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31.
Quality-guided algorithm is a widely used method in phase unwrapping. This paper shows an accurate quality map based on fringe contrast for 3D shape measurement. Phase-shifted fringe patterns are projected onto an object surface by a programmable liquid crystal projector and recorded by a CCD camera. A wrapped phase map and a fringe contrast map are extracted from the deformed fringe patterns by the phase-shifting technique. Guided by the contrast map, the quality-guided unwrapping algorithm minimizes unwanted shadow and non-uniform surface reflectance effects and is able to retrieve a correct surface profile. Validity of the proposed method is tested on a fish model and a cutting tool specimen. 相似文献
32.
A method for generating a high visibility digital speckle shearing fringe pattern is proposed. A three-step phase shifting technique which involves the introduction of arbitrary phases is utilized. The phase shifting technique is carried out using a rotating mirror and a theoretical model which involves a linear correlation algorithm is discussed. Experimental results showing correlation fringe patterns and a deformation phase map are presented. 相似文献
33.
Shape identification using phase shifting interferometry and liquid-crystal phase modulator 总被引:6,自引:0,他引:6
A phase shifting technique using a Michelson interferometry system is presented and applied to surface contour measurement. Hyperbolic fringes are produced by the interference of two spherical wavefronts expanded from a beam expander. The fringe pattern is projected on an object surface and the deformed grating image is captured by a CCD camera for subsequent analysis by a PC. Phase variation is achieved by a liquid-crystal device incorporated in the Michelson interferometry system. Results obtained using the proposed method for objects of various shapes and sizes compared well with those from a conventional profilometer. 相似文献
34.
35.
This paper presents an optical method which is based on speckle-shearing interferometry for the measurement of the slope at any point of an object. The object under study is illuminated by an expanded laser beam and its image is recorded on a photographic plate placed at the image plane of an image-shearing camera. A second exposure on the photographic film is made after the light source is moved slightly. The resulting photograph yields a fringe pattern which represents lines of constant displacement gradients. Theory of the method as well as some experimental results are presented. 相似文献
36.
CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
37.
The electrolytic efficiency of the wall-jet detector in normal-phase high-performance liquid chromatography (between 0.1 and 5%) is significantly less than its efficiency in reversed-phase separations. A large-volume wall-jet cel with a Ag/Ag+ reference serves as the detector system in evaluating the effects of various chromatographic conditions on efficiency. Anthraquinone, phenanthrenaquinone (both at 10-3–10-4 M) and three estrogen gen steroids (at 10-2–10-3 M) are used as samples with ethanol/ hexane eluents. The effect of pH depends on the sample; increased ethanol concentrations and lower flow rates improve the efficiency. 相似文献
38.
39.
The composite of silver-modified lithium manganese oxide were prepared using thermal decomposition method of different mole
ratio. Structural characterization was carried out by X-ray diffraction (XRD). XRD analysis revealed different patterns as
the content of the dopant in the spinel increases. Phase analysis shows that Ag particles were dispersed on the LiMn2O4 surface instead of entering the spinel structure. On the other hand, the electrochemical behavior of cathode powder was examined
by using two-electrode test cells consisting of a cathode, metallic lithium as anode, and a solid polymer electrolyte of 0.87PEO-0.13LiCF3SO3-0.10DBP. According to the electrochemical tests results, the influence of the Ag additive content on the electrochemical
properties of Ag/LiMn2O4 composites is clearly shown. 相似文献
40.
We investigate the water-oil interface using molecular dynamics simulations of realistic models of alkanes and water. The intrinsic density profiles are computed using a methodology that removes the smoothing effect of the capillary waves. We show that at 300 K the intrinsic width of the gap separating the oil and water phases spans little more than one water molecule diameter, and undergoes very weak short-ranged fluctuations, indicating that the water-oil interface is a rigid molecular structure at ambient temperature. Only near the drying transition (above 500 K for dodecane), the gap features uncoupled fluctuations of the oil and water surfaces, as expected in a typical drying structure. We find that the intrinsic structure of water next to the oil phase is remarkably similar to the bare water-vapor interface. 相似文献