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121.
122.
Vijaya Gracias Alan F. Gasiecki Joel D. Moore Irini Akritopoulou-Zanze Stevan W. Djuric 《Tetrahedron letters》2006,47(50):8977-8980
A general method for the preparation of diaza-spirocycles is reported. This method used an olefin metathesis in order to construct the desired spirocyclic framework. Beginning with commercially available protected amino ketones, this strategy ultimately produced pharmacologically relevant diaza-scaffolds in an efficient and high-yielding process. 相似文献
123.
M. F. Gamal' 《Journal of Mathematical Sciences》2006,134(4):2263-2271
We consider a class of C·0-contractions that is a generalization of the class of C·0-contractions with finite defect indices. Some results of Uchigama and Wu for C·0-contractions with finite defect indices are generalized: the lattices of hyperinvariant subspaces of such a contraction T
is isomorphic to that of its Jordan model and is generated by subspaces of the form Ker ϕ(T) and Ran ϕ(T), where ϕ ∈ H∞. The form of the inverse to an isomorphism of the invariant subspace lattices given by an intertwining quasiaffinity is also
studied. Next, for C·0-contractions in question, the characteristic disc related to the lattice of invariant subspaces is computed. Bibliography:
13 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 315, 2004, pp. 48–62. 相似文献
124.
Kurenkov V. F. Zaitseva O. A. Kirdyashova G. N. 《Russian Journal of Applied Chemistry》2002,75(4):641-644
The kinetics of radical copolymerization of acrylamide with lithium, sodium, and potassium 2-acrylamido-2-methylpropanesulfonates in concentrated aqueous solutions in the presence of potassium persulfate as initiating agent at pH 9 and 50°C was studied by dilatometry. 相似文献
125.
We consider the problem of contact of two elastic wedges and assume that only the vertices of the wedges touch before loading. After loading, the edges of both wedges come in contact near their common vertex. We reduce the constructed system of dual integral equations to a Fredholm integral equation of the second kind with difference kernel given on the semiaxis. We analytically solve the Fredholm equation by reducing it to the boundary-value Riemann problem for analytic functions. We obtain an analytic expression for contact stresses. 相似文献
126.
F. JACOBSEN 《Journal of sound and vibration》2002,256(5):849-859
The influence of instrumentation amplitude and phase mismatch on finite difference measurement of mean square particle velocity is examined. It is shown theoretically and demonstrated experimentally that the resulting error depends on two properties of the sound field, the ratio of the active intensity to the mean square particle velocity and the ratio of the reactive intensity to the mean square particle velocity. Very large errors can occur near particle velocity nodes in interference fields even with well-matched state-of-the-art sound intensity measurement systems. However, outside of such regions, moderate phase mismatch has very little influence on the performance of the measurement system. Amplitude mismatch is somewhat more problematic. 相似文献
127.
Afraimovich É. L. Vodyannikov V. V. Voyeikov S. V. Perevalova N. P. Yakovets A. F. 《Radiophysics and Quantum Electronics》2002,45(10):741-757
Using the COPHASE method and the GPS interferometry method for travelling ionospheric disturbances, we analyze in detail the spatio-temporal properties of travelling wave packets (TWP) of total electron content (TEC) disturbances. The analysis is performed on the example of a clearest TWP manifestation observed in California, USA, in October 18, 2001, using the GLOBDET technique, developed at the Institute of Solar-Terrestrial Physics of the Siberian Branch of RAS for global detection and monitoring of natural and technogenic ionospheric disturbances on the basis of TEC variations retrieved from the global network of GPS receivers. In the time domain, TWPs are quasi-periodic TEC oscillations of duration about 1 h, period of 10–20 min, and amplitude exceeding that of the background TEC fluctuations by at least one order of magnitude. The velocity and direction of TWP motion are similar to those of mid-latitude mesoscale travelling ionospheric disturbances, as obtained earlier from the analysis of phase parameters of HF radio signals and the signals of geostationary satellites and discrete space radio sources. 相似文献
128.
F. Balibrea 《Topology and its Applications》2006,153(12):2092-2095
Recently, Forti, Paganoni and Smítal constructed an example of a triangular map of the unite square, F(x,y)=(f(x),g(x,y)), possessing periodic orbits of all periods and such that no infinite ω-limit set of F contains a periodic point. In this note we show that the above quoted map F has a homoclinic orbit. As a consequence, we answer in the negative the problem presented by A.N. Sharkovsky in the eighties whether, for a triangular map of the square, existence of a homoclinic orbit implies the existence of an infinite ω-limit set containing a periodic point. It is well known that, for a continuous map of the interval, the answer is positive. 相似文献
129.
F. Ameli M. Bonori F. Massa 《The European Physical Journal C - Particles and Fields》2002,25(1):67-75
We describe the measurement of the deep sea optical background in some sites south of Capo Passero, Sicily. A continuous
flux of about 440 photons cm
-2
s
-1
in the wavelength interval 440-550 nm is estimated due to the decays of the 40K contained in the sea water. Bioluminescence light bursts are also observed and an example of time evolution is reported.
All the measurements were accomplished using a deep sea module also described in this article.
Received: 20 April 2002 / Published online: 26 July 2002 相似文献
130.
On mechanical characteristics of nanocrystals 总被引:2,自引:0,他引:2
The dependence of the elastic moduli of a nanocrystal on its size is investigated theoretically with reference to a two-dimensional single-crystal strip. It is shown that the uncertainty (of a fundamental nature) in the size of a nanocrystal causes the determination of many of its mechanical characteristics to be ambiguous. It is found that the Cauchy-Green relations are modified and the elastic-constant tensor ceases to be symmetric; the size and shape of a nanocrystal render its mechanical properties more anisotropic. For a single-crystal strip, the Poisson ratio decreases and the Young modulus increases with decreasing thickness of the strip; in the case of a very thin crystal film (two atomic layers thick), these elastic moduli can differ from their macroscopic values by a factor of two. The size effects which make the continuum elasticity theory inapplicable to nanocrystals are estimated. The size effects that occur when the molecular dynamics method is applied for modeling macroscopic objects are also discussed. 相似文献