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41.
This paper reports conduction mechanism in a-Sb2Se3 over a wide range of temperature (238 to 338 K) and frequency (5 Hz to 100 kHz). The d.c. conductivity measured as a function
of temperature shows semiconducting behaviour with activation energy ΔE=0.42 eV. Thermally induced changes in the electrical and dielectric properties of a-Sb2Se3 have been examined. The a.c. conductivity in the material has been explained using modified CBH model. The band conduction
and single polaron hopping is dominant above room temperature. However, in the lower temperature range the bipolaron hopping
dominates. 相似文献
42.
The ground state of a double-exchange model for orbitally degenerate e(g) electrons with Jahn-Teller lattice coupling and weak disorder is found to be spatially inhomogeneous near half filling. Using a real-space Monte Carlo method we show that doping the half-filled orbitally ordered insulator leads to the appearance of hole-rich disordered regions in an orbitally ordered environment. The doping driven orbital order to disorder transition is accompanied by the emergence of metallic behavior. We present results on transport and optical properties along with spatial patterns for lattice distortions and charge densities, providing a basis for an overall understanding of the low-doping phase diagram of La1 - xCaxMnO3. 相似文献
43.
44.
Sanjeev Kumar Raghuwanshi 《Indian Journal of Physics》2010,84(7):831-846
In this paper we have studied the asymmetric versus symmetric planar waveguide in terms of their usefulness in optical fiber communication systems. We have explored the thin
waveguide versus thick waveguide first. Later on usefulness of asymmetric versus symmetric waveguide is carried out to target for WDM optical network application. All kinds of optical network components
are fabricated on Si substrate with the point of view of their application. Here asymmetric planar structure may be more useful
compared to symmetric waveguide in terms of their non-uniform power confinement properties. However, the symmetric waveguide
structure may be more useful for their high power confinement properties. It is well known that the thin symmetric waveguide
supports at least one mode. However the thick waveguide may support many even as well as odd modes. We study the power confinement
properties for symmetric as well as asymmetric waveguide structure. We conclude that higher order modes show the nonlinear
power variations. Mode field profile for various cases is discussed as well. Comparative study between asymmetric versus symmetric waveguide has a lot of significance in optical network area. It has been shown through analysis that in asymmetric
waveguide, the power flows more through film region in the case of fundamental mode. Power confinement properties for asymmetric
waveguide versus symmetric waveguide have been studied. 相似文献
45.
Shweta Srivastava Shinoo Srivastava Seema Srivastava Vishwambhar Dayal Gupta Sanjeev John La'Verne 《Journal of Macromolecular Science: Physics》2013,52(1):157-173
A study of the normal modes of vibration and their dispersion in polypyrrole (PPY) based on the Urey-Bradley force field is reported. It gives a fuller interpretation of previously reported FTIR spectra. Characterstic features of dispersion curves, such as regions of high density-of-states, repulsion, and character mixing of dispersive modes, are discussed. Predictive values of heat capacity as a function of temperature are reported. 相似文献
46.
N. Shashank Vikram Singh Sanjeev K. Gupta K. V. Madhu J. Akhtar R. Damle 《辐射效应与固体损伤》2013,168(4):313-322
Ni/SiO2/Si MOS structures were fabricated on n-type Si wafers and were irradiated with 50 MeV Li3+ ions with fluences ranging from 1×1010 to 1×1012 ions/cm2. High frequency C–V characteristics are studied in situ to estimate the build-up of fixed and oxide charges. The nature of the charge build-up with ion fluence is analyzed. Defect levels in bulk Si and its properties such as activation energy, capture cross-section, trap concentration and carrier lifetimes are studied using deep-level transient spectroscopy. Electron traps with energies ranging from 0.069 to 0.523 eV are observed in Li ion-irradiated devices. The dependence of series resistance, substrate doping and accumulation capacitance on Li ion fluence are clearly explained. The study of dielectric properties (tan δ and quality factor) confirms the degradation of the oxide layer to a greater extent due to ion irradiation. 相似文献
47.
48.
Novel montmorillonite-based ceramic membrane (CM) has been prepared with poly(vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP) copolymer as binder. Physical properties such as surface morphology, porosity, liquid electrolyte uptake and thermal stability were analysed. The ceramic membrane was activated by soaking it in a non-aqueous liquid electrolyte (1.0 M LiPF6 solution in 1/1 v/v ethylene carbonate/diethyl carbonate mixture) for 10 min. The compatibility of the membrane with lithium metal anode as a function of storage time was analysed by assembling a Li/CM/Li symmetric cell. Finally, a lab-scale cell composed of Li/CM/LiFePO4 is assembled and its cycling performance analysed at different C-rates. Although the ceramic membrane is not flexible, it shows high thermal stability and stable interfacial properties when in contact with the lithium metal anode. A stable cycling behaviour is demonstrated even at 1C-rate with limited fade in capacity. 相似文献
49.
50.
Ranveer Singh Maxime Vallet Vijay Singh Sanjeev K. Srivastava Alain Claverie Tapobrata Som 《Surface and interface analysis : SIA》2023,55(2):151-161
Due to its outstanding physical properties, CdTe is used to fabricate high efficiency solar cells. However, its high work function poses a challenge, and hence, to fabricate an efficient CdTe-based solar cell, Cu-doping may be useful. Here, we present the role of temperature-dependent Cu-doping in radio frequency sputter-deposited CdTe films and the related changes occurring in their optical, electrical, structural and microstructural properties. For instance, Cu-doping at different temperatures leads to an increase in the grain size and a reduction in the optical reflectance with increasing temperature. In addition, Kelvin probe force microscopy measurements reveal that the work function is found to be smaller corresponding to the annealing temperature of 473 K, whereas resistivity measurements show that it decreases with increasing temperature (the lowest value of resistivity is found to be 1.8 × 10−2 Ω-cm). To understand the electronic structure of CdTe before and after Cu-doping, we have carried out first-principles density functional theory (DFT) simulation, which reveals a strong hybridization among Cu, Cd and Te atoms. This study paves the way to fabricate efficient Cu-doped CdTe-based solar cells. 相似文献