Maximum Genus of Graphs Embedded in the Klein Bottle;
嵌入在克莱茵瓶上的图的最大亏格
Klein bottle,in term s of[1],is an odd bottle w hich m ay be draw ed but can not be m aked.
在文献［１］中，克莱因瓶被描绘成一种“不可能的画”，即按文［１］的意思，克莱因瓶是一种可以画出来而不能制作的怪瓶。
Only four surfaces are possible for such embedding:the sphere,the torus,the Klein bottle and the projective plane.
这样的嵌入只能在球面、环面、克莱因瓶和射影平面上实现,其五边形面的个数分别为12,0,0和6。
2,6-Diacteylpyridine was synthesized via esterification and the Claisen condensation using 2,6-pyridinedicarboxylic acid as the starting material,with the metallic sodium being used as the base reagent for the first time.
以2,6-吡啶二甲酸为原料,经酯化后以金属钠作为新型碱性试剂,通过克莱森缩合制备出标题化合物,两步反应收率分别高达93。
Ethyl-dibenzoylmethane,which is one of the good light absorbents,was synthesized by using benzoyl acetate and ethyl phenyl ketone as their original raw materials,dibenzoylmethane was obtained through Claisen condensation,and then ethyl-dibenzoylmethane was got by alkylation.
该法以苯甲酸乙酯和苯乙酮为起始原料,经克莱森缩合生成二苯甲酰甲烷,再与溴乙烷进行烷基化反应,最后生成乙基二苯甲酰甲烷,并对合成产物进行结构分析及紫外光吸收性能表征。
