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961.
962.
Masaru Yoneyama Randy A. Johnson Lon J. Mathias 《Journal of polymer science. Part A, Polymer chemistry》1995,33(11):1891-1899
Thianthrene-2,3,7,8-tetracarboxylic dianhydride was synthesized via nucleophilic aromatic substitution of N-phenyle-4,5-dichlorophthalimide with thiobenzamide, thioacetamide, and sodium sulfide. This monomer was then polymerized with aromatic diamines by the con-ventional low temperature technique in N,N-dimethylacetamide (DMAc) to yield soluble poly(amic acid)s. Polyimides were obtained by thermal cyclization of the poly(amic acid) films. Polymers obtained formed creasable thin films and had excellent thermal stability in air and nitrogen. The bent thianthrene structure limited crystallization and chain packing, as indicated by x-ray analysis. The amorphous thianthrene-containing polyimides were only soluble in H2SO4. © 1995 John Wiley & Sons, Inc. 相似文献
963.
In order to simulate the nonlinear behaviour of elastomer composite materials, we use a homogenization technique which induces nonlinear problems. This paper presents a non-incremental solving method which allows the reduction of computational costs. In this paper the equivalence between the proposed solving method and a Newton-type method is proved, which allows us to prove the convergence under realistic assumptions. Numerical results on a composite illustrate the performances of this method. 相似文献
964.
965.
966.
Achim Hartschuh Hermenegildo N Pedrosa Jeffrey Peterson Libai Huang Pascal Anger Huihong Qian Alfred J Meixner Mathias Steiner Lukas Novotny Todd D Krauss 《Chemphyschem》2005,6(4):577-582
This Minireview discusses novel insights into the electronic structure of carbon nanotubes obtained using single-molecule fluorescence spectroscopy. Fluorescence spectra from single nanotubes are well described by a single, Lorentzian lineshape. Nanotubes with identical structures fluoresce with different energies due to local electronic perturbations. Carbon nanotube fluorescence unexpectedly does not-show any intensity or spectral fluctuations at 300 K The lack of intensity blinking or bleaching demonstrates that carbon nanotubes have the potential to provide a stable, single-molecule infrared photon source, allowing for the exciting possibility of applications in quantum optics and biophotonics. 相似文献
967.
968.
Rogerson AK Aguilar JA Nilsson M Morris GA 《Chemical communications (Cambridge, England)》2011,47(25):7063-7064
Mixture analysis by high resolution diffusion-ordered NMR spectroscopy (HR-DOSY) requires differences in both chemical shift and diffusion coefficient; resolution can be greatly enhanced by exploiting the chemical specificity of lanthanide shift reagent binding to increase chemical shift and diffusion dispersion simultaneously. 相似文献
969.
Solomon SA Bickelhaupt FM Layfield RA Nilsson M Poater J Solà M 《Chemical communications (Cambridge, England)》2011,47(21):6162-6164
A donor-functionalized, silyl-substituted pentadienyllithium has been synthesized and characterized by crystallography and NMR spectroscopy. The pentadienyl negative charge was found to be partially localized, which DFT revealed to be due to the polarizing power of the lithium cation. 相似文献
970.
Kohler FT Morain B Weiss A Laurin M Libuda J Wagner V Melcher BU Wang X Meyer K Wasserscheid P 《Chemphyschem》2011,12(18):3539-3546
The influence of confinement on the ionic liquid crystal (ILC) [C(18)C(1)Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid-to-liquid-crystalline phase transition observed for the neat ILC. For applications within the "supported ionic liquid phase (SILP)" concept, the experiments show that in pores of diameter 50 nm a pore filling of α>0.4 is sufficient to reproduce the phase transitions of the neat ILC. 相似文献