排序方式: 共有49条查询结果,搜索用时 35 毫秒
21.
Mria Balogh Istvn Hermecz Zoltn Mszros Levente Pusztay 《Journal of heterocyclic chemistry》1980,17(1):175-179
1,4-Disubstituted-semicarbazide and thiosemicarbazide derivatives were synthetized from 5-substituted-4-oxo-1,4-dihydro-3-pyridinecarbohydrazides and cyclized to 3-mercapto-4H-1,2,4-triazoles. The obtained compounds could be S-methylated with methyl iodide in methanol. The new compounds were tested for antibacterial and antifungal activities. 相似文献
22.
Mria Balogh Istvn Hermecz Klmn Simon Levente Pusztay 《Journal of heterocyclic chemistry》1989,26(6):1755-1769
Ethyl 4-substituted 2-methyl-5-oxo-5,6-dihydro-1,6-naphthyridine-3-carboxylates 3a-h were synthetized in a one-step reaction from diethyl 2,6-diraethylpyridine-3,5-dicarboxylates 1a-h by aminomethinylation with 1,3,5-triazine (2). The 6-substitued derivatives 6a-z,aa-ff could be obtained from diethyl 2-[2-(dimethylamino)-vinyl]-6-methylpyridine-3,5-dicarboxylate ( 4 ) either directly or via the isolated intermediate 2-[2-(arylamino)-vinyl]pyridine compounds 5a-i. 相似文献
23.
An automatic focus map extraction method is presented that uses a modification of blind deconvolution for estimation of localized blurring functions. We use these local blurring functions [so-called point-spread functions (PSFs)] for extraction of focus areas on ordinary images. In this inverse task our goal is not image reconstruction but the estimation of localized PSFs and the relative focus map. Thus the method is less sensitive than general deconvolution is to noise and ill-posed deconvolution problems. The focus areas can be estimated without any knowledge of the shooting conditions or of the optical system used. 相似文献
24.
Tamás Németh József Levente Petró Ibolya Leveles Tünde Tóth György Tibor Balogh Beáta G. Vértessy Péter Huszthy 《Structural chemistry》2018,29(1):113-118
This paper describes the X-ray crystal structure of a complex of acridino-18-crown-6 ether (S,S)-2 and sodium perchlorate. The structure shows a homodimer in the crystal and suggests the potential for π–π bonded interactions between the monomers. The average distance of the two tricyclic units (3.49 ± 0.1 Å) may indicate a considerably strong π–π interaction. Fluorescence titration was performed in order to determine the stoichiometry and stability constant (K s) of the sodium ion-(S,S)-2 complex. Based on the global fitting of the fluorescence spectra, we suggest the formation of a complex with 1:1 ligand to metal ion ratio, and the logK value determined by nonlinear regression analysis was 5.23. 相似文献
25.
This paper provides a general framework for establishing the relation between various moments of matrix exponential and Markovian
processes. Based on this framework we present an algorithm to compute any finite dimensional moments of these processes based
on a set of required (low order) moments. This algorithm does not require the computation of any representation of the given
process. We present a series of related results and numerical examples to demonstrate the potential use of the obtained moment
relations.
This work is partially supported by the Italian-Hungarian bilateral R&D programme, by OTKA grant n. T-34972, by MIUR through
PRIN project Famous and by EEC project Crutial. 相似文献
26.
27.
Csoka L Hoeger IC Peralta P Peszlen I Rojas OJ 《Journal of colloid and interface science》2011,363(1):206-212
Ultrathin films of cellulose nanocrystals (CNCs) are obtained by using a convective assembly setup coupled with a low-strength external AC electric field. The orientation and degree of alignment of the rod-like nanoparticles are controlled by the applied field strength and frequency used during film formation. Calculated dipole moments and Clausius-Mossotti factors allowed the determination of the critical frequencies, the peak dielectrophoresis as well as the principal orientation of the CNCs in the ultrathin films. As a result of the combination of shear forces and low electric field highly ultrathin films with controlled, unprecedented CNC alignment are achieved. 相似文献
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29.
Meszaros LK Dose A Biagini SC Blower PJ 《Dalton transactions (Cambridge, England : 2003)》2011,40(23):6260-6267
6-Hydrazinonicotinic acid (HYNIC, 1) is a well-established bifunctional technetium-binding ligand often used to synthesise bioconjugates for radiolabelling with Tc-99m. It is capable of efficient capture of technetium at extremely low concentrations, but the structure of the labelled complexes is heterogeneous and incompletely understood. In particular, it is of interest to determine whether, at the no-carrier-added level, it acts in a chelating or non-chelating mode. Here we report two new isomers of HYNIC: 2-hydrazinonicotinic acid (2-HYNIC, 2), which (like 1) is capable of chelation through the mutually ortho hydrazine and pyridine nitrogens and 4-hydrazinonicotinic acid (4-HYNIC, 3), which is not (due to the para-relationship of the hydrazine and pyridine nitrogens). LC-MS shows that the coordination chemistry of 2 with technetium closely parallels that of conventional 1, and no advantages of one over the other in terms of potential labelling efficiency or isomerism were discernable. Both 1 and 2 formed complexes with the loss of 5 protons from the ligand set, whether the co-ligand was tricine or EDDA. Ligand 3, however, failed to complex technetium except at very high ligand concentration: the marked contrast with 1 and 2 suggests that chelation, rather than nonchelating coordination, is a key feature of technetium coordination by HYNIC. Two further new HYNIC analogues, 2-chloro-6-hydrazinonicotinic acid (2-chloro-HYNIC, 4a) and 2,6-dihydrazinonicotinic acid (diHYNIC, 5) were also synthesised. The coordination chemistry of 4a with technetium was broadly parallel to that of 1 and 2 although it was a less efficient chelator, while 5 also behaved as an efficient chelator of technetium, but its coordination chemistry remains poorly defined and requires further investigation before it can sensibly be adopted for (99m)Tc-labelling. The new analogues 4a and 5 present an opportunity to develop trifunctional HYNIC analogues for more complex bioconjugate synthesis. 相似文献
30.
Sándor Nagy Zsuzsanna Fehér Levente Kárpáti Dr. Péter Bagi Péter Kisszékelyi Dr. Béla Koczka Prof. Péter Huszthy Prof. Béla Pukánszky Dr. József Kupai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(59):13513-13522
This work presents the immobilization of cinchona squaramide organocatalysts on poly(glycidyl methacrylate) solid supports. Preparation of the well-defined monodisperse polymer microspheres was facilitated by comprehensive parameter optimization. By exploiting the reactive epoxy groups of the polymer support, three amino-functionalized cinchona derivatives were immobilized on this carrier. To explore the effect of the amino linker, these structurally varied precatalysts were synthesized by modifying the cinchona skeleton at different positions. The catalytic activities of the immobilized organocatalysts were tested in the Michael addition of pentane-2,4-dione and trans-β-nitrostyrene with excellent yields (up to 98 %) and enantioselectivities (up to 96 % ee). Finally, the catalysts were easily recovered five times by centrifugation without loss of activity. 相似文献