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951.
952.
Jan Svoboda Jan Sedláček Jiří Zedník Gita Dvořáková Olga Trhlíková Dana Rédrová Hynek Balcar Jiří Vohlídal 《Journal of polymer science. Part A, Polymer chemistry》2008,46(8):2776-2787
3‐Ethynylthiophene (3ETh) was polymerized with Rh(I) complexes: [Rh(cod)acac], [Rh(nbd)acac], [Rh(cod)Cl]2, and [Rh(nbd)Cl]2 (cod is η2:η2‐cycloocta‐1,5‐diene and nbd η2:η2‐norborna‐2,5‐diene), used as homogeneous catalysts and with the last two complexes anchored on mesoporous polybenzimidazole (PBI) beads: [Rh(cod)Cl]2/PBI and [Rh(nbd)Cl]2/PBI used as heterogeneous catalysts. All tested catalyst systems give high‐cis poly(3ETh). In situ NMR study of homogeneous polymerizations induced with [Rh(cod)acac] and [Rh(nbd)acac] complexes has revealed: (i) a transformation of acac ligands into free acetylacetone (Hacac) occurring since the early stage of polymerization, which suggests that this reaction is part of the initiation, (ii) that the initiation is rather slow in both of these polymerization systems, and (iii) a release of cod ligand from [Rh(cod)acac] complex but no release of nbd ligand from [Rh(nbd)acac] complex during the polymerization. The stability of diene ligand binding to Rh‐atom in [Rh(diene)acac] catalysts remarkably affects only the molecular weight but not the yield of poly(3ETh). The heterogeneous catalyst systems also provide high‐cis poly(3ETh), which is of very low contamination with catalyst residues since a leaching of anchored Rh complexes is negligible. The course of heterogeneous polymerizations is somewhat affected by limitations arising from the diffusion of monomer inside catalyst beads. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2776–2787, 2008 相似文献
953.
Olga S. Jarrett 《School science and mathematics》1998,98(4):181-187
Research suggests that teacher preparation courses should model hands-on activities promoting positive attitudes toward science. This study investigated the qualities of activities in a field-based science methods course that motivate preservice elementary teachers to implement them in their own classrooms. Ratings of the activities as fun, interesting, and having a high potential for learning were highly correlated, and the preservice teachers predicted that they would more likely implement activities they rated high on these qualities. A comparison of activities ranked high and low in fun suggests that activities ranked high tended to be exploratory in nature, taught process skills in context, enabled the preservice teachers to experience something new in a nonthreatening way, and promoted social interactions. 1 相似文献
954.
Vladimir N. Chernega Olga V. Man’ko Vladimir I. Man’ko Oleg V. Pilyavets Vadim G. Zborovskii 《Journal of Russian Laser Research》2006,27(2):132-166
Spin states are studied in the tomographic-probability representation. The standard probability distribution of spin projection
onto a direction in space is used instead of the spinor or the density matrix to identify the quantum state. The Shannon entropy
and information are associated with the spin tomographic probability. A short review of the probability-theory notions is
presented. Analysis of tomographic entropy and tomographic information for the Werner state is considered. The probability
representation is used to describe a spin-3/2 particle and two qubits. The connection of tomographic entropy with the von
Neumann entropy is discussed. 相似文献
955.
In this paper we consider the problem of characterizing the invariant factors of three matrices AB, and C, such that AB — C Our matrices have entries over a principal ideal domain or over a local domain. In Section 2 we show that this problem is localizablc
The above problem lias a well-known solution in terms of Littlewood-Richardson sequences. We introduce the concept of a matrix realization of a Littlewood-Richardson sequence. The main result is an explicit construction of a sequence of matrices which realizes a previously given Littlewood Richardson sequence. Our methods offer a matrix theoretical proof of a well-known result of T, Klein on extensions of p-modules. 相似文献
The above problem lias a well-known solution in terms of Littlewood-Richardson sequences. We introduce the concept of a matrix realization of a Littlewood-Richardson sequence. The main result is an explicit construction of a sequence of matrices which realizes a previously given Littlewood Richardson sequence. Our methods offer a matrix theoretical proof of a well-known result of T, Klein on extensions of p-modules. 相似文献
956.
957.
Our earlier methods of interpretation of the resonances in ion-ion scattering (such as 12C + 12C, 12C + 16O, or 16O + 16O where they appear both experimentally and via optical-model calculations) in terms of nuclear surface waves are applied to the case of α-40Ca scattering. The optical-model resonance results of Brink et al. are here extended in order to render them suitable for a surface-wave picture as well. Recent experimental results on 12C + 12C scattering are used to demonstrate the existence of surface waves of both Rayleigh and whispering gallery type in this system. 相似文献
958.
Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen‐Dependent Photodynamic Cancer Therapy 下载免费PDF全文
Dr. Oleg Babii Dr. Sergii Afonin Prof. Liudmyla V. Garmanchuk Dr. Viktoria V. Nikulina Tetiana V. Nikolaienko Olha V. Storozhuk Dmytro V. Shelest Dr. Olga I. Dasyukevich Prof. Liudmyla I. Ostapchenko Dr. Volodymyr Iurchenko Dr. Sergey Zozulya Prof. Anne S. Ulrich Prof. Igor V. Komarov 《Angewandte Chemie (International ed. in English)》2016,55(18):5493-5496
Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene‐derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light‐sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV‐generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light. 相似文献
959.
The choice of appropriate density functional for the calculation of static first hyperpolarizability of azochromophores and stacking dimers 下载免费PDF全文
Olga D. Fominykh Anastasiya V. Sharipova Marina Yu. Balakina 《International journal of quantum chemistry》2016,116(2):103-112
The effect of the stacked azo‐chromophore dimer formation on the values of static first hyperpolarizability is studied in the framework of the DFT‐based approach; calculations were also performed at the MP2 level. A number of dispersion‐corrected density functionals—В97D, ωВ97X‐D, and M06‐2X—is tested to calculate the structure of the dimer, the value of binding energy, and molecular nonlinear optical characteristics. According to the QTAIM analysis, the presence of bond critical points is revealed in the intermolecular region, the signs and values of topological characteristics giving evidence for the noncovalent van der Waals interaction between the chromophores. The formation of stacks results in moderate increase of dimer static first hyperpolarizability as compared to that of a single chromophore, the effect depending on the relative shift of the chromophores in dimer. In a special case of greatly shifted chromophores, this enhancement of the first hyperpolarizability becomes appreciable and achieves 72%. © 2015 Wiley Periodicals, Inc. 相似文献
960.
Olga A. Simakova Pavel A. Simonov Anatoly V. Romanenko Irina L. Simakova 《Reaction Kinetics and Catalysis Letters》2008,95(1):3-12
Pd/Sibunit catalysts were prepared by deposition of palladium hydroxide onto the support surface in an alkaline medium. It
was found that the palladium distribution throughout the catalyst grain, and the dispersion of Pd particles depend on (i) the order of the addition of H2PdCl4 and Na2CO3 to carbon suspension, (ii) Na2CO3 to H2PdCl4 ratio, and (iii) aging time of the mixture H2PdCl4 + Na2CO3 before its addition to the carbon. The catalysts were tested in the hydrogenation of cyclohexene and rapeseed oil under static
conditions. The yield of trans-isomers as products of partial hydrogenation of rapeseed oil was found to decrease with decreasing the Pd particle size in
the catalysts, as well as with increasing the Pd concentration on the periphery of the support grains. 相似文献