,N-trans-coumaroyltyramine （5）,N-trans-coumaroyloctopamine（6）, N-trans-feruloyltyramine （7）, 4-hydroxycinnamic acid （8）, caffeic acid （9）, and ferulic acid （10） on the basis of spectroscopic analyses. Compounds 4, 6, 7, 9, 10 were obtained from this genus for the first time. The cytotoxic activities of 1, 2, 4, 5, 6, 7, 9 and 10 against Hela and Hep2 cells are described.
