Plant invasion refers to the phenomenon that some plants grow too fast due to they are far away from the original living environment or predators, affecting the local environment. With the development of tourism and t...Plant invasion refers to the phenomenon that some plants grow too fast due to they are far away from the original living environment or predators, affecting the local environment. With the development of tourism and trade, the harm caused by invasive plants will be more and more serious. Therefore, it is necessary to ex- plore an effective method for controlling plant invasion through qualitative and quan- titative research. In this paper, the models were established for the early and late harmful plant invasion control. The huge computation was completed by the com- puter programming to obtain the optimal solutions of the models. The real meaning of the optimal solution was further discussed. Through numerical simulations and discussion, it could be concluded that the quantitative research on the invasive plant control had a certain application value.展开更多
An optimal allocation of earth is of great significance to reduce the project cost and duration in the construction of rock-fill dams. The earth allocation is a dynamic system affected by various time-space constraint...An optimal allocation of earth is of great significance to reduce the project cost and duration in the construction of rock-fill dams. The earth allocation is a dynamic system affected by various time-space constraints. Based on previous studies, a new method of optimizing this dynamic system as a static one is presented. In order to build a generalized and flexible model of the problem, some man-made constraints were investigated in building the mathematic model. Linear programming and simplex method are introduced to solve the optimization problem of earth allocation. A case study in a large-scale rock-fill dam construction project is presented to demonstrate the proposed method and its successful application shows the feasibility and effectiveness of the method.展开更多
Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important pharmacological properties, such as anti-cancer and anti-HIV activities. In order to obtain derivatives potentia...Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important pharmacological properties, such as anti-cancer and anti-HIV activities. In order to obtain derivatives potentially useful for detailed pharmacological studies, betulinic acid derivatives were synthesized by reaction of betulinic acid with benzoyl chloride and with acetic anhydride using lipase as catalyst. Enzyme-catalyzed of betulinic acid with benzoyl chloride converted betulinic acid into 3β-benzoil-lup-20（29）-ene-28-oic acid ester （BCL） whereas with acetic anhydride converted betulinic acid into 3β-acetoxy-lup-20（29）-ene-28-oic acid ester （BAA）. The BAA then underwent further reaction with l-decanol to produce 3β-acetoxy-lup-20（29）-ene-28 decanoate （BAAD）. Betulinic acid derivatives prepared were tested for cytotoxic activity on three cancer cell lines in vitro： all tested compounds showed stronger cytotoxic activity than betulinic acid,展开更多
文摘Plant invasion refers to the phenomenon that some plants grow too fast due to they are far away from the original living environment or predators, affecting the local environment. With the development of tourism and trade, the harm caused by invasive plants will be more and more serious. Therefore, it is necessary to ex- plore an effective method for controlling plant invasion through qualitative and quan- titative research. In this paper, the models were established for the early and late harmful plant invasion control. The huge computation was completed by the com- puter programming to obtain the optimal solutions of the models. The real meaning of the optimal solution was further discussed. Through numerical simulations and discussion, it could be concluded that the quantitative research on the invasive plant control had a certain application value.
文摘An optimal allocation of earth is of great significance to reduce the project cost and duration in the construction of rock-fill dams. The earth allocation is a dynamic system affected by various time-space constraints. Based on previous studies, a new method of optimizing this dynamic system as a static one is presented. In order to build a generalized and flexible model of the problem, some man-made constraints were investigated in building the mathematic model. Linear programming and simplex method are introduced to solve the optimization problem of earth allocation. A case study in a large-scale rock-fill dam construction project is presented to demonstrate the proposed method and its successful application shows the feasibility and effectiveness of the method.
文摘Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important pharmacological properties, such as anti-cancer and anti-HIV activities. In order to obtain derivatives potentially useful for detailed pharmacological studies, betulinic acid derivatives were synthesized by reaction of betulinic acid with benzoyl chloride and with acetic anhydride using lipase as catalyst. Enzyme-catalyzed of betulinic acid with benzoyl chloride converted betulinic acid into 3β-benzoil-lup-20（29）-ene-28-oic acid ester （BCL） whereas with acetic anhydride converted betulinic acid into 3β-acetoxy-lup-20（29）-ene-28-oic acid ester （BAA）. The BAA then underwent further reaction with l-decanol to produce 3β-acetoxy-lup-20（29）-ene-28 decanoate （BAAD）. Betulinic acid derivatives prepared were tested for cytotoxic activity on three cancer cell lines in vitro： all tested compounds showed stronger cytotoxic activity than betulinic acid,
