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21.
Volker D. Burkert 《Czechoslovak Journal of Physics》1996,46(7-8):627-671
In these lectures the status of electromagnetic excitation of nucleon resonances is reviewed and some of the open problems of the structure and spectroscopy of light-quark baryons are discussed. The basic formalism for describing electromagnetic processes is introduced but not derived.Lecture given at the 8th Summer School on Intermediate-Energy Physics: Hadron Dynamics at Low and Intermediate Energies, Prague, July 10–14, 1995. 相似文献
22.
We present optimal estimates for the asymptotic behavior of
strongly continuous semigroups in terms of growth abscissas of the resolvent function of the generator . In particular we give Ljapunov's classical stability condition a definite form for (infinite dimensional) abstract Cauchy problems: The abscissa of boundedness of equals the growth bound of the classical solutions of .
strongly continuous semigroups in terms of growth abscissas of the resolvent function of the generator . In particular we give Ljapunov's classical stability condition a definite form for (infinite dimensional) abstract Cauchy problems: The abscissa of boundedness of equals the growth bound of the classical solutions of .
23.
24.
Andreas Stockhammer Klaus-Hermann Dahmen Tobias Gerfin Luigi M. Venanzi Volker Gramlich Walter Fetter 《Helvetica chimica acta》1991,74(5):989-992
The cluster compounds [Pt3(μ-CO)3(PR3)3] act as Lewis bases towards the metal halides of Group XI, MX, Group XII, MX2, and Group XIII, MX3, to form cluster compounds of the composition [{MXn}{Pt3(μ-CO)3(PR3)3}]. The X-ray crystal structure, NMR and IR data are given for the compound [{ZnI}{Pt3(μ-CO)3(PPh(i-Pr)2)3}]. 相似文献
25.
Fausi?RassoulEmail author Heinz?L?ster Volker?Richter 《Monatshefte für Chemie / Chemical Monthly》2005,136(8):1501-1507
Summary. L-Carnitine, L-(−)-β-hydroxy-γ-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L-carnitine on hyperlipidaemias, the experimental model of the sucrose-induced hypertriglyceridaemia of the rat was used. In these experiments L-carnitine in the dose of 11 mg per day and 100 g body weight (over the period of 1 week) was able to antagonize the sucrose-induced hypertriglyceridaemia and the increase of serum free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic enzymes and fatty acid synthesis in the liver. However, L-carnitine increases the rate of hepatic fatty acid oxidation. Our results indicate a hypotriglyceridemic and free fatty acid lowering effect of L-carnitine, and suggest the use of this compound in the therapy of hyperlipidaemias. 相似文献
26.
Abstract The Primary reactions of the cosin-and fluorescein-photosensitized autoxidation of L-tyrosine were studied in aqueous media (pH = 8.6) by the flash-photolysis technique. The dye molecules were quantitatively converted to their triplet states in a single flash. The triplet dye molecules were found to react with tyrosine or oxygen. Ground state or radical dye molecules were formed in these reactions. Some 40 per cent of the triplet-tyrosine reactions yielded radicals, in triplet dye-oxygen reactions the corresponding yield was less than 10 per cent. The ground state dye was regenerated from the semireduced dye in reactions with oxygen and from the semioxidized dye in reactions with tyrosine. In the absence of oxygen the radicals formed in the photoinduced electron-transfer between the triplet dye and tyrosine recombined to a large extent. 相似文献
27.
Bromoacetyl chloride and bromoacetyl bromide are studied by gas phase electron diffraction at nozzle-tip temperatures of 70°C and 77°C, respectively. Both compounds exist as mixtures of anti and gauche conformers. The mole fraction anti, with uncertainties estimated at 2σ, was found to be 0.474(0.080) for bromoacetyl chloride and 0.615(0.069) for bromoacetyl bromide. The results for the distance (ra)and angle (∠α) parameters, with parenthesized uncertainties of 2σ including estimated uncertainty in the electron wave length and correlation effects are as follows: (1) bromoacetyl chloride, r(C-H) = 1.086(0.062) Å, r(CO) = 1.188(0.009) Å, r(C-C) = 1.519(0.018) Å, r(C-Cl) = 1.789(0.011) Å, r(C-Br) = 1.935(0.012) Å, ∠C-CO = 127.6(1.3)°, ∠C-C-Cl = 111.3(1.1)°, ∠C-C-Br = 111.0(1.5)°, ∠H-C-H = 109.5°(assumed), /o (gauche torsion angle relative to 0° for the anti form) = 110.0°(assumed); (2) bromoacetyl bromide, r(C-H) =1.110(0.088) Å, r(C=O) = 1.175(0.013) Å, r(C-C) = 1.513(0.020) Å, r(CO-Br) = 1.987(0.020) Å, r(CH2-Br) = 1.915(0.020) Å, ∠C-CO = 129.4(1.7)°, ∠CH2-CO-Br = 110.7(1.5)°, ∠CO-CH2-Br = 111.7(1.8)°, ∠H-C-H = 109.5°(assumed), ∠ø (gauche torsion angle relative to 0° for the anti form) = 105.0°(assumed). The structural results are discussed in connection with the structures of related molecules. 相似文献
28.
It is shown that azulenium cations in the first electronically excited state S1 are stronger acids than in the ground state S0. Their apparent pK″*, obtained from the H0-dependence of the quenching of the azulenium cation S1 → S0 fluorescence does not correspond to a true acid-base equilibrium in the electronically excited state S1. The pK″* values are kinetically controlled, the rate of reprotonation of azulene in the S1 state being too low to compete with the internal conversion to S0. 相似文献
29.
H. Hagen 《Journal of Geometry》1983,21(1):157-163
In this paper we investigate (k+1)-dimensional generalized ruled surfaces generated by a one-parameter family of k-dimensional linear subspaces of the n-dimensional Euclidean space \(\mathbb{E}^n \) . 相似文献
30.
Volker Enss 《Communications in Mathematical Physics》1983,89(2):245-268
In quantum mechanical potential scattering theory we use selected observables to describe the asymptotic properties of scattering states for long times. E.g., we show for the position and momentum operators that for Ωε?cont(H), $$\left( {m\frac{x}{t} - p} \right)e^{ - iHt} \Psi \to 0,$$ and that the set of outgoing states is absorbing. This is obtained easily without any detailed analysis of the interacting time evolution. The class of forces includes highly singular and very long range potentials. The results may serve as an intermediate step in a proof of asymptotic completeness; as a particular application we present a simple proof of completeness for Coulomb systems. 相似文献