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31.
Abdallah Laradji 《Algebras and Representation Theory》2010,13(6):719-722
We show that if the direct product of countably many copies of a noetherian ring R is pure in a direct sum of finitely generated modules, then R satisfies the descending chain condition on two-sided ideals. This extends a recent result of Buchweitz and Flenner. 相似文献
32.
T. A. El-Brolossy S. Abdallah T. Abdallah M. B. Mohamed S. Negm H. Talaat 《The European physical journal. Special topics》2008,153(1):365-368
We report on the optical absorption properties of as
prepared CdSe quantum dots (QDs) measured by the photoacoustic (PA) method.
CdSe QDs were fabricated by the chemical solution deposition (CD) technique.
With increasing growing time, the redshift of the PA spectra can be clearly
observed and optical absorption in the visible region due to CdSe Q-dots is
demonstrated. The average diameters of the CdSe QDs for each growth time
interval is estimated using the effective mass approximation giving
diameters ranging from 2.6 nm to 3.4 nm. These values are comparable to
those obtained by scanning tunnelling microscope (STM). Thus, PA
spectroscopy is useful to obtain the QDs sizes as grown and with no further
preparation. In addition, PA measurements provide also the thermal
diffusivity of samples of different sizes which in this case show an
increase by at least an order of magnitude than the bulk value. 相似文献
33.
Abdallah A. Badr 《Journal of Applied Mathematics and Computing》2000,7(2):455-463
In this work, we solve the Fredholm-Volterra integral equation (FVIE) when the kernel takes a potential function form under given conditions. We represent this kernel in the Weber-Sonin integral form. 相似文献
34.
John P. Shockcor Ronald C. Crouch Gary E. Martin Abdallah Cherif Jiann-Kuan Luo Raymond N. Castle 《Journal of heterocyclic chemistry》1990,27(2):455-458
One-dimensional ( 1D ) variants of two-dimensional ( 2D ) nmr techniques can frequently provide the required information in a much shorter period of time than the 2D experiment from which they were derived. Application of the 1D homonuclear Hartmann-Hahn (1D-HOHAHA) experiment to establish proton-proton connectivity networks in highly overlapped four-spin systems in the proton nmr spectra of polynuclear aromatics is described. Selective subspectra are contrasted to the data obtained in a COSY experiment on the same molecule, benzo[f][l]benzothieno [2,3 -c]quinoline. Results from the 1D-HOHAHA technique are especially useful when component resonances from several spin systems are heavily overlapped. Relayed 1D-HOHAHA provides the means of exploiting small, long range coupling pathways of polynuclear aromatics. 相似文献
35.
Turky Abdallah Bayoumi Ashraf H. Sherbiny Farag F. El-Adl Khaled Abulkhair Hamada S. 《Molecular diversity》2021,25(1):403-420
Molecular Diversity - The discovery of potent STAT3 inhibitors has gained noteworthy impetus in the last decade. In line with this trend, considering the proven biological importance of... 相似文献
36.
Abstract
The effect of Ni2+ cation, imidazole, and mixtures of them on the corrosion behavior of carbon steel in 0.5 M H2SO4 solution was studied by using galvanostatic polarization, potentiodynamic anodic polarization, and weight-loss techniques. Ni2+ cation, imidazole, and mixtures of them provide a good protection to carbon steel against pitting corrosion in chloride-containing solutions. The inhibiting solutions were analyzed by using UV–Vis spectrophotometry. The inhibition was explained on the basis of formation of a complex between the two components. The inhibition mechanism was discussed in terms of the results derived from corrosion and UV–Vis spectrophotometric measurements as well as conductometric investigations. 相似文献37.
Theoretical methods have been employed to investigate the structural, spectroscopic and energetic properties of difluoro(germylthio)phosphine in the Cs symmetry in the gas phase. The levels of theory used are MP2 and DFT/B3LYP and the basis set used for all atoms is 6-311G(d,p). The computed structural parameters, namely, bond lengths and bond angles and spectroscopic parameters, namely, infrared frequencies, Raman activities and NMR chemical shifts have been compared with experimental data reported in literature. The structure of this compound has been analysed using natural bond orbital approach. Both the ab initio methods perform satisfactorily when the predicted and experimental parameters are compared. We have extended this study, using the same methods and basis set, to the selenium analogue, namely, difluoro(germylseleno)phosphine for which literature is elusive. The MP2/6-311G(d,p) geometrical parameters for difluoro(germylseleno)phosphine are: r(P–Se) = 2.270, r(Ge-Se) = 2.386, r(P–F) = 1.604, r(Ge–H) = 1.530 Å, ∠(Ge–Se–P) = 91.4, ∠(F–P–F) = 96.7, ∠(Se–P–F) = 99.9 and ∠(Se–Ge–H) = 109.5°. Apart from these, we have also studied the energetic parameters for their synthesis. The results indicate that formation of the sulphur-containing compound is favoured thermodynamically. 相似文献
38.
Kamel Khimeche Abdallah Dahmani Ilham Mokbel 《The Journal of chemical thermodynamics》2010,42(7):829-833
The vapour pressures of liquid {3-diethylaminopropylamine (3-DEPA) + cyclohexane} were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar volumes VE at 298.15 K and excess molar enthalpies HE at 303.15 K were also measured. The molar excess Gibbs free energies GE were obtained with Barker’s method and fitted to the Redlich–Kister equation. The Wilson equation was also used. Deviations between experimental and predicted GE and HE, by using DISQUAC model, were evaluated 相似文献
39.
Ahmed Mekki Kamel Khimeche Abdallah Dahmani 《The Journal of chemical thermodynamics》2010,42(8):1050-1055
A differential scanning calorimetry (d.s.c.) was used to determine binary (solid + liquid) phase equilibria (SLE) for four binary mixtures, viz. (n-nitrosodiphenylamine + diphenylamine), (2-nitrodiphenylamine + ethyl centralite), (2,4-dinitro-N-ethylaniline + methyl centralite), and (2,4-diphenylamine + 4,4′-dinitroethylcentralite). These compounds are used as stabilizers in gun powders and propellants. Results obtained with this technique are compared with those correlated by NRTL and ideal models. It was found out that all the systems are simple eutectic systems and deviations between experimental and predicted SLE results were observed. 相似文献
40.
In this paper the effective mass approximation and the k·p multi-band models, describing quantum evolution of electrons in
a crystal lattice, are discussed. Electrons are assumed to move in both a periodic potential and a macroscopic one. The typical
period e{\epsilon} of the periodic potential is assumed to be very small, while the macroscopic potential acts on a much bigger length scale.
Such homogenization asymptotic is investigated by using the envelope-function decomposition of the electron wave function.
If the external potential is smooth enough, the k·p and effective mass models, well known in solid-state physics, are proved
to be close (in the strong sense) to the exact dynamics. Moreover, the position density of the electrons is proved to converge
weakly to its effective mass approximation. 相似文献