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洪文豪邱正萍宋玲汤自凯 《数学理论与应用》2020,(3):77-84
设G是一个由n个顶点,m条边构成的简单连通图.如果图G所有顶点的度相同,则我们称图G是正则图,反之,称图G是不规则图.对于一个不规则图G,由其不变量定义的度偏差为s(G)=∑_(i=1)^(n)|d_(i)-2m/n|,其中d_(i)表示G的第i个顶点的度.本文给出极大外平面图的度偏差的极大值和极小值,并刻画其对应的极值图. 相似文献
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聚鲁米诺-金属离子复合物膜的电化学发光特性及其分析应用研究 总被引:1,自引:0,他引:1
建立了一种基于电聚合和配位效应构建聚鲁米诺-金属离子复合物膜修饰电极测定尿素的电化学发光分析新方法, 并且提出了一种优化聚鲁米诺电化学发光分析特性的新思路. 在最佳条件下, 增敏电化学发光信号与尿素的质量浓度在2.0×10-9—1.0×10-7 g/mL 范围内呈线性关系, 检出限为1.7×10-10 g/mL. 相似文献
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A novel polymeric Pr2Cu3 complex of iminodiacetic acid (H2L1=NH{CH2COOH}2) [Pr2Cu3(L1)6]n , 1, has been synthesized and structurally characterized. The title complex Pr2Cu3O24N6C24H30 (Mr=1258.97) crystallized in trigonal space group Pc1 (No. 165) with a = 13.424(4), c=14.752(6)(); V=2303(1)()3; F(000)=1226; λ(MoKα)=35.2 cm-1; Dc=1.820 g.cm-3; Z=2. The final R and Rw are 0.072 and 0.081 respectively for 1412 reflections with I>3σ(I). In crystal 1, the Pr3+ ion is nine-coordinated by 6 O atoms from three bidentate chelating carboxylate groups and 3 O atoms from three anti-anti bridging carboxylic groups of six L1 ligands; the Cu2+ ion is six-coordinated by 4 O and 2 N atoms from two pentadentate L1 ligands. Each pair of Pr(Ⅲ) atoms is bridged by three L1 ligands, each of which also chelates with one copper(Ⅱ) ion, thus forming a Pr2Cu3 cluster unit. Such cluster units are cross-linked by flexible L1 ligands into a three-dimensional coordination framework. 相似文献
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提出了一种基于接收方数据流驱动的标签分配机制构建MPLS域中LSP组播树的方案,给出了MPLS网络中成员加入和退出组播组以及组播包的复制和转发算法。并且对网络仿真工具NS的MPLS模块进行扩展以支持所提出的组播算法。性能分析和仿真实验结果表明:与传统组播相比,MPLS的组播技术能利用MPLS的快速转发能力有效地减少组播包的传输时延。 相似文献
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