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51.
Norbert Kuhn Martin Ghner Martin Grathwohl Jrg Wiethoff Gernot Frenking Yu Chen 《无机化学与普通化学杂志》2003,629(5):793-802
2‐Iminoimidazolines — Strong Nitrogen Bases als Ligands in Inorganic Chemistry Due to the tendency of the 5‐membered cyclic fragment to accept a positive charge which yields an ylide type bonding situation, 2‐iminoimidazolines are strong nitrogen bases. They can serve as neutral ligands being 2+2 electron donors. Deprotonation leads to the anions which are potential 2+4 electron donors. We describe first the synthesis and characterization of the title compound 2‐imino‐1, 3‐dimethylimidazoline (ImNH, 8 ) and its anion 9 . Next we demonstrate their properties as ligands in complexes of main group elements and transition metals. In a third chapter we describe attempts to functionalize iminoimidazolines with the goal to create neutral ligands that coordinate in a semistable fashion. On this way we want to make a contribution to the chemistry of complex compounds directed towards catalysis. 相似文献
52.
Dr. Norbert Köhler 《Monatshefte für Mathematik》1981,92(2):105-116
Those non-hamiltonian graphsG withn vertices are characterized, which satisfy the Ore-type degree-conditiond(x)+d(y)n–2 for each pairx,yM of different nonadjacent vertices whereM consists of two vertices ofG. As an application a theorem on hamiltonian connectivity of graphs is given. Furthermore, a condition is presented which is sufficient for the existence of a covering of a graph by two disjoint paths with prescribed set of startpoints and prescribed set of endpoints. A class of graphs is described which have no covering of this kind. 相似文献
53.
Norbert Kalus 《Journal of statistical physics》1981,25(4):635-643
We describe a new class of single spin measures on then-dimensional sphereS
r
n
of radiusr (n 4) for which Lebowitz-type [J. Lebowitz,J. Stat. Phys.
16:463 (1977)] inequalities hold. This is achieved by an appropriate parametrization ofS
r
n
. The above class includes the uniform measures onxs Rn ¦x¦ r for any 0 p r. The second topic of this paper is an abstract formulation of the first Griffiths inequality [R. B. Griffiths,J. Math. Phys.
8:478 (1967)] and the underlying symmetry property. 相似文献
54.
We investigate the nature of the phase transition from the superconducting to the uniformly ordered magnetic phase in ferromagnetic superconductors by renormalization group methods. For this purpose Halperin, Lubensky, Ma's application of the-expansion to pure superconductors is extended to include the influence of magnetic order as well. Our treatment shows that in the vicinity of the ferromagnetic to superconducting phase-boundary critical fluctuations of the magnetization are absorbed into fluctuations of the magnetic field. As a consequence the transition always is first order. An additional indication to the dominance of electromagnetic effects is the irrelevance of the coupling corresponding to spin flip scattering. 相似文献
55.
Norbert Köhler 《manuscripta mathematica》1976,19(2):151-164
The following statements are valid:The complete directed graph ¯Kn, n1 (mod 2p), is decomposable into directed 2p-cycles.The complete directed bipartite graph ¯Km,n is decomposable into 2p-cycles if p is a divisor of m and np.If p is a prime, then this condition is necessary, too.The complete directed graph ¯Kn, n12, is decomposable into 6-cycles if and only if 6 相似文献
56.
Quentin Coquerel Claire Legendre Jacinthe Frangieh Stephan De Waard Jrme Montnach Leos Cmarko Joseph Khoury Charifat Said Hassane Dimitri Brard Benjamin Siegler Ziad Fajloun Harold De Pomyers Kamel Mabrouk Norbert Weiss Daniel Henrion Pascal Richomme Csar Mattei Michel De Waard Anne-Marie Le Ray Christian Legros 《Molecules (Basel, Switzerland)》2022,27(13)
Voltage-gated Na+ (NaV) channels are significant therapeutic targets for the treatment of cardiac and neurological disorders, thus promoting the search for novel NaV channel ligands. With the objective of discovering new blockers of NaV channel ligands, we screened an In-House vegetal alkaloid library using fluorescence cell-based assays. We screened 62 isoquinoline alkaloids (IA) for their ability to decrease the FRET signal of voltage sensor probes (VSP), which were induced by the activation of NaV channels with batrachotoxin (BTX) in GH3b6 cells. This led to the selection of five IA: liriodenine, oxostephanine, thalmiculine, protopine, and bebeerine, inhibiting the BTX-induced VSP signal with micromolar IC50. These five alkaloids were then assayed using the Na+ fluorescent probe ANG-2 and the patch-clamp technique. Only oxostephanine and liriodenine were able to inhibit the BTX-induced ANG-2 signal in HEK293-hNaV1.3 cells. Indeed, liriodenine and oxostephanine decreased the effects of BTX on Na+ currents elicited by the hNaV1.3 channel, suggesting that conformation change induced by BTX binding could induce a bias in fluorescent assays. However, among the five IA selected in the VSP assay, only bebeerine exhibited strong inhibitory effects against Na+ currents elicited by the hNav1.2 and hNav1.6 channels, with IC50 values below 10 µM. So far, bebeerine is the first BBIQ to have been reported to block NaV channels, with promising therapeutical applications. 相似文献
57.
Norbert Karpitschka 《Mikrochimica acta》1961,49(5):738-740
Zusammenfassung Bei der O-Methylbestimmung unter den normalen Reaktionsbedingungen nachZeisel wurden bei quartären Trimethylammonium-pyrimidin-chloriden zu hohe Werte erhalten. Die kochende Jodwasserstoffsäure spaltet langsam eine Methylgruppe unter Bildung von Methyljodid ab.
Summary Too high values are obtained for quaternary trimethylammonium pyrimidine chlorides in the O-methyl determination afterZeisel under the normal reaction conditions. The boiling hydriodic acid slowly splits off a methyl group with production of methyl iodide.
Résumé On a obtenu des valeurs trop fortes poux les chlorures quaternaires de triméthylammoniumpyrimidine, dans le cas du dosage des groupes O-méthyles dans les conditions de réactions normales, suivantZeisel. L'acide iodhydrique bouillant scinde lentement un groupement méthyle en donnant ensuite de l'iodure de méthyle.相似文献
58.
59.
Following the strategy of using polyfunctional phosphonic acids for the synthesis of open-framework metal phosphonates, the phosphonocarboxylic acid (H2O3PCH2)2NCH2C6H4COOH was used in the hydrothermal synthesis of new Ba phosphonates. Its decomposition led to the first open-framework barium phosphonate [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O. The synthesis was also successfully performed using iminobis(methylphosphonic acid), (H2O3PCH2)2NH, as a starting material, and the synthesis was optimized to obtain as a pure material. The reaction setup as well as the pH are the dominant parameters, and only a diffusion-controlled reaction led to the desired compound. The crystal structure was solved from single-crystal data: monoclinic; C2/c; a=2328.7(2), b=1359.95(7), and c=718.62(6) pm; beta=98.732(10) degrees ; V=2249.5(3)x10(6) pm3; Z=4; R1=0.036; and wR2=0.072 (all data). The structure of [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O is built up from BaO8 and BaO10 polyhedra forming BaO chains and layers, respectively. These are connected to a three-dimensional metal-oxygen-metal framework with the iminobis(methylphosphonic acid) formally coating the inner walls of the pores. The one-dimensional pores (3.6x4 A) are filled with H2O molecules that can be thermally removed. Thermogravimetric investigations and temperature-dependent X-ray powder diffraction demonstrate the stability of the crystal structure up to 240 degrees C. The uptake of N,N-dimethylformamide and H2O by dehydrated samples is demonstrated. Furthermore, IR, Raman, and 31P magic-angle-spinning NMR data are also presented. 相似文献
60.
Agrobacterium fabrum is a widely used model bacterium for gene transfer from pro‐ to eukaryote, for genetics and metabolism. The phytochrome system of Agrobacterium, encompassing the two phytochromes Agp1 and Agp2, has provided deep insight into phytochrome action in a bacterial organism. This review summarizes recent results on phytochrome evolution, phytochrome regulation of conjugation and plant infection and biochemical studies including the crystal structure of Agp1‐PCM, the photosensory core module of Agp1. 相似文献