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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
A soluble fraction of a chickenMusculus gastrocnemius muscle was used to characterize the catalyst of linoleate oxidation. Separation of the chicken muscle extract into low (free
metal) and high (protein) molecular weight fractions revealed that the molecular weight of the major catalyst of linoleate
oxidation in chicken muscle extract was greater than 700 daltons. Catalysis of linoleate oxidation by the protein fraction
exhibited a pH optimum of 5.9. Subjecting the protein fraction to heat treatments at increasing temperatures (30–90 C) decreased
the catalysis of linoleate oxidation. Addition of two mM EDTA had no effect on the catalysis of linoleate oxidation. Cyanide
(2 mM), glutathione (1 mM) and cysteine (1 mM) decreased the oxidation of linoleate by the protein fraction 21.0%, 22.9% and
29.0% respectively. Characterization of the oxidative catalyst in chicken muscle extract indicated that free metals and hemoproteins
contribute to overall catalysis of linoleate oxidation but are not the sole catalysts. Heat inactivation of the oxidative
catalyst and the observed pH optimum suggests that the unidentified catalyst is proteinacious and may be an enzyme. 相似文献
993.
994.
New and simple modification of vapor-liquid-solid process for Si nanowires growth based on microwave plasma enhanced chemical vapor deposition that uses solid-state Si target as a source of Si atoms was developed. The method was temperature and pressure controlled evaporation of solid phase of Si source in hydrogen microwave plasma. Aligned growth of Si nanowires was performed in local electric field by applying of constant negative bias to substrate holder. Deposited Si nanowires were studied by scanning electron microscopy (SEM), Raman and photoluminescence spectroscopy. Correlation between photoluminescence spectra and Si nanowires properties were studied. 相似文献
995.
Our earlier experimental studies of the solid-phase reduction of disseminated lump ores demonstrate that an oxide lattice transforms into a metal lattice via the saturation of the oxide crystal lattice by charged oxygen vacancies. Low-charge metal cations appear in the oxide crystal lattice, and they are related to oxygen vacancies by the condition of local electrical neutrality. As oxygen vacancies are accumulated (i.e., during reduction), the number of oxygen vacancy-low charge cation complexes in the initial oxide increases. The total composition of the oxide phase in the range of a crystal lattice of a certain type changes continuously from the initial oxide to the end product of reduction, i.e., to the lower oxide or a metal. Therefore, it is necessary to determine the thermal characteristics of not only all possible stoichiometric compounds in the M-O system but also MOx oxides of variable compositions. Equations for calculating the standard heat capacities of complex stoichiometric oxides and oxides of variable compositions in the Fe-O-Ti system are derived using a mathematical model developed earlier, and these characteristics are calculated. 相似文献
996.
Valla M. Montagna G. Castello R. Tonietto R. Bietti I. 《Solid-State Circuits, IEEE Journal of》2005,40(4):970-977
A direct conversion 802.11a receiver front-end including a synthesizer with quadrature VCO has been integrated in a 0.13-/spl mu/m CMOS process. The chip has an active area of 1.8 mm/sup 2/ with the entire RF portion operated from 1.2 V and the low frequency portion operated from 2.5 V. Its key features are a current driven passive mixer with a low impedance load that achieves a low 1/f noise corner and an high I-Q accuracy quadrature VCO. Measured noise figure is 3.5 dB with an 1/f noise corner of 200 kHz, and an IIP3 of -2 dBm. The synthesizer DSB phase noise integrated over a 10 MHz band is less than -36 dBc while its I-Q phase unbalance is below 1 degree. 相似文献
997.
G. Lucovsky J.G. Hong C.C. Fulton N.A. Stoute Y. Zou R.J. Nemanich D.E. Aspnes H. Ade D.G. Schlom 《Microelectronics Reliability》2005,45(5-6):827
This paper uses X-ray absorption spectroscopy to study the electronic structure of the high-k gate dielectrics including TM and RE oxides. The results are applicable to TM and rare earth (RE) silicate and aluminate alloys, as well as complex oxides comprised of mixed TM/TM and TM/RE oxides. These studies identify the nature of the lowest conduction band d* states, which define the optical band gap, Eg, and the conduction band offset energy with respect to crystalline Si, EB. Eg and EB scale with the atomic properties of the TM and RE atoms providing important insights for identification high-k dielectrics that meet performance targets for advanced CMOS devices. 相似文献
998.
O. G. Devoino M. A. Kardapolova S. Laber E. A. Feldstein O. V. Diyachenko 《Journal of Engineering Physics and Thermophysics》2004,77(2):372-376
The wear resistance of Ni–Cr–B–Si–C coatings after laser treatment with a doping covering under dry friction conditions has been investigated. The microstructure of coatings after fusion by a gas burner and a laser beam and the roughness and waviness parameters of the friction surfaces before and after wear have been investigated. 相似文献
999.
da Costa D.B. Yacoub M.D. Filho J.C.S.S. Fraidenraich G. Mendes J.R. 《Communications Letters, IEEE》2006,10(1):13-15
This paper provides simple, exact, new closed-form expressions for the generalized phase crossing rate of Nakagami-m fading channels. Sample numerical results obtained by simulation are presented that validate the formulations developed here. A special case of this formulation is the Rayleigh case, whose result agrees with that obtained elsewhere in the literature. In passing, several new closed-form results concerning the statistics of the envelope, its in-phase and quadrature components, phase, and their time derivatives are obtained. 相似文献
1000.
Perello J. Escalona E. Spadaro S. Comellas J. Junyent G. 《Communications Letters, IEEE》2006,10(12):852-854
In this letter, we propose two novel mechanisms which enable GMPLS LMP to cope with the automatic discovery of all-optical transport planes. The feasibility of our contributions and their performances are assessed by simulations as well as experimental results over the ASON/GMPLS CARISMA field-trial 相似文献