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961.
Yu.?A.?ZakharovEmail author O.?B.?Kokorina A.?Kh.?Gilmutdinov 《Journal of Applied Spectroscopy》2005,72(2):271-275
To increase the sensitivity of the atomic-absorption analysis, we suggest concentrating the analytes on a tungsten probe through multiple fractional condensation of the sample vapor obtained in a graphite atomizer. This technique makes it possible to additionally reduce the matrix interference. To this end, a sample with a high interference level is preliminarily diluted to the level eliminated by the stage of fractional condensation and then concentrated on the probe. The influence of potassium sulfate on the Pd, Cd, and Ag absorption has been reduced by a factor of 1.5–4.5 and that of sodium chloride — by a factor of 4–300 compared to the influences in the longitudinally heated atomizer with a platform, a modifier, and a background corrector based on the Zeeman effect. In a number of cases, advantages over the transversely heated atomizer have been attained.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 256–259, March–April, 2005. 相似文献
962.
We introduce a novel class of spatially localized self-trapped ringlike singular optical beams in nonlinear media, the so-called azimuthons, which appear due to a continuous azimuthal deformation of vortex solitons. We demonstrate that the azimuthons are characterized by two independent integer indices, the topological charge m and the number N of the intensity peaks along the ring. Each soliton family includes azimuthons with negative, positive, and zero angular velocity. 相似文献
963.
A method for polarimetric measurement that uses a discrete space-variant subwavelength dielectric grating is presented. One retrieves the polarization state by measuring the far-field intensity of a beam emerging from the grating followed by a polarizer. The analysis for a partially polarized, quasi-monochromatic beam is performed by use of the beam coherence polarization matrix along with an extended van Cittert-Zernike theorem. We experimentally demonstrate polarization measurements of both fully and partially polarized light. 相似文献
964.
We suggest a novel approach to soliton control and routing based on Bloch-wave filtering in periodic photonic structures. Taking a binary waveguide array as an example, we demonstrate that spatial solitons that belong to different spectral gaps can be selectively reflected from or transmitted through an engineered defect, which acts as a low- or high-pass filter for Bloch waves. 相似文献
965.
We report on the demonstration of surface-emitted terahertz- (THz-) wave difference-frequency generation from two-dimensional (2D) periodically poled lithium niobate (PPLN). The two orthogonal periodic structures individually compensate for both the phase mismatch of the launched lasers and the generated THz wave. Tunable 1.5-1.8 THz wave generation with a bandwidth of 10-GHz was obtained by use of two 2D PPLN crystals. We also confirmed that THz waves were simultaneously generated into two opposite directions, which suggests the possibility of higher THz-wave output power. 相似文献
966.
967.
Yuri A. Abramovich 《Mathematische Zeitschrift》1989,200(4):601-602
968.
969.
Hans Georg von Schnering Jen‐Hui Chang Karl Peters Eva‐Maria Peters Frank R. Wagner Yuri Grin Gerhard Thiele 《无机化学与普通化学杂志》2003,629(3):516-522
The crystal structure of Pt6Cl12 (β‐PtCl2) was redetermined ( ah = 13.126Å, ch = 8.666Å, Z = 3; arh = 8.110Å, α = 108.04°; 367 hkl, R = 0.032). As has been shown earlier, the structure is in principle a hierarchical variant of the cubic structure type of tungsten (bcc), which atoms are replaced by the hexameric Pt6Cl12 molecules. Due to the 60° rotation of the cuboctahedral clusters about one of the trigonal axes, the symmetry is reduced from to ( ). The molecule Pt6Cl12 shows the (trigonally elongated) structure of the classic M6X12 cluster compounds with (distorted) square‐planar PtCl4 fragments, however without metal‐metal bonds. The Pt atoms are shifted outside the Cl12 cuboctahedron by Δ = +0.046Å ( (Pt—Cl) = 2.315Å; (Pt—Pt) = 3.339Å). The scalar relativistic DFT calculations results in the full symmetry for the optimized structure of the isolated molecule with d(Pt—Cl) = 2.381Å, d(Pt—Pt) = 3.468Å and Δ = +0.072Å. The electron distribution of the Pt‐Pt antibonding HOMO exhibits an outwards‐directed asymmetry perpendicular to the PtCl4 fragments, that plays the decisive role for the cluster packing in the crystal. A comparative study of the Electron Localization Function with the hypothetical trans‐(Nb2Zr4)Cl12 molecule shows the distinct differences between Pt6Cl12 and clusters with metal‐metal bonding. Due to the characteristic electronic structure, the crystal structure of Pt6Cl12 in space group is an optimal one, which results from comparison with rhombohedral Zr6I12 and a cubic bcc arrangement. 相似文献
970.