晚稻品种密度肥料五因素正交试验

我们褚石大队科技组搞稻麦油菜络麻的育种工作已有二十多年的历史.文化大革命以来,我组育种工作蓬勃发展,已育成良种二十多个,为国家和兄弟社队提供良种二百多万斤.每年有几百个品种和品系要进行鉴定和对比试验.过去,搞品种试验,一向沿用单因素随机区组法,在相同的栽培条件下对比各品种的优劣.因此对不同品种要求不同的     

双圈图的零度与其匹配数之间的关系

Let G be a graph with n(G) vertices and m(G) be its matching number.The nullity of G,denoted by η(G),is the multiplicity of the eigenvalue zero of adjacency matrix of G.It is well known that if G is a tree,then η(G) = n(G)-2m(G).Guo et al.[Jiming GUO,Weigen YAN,Yeongnan YEH.On the nullity and the matching number of unicyclic graphs.Linear Alg.Appl.,2009,431:1293 1301]proved that if G is a unicyclic graph,then η(G)equals n(G)-2m(G)-1,n(G)-2m(G),or n(G)-2m(G) +2.In this paper,we prove that if G is a bicyclic graph,then η(G) equals n(G)-2m(G),n(G)-2m(G)±1,n(G)-2m(G)±2or n(G)-2m(G) + 4.We also give a characterization of these six types of bicyclic graphs corresponding to each nullity.