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991.
992.
M. M. Bülbül Ş. Altındal F. Parlaktürk A. Tataroğlu 《Surface and interface analysis : SIA》2011,43(13):1561-1565
Bismuth titanate (Bi4Ti3O12) (BTO) thin films were fabricated on an n‐type Si substrate and annealed by rapid thermal annealing methods. The I‐V measurement shows that the device has properties of Schottky diode with the ΦB0 of 0.76 eV, n of 2.42, and leakage current of about 10?7 A at ? 8 V. The experimental C‐V‐f and G/w‐V‐f characteristics of metal‐ferroelectric‐insulator‐semiconductor (MFIS) structures show fairly large frequency dispersion especially at low frequencies due to interface states Nss. The energy distribution of (Nss) has been determined by using the high‐low frequency capacitance (CHF? CLF) and conductance method. The relaxation time (τ) of interface states was calculated from the conductance method. It has been shown that both the Nss and relaxation time increase almost exponentially with bias, which activates traps located at deeper gap energies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
993.
A practical synthesis of novel α-dibromoalkyl- and trimethylsilylmethyl-aminoboranes and derivatives
Söyleyici HC Fırıncı E Eyduran F Akbulat F Sahin Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(3):1139-1142
Addition of LDA to a mixture of trimethylborate and dibromomethane in THF at a temperature of -78°C leads to the formation of dibromomethyllithium and its capture by borate ester. ClB(OMe)(2) converts the resulting borate salt to dimethoxy(dibromomethyl)borane 2. N,N-Dimethylamino(methoxy)(dibromomethyl)borane 3 and N,N-bis(dimethylamino)(dibromomethyl)borane 4 were prepared by an amination reaction between N,N-dimethylaminotrimethylsilane and dimethoxy(dibromomethyl)borane 2. To obtain dichlorotrimethylsilylmethylborane 7 not containing the α-halomethyl group, N,N-bis(dimethylamino)(trimethylsilylmethyl)borane 5 was first obtained from the reaction of ClB(NMe(2))(2) with an organolithium reagent. Dimethoxy(trimethylsilylmethyl)borane 6 was then prepared by methoxylation of compound 5. Finally, compound 7 was prepared by chlorination of 6 using BCl(3). The chemical structures of these compounds were determined using (13)C, (1)H, (11)B NMR and GC/MS/MS techniques. 相似文献
994.
We study the exclusive Λb→Λℓ+ℓ- decay in the Appelquist, Chang, Dobrescu model with a single universal extra dimension. We investigate the sensitivity of
the branching ratio, lepton polarization and forward–backward asymmetry to the compactification parameter 1/R. We obtain the result that the branching ratio for the Λb→Λℓ+ℓ- (ℓ=μ,τ) decay changes about 25% compared to the SM value when 1/R=250 GeV, and the zero position of the forward–backward
asymmetry is shifted to the left compared to the SM result. Therefore, measurement of the branching ratio of Λb→Λℓ+ℓ- decay and determination of the zero position of are very useful in looking for new physics in the framework of the UED models.
PACS 12.60.-i; 13.30.-a; 14.20.Mr 相似文献
995.
We obtain the static spherically symmetric solutions of a class of gravitational models whose additions to the General Relativity
(GR) action forbid Ricci-flat, in particular, Schwarzschild geometries. These theories are selected to maintain the (first)
derivative order of the Einstein equations in Schwarzschild gauge. Generically, the solutions exhibit both horizons and a
singularity at the origin, except for one model that forbids spherical symmetry altogether. Extensions to arbitrary dimension
with a cosmological constant, Maxwell source and Gauss-Bonnet terms are also considered. 相似文献
996.
In this paper, a numerical solution of the (2+1)-dimensional coupled Burgers system is studied by using the Homotopy Perturbation Method (HPM). For this purpose, the available analytical solutions obtained by tanh method will be compared to show the validity and accuracy of the proposed numerical algorithm. The results approve the convergence and accuracy of the Homotopy Perturbation Method for numerically analyzed (2+1) coupled Burgers system. 相似文献
997.
Mete Kaan Ekmekçi Mustafa İlhan Arzu Ege Mehmet Ayvacıklı 《Journal of fluorescence》2017,27(3):973-979
Undoped and different concentration Nd3+ doped SrNb2O6 powders with columbite structure were synthesized by molten salt process using a mixture of strontium nitrate and niobium (V) oxide and NaCl-KCl salt mixture as a flux under relatively low calcining temperature. X-ray diffraction analysis results indicated that SrNb2O6 phases found to be orthorhombic columbite single phase for undoped, 0.5 and 3 mol% Nd3+ doping concentrations. Phase composition of the powders was examined by SEM-EDS analyses. Radioluminescence properties of Nd3+ doped samples from UV to near-IR spectral region were studied. The emissions increased with the doping concentration of up to 3 mol%, and then decreased due to concentration quenching effect. There is a sharp emission peak around 880 nm associated with 4F5/2 → 4I9/2 transition in the Nd3+ ion between 300 and 1100 nm. The broad emission band intensity was observed from 400 to 650 nm where the peak intensities increased by increasing Nd3+ doping concentration. All the measurements were taken under the room temperature. 相似文献
998.
D. Schrader S. Kuhr W. Alt M. Müller V. Gomer D. Meschede 《Applied physics. B, Lasers and optics》2001,73(8):819-824
Using optical dipole forces we have realized controlled transport of a single or any desired small number of neutral atoms
over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number
of cesium atoms from a magneto-optical trap. Mutual detuning of the counter-propagating laser beams moves the interference
pattern, allowing us to accelerate and stop the atoms at preselected points along the standing wave. The transportation efficiency
is close to 100%. This optical ‘single-atom conveyor belt’ represents a versatile tool for future experiments requiring deterministic
delivery of a prescribed number of atoms on demand.
Received: 6 July 2001 / Published online: 23 November 2001 相似文献
999.
Cu2S thin films deposited on glass substrate by chemical bath deposition were studied at different deposition temperatures and times. The results of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), the Hall Effect measurement system and UV-Vis absorption spectroscopy indicate that both deposition temperature and time are important to obtain polycrystalline thin films. XRD showed that the polycrystalline Cu2S thin films have monoclinic structure. Meanwhile, the structural variations were analyzed using SEM. EDX analysis results of the thin film showed that the atomic ratio of Cu/S was close to 2:1. It was found from the Hall Effect measurement that the resistivity varied from 4.59?×?10?3 to 13.8?×?10?3 (Ω?cm). The mobility values of the Cu2S thin films having p-type conductivity varied from 15.16 to 134.6?cm2/V.s. The dark electrical resistivity measurements were studied at temperatures in the range 303–423?K. The electrical activation energies of Cu2S thin films were calculated by using Arrhenius plots, from which two different activation energy values are estimated for each thin film. Using UV-Vis absorption spectroscopy (Ultraviolet/visible), the direct and indirect allowed optical band gap values were determined to lie between 2.16 and 2.37?eV and 1.79 and 1.99?eV, respectively. In addition, the values of the refractive index (n) and the extinction coefficient (k) were determined. 相似文献
1000.
AbstractThe nodal-line semimetals are new and very promising materials for technological applications. To understand their structural, mechanical, lattice dynamical and thermal properties in detail, we have investigated theoretical study of ZrXY (X = Si,Ge; Y = S,Se) using Density Functional Theory for the first time. Obtained lattice parameters are in excellent agreement with previous experimental data. These nodal-line semimetals obey the mechanical stability conditions for tetragonal structure. We obtain Bulk modulus, Shear modulus, Poisson’s ratio, Pugh ratio, sound velocities and thermal conductivity using elastic constant. All the materials behave in brittle manner. Poisson’s ratio data and Bader charge analysis results indicate that the ionic bonding characters are dominant. Next, the lattice dynamical properties are calculated. Phonon density of states shows that nodal-line semimetals ZrXY are also dynamically stable in the tetragonal structure. Raman and IR active phonon modes are determined. Highest optical mode at gamma point corresponds to A2u (IR active) and Eg (Raman active) modes for ZrXSe and ZrXS, respectively. Based on phonon density of states, thermal properties such as Helmholtz free energy, entropy, heat capacity at constant volume and Debye temperature are also presented and discussed. 相似文献