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941.
We present a shape model of mineral dust particles for use in light-scattering calculations. A spatial Poisson-Voronoi tessellation was applied to simulate the aggregate structure and, therefore, the rough surface of the mineral particles. To develop the shape model, we took into account statistics of shape parameters derived from the cross-sectional areas, maximum dimensions, and perimeters of field-collected dust particles. Light-scattering properties of the modeled Voronoi aggregates were examined by the finite-difference time-domain (FDTD) method. The results of randomly oriented scattering properties agreed with previously reported laboratory measurements of mineral dust particles.  相似文献   
942.
Elimination of the arsenic (III) impurity AsF3 from anhydrous hydrogen fluoride has been demonstrated using a bench-scale apparatus (∼500 mL of HF), with a Ag(II) salt AgFAsF6 as a mediator. In this process, AsF3 is oxidized by AgFAsF6 to AsF5. In the next step, AsF5 is eliminated from HF by reaction with NaF. The oxidizer, AgFAsF6, is reduced to AgAsF6 which is regenerated to AgFAsF6 by F2 in HF at room temperature. This method can reduce the arsenic content in HF from a few hundred ppm to the industrially required level (<3 ppm). The results for three other methods (distillation, oxidation by F2 gas, and oxidation by K2NiF6) are reported and compared with the AgFAsF6 method in a preliminary examination (using ∼4 mL of HF).  相似文献   
943.
This paper describes an electrostatic ion chromatographic system in which the separation selectivity for inorganic anions, especially for sulfate and phosphate, could be manipulated by altering the molar ratio of the zwitterionic and cationic surfactants in the column coating solution used to prepare the stationary phase. The zwitterionic surfactant used for this study was 3-(N,N-dimethyltetradecylammonio)propanesulfonate (Zwittergent-3-14) and the cationic surfactant was tetradecyltrimethylammonium (TTA). Using a reversed-phase C18 column (250×4.6 mm I.D.) coated with 10/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the stationary phase and either NaHCO3 or Na2CO3 aqueous solution as the eluent, together with suppressed conductivity detection, baseline separation of seven model inorganic anions was obtained. The elution order for those anions was found to be F42−42−23. Under the same conditions but using 1/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the column coating solution, the elution order for these model ions was F42−42−23. The early elution of phosphate and sulfate is a unique attribute of this system. Detection limits for F, HPO42−, Cl, SO42−, NO2, Br and NO3 (S/N=3, sample injection volume 100 μl) were 0.11, 0.12, 0.12, 0.18, 0.49, 0.49, 0.52 μM, respectively.  相似文献   
944.
A series of copolymers composed of two monomer units having a polar phosphorylcholine group and an apolar fluorocarbon group with a controlled monomer unit sequence were synthesized by a reversible addition‐fragmentation chain transfer (RAFT) living radical polymerization method. 2‐Methacryloyloxyethyl phosphorylcholine (MPC) and 2,2,2‐trifluoroethyl methacrylate (TFEMA) were selected as the monomers, because they have disparate polarity. Furthermore, to investigate the influence of the monomer unit sequence in a polymer chain on the phase‐separated structure in the bulk and surface structure, copolymers having a continuous change in the monomer unit composition along the polymer chain (gradient copolymer) were synthesized, as well as random and block copolymers. The analysis of instantaneous composition revealed a continuous change in the monomer unit composition in the gradient copolymer and the statistical monomer unit sequence in the random copolymer. Thermal analysis assumed that the gradient sequence of the monomer unit would make the phase‐separated structure in the bulk ambiguous, while the well‐defined and monodispersive block sequence would undergo the distinct phase‐separation due to the extreme difference in the polarity of the component monomer units. The preliminary surface characterization of the synthesized polymers indicated the monomer unit sequence in the polymer chain would much influence on the surface structure. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6073–6083, 2005  相似文献   
945.
We observed multiple diffraction rings of a cw Ar+ laser beam from a nitrobenzene solution of saturable absorber BDN (bis-(4-dimethylaminodithiobenzil)-nickel) caused by the spatial self-phase modulation at low incident optical intensities. We obtained 37 rings for a 200-μm thick sample at an optical intensity of 38 W/mm2. The refractive-index change Δ;n and effective nonlinear refractive index n2 were determined from the number of observed rings and by the z-scan technique. We obtained large values of Δ;n∼0.1 and n2 = -2.9×;10-5 cm2/W. This large nonlinearity is attributed to a thermal effect resulting from linear absorption.  相似文献   
946.
947.
The structure factor, S(Q), of liquid bismuth near the melting temperature at pressures up to 7.3 GPa has been measured by an energy-dispersive X-ray diffraction method, using synchrotron radiation and a cubic-type high-pressure apparatus. The structure of liquid bismuth at atmospheric pressure shows similarity to high-pressure solid phases rather than to the atmospheric-pressure phase. With increasing pressure below 7 GPa, S(Q) changes continuously, becoming simpler in form and with the first peak becoming higher. In addition, the structure factor obtained at 7.3 GPa is totally different from those at lower pressures. It has extremely sharp peaks located at regular intervals in Q. It is concluded that liquid bismuth changes its structure drastically between 6 and 7 GPa. A model for the structure of liquid bismuth above this structural change is proposed.  相似文献   
948.
The fluorescence from Yb+ ions trapped in an rf trap was detected by driving the2S1/22P1/2 transition at 369.52 nm with the radiation generated by sum-frequency mixing of diode-laser and argon-ion-laser radiation. The rf resonance absorption signal as well as the fluorescence signal, when the Yb+ ions were continuously irradiated by the resonant uv radiation, faded out with a decay time shorter than the storage time. This observation suggests that the Yb+ ions disappeared from the trap with the irradiation of the resonant uv radiation.  相似文献   
949.
The mutual intensity of the optical field in the Fraunhofer diffraction region produced from the end of an optical fibre under illumination of a coherent beam, is theoretically analysed by using an optical fibre-end source model. In this source model, the optical field at the end of the fibre is expressed as an aggregation of independent plane waves with random directions and phases, because the guided modes propagating through the fibre may be regarded as a stochastic process. It is found that the optical field in the diffraction region from the multimode optical fibre is not homogeneous butquasi homogeneous in a statistical sense. The spatial coherence properties in the field are discussed in connection with theV number (the normalized frequency) of the fibre and in comparison with those in the field produced from an incoherent source obeying the van Cittert-Zernike theorem.  相似文献   
950.
We report a guest adduct X-ray structures and gas adsorption capability of 9,10-bis(4″,4-dihydroxyl-m-terphen-5″-yl)anthracene, which is an analogue of anthracene-bis(resorcinol) derivative reported by Aoyama et al. The gas adsorption capability is double scale of guest inclusion than that of anthracene-bis(resorcinol) derivative.  相似文献   
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