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101.
D. A. Konevetz I. E. Beck G. V. Shishkin V. V. Vlassov V. N. Silnikov 《Russian Chemical Bulletin》2002,51(7):1100-1111
The review surveys the results of our studies devoted to the design of highly efficient catalysts of hydrolysis of the phosphodiester bonds in RNA. These catalysts contain the imidazole residue in the catalytic domain, one or several bis-quaternized rings of 1,4-diazabicyclo[2.2.2]octane as a polycationic RNA-binding domain, and a lipophilic radical. A versatile approach to artificial ribonucleases of this type was proposed, which allows one to vary not only the number of positive charges in the RNA-binding domain, the structure of the catalytic site, and their mutual arrangement but also the domain structure of the molecule as a whole. Analysis of the catalytic properties of the synthesized constructs makes it possible to optimize the domain structure and the geometry of the molecule ensuring its maximum ribonuclease activity. 相似文献
102.
We consider the crystal structure of the level zero extremal weight modules V() using the crystal base of the quantum affine algebra constructed in Duke Math. J.
99 (1999), 455–487. This approach yields an explicit form for extremal weight vectors in the U
– part of each connected component of the crystal, which are given as Schur functions in the imaginary root vectors. We show the map
induces a correspondence between the global crystal base of V() and elements
. 相似文献
103.
Formation of Compounds in the Quasi-binary Systems AcX4? MX2 (Ac = Th, U; M = Ca, Sr, Ba, Eu, Ge, Sn, Pb; X = Br, I) T,x-phase diagrams of the systems ThI4? SnI2, ThI4? PbI2, ThI4? CaI2, and ThI4? SrI2 were established using thermoanalysis and x-ray methods. The only ternary compounds have a 1:1 composition. Further AcMX6 compounds (Ac: Th, U; M: Ca, Sr, Ba, Eu, Ge, Sn, Pb; X: Br, I) were synthesized and their structures investigated. Four structure types are found depending on the temperature and the Ac/M combinations. The structures of γ-ThSnI6 and β-ThSnI6 were determined with single crystal methods as representatives of a whole series of isotypic compounds. 相似文献
104.
The results of high pressure experiments with ternary iodides of the general formula ABI6 with A = Ca, Dy, Ge, Sn, Pb and B = Th, U are described. These compounds transform from a β- to a γ-SnThI6-type structure, both variants of known trihalide structures (BiI3- and PuBr3-type). Trends and pecularities in the values for the minimal transformation pressures and in the velocities of transition are pointed out, and they are discussed in terms of geometric and electronic factors. 相似文献
105.
Angelika Jungmann R. Claessen R. Zimmermann Ge Meng P. Steiner S. Hüfner S. Tratzky K. Stöwe H. P. Beck 《Zeitschrift für Physik B Condensed Matter》1995,97(1):25-34
The electronic structure of the layered compounds LaI2 and CeI2 was investigated by photoemission and electron energy loss spectroscopy. From the experimental results we are able to confirm the metallic nature of these compounds, and by using photon energy dependent measurements of the valence band we can identify the orbital character of the conduction band as essentially 5d1-like. A detailed analysis of the Ce 3d and 4f spectra yields a remarkably small 4f-5d hybridization strength, almost completely decoupling the f-electron from the conduction band, which makes CeI2 a somewhat unusual system compared to other metallic Ce compounds. Band structure calculations by Jepsen and Andersen [1] confirm these experimental results. 相似文献
106.
107.
The Auger-recombination coefficient is determined to be Cn = 1,7·10?31 cm6 sec?1 and Cp = 1,2·10?31 cm6 sec?1 in Si. The Auger-recombination is not momentum conserving. 相似文献
108.
József Beck 《Journal of Combinatorial Theory, Series A》1981,30(2):117-133
Let {Ai} be a family of sets and let S = ∩iAi. By a positional game we shall mean a game played by two players on {Ai}. The players alternately pick elements of S and that player wins who fist has all the elements of one of the Ai. This paper deals with almost disjoint hypergraphs only, i.e., |Ai∪Aj| ? 1 if i ≠ j. Let be the smallest integer for which there is an almost disjoint n-uniform hypergraph , so that the first player has a winning strategy. It is shown that , which was conjectured by Erdös. The same method is applied to prove a conjecture of Hales and Jewett on r-dimensional tick-tack-toe if r is large enough. Finally we prove that for an arbitrary almost disjoint n-uniform hypergraph the second player has such a strategy that the first player unable to win in his mth move if m < (2 ? ?)n. 相似文献
109.
110.