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991.
992.
We investigate the energy spectrum of fermionized bosonic atoms, which behave very much like spinless noninteracting fermions, in optical lattices by means of the perturbation expansion and the retarded Green's function method. The results show that the energy spectrum splits into two energy bands with single-occupation; the fermionized bosonic atom occupies nonvanishing energy state and left hole has a vanishing energy at any given momentum, and the system is in Mott-insulating state with a energy gap.Using the characteristic of energy spectra we obtained a criterion with which one can judge whether the Tonks-Girardeau (TG) gas is achieved or not. 相似文献
993.
We present a theoretical investigation of optical bistability in a nonlinear semiconductor ring resonator, by taking into account the two-photon absorption and the free-carrier absorption. By solving the intensity equation within the ring resonator, a parametric formulation is obtained for describing the bistability relation between the input and the output intensities. Numerical results show that the nonlinear absorption effects can affect the critical points and domain of the optical bistability. 相似文献
994.
Hongsheng Guo Gregory J. Smallwood Fengshan Liu Yiguang Ju
mer L. Gülder 《Proceedings of the Combustion Institute》2005,30(1):303-311
The effect of hydrogen addition to ultra lean counterflow CH4/air premixed flames on the extinction limits and the characteristics of NOx emission was investigated by numerical simulation. Detailed chemistry and complex thermal and transport properties were employed. The results show that the addition of hydrogen can significantly enlarge the flammable region and extend the flammability limit to lower equivalence ratios. If the equivalence ratio is kept constant, the addition of hydrogen increases the emission of NO in a flame due to the enhancement in the rate of the NNH or N2O intermediate NO formation routes. The addition of hydrogen causes a monotonic decrease in the formation of NO2 and N2O, except flames near the extinction limits, where the emission of NO2 and N2O first increases, and then decreases with the increase in the fraction of hydrogen. Overall, hydrogen enrichment technology allows stable combustion under ultra lean conditions, resulting in significant CO2 and NO emission reduction. 相似文献
995.
Level-set G-equation and stationary flamelet chemistry are used in large eddy simulation of a propane/air premixed turbulent flame stabilized by a bluff body. The aim was to study the interaction between the flame front and turbulent eddies, and in particular to examine the effect of sub-grid scale (SGS) eddies on the wrinkling of the flame surface. The results indicated that the two types of turbulence eddies—the resolved large scale eddies and the unresolved SGS eddies—have different effects on the flame. The fluctuation of the flame surface, which is responsible for the broadening of the time averaged mean flame brush by turbulence, depends on the large resolved turbulence eddies. Time averaged mean flow velocity, temperature, and major species concentrations mainly depend on the large scale resolved eddies. The unresolved SGS eddies contribute to the wrinkling at the SGS level and play an important role in the enhancement of the propagation speed of the resolved flame front. In addition, the spatially filtered intermediate species, such as radicals, and the spatially filtered reaction rates strongly depend on the small SGS eddies. The asymptotic behavior of flame wrinkling by the SGS eddies, with respect to the decrease in filter size and grid size, is investigated further using a simplified level-set equation in a model shear flow. It is shown that to minimize the influence of the SGS eddies, fine grid and filter size may have to be used. 相似文献
996.
An anatomically accurate eye model with a shell-structure lens 总被引:1,自引:0,他引:1
A human eye model based on anatomically accurate eye model previously proposed by Liou, has been transformed into a new eye model, in which laminated structure of the lens is considered. The crystalline lens is presented in the form of hundreds of shells with rotational symmetry, and with constant index within each shell. The refractive index increases from the cortical shell to the inner one, according to the equation proposed by Smith G. et al. The anterior surface of the lens is prolate, whereas the posterior surface of the lens is oblate which is consistent with the anatomical data. A ray tracing procedure has been applied to study the refractive structure of the eye. The optical characters of the model have been studied. The reason that the wings occur on the spherical aberration curve has been given. And we found that the lens with gradient refractive index and lens with shell structure can give same longitudinal spherical aberration results. 相似文献
997.
Positron-lifetime experiments have been carried out on two undoped n-type liquid encapsulated Czochralski (LEC)-grown InP samples with different stoichiometric compositions in the temperature range 10-300 K. For temperatures below 120 K for P-rich InP and 100 K for In-rich InP, the positron average lifetime began to increase rapidly and then leveled off, which was associated with the charge state change of hydrogen indium vacancy complexes from (VInH4)+ to (VInH4)0. This phenomenon was more obvious in P-rich samples that have a higher concentration of VInH4. The transformation temperature of approximately 120 K suggests that the complex VInH4 is a donor defect and that the ionization energy is about 0.01 eV. The ionization of neutral VInH4 accounted for the decrease of the positron average lifetime when the sample was illuminated with a photon energy of 1.32 eV at 70 K. These results provide evidence for hydrogen complex defects in undoped LEC InP. 相似文献
998.
The crystal structure, magnetic and magnetotransport properties of the variation of B′-site transition metal in Sr2FeMO6 (M=Mo, W) with double perovskites structure have been investigated systematically. Measurements of magnetization vs. temperature at H=5 T show that Sr2FeMoO6 is a ferromagnet and Sr2FeWO6 is an antiferromagnet with TN∼35 K. Additionally, the large magnetoresistance ratio (MR) of ∼22% (H=3 T) at room temperature (RT) was observed in the Sr2FeWO6 compound. However, the Sr2FeMoO6 compound did not show any significant MR even at high fields and RT (MR∼1%; H=3 T and 300 K). The implications of these findings are supported by band structure calculations to explain the interaction between the 4d(Mo) and 5d(W) orbitals of transition metal ions and oxygen ions. 相似文献
999.
D. L. Phillips C. Zhao W. M. Kwok Y.L. Li X. Guan D. Wang 《光散射学报》2005,17(3):251-253
pacc:8240,8760E Acombinedexperimentalandtheoretical studyofthephotochemistryofCHBr3inpurewa terandinacetonitrile/watermixedsolventsisre portedthatelucidatesthereactionsandmecha nismsresponsibleforthephotochemicalconver sionofthehalogenatomsinCHBr3intothre… 相似文献
1000.
F. Jing H. Tong L. Kong C. Wang 《Applied Physics A: Materials Science & Processing》2005,80(3):597-600
This article describes a method of electroless gold deposition on a Si(100) wafer having a silver surface as seed layer. The seed layer was firstly deposited onto the surface of an etched wafer in an acidic solution of 0.005 mol/L AgNO3+0.06 mol/LHF. The electroless gold deposition is performed by immersing the Ag-activated wafer in an electroless bath with a composition of 1.27×10-3 mol/L[AuCl4]-+2.00×10-2 mol/LNaH2PO2+8.32×10-2 mol/L NH2CH2CH2NH2 (pH = 9.0–9.5). The bath temperature is 50–70 °C. The morphology of the seed layer and the gold film were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS).PACS 82.45.Mp; 81.15.Pq; 81.10.Dn 相似文献