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Epitaxial Sr(VxCryTi1−x−y)O3 (0≤x+y≤0.05) ternary composition spreads were grown on two different single crystal substrates, LaAlO3 and Nb-doped SrTiO3, by use of combinatorial laser molecular beam epitaxy with a specially patterned slide masking plate. The photocatalytic activity on the composition spreads was evaluated by the photo-reduction of Ag+ in an AgNO3 aqueous solution to deposit Ag metal on the spreads. The V-doping effect was found to depend greatly on the substrate: the photodeposition of Ag was much enhanced in the composition region of SrV0.05Ti0.95O3 only on the Nb-doped SrTiO3, but not on the LaAlO3 and non-doped SrTiO3. 相似文献
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W. Limmer K. Bitzer R. Sauer 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):455
The growth of AlGaAs layers on patterned GaAs substrates by molecular-beam epitaxy is strongly determined by the interfacet surface migration of Ga adatoms, leading to a pronounced variation of the local Al concentration. Taking advantage of this migration process, we have overgrown mesa structures, that consist of intersecting stripes or partially overlapping squares, to obtain a local maximum or minimum, respectively, of the AlGaAs band gap on top of the mesas. 相似文献
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用分子束外延(MBE)的方法在c面蓝宝石衬底上生长出了高质量的ZnO单晶薄膜和BexZn1-xO合金薄膜。X射线光电子能谱(XPS)测试结果表明,合金材料中Be元素的摩尔分数分别为1.8%、4.9%、8.0%和15.3%。在此基础上制备了ZnO基和BexZn1-xO基的金属-半导体-金属(MSM)结构紫外探测器。ZnO单晶探测器的响应波长为375nm,在1V电压下,350nm处的光响应度高达43A/W,光电流和暗电流之比达到105量级。在BexZn1-xO基紫外探测器中,其截止响应波长随着合金中Be含量的增加逐渐蓝移,其中Be0.153-Zn0.847O合金探测器的截止响应波长为366nm,紫外波段和可见波段的光电流之比达到2~3个数量级,具有良好的信噪比。此外,提出了氧气等离子体表面处理降低探测器暗电流的方法,并使ZnO单晶探测器的暗电流降低了4个数量级。 相似文献
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We have studied structural properties of InGaAs/GaAs superlattice sample prepared by Molecular Beam Epitaxy (MBE) using high resolution X‐ray diffractometer (HRXRD). Increasing strain relaxation and defect generations are observed with the increasing Rapid Thermal Annealing (RTA) temperature up to 775 °C. The higher temperatures bring out relaxation mechanisms; interdiffusion and favored migration. The defect structure and the defects which are observed with the increasing annealing temperature were analyzed. Firstly, the in‐plane and out‐of‐plane strains after the annealing of sample were found. Secondly, the structural defect properties such as the parallel X‐ray strain, perpendicular X‐ray strain, misfit, degree of relaxation, x composition, tilt angles and dislocation that are obtained from X‐ray diffraction (XRD) analysis were carried out at every temperature. As a result, we observed that the asymmetric peaks especially in asymmetric (224) plane was affected more than symmetric and asymmetric planes with lower polar or inclination angles due to c‐direction at low temperature. These structural properties exhibit different unfavorable behaviors for every reflection direction at the increasing temperatures. The reason is the relaxation which is caused by spatially inhomogeneous strain distribution with the increasing annealing temperature. In the InGaAs superlattice samples, this process enhances preferential migration of In atoms along the growth direction. Further increase in the annealing temperature leads to the deterioration of the abrupt interfaces in the superlattice and degradation in its structural properties. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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B. H. Koo Y. -G. Park H. Makino J. H. Chang T. Hanada D. Shindo T. Yao 《Applied Surface Science》2002,190(1-4):226-230
Self-assembled InAs quantum dots (QDs) on In0.52Al0.48As layer lattice matched to (1 0 0) InP substrates have been grown by molecular beam epitaxy (MBE) and evaluated by transmission electron microscopy (TEM) and photoluminescence (PL). TEM observations indicate that defect-free InAs QDs can be grown to obtain emissions over the technologically important 1.3–1.55 μm region. The PL peak positions for the QDs shift to low energy as the InAs coverage increases, corresponding to increase in QD size. The room temperature PL peak at 1.58 μm was observed from defect-free InAs QDs with average dot height of 3.6 nm. 相似文献
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A systematic study was performed to control the geometrical anisotropy of GaSb(As)/GaAs quantum dot structures formed by the Stranski–Krastanov growth mode of molecular beam epitaxy. In particular, effects of both the Sb4 beam flux and the As4 background pressure on the geometrical anisotropy were clarified and elongated QDs with lateral aspect ratio greater than 3 were successfully formed. Under a low As4 background pressure, As4 is found to act as surfactant to influence the adatom diffusion and change the density of QDs. By contrast, under high As4 background pressure, the intermixing of As and Sb takes place and reduces strains induced by the lattice mismatch. 相似文献