Chiral sulfonamides derived from(d)-10-camphorsulfonyl chloride and chiral amines were prepared and used in the copper-catalyzed conjugate addition of organometallic reagents to enones.The chiral sulfonamides/CuCN cat...Chiral sulfonamides derived from(d)-10-camphorsulfonyl chloride and chiral amines were prepared and used in the copper-catalyzed conjugate addition of organometallic reagents to enones.The chiral sulfonamides/CuCN catalysts provided high catalytic activity and moderate enantioselectivity in the conjugate addition of diethylzinc to 2-cyclohexenone and 2-cyclohepteneone,but low enantioselectivity to the 2-cyclopentenone and acyclic enones.展开更多
文摘讨论了人工神经网络在金融汇率预报中的应用。其中介绍了广义交互验证 (GeneralizedCrossValidation)法如何应用于确定神经网络中隐层的个数 ,并用实例说明了该方法甚至对复杂的非线性函数也可以得到很好的逼近。详细地介绍了运用人工神经网络作两周向前汇率预报的计算步骤。其平均相对误差 (APE)为 10 E - 3的数量级 ,而国际上通用的状态空间模型及Box Jen kins的ARIMA模型的预报误差都在 10 E -
文摘Chiral sulfonamides derived from(d)-10-camphorsulfonyl chloride and chiral amines were prepared and used in the copper-catalyzed conjugate addition of organometallic reagents to enones.The chiral sulfonamides/CuCN catalysts provided high catalytic activity and moderate enantioselectivity in the conjugate addition of diethylzinc to 2-cyclohexenone and 2-cyclohepteneone,but low enantioselectivity to the 2-cyclopentenone and acyclic enones.