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Frederick L. Hedberg Patricia M. Lindley Charles Y-C. Lee Ivan J. Goldfarb 《Journal of polymer science. Part A, Polymer chemistry》1982,20(11):3069-3078
The Synthesis of 3,3′-bis(4-[3-ethynylphenoxy]phenyl)-7,7′-bis(phenylethynyl)-2,2′-diphenyl-6,6′-biquinoxaline (I) was accomplished by the reaction of 2,2′-bis(phenylethynyl)-5,5′-diaminobenzidine (II) and 4-(3-ethynylphenoxy)benzil. Thermal analysis of I indicated a softening temperature of 107°C, followed by an exotherm above 150°C that corresponded to a independent crosslinking reaction of the terminal acetylene groups and an intramolecular cycloaddition (IMC) reaction of the 2,2′-bis(phenylethynyl)biphenyl moieties. In the synthetic work substantial improvements were made in the synthesis of II. The sample of I was cured at 200°C and the maximum partially cured transition temperature attained was 280°C. A sample of 3,3′-bis(4,[3-ethynylphenoxy]phenyl)-2,2′-diphenyl-6,6′-biquinoxaline (IV) was similarly tested as a model without IMC capability and its corresponding value was 250°C. The difference between these two values is discussed briefly. 相似文献
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The difference between strong and weak nonlinear systems is discussed. A classification of strong nonlinearities is given. It is based on the divergence or inanity of series expansions of the equation of state commonly used in the study of weak nonlinear phenomena. Such power or functional series cannot be used in three cases: (i) if the equation of state contains a singularity; (ii) if the series diverges for strong disturbances; (iii) if the linear term is absent, and higher nonlinearity dominates. Strong nonlinearities are known in acoustics, optics, mechanics and in quantum field theory. Mathematical models, solutions and observed phenomena are presented. For example, an equation of Heisenberg type and its generalization for strongly nonlinear wave system are given. In particular, exact solutions of new “quadratically cubic” Burgers and Riemann-Hopf equations are discovered. 相似文献
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Nonlinear Dynamics - Brand-new equations which can be regarded as modifications of Khokhlov–Zabolotskaya–Kuznetsov or Ostrovsky–Vakhnenko equations are suggested. These equations... 相似文献
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Stebelkov V. Elantyev I. Hedberg M. Wallenius M. Fauré A.-L. 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):417-423
Journal of Radioanalytical and Nuclear Chemistry - From the 16 laboratories participating in CMX-4, three laboratories (Buonarroti, Matisse, and Pollock) have utilized secondary ion mass... 相似文献
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The molecular structure of gaseous 2-cyclopentene-1,4-dione has been studied by electron diffraction. The molecule is planar to within the experimental error. The results obtained for some of the more important parameters with estimated uncertainties of 2σ are r(C-H) = 1.093 Å (0.013), r(C0) = 1.208 Å (0.002), r(CC) = 1.341 Å (0.005), r(CH-CO) = 1.493 Å (0.005), r(CO-CH2) = 1.525 Å (0.005), ∠CC-C = 110.4° (0.3), ∠CH-CO = 124.9° (1.1), ∠CC-H. = 118.7° (5.8), ∠H-C-H = 113.2° (8.7) l(C-H) = 0.0853 A (0.0113), l(CO) = 0.0428 Å (0.0021), l(CC) = 0.0448 Å (0.0037) and l(C-C) = 0.0561 Å (0.0029). The structure is discussed in connection with the structures of related molecules. 相似文献
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A simple mechanical system containing a low-frequency vibration mode andset of high-frequency acoustic modes is considered. The frequencyresponse is calculated. Nonlinear behaviour and interaction betweenmodes is described by system of functional equations. Two types ofnonlinearities are taken into account. The first one is caused by thefinite displacement of a movable boundary, and the second one is thevolume nonlinearity of gas. New mathematical models based on nonlinearequations are suggested. Some examples of nonlinear phenomena arediscussed on the base of derived solutions. 相似文献
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