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91.
In this paper, a rigorous theoretical analysis has been made to study the dispersion relation of EM waves in periodic ternary one-dimensional photonic crystal having two different structures. In one case we have chosen glass-plasma and ZnS in one unit cell and in other case we have considered glass-plasma and MgF2 in one unit cell. Using Kronig-Penney model the dispersion relation for proposed structures has been obtained and numerical results are presented in the form of dispersion curves. The dependence of photonic band gap (PBG) characteristics on plasma frequency, plasma width and the width of dielectric media are discussed in the light of frequency gap and cutoffs of binary one-dimensional plasma photonic crystal. An attempt has been made to show how the PBG characteristic of a particular structure changes when the dielectric materials of its unit cell is changed by the other dielectric material. It is found that the structure having glass-plasma-ZnS in unit cell is more useful for broad band filtering and other plasma functioning devices compared to the structure having glass-plasma-MgF2 in one unit cell. 相似文献
92.
The structural, electronic, vibrational and thermodynamical properties of transition metal carbides RuC, RhC, PdC and AgC are investigated using the plane-wave pseudopotentials method within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT). There is a good agreement between present theoretical and available experimental theoretical data in the case of ground state properties such as lattice parameter and bulk modulus. The electronic band structure of these compounds show that all compounds except RuC in zinc blende phase are metallic in nature. RuC in zinc blende phase is semiconducting in nature with an indirect band gap. The phonon properties of RhC, PdC and AgC are investigated for the first time. The phonon frequencies in the phonon dispersion curves are positive throughout the Brillouin zone for zinc blende RuC and AgC and rocksalt RhC and PdC indicating dynamical stability for these compounds in the said phases. Temperature variation of thermodynamical properties for noble metal carbides are calculated and discussed. 相似文献
93.
Structural, elastic, electronic and thermal properties of the MAX phase Nb2SiC are studied by means of a pseudo-potential plane-wave method based on the density functional theory. The optimized zero pressure geometrical parameters are in good agreement with the available theoretical data. The effect of high pressure, up to 40 GPa, on the lattice constants shows that the contractions along the c-axis were higher than those along the a-axis. The elastic constants Cij and elastic wave velocities are calculated for monocrystal Nb2SiC. Numerical estimations of the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, average sound velocity and Debye temperature for ideal polycrystalline Nb2SiC aggregates are performed in the framework of the Voigt-Reuss-Hill approximation. The band structure shows that Nb2SiC is an electrical conductor. The analysis of the atomic site projected densities and the charge density distribution shows that the bonding is of covalent-ionic nature with the presence of metallic character. The density of states at Fermi level is dictated by the niobium d states; Si element has a little effect. Thermal effects on some macroscopic properties of Nb2SiC are predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variations of the primitive cell volume, volume expansion coefficient, bulk modulus, heat capacity and Debye temperature with pressure and temperature in the ranges of 0-40 GPa and 0-2000 K are obtained successfully. 相似文献
94.
Zadjia Atik 《Journal of Molecular Liquids》2011,163(2):89-92
The volumetric properties were evaluated from density data for the binary mixtures of (fluorobenzene + tert-butylmethyl ether), (α,α,α-trifluorotoluene + tert-butylmethyl ether), (tert-butylmethyl ether + ethanol), and the ternary mixtures of (fluorobenzene + tert-butylmethyl ether + ethanol) and (α,α,α-trifluorotoluene + tert-butylmethyl ether + ethanol). The observed densities were obtained by means of a vibrating-tube densimeter at the temperature 298.15 K and the pressure 101 kPa.The excess molar volumes of the ternary mixtures were estimated from binary solution data using several empirical equations with mean standard deviation less than 0.03 cm3·mol-1. Stable chemical cross-associations among the molecules forming the mixtures were revealed. 相似文献
95.
M. ElMassalami D. da S. OliveiraH. Takeya 《Journal of magnetism and magnetic materials》2011,323(16):2133-2136
Based on extensive Mossbauer effect (ME) and magnetization measurements, the orthorhombic AlFe2B2 was characterized as a ferromagnet (FM) because this character is evident as an onset of a FM transition at Tc=320 K and characteristic magnetizations isotherms below Tc. At liquid helium temperatures, the magnetization saturates to μsat≈1μB per Fe atom; a value which is half the one reported for the iron metal indicating a relatively more filled 3d band. The ME analysis revealed a hyperfine field H(0) of 88(2) kOe, an isomer shift (relative to Fe) of 0.50(2) mm/s, and a quadrupole parameter of 0.02 mm/s: all parameters extrapolated to zero Kelvin. The itinerant character of the magnetic moment will be discussed. 相似文献
96.
A ternary complex reagent of lithium ester enolate-chiral diether-lithium diisopropylamide was formed in an equimolar mixture of these reagents in toluene based on low-temperature NMR spectroscopy. The use of [6Li,15N]-lithium diisopropylamide as a lithiodeprotonation and complexing reagent produced two sets of doublet peaks in 6Li NMR of a 1:1:1 mixture of lithium enolate-chiral diether-lithium diisopropylamide, indicating the formation of a ternary complex reagent. 相似文献
97.
Scandium dysprosium antimonide ScDySb was synthesized from scandium metal and DySb in an all‐solid state reaction at 1770 K. According to X‐ray analysis of the crystal structure [P4/nmm, Z = 4, a = 430.78(1) pm, c = 816.43(4) pm, R1 = 0.0238, wR(all) = 0.0688, 268 independent reflections], ScDySb adopts the anti‐PbFCl type of structure, but with pronounced deviations in structural details, which are related to specific bonding interactions between the atoms involved. ScDySb shows antiferromagnetic ordering below 35.4 K, which was verified by susceptibility, heat capacity, and resistivity measurements. X‐ray structure determination, performed at 30 K, showed no significant structural changes to occur during the magnetic phase transition. The band structure was calculated in the framework of Density Functional Theory. The bonding properties are comparable to those of Sc2Sb. Pronounced basins of the Electron Localization Function (ELF) appear in the tetragonal pyramidal Sc4Dy voids. 相似文献
98.
Suk Yung OhYoung Chan Bae 《Fluid Phase Equilibria》2011,307(2):202-207
In our previous study [S.Y. Oh, Y.C. Bae, J. Phys. Chem. B 114 (2010) 8948-8953], we presented a new method to predict liquid-liquid equilibria in ternary simple liquid mixtures by using a combination of a thermodynamic model and molecular simulations. As a continuation of that effort, we extend our previously developed method to ternary polymer systems. In the simulations, we used the dummy atoms to calculate the pair interaction energy values between the polymer segments and the solvent molecules. Furthermore, a thermodynamic model scaling concept is introduced to consider the chain length dependence of the energy parameters. This method was applied to ternary mixtures incorporating low to high molecular weight polymers. The method presented here well described the experimental observations using one or no adjustable parameters. 相似文献
99.
Binary 3-point scheme, developed by Hormann and Sabin [Hormann, K. and Sabin, Malcolm A., 2008, A family of subdivision schemes with cubic precision, Computer Aided Geometric Design, 25, 41-52], has been modified by introducing a tension parameter which generates a family of C1 limiting curves for certain range of tension parameter. Ternary 3-point scheme, introduced by Siddiqi and Rehan [Siddiqi, Shahid S. and Rehan, K., 2009, A ternary three point scheme for curve designing, International Journal of Computer Mathematics, In Press, DOI: 10.1080/00207160802428220], has also been modified by introducing a tension parameter which generates family of C1 and C2 limiting curves for certain range of tension parameter. Laurent polynomial method is used to investigate the continuity of the subdivision schemes. The performance of modified schemes has been demonstrated by considering different examples along with its comparison with the established subdivision schemes. 相似文献
100.
Zn-doped sprayed thin films have been grown on binary In2S3 substrates under the mean temperature (Td = 320 °C). Further studies Amlouk et al. [M. Amlouk, M.A. Ben Said, N. Kamoun, S. Belgacem, N. Brunet, D. Barjon, Japan Journal of Applied Physics 38 (1999) 26-30]; Lazzez et al. [S. Lazzez, K. Boubaker, M. Amlouk, Indirect measurement of Zn-doped In2S3 NANO films SPECIFIC heat capacity, International Journal of Nanoscience 7 (2008) 1–5.]; Lazzez et al. [S. Lazzez, K. Boubaker, T. Ben Nasrallah, M. Mnari, R. Chtourou, M. Amlouk, S. Belgacem, Structural and optoelectronic properties of InZnS sprayed layers, Acta Physica Polonica A 114 (2008) 869–880.] investigated the band gap shift, the structural and morphological changes induced by this doping. In this study, a quantitative comparative evaluation of the thermal properties of the as-grown layers is carried out. The obtained results, parallel to further information, plea for the superior thermal efficiency of the recently proposed Zn-doped ternary compounds. 相似文献