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1.
Adhesive and cohesive properties of the plasma-sprayed hydroxyapatite (HA) coatings, deposited on Ti-6Al-4V substrates by varying the plasma power level and spray distance (SD), were evaluated by an indentation method. The crystallinity and the porosity decreased with increasing both of these two parameters. The microhardness value, Young's modulus (E) and coating fracture toughness (KC) were found to increase with a combinational increase in spray power and SD. The Knoop and Vickers indentation methods were used to estimate E and KC, respectively. The critical point at which no crack appears at the interface was determined by the interface indentation test. This was used to define the apparent interfacial toughness (KCa) which is representative of the crack initiation resistance of the interface. It was found that KCa reaches to a maximum at a medium increase in both spray power and SD, while other mechanical properties of the coatings reaches to the highest value with further increase in these two plasma parameters. The tensile adhesion strength of the coatings, measure by the standard adhesion test, ISO 13779-4, was shown to alter in the same manner with KCa results. It was deduced that a combinational increase in spray power and SD which leads to a higher mechanical properties in the coatings, does not necessarily tends to a better mechanical properties at the interface.  相似文献
2.
Magnetic anisotropies in FeCo fine particles   总被引:1,自引:0,他引:1  
 The single-domain particles, especially FeCo fine particles have many applications in magnetic information technology. We have prepared Fe1−xCox fine particles for different x by borohydride method and measured the magnetic and structural properties of the samples. We have then determined the variations of coercivity and anisotropy energy versus x in Fe1−xCox fine particles. The obtained results have been analyzed on the basis of various magnetic anisotropies. Magnetic anisotropies affect the coercivity of the medium for each x as follows: shape and crystal anisotropies for x=0, surface and crystal anisotropies for x=1, shape, induced and crystal anisotropies for x=0.3 and 0.5, and shape and induced anisotropies for x=0.45.  相似文献
3.
Application of Davidenko's Method to a Lossy Nonlinear Waveguide   总被引:1,自引:0,他引:1  
Davidenko's method is implemented for determining the complex propagation constants (Modal index and attenuation coefficient) of nonlinear TE waves guided by an asymmetrical lossy nonlinear dielectric wave-guide. The waveguide structure has a generalized nonlinear substrate with a permittivity of the form | E |and an absorbing cover making the propagation constant to be complex. Davidenko's method shows to be a fast and accurate analysis in finding the complex propagation constants. The effects of initial condition parameter on the propagation characteristics are investigated, analyzed and discussed.  相似文献
4.
Direct Limits of Effect Algebras   总被引:1,自引:0,他引:1  
In this paper, we prove that direct limits exist in the category of effect algebrasand effect algebra-morphisms. Then, as a consequence, we obtain similar knownresults for the categories of orthomodular posets and orthomodular lattices.  相似文献
5.
A rail noise prediction model for the Tehran-Karaj commuter train   总被引:1,自引:0,他引:1  
Rail noise prediction models enable consideration of different scenarios for the optimal management of noise prevention and mitigation. This project is aimed at developing an equation that enables computation of LA,max for the Tehran-Karaj commuter train, a type of Diesel-Electric Locomotive. The form of the proposed model is derived from equations for predicting LA,max for a single locomotive pass-by, proposed in the manual prepared by Harris Miller Miller & Hanson Inc. for the US Federal Transit Administration, and in the French rail noise prediction model. The algorithm for predicting LA,max for the Tehran-Karaj commuter train has been developed on the basis of the 50 measurements from 5 locations at distances of 25 m, 35 m, 45 m, 55 m, and 65 m from the centre of the track and at a height of 1.5 m. In the field measurements, the reference distance and the reference vehicle speed have respectively been set equal to 25 m and 80 km per hour. The reference LA,max, length and the speed correction coefficients have been estimated from the field measurements and have been found to be 86.2 dB(A), 11.3, and 18.4 respectively. The fitness test (Kolmogorov-Smirnov) and regression analysis indicate satisfactory results.  相似文献
6.
This paper introduces a carbon paste electrode modified with ferrocene and carbon nanotubes as a voltammetric sensor for determination of sulfite at pH 7.0. The results showed that under the optimum condition (pH 7.0) in cyclic voltammetry, the oxidation of sulfite occurred at a potential about 280?mV less positive than the unmodified carbon paste electrode. Kinetic parameters such as electron transfer coefficient (??) and heterogeneous rate constant (k) for sulfite were also determined using electrochemical approaches. Under the optimized conditions, the electrocatalytic oxidation peak current of sulfite showed two linear dynamic ranges with a detection limit of 0.1???M for sulfite. The proposed method was examined as a selective, simple, and precise method for voltammetric determination of sulfite in some real samples such as weak liquor from wood and paper industry, boiler water, river water, industrial water, and tap water.  相似文献
7.
Nano-sized nickel selenide powders have been successfully synthesized via an improved hydrothermal route based on the reaction between NiCl2·6H2O, SeCl4 and hydrazine (N2H4·H2O) in water, in present of cetyltrimethyl ammonium bromide (CTAB) as surfactant, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Effects of temperature, reaction time and reductant agent on the morphology, the particle sizes and the phase of the final products have been investigated. It was found that the phase and morphology of the products could be greatly influenced by these parameters. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. Photoluminescence (PL) was used to study the optical properties of NiSe samples.  相似文献
8.
Novel bionanocompoites (BNCs) were prepared using zinc oxide (ZnO) nanoparticles which functionalized by γ-methacryloxypropyltrimethoxysilane (KH570) as a coupling agent. Poly(ester-amide) (PEA) based on tyrosine natural amino acid was synthesized and used as a polymer matrix. PEA/ZnO BNCs were characterized by fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). All the results confirmed that the surface of ZnO particle has sufficient compatibility with PEA through the link of the coupling agent between ZnO and polymer and also proved that the presence of ZnO nanoparticles appeared to be dispersed in nanosize in polymer composite matrix. In addition, thermogravimetric analysis (TGA) data indicated an enhancement of thermal stability of new BNC materials compared with the pure polymer.  相似文献
9.
CuO nanostructures at different morphologies were synthesized in controlled manner using a simple low-temperature solvothermal technique. Controlling the pH of content the reaction mixture, nanoparticles, nanorods and nanocloud CuO structures were synthesized at temperature of 100-150 °C with excellent reproducibility. High-resolution electron microscopy revealed the well crystalline nature of all the nanostructures with preferential growth along the [0 0 2] direction for linear structures. Photoluminescence spectrum of the as-grown nanostructures revealed oxygen-vacancy-related defects in them. The average sizes of NP-CuO (nanoparticles of CuO) at different morphologies were between 40 and 100 nm. The structure, morphology and size of NP-CuO were determined by X-ray diffraction powder (XRD), scanning electron microscopy (SEM), solid state Photo Luminescent (PL) and EDAX analysis.  相似文献
10.
Characterization and aging effect study of nitrogen-doped ZnO nanofilm   总被引:1,自引:0,他引:1  
The influence of sputtering and annealing conditions and aging effect on properties of sputtered ZnO:N thin films were investigated. Achieved results confirmed a planar growth of nitrogen-doped ZnO film with a high uniform and smooth surface morphology. Incorporation of nitrogen in the ZnO films made new Raman shifts. X-ray diffraction spectra showed only the ZnO (0 0 2) diffraction peak, which was slightly shifted toward lower angels, compared to pure ZnO, which is the result of incorporating nitrogen in the ZnO films. The amount of this shift was proportional to N concentration. In addition, annealed samples showed better crystallinity with lower shift due to dramatically reduction of N atoms during the annealing. The Hall effect measurements exhibited p-type behaviour on annealed ZnO:N thin films while the un-annealed samples showed n-type conductivity. Aging effect studies demonstrated that the N content of thin films decreased dramatically as time passed. The reduction of N concentration in annealed samples was lower than un-annealed ones after 6 months.  相似文献
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