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41.
42.
Elói Medina Galego 《Monatshefte für Mathematik》2002,136(2):87-97
We study the relation of to the subspaces and quotients of Banach spaces of continuous vector-valued functions , where K is an arbitrary dispersed compact set. More precisely, we prove that every infinite dimensional closed subspace of totally incomparable to X contains a copy of complemented in . This is a natural continuation of results of Cembranos-Freniche and Lotz-Peck-Porta. We also improve our result when K is homeomorphic to an interval of ordinals. Next we show that complemented subspaces (resp., quotients) of which contain no copy of are isomorphic to complemented subspaces (resp., quotients) of some finite sum of X. As a consequence, we prove that every infinite dimensional quotient of which is quotient incomparable to X, contains a complemented copy of . Finally we present some more geometric properties of spaces.
Received 8 November 2000; in revised form 7 December 2001 相似文献
43.
E.H. El Abdalaoui F. Parreau A.A. Prikhod'ko 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2006,42(6):671-681
It is shown that for any family of probability measures in Ornstein type constructions, the corresponding transformation has almost surely a singular spectrum. This is a new generalization of Bourgain's theorem [J. Bourgain, On the spectral type of Ornstein class one transformations, Israel J. Math. 84 (1993) 53–63], same result is proved for Rudolph's construction [D. Rudolph, An example of a measure-preserving map with minimal self-joining and applications, J. Anal. Math. 35 (1979) 97–122]. 相似文献
44.
Roshdi Khalil 《Annali di Matematica Pura ed Applicata》1990,157(1):245-249
Summary In this note we prove that: if T is a contraction in L(lp) that maps elements of disjoint support to elements of disjoint support, then T is an extreme point of the unit ball of L(lp), 1
i) form a p-orthonormal sequence or the nonzero elements of (yi) form a p-orthonormal sequence for which supp (yi)=N. 相似文献
45.
M. N. El Tarazi 《BIT Numerical Mathematics》1990,30(3):484-489
The interpolation problem at uniform mesh points of a quadratic splines(x
i)=f
i,i=0, 1,...,N ands(x
0)=f0 is considered. It is known that s–f=O(h
3) and s–f=O(h
2), whereh is the step size, and that these orders cannot be improved. Contrary to recently published results we prove that superconvergence cannot occur for any particular point independent off other than mesh points wheres=f by assumption. Best error bounds for some compound formulae approximatingf
i
andf
i
(3)
are also derived. 相似文献
46.
47.
F. El Akkad H. F. Ragaie M. Abdel Naby 《Applied Physics A: Materials Science & Processing》1989,48(5):493-495
Zn
x
Cd1–x
S thin films (0x0.20) were prepared using rf sputtering in argon atmosphere and characterized using X-ray diffraction, optical transmission, electrical resistivity and photoconductive decay measurements. The films were found to possess hexagonal structure. The crystallite size and degree of preferential orientation were found to decrease with the increase ofx and to improve upon annealing in vacuum at 250 °C. The transmission edge shifted towards shorter wavelengths with the increase ofx in agreement with the expected shift in the energy band gap. The films were found to exhibit room temperature resistivity in the range 100–1000 cm. The obtained values of long wavelength transmission (70–80%) and minority carrier diffusion length (30 m) are high enough for the application of these films in the field of solar cells. 相似文献
48.
Hung‐Chuan Cheng Li‐Tang Wang Ashraf Taha Khalil Yao‐To Chang Yu‐Chi Lin Ya‐Ching Shen 《中国化学会会志》2004,51(2):431-435
Phytochemical investigation of the stem bark of Calophyllum inophyllum resulted in the isolation of a new dipyrenoxanthone, calophinone ( 1 ), together with four related xanthones ( 2–5 ). Identification of the isolated compounds was achieved through intensive studies of their spectral data, especially 2D NMR. 相似文献
49.
50.
E. O. Chukhadzhyan K. G. Shakhatuni El. O. Chukhadzhyan N. T. Gevorkyan 《Chemistry of Heterocyclic Compounds》1999,35(3):343-347
Quaternary ammonium salts containing propargyl and 3-(2-methyltetrazol-5-yl)propargyl groups undergo base-catalyzed cyclization at room temperature with self heating to form condensed heterocyclic systems containing the tetrazole ring. Heating at 90–92°C for 2 h is necessary to cyclize the allyl analogs of the starting salts.Communication 234 of the series Research on Amines and Ammonium Compounds. For 233, see [1].Institute of Organic Chemistry, National Academy of Sciences of the Republic of Armenia, Erevan 375094. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 390–394, March, 1999. 相似文献