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81.
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
82.
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
83.
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
84.
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
85.
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
86.
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
87.
The angular distribution of the polarization of neutrons from the9Be(,n)12C reaction leading to the ground state in12C has been investigated at -energies of 2.40 and 2.80 MeV. The polarization has been determined by left-right asymmetry measurements of the intensities of neutrons elastically scattered on4He nuclei. Values of the analysing power of4He have been calculated using the phase shift data of Stammbach and Walter [1]. The degree of polarization observed varies between + 55% and —44%. All results obtained in this experiment are in good agreement with the results of polarization measurements of other authors except the results of Lietz et al. [2]. 相似文献
88.
In this paper was discuss the index problem for geometric differential operators (Spin–Dirac opreatorm Gauβ–Bonnet operator, Singnature operator) on manifolds with metric horns. On singular manifolds these operators in general do not unique closed extensions. But there always exist two extremal extensions D$sub:min$esub:and D$sub:max$esub: We describe the quotient D (D$sub:max$esub:)/D(D$sub:esub:) explicitely in geometric resp.topological terms of the base manifolds of the metric horns. We derive index formulas for the3 Spin–Dirac and GauβBonnet operator. For the Singnature operator we present a partial result. 相似文献
89.
Ulrich A. HarrÉus Barbara C. Wallner Ernst R. Kastenbauer Norbert H. Kleinsasser 《International journal of environmental analytical chemistry》2013,93(6):395-401
Surfactants, which are prevalent at industrial sites and in the environment generally, are potential risk factors in human carcinogenesis. The widespread industrial use of surfactants such as 4-alkylphenol ethoxylates and their prevalence in many cleaning products have provoked studies about surfactant concentrations in water and their toxicity levels. Up to now, these substances have mainly been tested on aquatic organisms. Though tests on human cell lines are rare. The alkaline Comet assay was performed to evaluate the genotoxicity of 4-nonylphenol ethoxylate, a biodegradable product of 4-alkylphenol ethoxylate, in human lymphocytes. Concentrations tested ranged from 0.15 to 150 µg/mL. Test concentrations of 10 to 15 µg/mL caused an increase level of DNA migration in human cells, but without inducing excessive toxicity (viability > 80%). Though induced levels of DNA migration starting at concentrations of 30 µg/mL may have been due to excessive levels of cytotoxicity (viability < 70%). Based on these data, 4-nonylphenol ethoxylate can induce DNA damage in human lymphocytes but at higher concentrations than are normally found in river or drinking water. However, considering the prevalence of surfactants, the measured genotoxicity of these substances is of concern. Further investigations on human target cells are necessary to evaluate the carcinogenic impact of surfactants and reconsider their environmental acceptance. 相似文献
90.
Elvira Welzig Harald Pichler Rudolf Krska Dietmar Knopp Reinhard Niessner 《International journal of environmental analytical chemistry》2013,93(3-4):279-288
Abstract The development of an indirect competitive enzyme immunoassay for the sulfonylurea herbicide metsulfuron-methyl (MSM) is described. In contrast to traditional antibody generation in mammals, this extremely sensitive method is based on chicken egg yolk antibodies (IgY). They were raised in laying hens using an MSM-derivative-BSA hapten as immunogen. With a 1:10000 dilution of the antibody solution and a coating antigen (MSM-derivative-KLH) concentration of 10 μg L?1 the IC50 value achieved for the target analyte was 0.4 μg L?1. The least detectable dose was established at 13 ng L?1. Cross-reactivity was tested with 5 structurally related compounds, where only sulfometuron showed a significant binding. The ELISA was tested with spiked tap and surface water samples. This paper, for the first time, demonstrates the production of high-affinity IgY antibodies for a herbicide compound. 相似文献