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41.
Nondestructive testing of adhesive joints is of great interest. The method of second harmonic generation promises to give early information about failure of adhesive layers. In the case of resonance the amplitude of strain in a soft interface layer is strongly increased and, therefore, the layer considerably contributes to A2, the amplitude of the second harmonic. The nonlinear behavior of such a layer and its influence on A2 was studied by means of the finite element method. In the experimental situation all materials along the sound path contribute to A2. The dependence of the calculated and measured effects on the layer thickness, the velocity of sound, and the nonlinearity coefficient beta are reported. 相似文献
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Dietmar Glogar Sebastian Globits Andreas Neuhold Harald Mayr 《Magnetic resonance imaging》1989,7(6):611-617
To evaluate the potential of magnetic resonance imaging (MRI) in detection and quantification of mitral regurgitation, 26 pts. with echocardiographically or angiographically documented mitral regurgitation were examined using a 0.5 Tesla superconducting magnet. In each patient a multislice-multiphase study in a sagittal-coronal double angulated projection (four-chamber view equivalent) was performed to assess left and right ventricular volumes, ejection fraction and regurgitant fraction. Additionally a blood flow sensitive cine-study (fast field echo: FFE) was done to visualize direction and area of regurgitant jet. MRI data were compared with quantitative and qualitative assessment of mitral regurgitation by angiography, 2D echocardiography, Doppler sonography and color flow mapping. Using the FFE mode MRI was able to detect the regurgitant jet as a typical signal loss within the left atrium in all patients. The ratio of regurgitant jet area/left atrium area as determined by MRI showed a correlation with a comparable ratio from color Doppler sonography of R = 0.87 (p < 0.001). There was also good agreement in semiquantitative grading of mitral regurgitation between MRI and angiography (R = 0.77, p < 0.001). The determination of left and right ventricular stroke volume allowed the calculation of the regurgitant fraction, which showed a correlation with invasively determined regurgitation fraction of R = 0.84 (p < 0.001). These data provide additional information that MRI may be useful as a noninvasive technique to detect and quantify mitral regurgitation. 相似文献
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Karl Hensen Ralf Mayr‐Stein Bjrn Spangenberg Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):610-613
The reaction products of an addition reaction of five different silicon tetrahalides with the aromatic nitrogen base 4‐methylpyridine are presented. The following five structures are isomorphous: (I) tetrachlorobis(4‐methylpyridine)silicon, C12H14Cl4N2Si, (II) bromotrichlorobis(4‐methylpyridine)silicon, C12H14BrCl3N2Si, (III) dibromodichlorobis(4‐methylpyridine)silicon, C12H14Br2Cl2N2Si, (IV) tribromochlorobis(4‐methylpyridine)silicon, C12H14Br3ClN2Si, and (V) tetrabromobis(4‐methylpyridine)silicon, C12H14Br4N2Si. The molecules of (I) and (V), with D2h symmetry, have crystallographic C2h symmetry, while the molecules of (II), (III) and (IV) have a lower molecular symmetry, but as a result of the disorder of the halogen ligands, they appear to be of the same crystallographic symmetry. The environment around the Si atom can be described as a slightly distorted octahedron with the methylpyridine ligands occupying axial positions and the four halogen ligands in the equatorial plane. In spite of the different substitution pattern of the silicon centre, there are only insignificant differences between these five structures. 相似文献
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A. Janke H. Hiller R. Dworzak L. Ebert C. Mayr E. Kroupa G. Koller F. v. Wessely H. Lieb J. Schintlmeister M. Nießner G. Lock G. Ortner 《Mikrochimica acta》1942,30(1-2):181-192
Ohne Zusammenfassung 相似文献
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Karl Mayr 《Mathematische Zeitschrift》1939,44(1):91-103
Ohne ZusammenfassungUnter dem Titel: Über die Umkehrung von Potenzreihen hat der Verfasser auf dem deutschen Physiker- und Mathematikertag in Kreuznach (1937) über diesen Gegenstand berichtet. 相似文献