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11.
设k,n1和n2是3个正整数,G=(V1,V2;E)是一个二分图,使得|V1|=n1,|V2|=n2,其中n1≥2k+1,n2≥2k+1并且n1-n2≤1.如果对任意不相邻的x∈V1和y∈V2,都有d(x)+d(y)≥2k+2,则G包含k个相互独立的圈.以上结果部分地回答了Enomoto提出的关于二分图有独立圈的问题. 相似文献
12.
A spin mechanism for electron transfer control in the reaction center of purple bacteria in photosynthesis is proposed. Rotation
and conversion of the ortho/para spin isomers of two H2O molecules located near the special pair of the reaction center are treated as the sources of the coherent modulations of
transient kinetics. Modulation of the collective wave function of the reaction center electrons by the total proton spin of
ortho H2O is a key feature allowing the molecule to play the role of a gate controlling the electron transfer. The iron atom in the
reaction center with the gradient magnetic field is treated as a catalyst removing the strict forbiddenness of H2O ortho/para conversion. It is shown that the modulation of the reaction center stimulated emission kinetics observed in the
field of femtosecond pulses coincides with the rotational transitions of ortho/para H2O. Influence of the effect of the electric field (Stark effect) on the level displacement and ortho/para conversion rate is
discussed. 相似文献
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15.
GRIGORII YA. FRAIKIN MARINA G. STRAKHOVSKAYA EMMA V. IVANOVA REW B. RUBIN 《Photochemistry and photobiology》1989,49(4):475-477
Near-UV (337 nm) photoactivation of the 5-hydroxytryptophan decarboxylation reaction producing serotonin has been observed. The photoactivation effect was investigated as a function of fluence rate and fluence, and pH. Photoactivation of decarboxylase activity was found to occur at nearly neutral pH values (low activity of the enzyme in the dark). The findings indicate that the effect of light is similar to a pH shift toward the acid region, which causes the enzyme conversion from the inactive to active form. Pyridoxal phosphate, the decarboxylase cofactor, in the form of an adduct absorbing at 330-340 nm, is suggested as a candidate for the role of the photoactive chromophore of decarboxylase. 相似文献
16.
ÜMMÜHAN OCAK HALIT KANTEKIN YAŞAR GÖK H. BASIR ŞENTÜRK 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):87-91
The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N2O2S2-macrobicycle. Metal picrates such as Pb2+, Co2+, Zn2+, Ni2+,Cu2+ and Cd2+ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb2+ only among the other metals. The extraction constant (log K
ex) was determined to be 13.8 for Pb2+ complex. 相似文献
17.
E. A. PAZYUK A. V. STOLYAROV V. I. PUPYSHEV N. F. STEPANOV S. YA. UMANSKII A. A. BUCHACHENKO 《Molecular physics》2013,111(2):91-101
The valence electronic states of the iodine molecule are analysed by means of a simple atoms-in-molecule model which accounts for the lowest 2P states of iodine atoms and approximates the spin-orbit interaction by its atomic part. For this model, an inverse problem is solved, i.e. non-relativistic potential energy curves and diabatic couplings are determined by a least-squares fit to known relativistic potential energy curves. The resulting adiabatic wave functions are used to calculate the electronic matrix elements responsible for natural, hyperfine and magnetic predissociation of the iodine molecule in the B0+ u: state. The results are in reasonable agreement with experimental data, being stable enough with respect to the variation of input relativistic potentials. They also indicate the importance of diabatic couplings between the non-relativistic states of the same symmetry. 相似文献
18.
M.I. Yanovskaya N.M. Kotova N.V. Golubko N.YA. Turova 《Journal of Sol-Gel Science and Technology》1998,11(1):23-29
The interaction between magnesium and titanium alkoxides is studied in order to chose the best precursors for synthesis of MgTiO3. No reaction between magnesium and titanium methoxides and isopropoxides occurs. The solubility diagrams for Mg(OR)2-Ti(OR)4-ROH, R = Et,-Bu at 20°C are studied. Magnesium ethoxotitanates of variable composition MgnTi4-n (OEt)16-2n2nEtOH (n=2.0-0) which are structural analogs of Ti4(OR)16 (R = Me, Et) are isolated. This is a quite unusual example of statistical distribution of heteroatoms in molecular structures of metal alkoxides. Among the systems of metal alkoxides with simple aliphatic radicals only Mg(OBu)2-Ti(OBu)4-BuOH gives a convenient precursor for the synthesis of MgTiO3. A simple scheme of preparation of magnesium titanate from the alkoxide solutions is suggested. The phase purity of MgTiO3 is to a considerable extent dependent on the hydrolysis conditions. The alkoxy-derived magnesium titanate is obtained in the form of a uniform fine powder, it can be sintered into dense ceramics in the temperature range of 1140–1220°C which is 150–200°C lower in comparison with the conventional powders. 相似文献
19.
研究了酚醛型吸附树脂JDW 2在非水体系中对吡啶和N ,N 二甲基苯胺的静态吸附 .由实验结果推论正己烷中树脂对吡啶和N ,N 二甲基苯胺的吸附是以氢键吸附机理为主进行的 ,JDW 2酚醛型吸附树脂在正己烷中 ,等温吸附吡啶和N ,N 二甲基苯胺的平衡吸附数据符合Langmuir方程 ,相关系数在 0 99以上 ,因此 ,酚醛型吸附树脂在正己烷中吸附吡啶和N ,N 二甲基苯胺属单分子层吸附 ;同时对非水体系中乙醇或乙酸乙酯的含量对树脂吸附吡啶和N ,N 二甲基苯胺的影响进行了研究 相似文献
20.
Interval exchange transformations (IETs) are piecewise isometries of the interval, obtained permuting a certain number of
subintervals. We give a condition on IETs in the special subclass of IETs with periodic Rauzy-Veech cocycle which guarantees
weak mixing, i.e. the continuity of the spectrum. The proof involves the study of the associated spectral measures. The condition
can be checked explicitly by computing a certain Galois group of a field related to the Ravzy-Veech cocycle. Explicit examples
of weakly mixing IETs are constructed in the Appendix.
*Dedicated to the memory of F.A. Berezin 相似文献