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41.
Summary The successful application of the formerly presented concept of diffusion-averaged molecular weight, Md, to vacuum residues of crude oils, or their fractions, is described. The samples for establishing the calibration curve, logDvs. logM, were crude oil fractions with polydispersities smaller than 1.1. In a surprisingly good approximation the calibration curve is independent of the origin of these fractions if 500<M<10000. The validity of our calibration curve was demonstrated with more than 10 crude oil residues and with some of their hydrogenation residues [2]. 相似文献
42.
ágnes Horváth István Hermecz Marianna Pongor-Csákvári Zoltán Mészáros József Kökösi Gábor Tóth áron Szöllósy 《Journal of heterocyclic chemistry》1984,21(1):219-224
The structures of the title compounds bearing a five-, six- or seven-membered A ring have been investigated by uv and 1H and 13C nmr spectroscopy. The imine-enol-enamine (I-II-III) tautomerism of these compounds depends greatly on the ring size. A significant solvent-dependence is observed only for the five-membered-ring compounds 1 and 2 , which in ethanolic solution exist predominantly in the imine form I, and in chloroform solution in the enol form II. The compounds with a six-membered A ring, 3 and 4 , are mainly in the enamine form III. On protonation, 3 and 4 change into the E and Z isomeric mixture of the enol tautomer II. The seven-membered-ring compound 5 is a mixture of the imine I and the enamine III tautomers. 相似文献
43.
Katalin Mészáros Szécsényi I. Esztelecki G. Pokol 《Journal of Thermal Analysis and Calorimetry》2007,89(3):829-833
In order to increase the nutrition value of bread, one of the most commonly used foodstuff all over the world, different additives
are used in bread processing. In this paper we describe the thermal changes in bread and that of with 0.5% crude soybean lecithin
additive. Their thermal stability has been investigated by TG, DSC and EGD methods. The thermal changes were also followed
of soy products, lecithin and lysine, ingredients used as bread additives in order to check if they may suffer any thermal
degradation during the baking process. The data obtained can be of use only for qualitative conclusions. According to the
obtained data at the usual bread baking temperature only the additives in crust may partly decompose while in the crumb, at
lower temperatures the additives, due to baking, are not damaged. The thermal methods give a possibility for rapid estimation
of processes induced by heat effects in additives during the baking, and they are suitable to detect the changes during the
bread-making procedure. However, they are neither suitable to provide any quantitative data on these changes nor facts affecting
the nutrition value and of the bread. 相似文献
44.
45.
Mészáros Szécsényi K. Leovac V. M. Jaćimović Ž. K. Češljević V. I. Kovács A. Pokol G. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):573-581
The synthesis of copper(II) chloride complexes with 3,5-dimethylpyrazole, 1-carboxamidine-3,5-dimethylpyrazole, 5-amino-4-carboxamide-1-phenylpyrazole
and 4-acetyl-3-amino-5-methylpyrazole is described. The compounds are characterized by elemental analysis, FT-IR spectroscopy,
thermal methods, magnetic moment and molar conductivity measurements. Thermal decomposition of the dichloro-(3,5-dimethylpyrazole)-copper(II)
complex results in an unstable intermediate with a stochiometric composition. The decomposition of the other compounds is
continuous.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
46.
Istvn Hermecz Benjaminnyi Pod Zoltn Mszros Gyrgy Szsz Jzsef Kksi 《Journal of heterocyclic chemistry》1985,22(5):1373-1375
Fischer indolization of 6-arylhydrazono-6,7,8,9-tetahydro-11H-pyrido[2,1-b]quinazolin-11-ones 1 afforded substituted 7,8-dihydro-5H,13H-indolo[2′,3′:3,4]pyrido[2,1-b]quinazolin-5-ones 3-12 in high yields. 相似文献
47.
Knowledge of chemical shift-structure relationships could greatly facilitate the NMR chemical shift assignment and structure refinement processes that occur during peptide/protein structure determination via NMR spectroscopy. To determine whether such correlations exist for polar side chain containing amino acid residues the serine dipeptide model, For-L-Ser-NH(2), was studied. Using the GIAO-RHF/6-31+G(d) and GIAO-RHF/TZ2P levels of theory the NMR chemical shifts of all hydrogen ((1)H(N), (1)H(alpha), (1)H(beta1), (1)H(beta2)), carbon ((13)C(alpha), (13)C(beta), (13)C') and nitrogen ((15)N) atoms have been computed for all 44 stable conformers of For-L-Ser-NH(2). An attempt was made to establish correlation between chemical shift of each nucleus and the major conformational variables (omega(0), phi, psi, omega(1), chi,(1) and chi(2)). At both levels of theory a linear correlation can be observed between (1)H(alpha)/phi, (13)C(alpha)/phi, and (13)C(alpha)/psi. These results indicate that the backbone and side-chain structures of For-L-Ser-NH(2) have a strong influence on its chemical shifts. 相似文献
48.
P. Révész 《Probability Theory and Related Fields》1992,93(1):21-37
Summary We say that the discD()R
2, of radius , located around the origin isp-covered in timeT by a Wiener processW(·) if for anyzD() there exists a 0tT such thatW(t) is a point of the disc of radiusp, located aroundz. The supremum of those 's (0) is studied for which,D() isp-covered inT. 相似文献
49.
We consider the following (solitary) game: each node of a directed graph contains a pile of chips. A move consists of selecting a node with at least as many chips as its outdegree, and sending one chip along each outgoing edge to its neighbors. We extend to directed graphs several results on the undirected version obtained earlier by the authors, P. Shor, and G. Tardos, and we discuss some new topics such as periodicity, reachability, and probabilistic aspects.Among the new results specifically concerning digraphs, we relate the length of the shortest period of an infinite game to the length of the longest terminating game, and also to the access time of random walks on the same graph. These questions involve a study of the Laplace operator for directed graphs. We show that for many graphs, in particular for undirected graphs, the problem whether a given position of the chips can be reached from the initial position is polynomial time solvable.Finally, we show how the basic properties of the probabilistic abacus can be derived from our results. 相似文献
50.