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81.
82.
Igor V. Bliznets Grigory G. Aleksandrov Sergey M. Lukyanov 《Tetrahedron letters》2004,45(49):9127-9130
2-Methyl-3-cyanopyridines were converted into the corresponding 2-azidomethyl derivatives, which then underwent an intramolecular cycloaddition reaction. A novel heterocyclic system containing a 3-(tetrazol-5-yl)pyridine unit was obtained in this way. 相似文献
83.
J.-Q. Shen H.-Y. Zhu P. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):305-313
There exist a number of typical and interesting systems and/or models, which possess three-generator Lie-algebraic structure,
in atomic physics, quantum optics, nuclear physics and laser physics. The well-known fact that all simple 3-generator algebras
are either isomorphic to the algebra sl (2, C) or to one of its real forms enables us to treat these time-dependent quantum systems in a unified way. By making use of
both the Lewis-Riesenfeld invariant theory and the invariant-related unitary transformation formulation, the present paper
obtains exact solutions of the time-dependent Schr?dinger equations governing various three-generator Lie-algebraic quantum
systems. For some quantum systems whose time-dependent Hamiltonians have no quasialgebraic structures, it is shown that the exact solutions can also be obtained by working in a
sub-Hilbert-space corresponding to a particular eigenvalue of the conserved generator (i.e., the time-independent invariant that commutes with the time-dependent Hamiltonian). The topological property of geometric phase factors and its adiabatic limit in time-dependent systems is briefly
discussed.
Received 6 July 2002 / Received in final form 21 October 2002 Published online 11 February 2003 相似文献
84.
Mooson Kwauk 《中国颗粒学报》2004,(1)
IntroductionInmaterialscience,differentmicrostructuresofthesamematerialsmayinducediversebehaviorsanddifferentcharacteristics.Westwood(1988)showed,asanexample,thatthetreatmentofaluminumsurfacewithcommercialphosphoricacidproducedmechanicallyinterlockedoxide搘hiskers?approximately10nmindiameterand400nminlength,whichmechanicallyinterlocked.Thismicro-structurecankeepsuchaconglomeratebondedoverconsiderablerangesofstressandtemperature.Inahumidatmosphere,especiallythatcontainingchlorine,however,suchox… 相似文献
85.
Tomomi Kawasaki Miyuki Nagaoka Tomoko Satoh Ayako Okamoto Rie Ukon Atsuyo Ogawa 《Tetrahedron》2004,60(15):3493-3503
Claisen rearrangement triggered by enolization of 2-allyloxyindolin-3-ones with DBU was performed in order to prepare 3-allyl-3-hydroxyindolin-2-ones. Total synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine, as well as (±)-convolutamydines A and E, was achieved by transformation of the allyl moiety of 3-allyl-3-hydroxyindolin-2-ones. 相似文献
86.
Elżbieta Godlewska M. Mitoraj F. Devred B. E. Nieuwenhuys 《Journal of Thermal Analysis and Calorimetry》2007,88(1):225-230
A Ti–45.9Al–8Nb
(at%) alloy with a lamellar structure (γ+α2)
was oxidised in air at 700, 800, 850 and 900°C in isothermal and thermal
cycling conditions. The reaction progress was followed by thermogravimetric
measurements. In isothermal conditions the oxidation kinetics followed approximately
a parabolic rate law and the rate constants ranged from about 10–12
kg2 m–4 s–1
at 700°C to 10–10 kg2
m–4 s–1
at 900°C. The oxide scales were built of Al2O3
and TiO2, the former being the main component of the
outermost layer. The oxidation behaviour of Ti–45.9Al–8Nb was
referred to a commercial titanium alloy, WT4 (Ti–6Al–1Mn), and
selected oxidation-resistant alloys. 相似文献
87.
S. Sasa A. Nakashima Y. Nakajima M. Inoue 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):224
We fabricated nanoscale open-dot structures in an InAs surface inversion layer using an atomic-force-microscope oxidation process. Due to its superior nanofabrication capability, small open-dot structures with the feature size ranging between 100 and 300 nm were successfully fabricated. The magnetoresistance signal measured at 4.2 K showed reproducible fluctuations and a periodic oscillation component that varies in both amplitude and periodicity depending on the dot size. We show that the period of the oscillations corresponds to that of the Aharonov–Bohm effect and propose that the possible mechanism for the oscillations is due to the formation of a one-dimensional electron channel enclosing the open-dot structure as a result of the electron transfer from the InAs oxide to InAs. 相似文献
88.
A. V. Tarasov P. O. Yablonsky Yu. A. Moskvichev 《Chemistry of Heterocyclic Compounds》2003,39(1):119-122
Various methods were studied for the oxidation of 2-methyl-5-(phenylsulfonyl)benzenesulfamide and its derivatives. The oxidation by sodium dichromate in sulfuric acid was found most efficient. The effects of temperature, concentration, reagent ratio, and time of the oxidation reaction on the yield of the desired product were investigated. Conditions were proposed for obtaining the desired product in yields up to 95%. A synthesis was developed for a series of new saccharin derivatives. 相似文献
89.
Ya.G. Groda P. Argyrakis G.S. Bokun V.S. Vikhrenko 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(4):527-535
The selfconsistent diagram approximation (SCDA) is generalized for three-dimensional lattice gases with nearest neighbor repulsive
interactions. The free energy is represented in a closed form through elementary functions. Thermodynamical (phase diagrams,
chemical potential and mean square fluctuations), structural (order parameter, distribution functions) as well as diffusional
characteristics are investigated. The calculation results are compared with the Monte Carlo simulation data to demonstrate
high precision of the SCDA in reproducing the equilibrium lattice gas characteristics. It is shown that similarly to two-dimensional
systems the specific statistical memory effects strongly influence the lattice gas diffusion in the ordered states.
Received 7 August 2002 / Received in final form 22 January 2003 Published online 24 April 2003 相似文献
90.