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排序方式: 共有235条查询结果,搜索用时 15 毫秒
71.
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73.
Stable poly{(vinyl acetate)‐co‐[3‐dimethyl(methacryloyloxyethyl)ammonium propanesulfonate]} latexes with different compositions were synthesized by emulsifier‐free emulsion copolymerization. An unusual “overshooting” behavior of the copolymer tablets is explained based on the formation of specific clusters of oppositely oriented dipoles. The variation of their concentration with the zwitterionic monomer unit fraction, ionic strength and temperature is responsible for the differences in the swelling kinetics established. The results show that these parameters can be used to control swelling degree of copolymer matrices and their sustained drug delivery.
74.
I. Vankov S. E. Vasilev I. A. Golutvin Yu. V. Ershov V. Yu. Karjavin A. M. Makankin V. V. Perelygin V. A. Chekhovski 《Physics of Particles and Nuclei Letters》2013,10(7):783-787
The results of testing a detector based on a thick gas electron multiplier (GEM) are presented. Impact of the TGEM dielectric charging on detector physical parameters is assessed based on simulation and experimental results. The further development of the detector—TGEM with resistive coating was constructed and tested. The test results are presented and compared to a standard thick GEM. 相似文献
75.
Joana Ts. Zaharieva Maria M. Milanova Dimitar S. Todorovsky 《Central European Journal of Chemistry》2011,9(2):290-299
Results on the influence of mechanoactivation (3–30 min) in a planetary ball mill on the composition, crystal structure, IR
spectra and morphology of EuCl3·6H2O, dibenzoylmethane (HDBM) and mixtures of EuCl3·6H2O — HDBM and EuCl3·6H2O — HDBM — 1,10-phenathroline (phen) are presented. Mechanoactivation leads to a decrease of interplanar distances of the
EuCl3·6H2O and HDBM and partial synthesis of Eu(DBM)3 and Eu(DBM)3·phen in the respective mixtures. The fluorescence properties of the products of activation (excitation and emission spectra,
lifetime of the excited states) are similar to those of the complexes produced by the conventional “wet” methods, but the
strongest excitation of the mechanochemically produced solid state samples is achieved at higher wavelength. Crystals of different
forms (prismatic, needle-, long-length-leaf- and rod-like) are formed by mechanoactivation of the mentioned mixtures. 相似文献
76.
Kazakov V. A. Kokshina A. V. Razina A. G. Vasilev A. I. Vasilyeva O. V. Ksenofontov S. I. 《Journal of Applied Spectroscopy》2022,89(3):517-521
Journal of Applied Spectroscopy - The influence of the heating procedure and annealing temperature in air on the transmission spectra and morphology of linear-chain carbon films synthesized by the... 相似文献
77.
Simeon Sainov Margarita Mazakova Marga Pantcheva Dimitar Tontchev 《Molecular Crystals and Liquid Crystals》2013,570(1):609-615
Results are reported on the investigations on an electrically controlled phase holographic grating. It has a nearly sinusoidal profile with 1,4.μm deep grooves spaced at 12,5μm. The control voltage applied to the nematic liquid crystal has an amplitude of 0-25V and frequency 1-10 kHz. A light beam from a He-Ne laser (0,633μm) with a palarization parallel, perpendicular and at 45° the grooves of the grating is used. 相似文献
78.
Joana T. Zaharieva Maria Milanova Dimitar Todorovsky 《Central European Journal of Chemistry》2012,10(6):1907-1912
The paper considers the possibilities for mechanochemical synthesis of rare earth complexes. The complex Eu(TTA)3·phen (HTTA — 2-thenoyltrifluoroacetone, phen — 1,10-phenanthroline) is synthesized by mechanical treatment of a mixture of EuCl3.6H2O, HTTA, phen and NaOH in planetary ball mill Pulverisette 7 for 30 min at 800 min?1. The non reacted starting reagents and reaction side products are separated by treating activated mixture with water-ethanol solution following a procedure proposed in the literature. The elemental composition, X-ray diffraction pattern, IR spectra, optical properties (excitation and emission spectra, luminescence lifetime) and morphology of the mechanochemically synthesized complex are compared with those of the complex prepared from solution by the conventional method. The results confirm close similarity in the molecular structure and identity of the elemental composition, X-ray diffractograms and fluorescence properties of the compounds prepared by both methods. 相似文献
79.
Extraordinary optical transmission: coupling of the Wood-Rayleigh anomaly and the Fabry-Perot resonance 总被引:1,自引:0,他引:1
In this Letter, we demonstrate for the first time that by combining the effects of the Wood-Rayleigh anomaly (WRA) and the Fabry-Perot (FP) resonance, transmission efficiencies of one-dimensional metallo-dielectric gratings on substrates can be significantly improved compared to when these two phenomena work separately. Results of combining the WRA and the FP resonance can be utilized to eliminate the necessity of using the index matching technique and the core-shell structure for enhancing the performance of extraordinary optical transmission devices. Further, the outcomes of combining the WRA and the FP resonance can elucidate some of the unexplained results in the literature. 相似文献
80.
Novel poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes have been synthesized by an improved procedure
using the Atherton–Todd reaction conditions. N-ethyldiisopropylamine has been used as a mild base and propylene oxide as an
acid scavenger in order to obtain poly(oxyethylene phosphate) in yield and purity higher than those achieved by conventional
methods. The compounds have been characterized by 1H, 13C, and 31P NMR and FTIR techniques. Their absorption, fluorescent excitation and emission spectra of chloroform and abs. ethanol solutions
have been recorded and studied. The luminescent quantum yields and decay times have been determined and a dependence on the
length of the oxyethylene spacer between phosphate groups has been established. The new polymer complexes are water soluble
and have increased luminescence decay time in comparison with corresponding ternary complexes. 相似文献