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71.
Csilla Sepsey Für Gerg Riszter ron SzigetvrI Mikls Dkny Gyrgy Keglevich Lszl HazaI Hedvig BlcskeI 《Molecules (Basel, Switzerland)》2021,26(8)
In orderto synthesize new pyridazine derivatives anellated with different nitrogen heterocyclic moieties, spiro[cycloalkane]pyridazinones were transformed into the corresponding thioxo derivatives via a reaction with phosphorus pentasulfide. The reaction of the formed 2,3-diazaspiro[5.5]undec-3-ene-1-thiones with hydrazine provided the corresponding 1-hydrazono-2,3-diazaspiro[5.5]undec-3-ene, whose diazotization led to the desired spiro[cyclohexane-1,8′-tetrazolo[1,5-b]pyridazines. The reaction of dihydropyridazinethiones with benzhydrazide afforded the corresponding 7H-spiro[[1,2,4]triazolo[4,3-b]pyridazin-8,1′-cyclohexanes]. As a result of our work, seven new pyridazinethione intermediates were prepared, which served as starting materials for the synthesis of two kinds of new ring systems: tetrazolo-pyridazines and triazolo-pyridazines. The six new annulated derivatives were characterized by physicochemical parameters. The new N-heterocycles are valuable members of the large family of pyridazines. 相似文献
72.
73.
Mobile ad hoc networks (MANETs) are dynamic networks formed on-the-fly as mobile nodes move in and out of each others' transmission ranges. In general, the mobile ad hoc networking model makes no assumption that nodes know their own locations. However, recent research shows that location-awareness can be beneficial to fundamental tasks such as routing and energy-conservation. On the other hand, the cost and limited energy resources associated with common, low-cost mobile nodes prohibits them from carrying relatively expensive and power-hungry location-sensing devices such as GPS. This paper proposes a mechanism that allows non-GPS-equipped nodes in the network to derive their approximated locations from a limited number of GPS-equipped nodes. In our method, all nodes periodically broadcast their estimated location, in terms of a compressed particle filter distribution. Non-GPS nodes estimate the distance to their neighbors by measuring the received signal strength of incoming messages. A particle filter is then used to estimate the approximated location, along with a measure of confidence, from the sequence of distance estimates. Simulation studies show that our solution is capable of producing good estimates equal or better than the existing localization methods such as APS-Euclidean for the more difficult scenario when the network connectivity is low. 相似文献
74.
In earlier papers C. Mauduit and A. Sárközy have introduced and studied the measures of pseudorandomness for finite binary sequences. In [8] they extend this theory to sequences of k symbols: they give the definitions and also construct a “good” pseudorandom sequence of k symbols. In this paper these measures are studied for a “truely random” sequence. 相似文献
75.
Summary The maturation of wheat varieties with different harvest times has been examined by high-performance capillary electrophoresis.
The unique proteins of the albumin, gliadin and glutenin fractions of Hungarian winter wheat cultivars Bánkúti 1201 (early
harvest time), Martonvásári 23 (medium harvest time), and Martonvásári 15 (semi-late harvest time) were analysed. An acidic
phosphate buffer containing a polymeric additive and organic modifiers was used in capillary zone electrophoresis mode. Formation
of albumin followed the same time scale, and the patterns were quite similar, for all three cultivars. For gliadins and glutenins
the time scale and patterns were different and some correlation was observed between harvest time and gliadin formation.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
76.
77.
Edit Farkas Gergely Kovács Krisztina Imrik István Szilágyi Sándor Dóbé Ferenc Márta 《Reaction Kinetics and Catalysis Letters》2004,83(2):315-320
The discharge flow method with laser induced fluorescence detection of CH3O was applied to determine the rate constant, k
1, for the reaction CH3O + HBr → products (1) k
1 (298 K) = (8.41 ± 0.80(1σ)) 1011 cm3 mol-1 s-1. The unusually large k
1 value was explained by the polar nature of the transition state of the reaction.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
78.
NMR-spectra of several pyrromethenes were measured at different temperatures, concentrations and in different solvents. The chemical shifts of all protons were assigned and long range coupling constants determined. This variation of temperature, concentration and solvent provided evidence forintra- andinter-molecular proton transfer. In all pyrromethenes investigated the tautomeric NH exchanges are too fast—even at –100°C—to be measured by NMR.
Mit 2 Abbildungen 相似文献
Mit 2 Abbildungen 相似文献
79.
We have investigated characteristics of the local symmetry, such as cosine distribution of bond angles and second-order invariants of spherical harmonics for simple disordered systems with systematically varied radial distributions. Two types of variation were used at three different packing fraction values. None of the perturbations affected the basic features, but the extent of local order changed considerably. The most significant alterations were found for the case with the lowest packing fraction. The results presented in this paper may be used as guidelines for assessing the quality of agreement between radial distribution functions from different sources, such as that of simulations and diffraction experiments. 相似文献
80.
Szegvári D Horváth P Gergely A Németh S Görög S 《Analytical and bioanalytical chemistry》2003,375(5):713-717
Quick and accurate direct and indirect circular dichroism (CD) spectrometric methods were developed for the simultaneous determination of ethisterone (17alpha-ethinyl-17-hydroxy-4-androstene-3-one) and its delta(5)-isomer (delta(5)-ethisterone). The direct method is based on the selective negative Cotton effect of the delta(4)-3-oxo group in ethisterone (negative maximum at 348 nm in dioxan) and measurement of the ellipticity at 296 nm (positive maximum of delta(5)-ethisterone), where the measured ellipticity is the sum of those of the two isomers. In the indirect procedure delta(5)-ethisterone is transformed to ethisterone by base-catalysed isomerization and the ellipticities are measured at 339 nm in ethanol before and after isomerization. Preliminary experiments show the usefulness of CD detector in the HPLC determination of the mixture of the isomers. A major advantage of the direct CD spectrometric and the HPLC/CD methods is that the delta(5)-isomer with extremely low UV activity can also be directly measured with high sensitivity. 相似文献