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1.
Some of the properties of glasses obtained in the systems TeO2–MoO3 and TeO2–MoO3–V2O5 had been studied. A good correlation between the properties and the phase diagram of the TeO2–MoO3 system was established. The glass resistance-composition function varied between 6.85 · 109 ohm · cm and 2.93 · 1010 ohm · cm. The isolines of the properties (softening temperature, density, resistance at room and higher temperatures and activation energy) of the glasses obtained from the TeO2–MoO3–V2O5 system were ploted. The electrical resistance is influenced by the concentration of V2O5 and MoO3 and by temperature. The glass absorption characteristics of thin layers were determined in the visible range. 相似文献
2.
The mechanism of the keto-enol tautomerism of malonaldehyde was studied by ab initio methods using 6-21G** and 6-311G** basis functions at the HF level. Two separate mechanisms were examined: through-space proton transfer in the ω-shaped form and through-space proton transfer in a sickle-shaped form obtained from the ω form by rotation. The transition state structure of the ω form is non-planar, whereas that of the sickle form is planar. The sickle form is connected with a 2nd order saddle, indicating that there should exist a lower energy barrier, i.e. that the through-bond mechanism may be preferred. The calculated energy barriers of keto-enol tautomerism for the sickle form is twice as high as those for the omega form. 相似文献
3.
H. Reuther O. Nikolov S. Kruijer R. A. Brand W. Keune D. Liljequist S. Weber S. Scherrer 《Hyperfine Interactions》1994,92(1):1367-1372
-Fe surfaces were implanted with a nominal dose of 5×1017 Al ions/cm2 at 50 keV and a current density of about 3.7 A/cm2. Samples of different shapes and thicknesses have been used in order to test the influence of heat flow from specimen to target holder during implantation. Integral and energy differential (depth-selective)57Fe conversion electron Mössbauer spectroscopy (CEMS and DCEMS) were employed. The spectra indicated a magnetic phase characterised by a broad hyperfine field distributionP(B
hf), a non-magnetic phase, and -Fe. The relative intensity of the non-magnetic phase was enhanced if the thermal contact during implantation became worse. An energy dependence of DCEM spectra in the L-electron range was observed. Model calculations using L-electron weight functions and experimental concentration profiles obtained by secondary neutral mass spectroscopy (SNMS) yielded fair agreement between calculated and experimental phase signals. The results demonstrate that the non-magnetic Fe-Al alloy phase with high Al concentration is located closer to the surface than the magnetic alloy phase, which extends to much larger depth than expected. 相似文献
4.
An amperometric detector with a small thin mercury film electrode is described. The device demonstrates advantageous operational
characteristics such as small dispersion (D<2) and “memory effect” (me<0.6%), extensive maximum sample frequency (msf −200
samples/h), and high sensitivity. It has been proven useful in flow-injection analysis at a constant potential under hydrodynamic
conditions. 相似文献
5.
The Jorgensen [16] and Ros-Cotton [9, 10] methods have been used to calculate the electronic structure of VO(OH2)
5
2+
. The results are compared with those obtained from the simple Wolfsberg-Helmholz method and with the electronic absorption spectra. Good agreement with the experimental data is obtained in the latter case. When calculating the transition energies associated with charge transfer, we took into account the interaction of an excited electron with the effective charges in the complex and the redistribution of these charges when the excited state is populated. 相似文献
6.
7.
Katya Arishtirova Barbara Pawelec Rodimir N. Nikolov J. L. G. Fierro Sonia Damyanova 《Reaction Kinetics and Catalysis Letters》2007,91(2):241-248
The effect of Pt/Ni ratio on the surface properties and catalytic behavior of bimetallic PtNi catalysts for reforming of methane
with CO2 was studied. The TPR, FTIR of adsorbed CO and XPS data showed that introduction of a small amount of Pt (0.3 – 0.5 wt.%)
into the Ni catalyst leads to a decrease of the NiO size, its easy reduction and a uniform distribution of the nickel metal
particles. 相似文献
8.
Geno Nikolov 《Numerische Mathematik》1992,62(1):557-565
Summary LetI(f)L(f)=
k=0
r
=0
vk–1
a
k
f
()(X
k
) be a quadrature formula, and let {S
n
(f)}
n=1
be successive approximations of the definite integralI(f)=
0
1
f(x)dx obtained by the composition ofL, i.e.,S
n(f)=L(
n
), where
.We prove sufficient conditions for monotonicity of the sequence {S
n
(f)}
n=1
. As particular cases the monotonicity of well-known Newton-Cotes and Gauss quadratures is shown. Finally, a recovery theorem based on the monotonicity results is presented 相似文献
9.
Mircho Georgiev Tatiana Popova Zhorro S. Nickolov Nikolay Goutev Georgi Georgiev Hiroatsu Matsuura 《Central European Journal of Chemistry》2004,2(4):617-626
The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water
molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching
region for four short-chain POEs (C 1E
n
C 1 withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H2O/O
ether
from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the
POE molecule participate in hydrogen bonding with water molecules has been made. 相似文献
10.
Nikolov I Gaydardzhiev A Buchvarov I Tzankov P Noack F Petrov V 《Optics letters》2007,32(22):3342-3344
Ultrabroadband parametric amplification of a white-light continuum in the near IR (approximately 100 THz, 1.2-2.4 microm) is demonstrated in BiB3O6 pumped by 45 fs long pulses at 800 nm at a repetition rate of 1 kHz. The energy obtained with a 5 mm thick crystal reached 50 microJ, corresponding to external conversion efficiency of 20%. 相似文献