To realize the accurate control of water hammer in pipes by valve stroking, based on basic differenti-al equations of wa......

In this paper,the extremum of second-order directional derivatives,i.e.the gradient of first-order derivatives is discus......

图 G 的 Randi?指数,χ(G),是分子图的一种拓扑指标,它的值可以反映分子的许多物理化学性质.在化学分子中双键是普遍存在的.为此,......