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41.
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43.
Reaction of the new asymmetric ligand 2-(N-isopropyl-N-((1-methylimidazolyl)methyl)aminomethyl)-6-(N-carboxylmethyl-N-((1-methylimidazolyl)methyl) aminomethyl)-4-methylphenol (ICIMP) with nickel perchlorate and diphenylacetic acid leads to the formation of tetranuclear nickel complexes, whose crystal structures reveal that they consist of dimers of dimers in which each Ni(2) unit has a coordination environment that is similar to the active site of urease. One complex has been shown to coordinate urea and catalyze the hydrolysis of an organophosphate monoester. 相似文献
44.
Bertram HC Rasmussen M Busk H Oksbjerg N Karlsson AH Andersen HJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,157(2):267-276
This study investigates the effects of developmental stage and muscle type on the mobility and distribution of water within skeletal muscles, using low-field (1)H-NMR transverse relaxation measurements in vitro on four different porcine muscles (M. longissimus dorsi, M. semitendinosus, M. biceps femoris, M. vastus intermedius) from a total of 48 pigs slaughtered at various weight classes between 25 kg and 150 kg. Principal component analysis (PCA) revealed effects of both slaughter weight and muscle type on the transverse relaxation decay. Independent of developmental stage and muscle type, distributed exponential analysis of the NMR T(2) relaxation data imparted the existence of three distinct water populations, T(2b), T(21), and T(22), with relaxation times of approximately 1-10, 45-120, and 200-500 ms, respectively. The most profound change during muscle growth was a shift toward faster relaxation in the intermediate time constant, T(21). It decreased by approx. 24% in all four muscle types during the period from 25 to 150 kg live weight. Determination of dry matter, fat, and protein content in the muscles showed that the changes in relaxation time of the intermediate time constant, T(21), during growth should be ascribed mainly to a change in protein content, as the protein content explained 77% of the variation in the T(21) time constant. Partial least squares (PLS) regression revealed validated correlations in the region of 0.58 to 0.77 between NMR transverse relaxation data and muscle development for all the four muscle types, which indicates that NMR relaxation measurements may be used in the prediction of muscle developmental stage. 相似文献
45.
A new class of saturated hydrocarbons, in which a spiropentane-type unit is bound by a cyclic hydrocarbon, has been investigated by using ab initio molecular orbital calculations at the B3-LYP and MP2 levels. These molecules have been given the trivial name hemispiroalkaplanes. Hemialkaplanes, which are analogous molecules built-up from a neopentane-type unit and a cyclic hydrocarbon, have also been examined. The hemispiroalkaplanes are predicted to contain a pyramidal-tetracoordinate carbon atom that possesses a lone pair of electrons. Protonation at this apical carbon atom is found to be highly favourable, resulting in a remarkably high basicity for a saturated hydrocarbon. The proton affinities of the hemispiroalkaplanes are calculated to be more than 1170 kJmol(-1), even greater than that of the diamine "proton sponges". Structural parameters, heats of formation and strain energies for the novel hydrocarbons are detailed. 相似文献
46.
An isomer of 161Lu with a half-life of 7.3 ± 0.4 ms has been discovered in the heavy-ion reaction 148Sm(19F, 6n)161mLu. Oneγ-ray transition with energy 135.8 ± 0.2 keV was observed, and a K-conversion coefficient of 1.1 ± 0.3 deduced in the decay of this isomer. 相似文献
47.
S.Brøgger Christensen Ulla Rasmussen Carsten Christophersen 《Tetrahedron letters》1980,21(39):3829-3830
The major skin irritating constituent of the root of Thapsia garganica L. has been shown to be a hexaoxygenated-C6-guaianolide esterificated with four carboxylic acids. 相似文献
48.
[structure: see text] Carbaporphyrinoid systems with semiquinone, cycloheptatriene, or indene subunits react under mild conditions with silver(I) acetate to give stable silver(III) organometallic derivatives. 相似文献
49.
G.?SrinivasanEmail author E.T.?Rasmussen A.A.?Bush K.E.?Kamentsev V.F.?Meshcheryakov Y.K.?Fetisov 《Applied Physics A: Materials Science & Processing》2004,78(5):721-728
Thick-film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite, La0.7Sr0.3MnO3 (LSMO), or La0.7Ca0.3MnO3 (LCMO) and lead zirconate titanate (PZT). Structural, magnetic, and ferromagnetic resonance characterization shows evidence for defect-free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite–PZT than in manganite–PZT. The ME voltage coefficient E at room temperature is the highest in NFO–PZT and the smallest for LCMO–PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. The magnitude of E correlates well with magnetic permeability for the ferrites. PACS 75.80.+q; 75.70.Gg; 75.60.-d 相似文献
50.
Larsen J Rasmussen BS Hazell RG Skrydstrup T 《Chemical communications (Cambridge, England)》2004,(2):202-203
A disphosphine-palladium(0) complex capable of recognising barbiturates has been prepared. Oxidative addition studies with a barbitiurate:aryl iodide conjugate provided new Pd(ii) complexes where the positioning of the Pd-bound aryl group is controlled by the molecular recognition event. 相似文献