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排序方式: 共有459条查询结果,搜索用时 93 毫秒
101.
J. H. Müller D. Bettermann V. Rieger K. Sengstock U. Sterr W. Ertmer 《Applied physics. B, Lasers and optics》1995,60(2-3):199-204
Matter-wave interferences in a four-pulse version of a Ramsey-Bordé atom interferometer have been utilized to study phase shifts. A topological phase shift analogous to the scalar Aharonov-Bohm effect proposed for charged-particle interferences in the presence of a pulsed electrostatic potential has been investigated. The time-dependent potential has been generated by the interaction of a laser field with an induced atomic dipole without spatial variation along the interferometer arms. The atom interferometer has been run with laser-cooled magnesium atoms stored in a magneto-optical trap.Dedicated to H. Walther on the occasion of his 60th birthday 相似文献
102.
Estela A. Gonzalez 《Solid State Communications》2004,131(2):81-85
Adsorption of hydrogen on the ordered FePd face centered tetragonal alloy is investigated using a tight binding theoretical method. The changes in the electronic structure and bonding in the (100), (110) and (111) surfaces are analyzed. A simplified model for H diffusion to the bulk is also developed. The H-surface bond is achieved at the expense of the metal-metal bond being the Pd-Pd the more affected in the (100) and (110) cases. 相似文献
103.
The effect of inelastic excitation of exotic light projectiles (proton-as well as neutron-rich)17F and11Be on fusion with heavy target has been studied at near-barrier energies. The calculations have been performed in the coupled
channels approach where, in addition to the normal coupling of the ground state of the projectile to the continuum, inelastic
excitation of the projectile to the bound excited state and its coupling to the continuum have also been taken into consideration.
The inclusion of these additional couplings has been found to have significant effect on the fusion excitation function of
neutron-rich11Be on208Pb whereas the effect has been observed to be nominal for the case of proton-rich17F on the same target. The pronounced effect of the channel coupling on the fusion process in the case of11Be is attributed to its well-developed halo structure. 相似文献
104.
The microstructures and field emission characteristics of hydrogenated amorphous carbon films prepared by using different hydrogen dilution ratio were investigated. It was found that a very low threshold electric field emission could be achieved for samples with moderated hydrogen dilution ratio. However, the field emission characteristics became worse for samples with high hydrogen dilution ratio. The change of field emission can be attributed to the change of electronic structures due to the hydrogen dilution in addition to the increase of the hydrogen surface termination. 相似文献
105.
To investigate the effects of nano-hydroxyapatite (HA) particles with different morphology on highly malignant melanoma cells, three kinds of HA particles with different morphology were synthesized and co-cultured with highly malignant melanoma cells using phosphate-buffered saline (PBS) as control. A precipitation method with or without citric acid addition as surfactant was used to produce rod-like hydroxyapatite (HA) particles with nano- and micron size, respectively, and a novel oil-in-water emulsion method was employed to prepare ellipse-like nano-HA particles. Particle morphology and size distribution of the as prepared HA powders were characterized by transmission electron microscope (TEM) and dynamic light scattering technique. The nano- and micron HA particles with different morphology were co-cultured with highly malignant melanoma cells. Immunofluorescence analysis and MTT assay were employed to evaluate morphological change of nucleolus and proliferation of tumour cells, respectively. To compare the effects of HA particles on cell response, the PBS without HA particles was used as control. The experiment results indicated that particle nanoscale effect rather than particle morphology of HA was more effective for the inhibition on highly malignant melanoma cells proliferation. 相似文献
106.
Electronic tunnelling through a one-dimensional quantum dot chain is theoretically studied, when two leads couple to the individual component quantum dots of the chain arbitrarily. If there are some dangling quantum dots in the chain outside the leads, the electron tunnelling through the quantum dot chain is wholly forbidden while the energy of the incident electron is just equal to the molecular energy levels of the dangling quantum dots, which is known as the antiresonance effect. In addition, the influence of electron interaction on the antiresonance effect is discussed within the Hartree-Fock approximation. 相似文献
107.
Masafumi Kashii Yoichiroh Hosokawa Hiroshi Kitano Yusuke Mori Kazufumi Takano Hiroyoshi Matsumura Tsuyoshi Inoue Satoshi Murakami Kazuomi Sugamoto Takatomo Sasaki Hiroshi Masuhara 《Applied Surface Science》2007,253(15):6447-6450
For precise X-ray diffraction (XRD) measurement giving the three-dimensional structure of proteins, it is important to prepare high-quality single crystals with suitable shape. As a new processing technique to obtain such protein crystals, we employed femtosecond laser-induced cleaving of protein crystal in a growth vessel containing water solution. An intact protein crystal was precisely processed without mechanical contact in its sealed growth vessel by focusing femtosecond laser pulses. We confirmed that three-dimensional processing of the crystal in its supersaturated solution was realized using multiphoton absorption and that the processing was efficiently enhanced by the cleaving behavior attributed to a photomechanical mechanism of the femtosecond laser ablation. 相似文献
108.
109.
Hideshi Maki Masahiko Tsujito Hiroyuki Nariai Minoru Mizuhata 《Magnetic resonance in chemistry : MRC》2014,52(3):69-81
The complexation behaviors of Be2+ with cyclo‐μ‐imido triphosphate anions, cP3O9?n(NH)n3? (n = 1, 2), have been investigated by both 9Be and 31P NMR techniques at ?2.3 °C in order to clarify the coordination structures of the complexes. The spectra showed that cP3O9?n(NH)n (n = 1, 2) ligands form ML, ML2, and M2L complexes with Be2+ ions, and the formation of complexes coordinating with nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. These complexation trends are very similar to those of Be2+‐cP3O6(NH)33? system, which has been reported by us. The peak deconvolution of 9Be NMR spectra made these beryllium complexes amenable to stability constant determinations. The stability constants of the complexes increase with an increase in the protonation constants of the ligands as the number of imino groups, which constitute the ligand molecules, is ascended. This increase is primarily attributable to the lower electronegativity of nitrogen atoms than oxygen atoms, which are directly bonded to central phosphorus atoms; moreover, tautomerism equilibrium in the entire of the imidopolyphosphate molecule is also responsible to the higher basicity. 31P NMR spectra measured concurrently have verified the formation of the complexes estimated by the 9Be NMR measurement. Intrinsic 31P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be2+ cations have been determined. Not only the protonation constants but also the stability constants of all Be2+ complexes increase approximately linearly with an increase in the number of imino groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
110.
Nobuhiro Yamanaka 《Hyperfine Interactions》2000,127(1-4):129-132
The Fermi contact parameter which represents hyperfine structure (hfs) has been accurately calculated for the ground state
of the 9Be+ ion in a previous paper. In the present paper, the calculated parameter is compared with a high precision measurement to
derive the hfs anomaly (the Bohr-Weisskopf effect), which is caused by nuclear magnetization distribution. The obtained hfs
anomaly shows a satisfactory agreement with the result of a nuclear shell model calculation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献