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261.
UsingX-bounding (lower bounds by Laplacians with mixed boundary conditions and discrete analogs), we obtain the Lifschitz exponent at the bottom of the spectrum for random operators of typeH =T+V , withT a (periodic) generator of a positivity-preserving semigroup, extending results by Kirsch and Simon.  相似文献   
262.
A model classical fluid is constructed by assuming that the direct correlation functionc(r – r) is independent of any applied external field. Thermodynamic consistency requires thatc(r – r) 0, and permits explicit representation of the model by a many-body interaction potential. In the canonical ensemble, the model shows a phase transition to an infinite density condensed phase, but in the grand canonical ensemble only an anomalous transition to zero density vapor is found to stably exist.  相似文献   
263.
A generalizedO(n) matrix version of the classical Heisenberg model, introduced by Fuller and Lenard as a classical limit of a quantum model, is solved exactly in one dimension. The free energy is analytic and the pair correlation functions decay exponentially for all finite temperatures. It is shown, however, that even for a finite number of spins the model has a phase transition in then limit. The transition features a specific heat jump, zero long-range order at all temperatures, and zero correlation length at the critical point. The Curie-Weiss version of the model is also solved exactly and shown to have standard mean-field type behavior for all finiten and to differ from the one-dimensional results in then limit.  相似文献   
264.
A low-temperature expansion for the free energy density of lattice animals is derived. Analysis of the series yields a collapse transition temperature ofT c - 0.54, in close agreement with previous estimates. It is demonstrated that p,k, the number ofp-particle,p-bond animals, obeys the asymptotic scaling law log p,k pg(k/p) + o(p). The low-temperature series and numerical data are used to estimate the scaling function.  相似文献   
265.
The spherical-model limitn of then-vector model in a random field, with either a statistically independent distribution or with long-range correlated random fields, is studied to demonstrate the correctness of the replica method in which then and replica limits limits are interchanged, provided the replica and thermodynamic limits are taken in the right order, in the case of long-range correlated random fields. A scaling form for the two-point correlation function relevant to the first-order phase transition below the lower critical dimensionality of the random system is also obtained.  相似文献   
266.
本文用变分过渡态理论,首次对无鞍点的释能反应O+CS→CO+S、O+CO→CO+O和S+CS→CS+S进行了动力学研究,考察了反应动力学瓶颈区性质,计算了反应的速度常数,并将O+CS反应的速度常数值与实验值及经典轨迹计算结果进行了比较,三者基本相符.  相似文献   
267.
    
Under the influence of perpendicularly applied positive electro-static field less than 103V/cm to silk fibron textiles, at the high frequency side of the C2–O bending reflection band (450350 cm–1), effect of step creation and step annihilation of the C2–O pseudo dending bands was induced in three stages at 600450 cm–1 region IR spectroscopically relating to the stepnized statistical transfer of the unbonded 2P2, electrons in carbon which present with density of 4.0×1014/cm2 in the surface mono-layer of silk fibroin from the states formed in (–C1–C2–N–)m spiral chains upto the pseudo-bending states formed in C2–O bondings. Fine 90 steps measured overlapping on these four types of C2–O reflection bands were analysed as to consist four step series and they were shown as,y = A·Jm + B cm–1 with A=20, B=521, m=0.55 and J=1, 2...18 for the B-series.And with A=39, B=283, m=0.63 and J=1, 2 ...17 for the C-series.y J = A·J + B cm–1 with A=11.42, B=201 and J=1, 2...13, for the D-series. And, stepnized C2–O bending bands including that of permanent oscillators and pseudo-bending oscillators induced by the effect of transfer of the unbonded 2P2 electrons in carbon atoms were shown as, EN=A·N2+B·N+C (eV) with A=–1.50×10–3, B=1.65×10–2 and C=2.4×10–2.  相似文献   
268.
用密度泛函理论(DFT) B3LYP方法, 在6-311+G*基组下, 对3-羟基哒嗪及其CH3, NO2和Cl取代衍生物分子醇式和酮式结构互变异构化反应进行了研究, 优化化合物的几何构型, 寻找反应的过渡态, 通过振动分析和内禀反应坐标(IRC)分析加以证实, 计算了反应的活化能. 结果表明, 3(2H)-哒嗪酮及其带取代基的衍生物不论是单体, 还是相对应的二聚体, 比其相对应的异构体能量低, 表明在通常情况下是以3(2H)-哒嗪酮及其衍生物形式稳定存在的, 这与前人通过实验数据对3-羟基哒嗪互变异构体的比率进行预测的结果是一致的. 根据计算结果讨论了异构化反应的机理.  相似文献   
269.
In this review anti-metatype antibodies are described invoking new principles in immunoassay development. Anti-metatype antibodies are immunological reagents specific for the conformation of the liganded antibody active site which do not interact with bound ligand or unliganded antibody. Relationships between anti-metatype antibody reactivity and the ligand-induced conformational state of monoclonal antibodies are reviewed with emphasis on the fluorescein hapten as a small molecule model system. One characteristic result of the interaction of anti-metatype antibodies with liganded antibodies is a significant delay in the dissociation rate (k2) of the ligand bound within the primary immune complex. The latter is an important consideration for assay development. Polyclonal and monoclonal anti-metatype antibody reagents are characterized in terms of their differential effects on the ligand dissociation rate. Anti-metatype antibody reactivity is further discussed in terms of protein-protein specificity patterns and relative interactions with idiotype-family members, structural derivatives, and site-specific mutants. Incorporation of principles inherent in the anti-metatype concept and their application to assay development are summarized.Abbreviations D2O deuterium oxide - Fab 50 kd antibody fragment containing VHCH1 + VLCL domains - FITC(I) fluorescein isothiocyanate (isomer I) - Fv 26 kd fragment of the antibody molecule containing the variable domains of the H and L chains - Ig immunoglobulin - IgG immunoglobulin G with a mol. wt. of 150 kd. - IgM immunoglobulin M with a mol. wt. of 106d - Id idiotype - Ka antibody affinity (k1/k2) in M–1 - k1 second order rate of ligand association in M–1s–1 - k2 first order rate of ligand dissociation in s–1 - KD dissociation constant or the reciprocal of the affinity constant (1/Ka) - Mab monoclonal antibody - Met metatype - NMR nuclear magnetic resonance - SCA single chain Fv derivative containing a synthetic linker between the two variable domains - VH variable domain of the antibody H chain - VL variable domain of the antibody L chain  相似文献   
270.
本文对不同组成的对苯二甲酸(TPA),对羟基苯甲酸(PHBA),联苯二酚(BP),间苯二甲酸(IPA)共聚酯采用热台偏光显微镜、电子显微镜、X-射线衍射、激光小角散射、差热等技术进行了研究.实验结果表明,在一定的组成范围内共聚酯熔体有很好的液晶性.重点讨论了分子组成、转变行为、液晶性的关系,并对液晶相的形态结构进行了表征.  相似文献   
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