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121.
N. V. Gérbéléu K. M. Indrichan V. B. Arion 《Theoretical and Experimental Chemistry》1991,27(2):187-192
The mass spectra of the coordination compounds of nickel(II) with the bis-S-substituted thiosemicarbazones of 2,4-pentanedione (R2H2L) with the general formula [NiR2HL]X and of 3-oxo-2,4-pentanedione (H2R2LO) with the general formula NiR2LO were studied. A distinguishing feature of the mass spectra of [NiR2HL]X is the absence of molecular ion peaks. The initial point of fragmentation is the [M - HX] ions. The strongest lines in spectra of NiR2LO are those due to the elimination of R and R-H. At the first stage the fragmentation of all the investigated compounds takes place mainly through only one of the thiosemicarbazide residues. At the second stage the 2,4-pentanedione (3-oxo-2,4-pentanedione) residue is eliminated, after which the remaining thiosemicarbazide part dissociates. A significant part of the fragmentation paths was confirmed by the peaks of the metastable ions and also by the mass spectra of the deuterated analogs.Institute of Chemistry, Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 2, 205–211, March–April, 1991. Original article submitted August 19, 1986. 相似文献
122.
S. Barlag H. Becker A. Bożek T. Böhringer M. Bosman V. Castillo V. Chabaud C. Damerell C. Daum H. Dietl A. Gillman R. Gilmore T. Gooch L. Görlich P. Gras Z. Hajduk E. Higon D. P. Kelsey R. Klanner S. Kwan B. Lücking G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Pałka M. Pepé J. Richardson K. Rybicki H. J. Seebrunner U. Stierlin H. G. Tiecke G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers M. Witek T. Zeludziewicz 《Zeitschrift fur Physik C Particles and Fields》1992,55(3):383-390
We combine highly complementary information on branching fractions of charmed mesonsD 0,D + andD s + coming from two experiments both yielding doublecharm samples. The NA 32 experiment provided exclusive branching fractions for channels with at least two charged decay products while a recent Mark III paper provides results on inclusive charm decay properties. The knowledge of channels withK 0's in the former is used to recalculate the charged multiplicity distribution in the latter. We obtain 〈n ch〉=2.25±0.08 forD 0, 〈n ch〉=1.96±0.08 forD + and 〈n ch〉=2.41±0.38 forD s + . In turn the knowledge of the charged multiplicity improves the overall normalization of exclusive branching fractions. This reanalysis yields model-independent results for charmed mesons. In particular we obtain branching fractions for 16D s + decay channels including $$BF(D_s^ + \to \phi \pi ^ + ) = \left( {4.4\begin{array}{*{20}c} { + 2.3} \\ { - 1.8} \\ \end{array} } \right)\% .$$ . 相似文献
123.
124.
A C1-class of plane closed curves is considered, which contains all ovals and rosettes. This class is divided into some subclasses for which greatest lower bounds of numbers of antipodal and arc-antipodal sets are determined. 相似文献
125.
M. Malinowski S. Krzyżanowski S. Szczepańska 《Journal of Thermal Analysis and Calorimetry》1972,4(3):281-292
Thermogravimetry was applied to the investigation of the phenomena of adsorption, chemisorption, desorption and surface reactions on solid catalysts. The measurements were carried out with 13 NaX and NaY type zeolites and with silica gels treated with sodium hydroxide, in the presence of cumene and methanol. On the basis of the quantitative results it is possible to give an interpretation of surface phenomena and to establish the existence of various active centres on the surface of the catalysts.
The authors express their gratitude to Prof. S. Malinowski for help and discussion and to Mr. W. Dziklinski for his technical help. 相似文献
Zusammenfassung Adsorptions-, Chemisorptions- und Desorptionserscheinungen, sowie Oberflächenreaktionen an festen Katalysatoren wurden thermogravimetrisch untersucht. Die Messungen wurden an Zeoliten der Typen 13 NaX und NaY und an mit Natriumhydroxid behandelten Silikagelen in Gegenwart von Cumol und Methanol durchgeführt. Aufgrund der quantitativen Ergebnisse war es möglich, die Oberflächenerscheinungen zu deuten und das Vorhandensein von verschiedenen aktiven Zentren an der Katalysatoroberfläche nachzuweisen.
Résumé On a appliqué la méthode thermogravimétrique à l'étude des phénomènes d'adsorption, de chemisorption et de désorption ainsi qu'aux réactions de surface sur des catalyseurs solides. Les mesures ont été effectuées sur zéolites de type 13 NaX et NaY et sur des silicagels traités par la soude en présence de cumène et de méthanol. Des résultats quantitatifs permettent de donner une interprétation des phénomènes de surface et d'établir l'existence de divers centres actifs à la surface des catalyseurs.
, , , . , , , , . 13 NaX NaY , . .
The authors express their gratitude to Prof. S. Malinowski for help and discussion and to Mr. W. Dziklinski for his technical help. 相似文献
126.
Vila-Romeu N Nieto-Suarez M Dynarowicz-Łatka P 《The journal of physical chemistry. B》2005,109(31):14965-14970
The behavior of binary mixed Langmuir monolayers from gramicidin A (GA) and ethyl nonadecanoate (EN), spread on aqueous subphases containing NaCl and CaCl2, was investigated on the basis of the analysis of surface pressure-average area per molecule (pi-A) isotherms complemented with Brewster angle microscopy (BAM) images. Compression modulus versus surface pressure (C(S-1)-pi) curves indicate the existence of interactions in the GA-EN mixed monolayers at low surface pressures (below 5 mN m(-1)). However, for mixtures in which the ester is the predominant component, both GA and EN are miscible within regions from fully expanded to collapse. To examine the interactions between both components in the studied system, values of the mean molecular area per molecule (A12) were plotted as a function of molar fraction of gramicidin A (X(GA)). A12-X(GA) plots exhibit negative deviations from ideality at high surface pressures, wherein beta-helices of GA are vertically oriented in respect to the interface. However, at surface pressures below the plateau transition, which is due to reorientation of GA, the binary system obeys the additive rule. Brewster angle microscopy (BAM) was applied for a direct visualization of the monolayers morphologies. The obtained images prove that for molar ratios of GA > or = 0.3 and at surface pressures above 5 mN m(-1), both components are immiscible at the interface. The observed negative deviations from the additively rule were attributed to the formation of a three-dimensional phase in the mixed film, which provokes its contraction at the interface. 相似文献
127.
Vinyl- and 1-alkenyldichloroboranes were used as dienophiles for the Diels–Alder reaction with representative aliphatic and cyclic 1,3-dienes. The organoborane adducts were transformed into the corresponding olefins either by protonolysis or by oxidation–mesylation–reduction. Direct protonolysis of the adducts gave in most cases mixtures of olefins whereas the reduction of mesylates with lithium triethylborohydride produced pure olefins in good yields. 相似文献
128.
Infrared spectra of K3[ReO2(CN)4] have been recorded using polarized radiation and oriented single crystals. The dichroic behaviour of the bands is analyzed and discussed on the basis of molecular geometry and the oriented molecular model. Experimentally determined dichroic ratios are used to obtain a full set of vibrational frequencies. By combining these data with those obtained from Raman spectra, the fundamental internal and lattice vibrations are assigned. 相似文献
129.
Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methylglutarates were prepared as solids with general formula MC6 H8 O4 ×n H2 O, where n =0–8. Their solubilities in water at 293 K were determined (7.0×10−2 −4.2×10−3 mol dm−3 ). The IR spectra were recorded and thermal decomposition in air was investigated. The IR spectra suggest that the carboxylate
groups are mono- or bidentate. During heating the hydrated complexes lose some water molecules in one (Mn, Co, Ni, Cu) or
two steps (Cd) and then mono- (Cu) or dihydrates (Mn, Co, Ni) decompose to oxides directly (Mn, Cu, Co) or with intermediate
formation of free metals (Co, Ni). Anhydrous Zn(II) complex decomposes directly to the oxide ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
130.
Michael Chariss Andrea Zickgraf Heike Stenger Elmar Bru Cristelle Desmarquet Martin Drger Silke Gerstmann Dainis Dakternieks James Hook 《Polyhedron》1998,17(25-26)
44 members of thecompound series Ph4−nMRn (M=Si, Ge, Sn, Pb; R=o-, m-, p-Tol; n=0–4) were synthesized (15 newcompounds). The crystal structures of Ph3Sn (o-Tol) and PhSn (o-Tol)3 were determined and compared to 16 known structures. Subject to the distanced (M–C), an interplay between through-space π–π repulsion and π–σ attraction leads to either elongated or compressed tetrahedral geometry. 29 Si-, 119 Sn- and 207 Pb-NMR chemical shifts were determined in solution and in the solid state. 73 Ge chemical shifts were measured only in solution. Anupfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a π–σcharge transfer which is constrained by torsion of the aromatic groups. 相似文献