青蒿茎段愈伤组织的诱导及植株再生

为了建立青蒿的快速繁殖与遗传育种体系,以青蒿茎段为外植体,研究其离体培养及试管苗再生途径.结果表明,青蒿基段愈伤组织诱导培养基为MS 6-BA1.0mg·L-1 NAA1.0mg·L-1,分化培养为MS 6-BA3.0·L-1 NAA0.5 mg·L-1,生根培养基为MS NN1.5mg·L-1.     

多阶段分散化投资组合效率估计

The existing multi-period portfolio diversification performance evaluation models are mainly divided into two categories. The first category is to build a performance evaluation model based on the return rate of portfolio at each period. The other category is to evaluate portfolio performance by using efficient frontier. However, the former ignores the dynamic relationship among the time periods, while the latter has limitations when there exists friction in financial market. To address this problem, the actual investment of the input-output process was clarified and defined, and the definition of multi-period portfolio efficiency were given based on the distance between portfolio under evaluation and its projection point on the efficient frontier. Under the multi-period mean-variance theoretical framework, the middle connection condition in the multi-period portfolio evaluation problem was derived by using the wealth dynamic process, so as to build a two-period portfolio efficiency estimation model under different orientation. Since the above-mentioned middle connection condition is random, it not workable in actual evaluation. Therefore, in this paper, the first moment and second moment of the above random conditions were used to replace the original one, and another kind of two-period portfolio efficiency estimation model was built. The numerical analyses show that this proposed model is effective.