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591.
In this work, we synthesized Ni2+-containing 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride ionic liquid on magnetic Fe3O4 nanoparticles. The catalytic activity of these novel nanocomposites was finally evaluated for the Heck reaction at 100 °C, and can be reused after washing without loss in activity. The immobilized ionic liquid catalysts proved to be effective and easily separated from the reaction media by applying an external magnetic field. This procedure has many obvious advantages compared to those reported in the previous literature, including avoidance of the use of the expensive Pd catalysts, mild reaction conditions, high yields, and simplicity of the methodology.  相似文献   
592.
Structural, bonding and electronic characteristics of complexes of anthraquinone and 1-arylazo-2-naphtol dyes and cellulose I β are studied using B3LYP density functional method with 6-31G** basis set based on the partially and fully optimized structures. Results reveal that for both partially and fully optimized complexes, there is a stabilizing attraction between dyes and cellulose surface. The hydrazone (Hy) tautomer in anionic state (Hy–SO3 ?) shows the strongest interaction with the cellulose surface. Natural bond orbital (NBO) and atoms-in-molecules (AIM) analyses have been carried out to study the nature of azo dyes-cellulose bonds in detail. According to NBO analysis, a remarkable charge transfer occurs between the –SO3 ? and –SO3H functional groups of the dye and the cellulose surface which can be regarded as the main source of the large dye–cellulose interaction energy. AIM analysis confirms the existence of hydrogen and van der Waals bonds between the azo dyes and cellulose. Furthermore, a very good agreement is observed between the number of hydrogen bonding sites and dye–cellulose interaction energies.  相似文献   
593.
The reaction of phosphorus ylide, acetylmethylenetriparatolylphosphorane (L) with HgX2 (X = Cl, Br, I and NO3) in equimolar ratios using acetone and dimethylformamide as solvents leads to binuclear products. 31P NMR spectroscopy was used to investigate the stoichiometry and stability of a HgX2 complex with CH3COCHP(p-tolyl)3 (L) in binary acetone–dimethylformamide mixtures of varying composition. In all cases studied, the variation of 31P NMR chemical shift with the [HgX2]/[L] mole ratio indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In all mercuric salts used, the stabilities of the resulting 1:1 complexes varied in the order Hg(NO3)2 > HgCl2 > HgBr2 > HgI2. It was found that, in the case of all complexes, an increase in the percentage of dimethylformamide in the solvent mixtures significantly decreases the stability of the complexes.  相似文献   
594.
The nano-particle image velocimetry technique uses evanescent-wave illumination generated by total internal reflection at the wall to excite colloidal neutrally buoyant fluorescent tracer particles. The displacement of these particles over time as they are convected by the flow then gives the flow velocity components tangential to the wall. Since the extent of the illumination region normal to the wall is comparable to the particle diameter, a major source of error in this technique is particle mismatch within a pair of images due to Brownian diffusion causing a particle to move in to or out of the illuminated region. The brightness (proportional to the amount of imaged fluorescence) and size of individual particle images in nPIV data are discussed. A sequence of artificial nPIV images are generated for a known uniform velocity field with the particles subject to hindered Brownian diffusion. The velocity fields calculated from these artificial images are compared with the known velocity field to determine the effect of Brownian diffusion-induced particle mismatch on nPIV accuracy. A similar analysis is carried out for experimental nPIV images. The results provide design guidance for experimental measurements using the nPIV technique.  相似文献   
595.
Javad Bagherian 《代数通讯》2013,41(9):3692-3704
From Burnside's pαqβ-Theorem, it follows that any nonabelian group of order pαqβ, where p and q are primes, cannot be simple. As a main result of this article, we state and prove an analog of the mentioned theorem for commutative association schemes.  相似文献   
596.
At the present paper, a new system of extended general nonlinear variational inclusions is introduced and using the resolvent operator technique, equivalence between the aforesaid system and the fixed point problem is verified. By using this alternative equivalent formulation, the existence and uniqueness theorem for solution of the system of extended general nonlinear variational inclusions is demonstrated and two new iterative schemes for solving this system of extended general nonlinear variational inclusions are suggested and analyzed. The convergence analysis of the proposed iterative methods under some suitable conditions is studied. Some errors in a recent article by Noor et al. (J Inequal Appl 2011:10, 2011) are found and the incorrectness of the results of the cited paper is proved. Also, the results of the aforementioned paper are revised and corrected.  相似文献   
597.
The design of micro-devices involving aerosol transport requires the study of the deposition of aerosols in micro-channels. In this study, the slip and no-slip boundary conditions for the gas flow regime were applied to the Navier-Stokes equations to obtain the particle deposition in simple and converging-diverging micro-channels. The equation of particle motion included inertial, viscous, Brownian, and gravity terms. It was found that the ratio of gravity to inertial effects controls the deposition of particles with diameters of 0.1-1 μm, and the ratio of diffusion to inertial effects controls the deposition of particles with diameters of 0.01-0.001 i~m. Comparison between the no-slip and slip flow regimes showed that the deposition of 0.1- to 1-μm-diameter particles was less and the deposition of 0.01- to 0.001-1μm-diameter particles was greater for the slip flow regime. There was no significant difference between slip and no-slip flow regimes for the deposition of 0.01- to 0.1-μm-diameter particles. Finally, it was shown that the stagnated gas in the corners of the converging-diverging micro-channel produced similar gas velocity profiles under the slip and no-slip flow regimes.  相似文献   
598.
A comparative study of Box–Behnken, central composite, and Doehlert matrix was performed on the adsorption of Pb (II) by Robinia tree leaves in a batch system. As a case study, uptake capacity (q) and removal efficiency (R) of Pb (II) biosorption have been evaluated with all theses approaches. The advantages and limitations of these different response surface techniques have been experimentally considered. The results show the different statistical predictability of Doehlert matrix and Box–Behnken design at 95% confidence level comparable with some extent with that of central composite design at some extreme conditions. An environmental and economical comparison was also carried out between individual and simultaneous optimization of removal efficiency (R) and uptake capacity (q) using desirability function. Optimization of q proves only to have advantages over R or simultaneous optimization of R and q in this particular biosorption process. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
599.
We introduced a procedure of using local density of states for increasing the quality factor and Purcell factor of photonic crystal cavities. We used multipole expansion method for accurate calculation of local density of photonic states, stationary field profile, Q-factor, mode volume and Purcell factor of photonic crystal cavities. We found out that the quality factor exponentially increases with the number of additional photonic crystal layers around the cavity while the mode frequencies stay unchanged. We also demonstrated the method in studying the defect mode??s behavior in photonic crystal cavities and showed that high Q-factor, small mode volume and high Purcell factor could be obtained with optimization of geometrical parameters of first neighboring layer.  相似文献   
600.
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