排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
K. Bach H. D. Baehr H. Bebelein A. Naumann F. W. Riegels D. Küchemann H. J. Zetzmann R. Ulken Th. Lehmann E. W. Huber E. Martyrer E. Strohbusch H. Rettig H. Meincke H. W. Hahnemann A. Steller H. Kicherer F. Frank K. Meerbeck W. Gohlke H. Weissbach J. Wotschke E. Kollmann 《Forschung im Ingenieurwesen》1963,29(5):164-168
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2.
Schlorf T Meincke M Kossel E Glüer CC Jansen O Mentlein R 《International journal of molecular sciences》2010,12(1):12-23
Superparamagnetic iron-oxide particles (SPIO) are used in different ways as contrast agents for magnetic resonance imaging (MRI): Particles with high nonspecific uptake are required for unspecific labeling of phagocytic cells whereas those that target specific molecules need to have very low unspecific cellular uptake. We compared iron-oxide particles with different core materials (magnetite, maghemite), different coatings (none, dextran, carboxydextran, polystyrene) and different hydrodynamic diameters (20-850 nm) for internalization kinetics, release of internalized particles, toxicity, localization of particles and ability to generate contrast in MRI. Particle uptake was investigated with U118 glioma cells und human umbilical vein endothelial cells (HUVEC), which exhibit different phagocytic properties. In both cell types, the contrast agents Resovist, B102, non-coated Fe(3)O(4) particles and microspheres were better internalized than dextran-coated Nanomag particles. SPIO uptake into the cells increased with particle/iron concentrations. Maximum intracellular accumulation of iron particles was observed between 24 h to 36 h of exposure. Most particles were retained in the cells for at least two weeks, were deeply internalized, and only few remained adsorbed at the cell surface. Internalized particles clustered in the cytosol of the cells. Furthermore, all particles showed a low toxicity. By MRI, monolayers consisting of 5000 Resovist-labeled cells could easily be visualized. Thus, for unspecific cell labeling, Resovist and microspheres show the highest potential, whereas Nanomag particles are promising contrast agents for target-specific labeling. 相似文献
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The plane-wave scattering matrix is used to characterize antennas that are located just above a planar interface that separates two media. The plane-wave transmitting spectrum for the field radiated downward into the lower medium is expressed directly in terms of the current distribution of the transmitting antenna. The transmitting spectrum for a reciprocal antenna determines the plane-wave receiving spectrum for the field that propagates upward in the lower medium. A measurement procedure is discussed for determining the plane-wave transmitting and receiving spectra from measurements with a probe that is located in the lower medium. 相似文献
5.
Thomas Schlorf Manuela Meincke Elke Kossel Claus-Christian Gl��er Olav Jansen Rolf Mentlein 《International journal of molecular sciences》2011,12(1):12-23
Superparamagnetic iron-oxide particles (SPIO) are used in different ways as contrast agents for magnetic resonance imaging (MRI): Particles with high nonspecific uptake are required for unspecific labeling of phagocytic cells whereas those that target specific molecules need to have very low unspecific cellular uptake. We compared iron-oxide particles with different core materials (magnetite, maghemite), different coatings (none, dextran, carboxydextran, polystyrene) and different hydrodynamic diameters (20–850 nm) for internalization kinetics, release of internalized particles, toxicity, localization of particles and ability to generate contrast in MRI. Particle uptake was investigated with U118 glioma cells und human umbilical vein endothelial cells (HUVEC), which exhibit different phagocytic properties. In both cell types, the contrast agents Resovist, B102, non-coated Fe3O4 particles and microspheres were better internalized than dextran-coated Nanomag particles. SPIO uptake into the cells increased with particle/iron concentrations. Maximum intracellular accumulation of iron particles was observed between 24 h to 36 h of exposure. Most particles were retained in the cells for at least two weeks, were deeply internalized, and only few remained adsorbed at the cell surface. Internalized particles clustered in the cytosol of the cells. Furthermore, all particles showed a low toxicity. By MRI, monolayers consisting of 5000 Resovist-labeled cells could easily be visualized. Thus, for unspecific cell labeling, Resovist and microspheres show the highest potential, whereas Nanomag particles are promising contrast agents for target-specific labeling. 相似文献
6.
Rubk T. Meaney P.M. Meincke P.. Paulsen K.D. 《Antennas and Propagation, IEEE Transactions on》2007,55(8):2320-2331
Breast-cancer screening using microwave imaging is emerging as a new promising technique as a supplement to X-ray mammography. To create tomographic images from microwave measurements, it is necessary to solve a nonlinear inversion problem, for which an algorithm based on the iterative Gauss-Newton method has been developed at Dartmouth College. This algorithm determines the update values at each iteration by solving the set of normal equations of the problem using the Tikhonov algorithm. In this paper, a new algorithm for determining the iteration update values in the Gauss-Newton algorithm is presented which is based on the conjugate gradient least squares (CGLS) algorithm. The iterative CGLS algorithm is capable of solving the update problem by operating on just the Jacobian and the regularizing effects of the algorithm can easily be controlled by adjusting the number of iterations. The new algorithm is compared to the Gauss-Newton algorithm with Tikhonov regularization and is shown to reconstruct images of similar quality using fewer iterations. 相似文献
7.
Higher order hierarchical discretization scheme for surface integral equations for layered media 总被引:2,自引:0,他引:2
Jorgensen E. Kim O.S. Meincke P. Breinbjerg O. 《Geoscience and Remote Sensing, IEEE Transactions on》2004,42(4):764-772
This paper presents an efficient technique for the analysis of electromagnetic scattering by arbitrarily shaped perfectly conducting objects in layered media. The technique is based on a higher order method of moments (MoM) solution of the electric field, magnetic field, or combined-field integral equation. This higher order MoM solution comprises higher order curved patches for the geometry modeling and higher order hierarchical basis functions for expansion of the electric surface current density. Due to the hierarchical property of the basis functions, the order of the expansion can be selected separately on each patch depending on the wavelength in the layer in which the patch is located and the size of the patch. In this way, a significant reduction of the number of unknowns is achieved and the same surface mesh can be reused in a wide frequency band. It is shown that even for fairly large problems, the higher order hierarchical MoM requires less memory than existing fast multipole method (FMM) or multilevel FMM implementations. 相似文献
8.
Burak Polat Peter Meincke 《AEUE-International Journal of Electronics and Communications》2004,58(5):362-366
A forward model for ground penetrating radar imaging of buried 3-D perfect electric conductors is addressed within the framework of diffraction tomography. The similarity of the present forward model derived within the physical optics approximation with that derived within the first Born approximation in an earlier investigation highlights analytically the reasons lying under the success of the Born models in identifying perfect electric conductors. 相似文献
9.
Hermann Meincke 《化学,工程师,技术》1977,49(7):560-562
10.
Daniel Moses Mark Sutton Robin L. Armstrong Peter P. M. Meincke 《Journal of Low Temperature Physics》1979,36(5-6):587-597
Measurements of the specific heat at low temperatures are reported for single-crystal samples of K2ReCl6, K2IrCl6, and K2PtCl6. The data for K2IrCl6 give strong evidence that in addition to the well-established antiferromagnetic phase transition occurring at a temperature T
N = 3.01 ± 0.01 K, a displacive phase transition occurs at T
c= 2.83 ± 0.02 K. Although the compounds are structurally similar, the background specific heats at low temperatures are significantly different. A careful analysis of these data plus previous data for K2OsCl6 shows that the reason for the large differences in the lattice specific heats is the presence of low-lying rotary modes. A Debye temperature of 91.1 ± 0.5 K is deduced and effective rotary mode frequencies of 28.6, 29.1, 30.0, and 37.9 cm–1 are found for K2ReCl6, K2OsCl6, K2IrCl6, and K2PtCl6, respectively.Supported in part by a NSERC grant. 相似文献