Ursolic acid(UA,3beta-hydroxy-urs-12-en-28-oic acid),a pentacyclic triterpene compound, exists abundantly in the plant kingdom as the major constituent of medicinal herbs. UA has been reported to display a remarkable spectrum of biochemical activities to influence processes capable of controlling cancer development. The pleuripotent anti-tumor activities of UA have stimulated the experts to research actively in this field. This paper summarizes the modification and pharmacological activity of ursolic acid derivatives according to literature and reports both at home and abroad熊果酸(UA,3beta-羟基-乌苏烷型-12-烯-28-羧酸),五环三萜化合物,作为药草的主要成分,存在于丰富的植物王国中.据报道,UA具有广 谱的生物活性,调控和控制肿瘤细胞形成.UA多效性的抗肿瘤活性激发了专家们在这方面的积极研究,现综合国内外文献报道,对熊果酸结构修饰物及其药理活性 进行综述
Water quality management is subject to large uncertainties due to inherent randomness in the natural system and vagueness in the decision-making process. For water quality management optimization models, this means that some model coefficients can be represented by probability distributions, while others can be expressed only by ranges. Interval linear programming (ILP) and risk explicit interval linear programming (REILP) models for optimal load reduction at the watershed scale are developed for the management of Lake Qionghai Watershed, China. The optimal solution space of an ILP model is represented using intervals corresponding to the lower and upper bounds of each decision variable. The REILP model extends the ILP model through introducing a risk function and aspiration levels (lambda(pre)) into the model formulation. The REILP model is able to generate practical solutions and trade-offs through solving a series of submodels, minimizing the risk function under different aspiration levels. This is illustrated in the present study by solving 11 submodels corresponding to different aspiration levels. The results show that the ILP model suffers severe limitations in practical decision support, while the REILP model can generate solutions explicitly relating system performance to risk level. Weighing the optimal solutions and corresponding risk factors, decision makers can develop an efficient and practical implementation plan based directly on the REILP solution.