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71.
H. K. Janssen 《Zeitschrift für Physik A Hadrons and Nuclei》1971,248(2):167-176
The autocorrelation function of an impurity spin in an infinite chain of spins withX-Y-coupling in thermal equilibrium is shown to be an example of “Onsager separation”. This separability ensures that the statistical entropy production associated with the impurity spin relaxation contains a phenomenological part which proves to be always positive. 相似文献
72.
Summary The separation and identification of metabolites of mecloqualone in human urine samples by GLC-MS analysis are described. Four hydroxylated mecloqualone derivates have been identified.
Zusammenfassung Die Trennung und Identifizierung von Metaboliten des Mecloqualons in Menschenharn durch Gas-Flüssigchromatographie und Massenspektrometrie wurde beschrieben. Vier Hydroxylderivate des Mecloqualons wurden identifiziert.相似文献
73.
In a study by AES of the surfaces of single crystal magnesium oxide and magnesium after various stages of oxidation, it has been shown that Auger energy shifts are produced by surface charging. Recognition of the charging effects has enabled the peak in the low energy spectrum of magnesium oxide crystal to be assigned. The low energy secondary electron spectra of both MgO crystal and oxidised magnesium are complicated by the presence of extra features which arise from diffraction of true secondary electrons, and in particular for oxidised magnesium a cross-transition occurring at the metal-oxide interface. Oxidation studies of sodium also reveal transitions arising from a similar process. 相似文献
74.
Gerhard Janssen 《manuscripta mathematica》1975,16(3):277-305
On the basis of the authors previous paper [6] the properties of the lattice of idempotents in a finite weakly closed Jordan algebra A are examined. The results then yield a unique direct decomposition A=Ad⊕Ac where Ad is a discrete and Ac is a continuous Jordan algebra. An application of Jacobsons coordinatization theorem shows Ac=H(D), D associative, since there exist sufficiently many strongly connected idempotents. Then we prove that D is a uniquely determined continuous real W* -algebra with finite normal faithful trace. 相似文献
75.
H. K. Janssen 《Zeitschrift für Physik A Hadrons and Nuclei》1973,258(3):243-250
Kinetic equations for the fluctuations and the fluctuation spectrum of the occupation numbers in a nonequilibrium stationary state are derived within a stochastic theory. The probability of changes of the distribution in infinitesimal time intervals is given by the “Stoßzahlansatz”. It is assumed for the decoupling of the higher correlations, that the occupation numbers are macroscopic variables. 相似文献
76.
Data have been obtained from Auger and energy loss processes in clean metallic Mg, Mg during stages of oxidation, and UHV cleaved MgO(100) surfaces. Particular attention has been paid to twenty features below 200 eV in the Auger spectra from these surfaces. A comparison of spectra from the metal, oxidised metal surface, and single crystal MgO has enabled estimates to be made of surface charging effects, and the MgO steady state surface potential is found to be near + 10 V above ground. All the Auger features are given assignments, two of which are interfacial processes involving ionic initial states and metallic final states. Several features in the low energy Auger spectrum are attributed to diffraction of true secondary electrons. 相似文献
77.
78.
Kastelein RA Janssen M Verboom WC de Haan D 《The Journal of the Acoustical Society of America》2005,118(2):1172-1179
Receiving beam patterns of a harbor porpoise were measured in the horizontal plane, using narrow-band frequency modulated signals with center frequencies of 16, 64, and 100 kHz. Total signal duration was 1000 ms, including a 200 ms rise time and 300 ms fall time. The harbor porpoise was trained to participate in a psychophysical test and stationed itself horizontally in a specific direction in the center of a 16-m-diameter circle consisting of 16 equally-spaced underwater transducers. The animal's head and the transducers were in the same horizontal plane, 1.5 m below the water surface. The go/no-go response paradigm was used; the animal left the listening station when it heard a sound signal. The method of constants was applied. For each transducer the 50% detection threshold amplitude was determined in 16 trials per amplitude, for each of the three frequencies. The beam patterns were not symmetrical with respect to the midline of the animal's body, but had a deflection of 3-7 degrees to the right. The receiving beam pattern narrowed with increasing frequency. Assuming that the pattern is rotation-symmetrical according to an average of the horizontal beam pattern halves, the receiving directivity indices are 4.3 at 16 kHz, 6.0 at 64 kHz, and 11.7 dB at 100 kHz. The receiving directivity indices of the porpoise were lower than those measured for bottlenose dolphins. This means that harbor porpoises have wider receiving beam patterns than bottlenose dolphins for the same frequencies. Directivity of hearing improves the signal-to-noise ratio and thus is a tool for a better detection of certain signals in a given ambient noise condition. 相似文献
79.
Yamauchi K Janssen JW Kentgens AP 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,167(1):87-96
Solid-state nuclear magnetic resonance (NMR) probeheads using solenoid microcoils with an inner diameter of 300-400 microm are developed for the study of mass-limited solid samples. Some attention is paid to the mechanical ruggedness of the probes allowing sample changing. The performance, in terms of sensitivity and RF-characteristics, of these probeheads is studied for (1)H, (31)P, and (27)Al in different model compounds in view of the feasibility of specific applications. The results show that the sensitivity is high enough to detect approximately 10(14) spins/sqrt Hz with a signal-to-noise ratio of 1 in a single scan. A specific advantage of microcoils for solid-state NMR applications is that they can generate extremely high RF-fields if implemented in appropriate circuits. Using RF-powers in the hundreds of Watts range, RF-fields well in excess of 1MHz can be made. This allows the excitation of spectra of nuclei whose resonance lines are dispersed of several megahertz. This is particularly useful for quadrupolar nuclei experiencing large quadrupolar interactions as is demonstrated for (27)Al in single crystal and powdered minerals. 相似文献
80.
B. Krusche J. Lehr J. Ahrens J. R. M. Annand R. Beck F. Bloch L. S. Fog D. Hornidge S. Janssen M. Kotulla J. C. McGeorge I. J. D. MacGregor J. Messchendorp V. Metag U. Mosel R. Novotny R. O. Owens M. Pfeiffer R. Sanderson S. Schadmand D. P. Watts 《The European Physical Journal A - Hadrons and Nuclei》2004,22(2):277-291
Photoproduction of neutral pions from nuclei (carbon, calcium, niobium, lead) has been studied for incident-photon energies from 200 MeV to 800 MeV with the TAPS detector using the Glasgow photon tagging spectrometer at the Mainz MAMI accelerator. Data were obtained for the inclusive photoproduction of neutral pions and the partial channels of quasifree single-
, double-
, and
photoproduction. They have been analyzed in terms of the in-medium behavior of nucleon resonances and the pion-nucleus interaction. They are compared to earlier measurements from the deuteron and to the predictions of a Boltzmann-Uehling-Uhlenbeck (BUU) transport model for photon-induced pion production from nuclei.PACS:
13.60.Le Meson production - 25.20.Lj Photoproduction reactions 相似文献