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51.
The interpretation of electrical resistivity measurement results of Al base alloys is critically discussed. Correct numerical data evaluation with respect to the atomistic properties rc/rp, rt and Pft/Pf is yet impossible for Al and its alloys because of the overlapping of Ic and Id recovery for those electron irradiations for which damage rate measurements exist and because of the unexplained scatter of initial damage rate data. 相似文献
52.
《Current Applied Physics》2018,18(2):200-208
The electronic structure and optical properties of La0.75Sr0.25MnO3-σ (LSMO3-σ) materials with 1 × 1 × 4 orthorhombic perovskite structure were performed by first-principles calculation. The structural changing of LSMO3 (ideal structure, σ = 0) was not obvious under generalized gradient approximation (GGA) and GGA + U arithmetic. On the contrary, the structural changing of LSMO3-σ (σ = 0.25, with oxygen vacancies defects in the z = 0, c/8, c/6, c/4, and c/2) with GGA + U were more obvious than the result of ideal. This structural distortion induced distinct changing in density of states (DOS) for LSMO3-σ materials. Oxygen vacancy defects caused a shift of the total density of states (TDOS) features toward low binding energies and LSMO3-σ keep half-metal properties as well as LSMO3 ideal structure. In addition, the hybridization between the Mn-eg and O-2p orbital was weakened and the partial density of states (PDOS) of Mn indicated a strong d-d orbital interaction. By the result of oxygen vacancy formation energy, oxygen vacancy defects can be more easily formed in La-O layers (z = 0 and c/6) to compare with other layers (z = c/8, c/4 and c/2). The calculation result of optical properties suggested that the ideal LSMO could be produced strong absorption in the range of ultraviolet and visible light, while the LSMO3-σ with oxygen vacancies defects were presented weak absorption in the range of visible light. 相似文献
53.
Electron channelling contrast imaging (ECCI) performed in a scanning electron microscope (SEM) is a rapid and non-destructive structural characterisation technique for imaging, identifying and quantifying extended defects in crystalline materials. In this review, we will demonstrate the application of ECCI to the characterisation of III-nitride semiconductor thin films grown on different substrates and with different crystal orientations. We will briefly describe the history and the theory behind electron channelling and the experimental setup and conditions required to perform ECCI. We will discuss the advantages of using ECCI, especially in combination with other SEM based techniques, such as cathodoluminescence imaging. The challenges in using ECCI are also briefly discussed. 相似文献
54.
S. Karashima 《辐射效应与固体损伤》2013,168(1-3):215-219
Abstract The stopping power and range for Xe ions in high temperature matter (partially ionized plasmas) have been calculated using the dielectric response function method. Calculations have been made for a target matter Al (Z = 13) over a wide range of temperatures and densities considering a finite temperature model. The stopping powers obtained have smaller values in comparison with those of a zero temperature model. The stopping power strongly depends on the density and temperature of the target material, and the projectile ion energy. 相似文献
55.
M. A. Sridhar N. K. Lokanath J. Shashidhara Prasad C. V. Yelammagad S. K. Varshney 《Liquid crystals》2013,40(1):45-49
The title compound, cholesteryl 6[4-(4-pentyloxyphenylethynyl)phenoxy]hexanoate (DMT5), a cholesterol-based dimesogen, crystallizes in the monoclinic space group P21 with the parameters a = 9.812(3) Å, b = 9.713(2) Å, c = 24.179(2) Å, β = 92.48(1)° V = 2302.2(9) Å3, Z = 2, F000 = 836, λ(MoKα) = 0.71069 Å, μ = 0.067 cm 1, final R = 0.0772. The structure has intermolecular hydrogen bonds; it is stabilized by the presence of intermolecular contacts whose spacings are less than van der Waals' radii. 相似文献
56.
We discuss the continuum medium theory that enables us to find the defect contribution to phase transition anomalies with the use of only a few phenomenological parameters. The theory is invalid in the immediate vicinity of the phase transition temperature and for high concentration of defects. The possibilities of interpretation of experimental data on the basis of the theory are also discussed. 相似文献
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59.
Carbon redistribution is known to occur during martensite ageing. The two associated processes most discussed in the literature are spinodal decomposition and carbon segregation to defects. In order to elucidate the topic, the ageing and tempering of two Fe–Ni–C alloys have been characterised by means of atom probe tomography and synchrotron radiation diffraction. Upon ageing at room temperature, carbon redistribution is clearly observed, where the process of carbon segregation to defects appears to be most likely to occur. Nevertheless, the possibility of spinodal decomposition is not entirely discarded, and the current work presents a series of discussion points that challenge our current understanding of the thermodynamic of ferrite in steels. 相似文献
60.
Density functional theory (DFT) studies are done to investigate structural and electronic properties of (5,5) chirality single walls boron nitride nanotubes (BNNTs) in the armchair model interacting with metformin (MF) on the surface and ends. Our calculations consider the exchange-correlation energies with the Hamprecht–Cohen–Tozer–Handy functional within the generalized gradient approximation (HCTH-GGA) and the double polarized DNP base function. The geometry optimization follows the minimum energy criterion for all six geometries we have considered. Results show that the MF is adsorbed through the groups NH2–NH at one end of the nanotube. The system polarity is increased which indicates the possible dispersion and solubility. Moreover the interaction between these species induces an increase in the chemical reactivity of the order of 0.42 eV. Meanwhile the solvation in water keeps the semiconductor characteristics of both nanotube and MF. The work function of the BNNT-MF is drastically reduced respect to the pristine system when the BN nanotube is doped at its surface and ends with carbon. This means that the functionalized BN nanotube facilitates conditions to improve field emission. 相似文献