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81.
82.
Abdelaziz Rhandi 《Positivity》1998,2(2):101-113
Using positivity, abstract extrapolation spaces, and a generalization of the Jörgens–Vidav-Voigt perturbation theorem for the essential spectral radius of strongly continuous semigroups given in [19], we study the asymptotic behavior of a linear age-dependent population problem with spatial diffusion where the birth and the death rates depend on the spatial variable. 相似文献
83.
Tho Berclaz Bassirou Ndiaye Shrinivasa Bhat Abdelaziz Jouaiti Michel Geoffroy 《Chemical physics letters》2007,440(4-6):224-228
[M(CO)4PPh3]− (M = Mo, W) were trapped at 77 K in X-irradiated single crystals of M(CO)5PPh3 and studied by EPR. Structures of [M(CO)4PPh3]− (M = Cr, Mo, W) were optimized by DFT; predicted g and 31P-hyperfine tensors agree with experiments for M = Mo, W. The anions adopt a slightly distorted pyramidal structure with PPh3 in basal position and the spin mostly delocalized in a metal-dz2 orbital and carbon-pz orbitals of carbonyls. The EPR tensors are slightly modified by annealing, they suggest that new constraints in the matrix distort the structure of [M(CO)4PPh3]− (M = Cr, Mo, W). 相似文献
84.
Shrinivasa N. Bhat Tho Berclaz Abdelaziz Jouaiti Michel Geoffroy 《Helvetica chimica acta》1994,77(1):372-382
Single crystals of 1-[2,4,6-tri(tert-butyl)phenyl]-2-phenylphosphaethene ( PPPE ) and of 2D- and 13C-enriched PPPE were studied by ESR after X-ray irradiation. Two phosphorus-centered radicals were trapped in the crystals. The first one was characterized by its 31P, 1H-, and 13C-hyperfine tensors, the second one exhibited coupling with 31P only. Comparison of these parameters with those predicted by ab initio calculations on some phosphinyl species indicates that these two radicals probably result, on the one hand, from an addition of a H-atom to the C-atom of the P?C bond and, on the other, from a cyclization of the parent molecule. The proposed mechanisms are consistent with the mutual orientations of the hyperfine eigenvectors and bond directions in the undamaged molecule. A C-centered radical which results from an addition of a H-atom to the P-atom of the phosphaethylene bond is also detected. 相似文献
85.
The electrochemical reduction of p-nitrophenyl sulfenyl chloride, o-nitrophenyl sulfenyl chloride as well as bis(4-nitrophenyl) disulfide and bis(2-dinitrophenyl) disulfide was investigated in acetonitrile at an inert electrode. Reduction standard potentials as well standard heterogeneous electron-transfer rate constants have been determined using convolution analysis. An unexpected big difference in the thermodynamics and kinetics of the initial electron-transfer process as well as a striking change in the reductive cleavage mechanism of the S-Cl bond as a function of the nitro group position on the aryl ring of the aryl sulfenyl chloride is observed. A computational study at the B3LYP level shows that this difference in behavior is due to the through-space nonbonded S...O interaction in the o-nitrophenyl sulfenyl chloride. 相似文献
86.
Mounir Afilal Tarek Merabtene Karim Rhofir Abdelaziz Soufyane 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2016,67(5):119
We consider two Cauchy problems for the one-dimensional thermoelastic Bresse model. Using the energy method in the Fourier space, we show that for the first model, the \({L^{2}}\)-norm of the solution decays with the rate \({(1+t)^{-1/12}}\). In addition, the same decay rate has been obtained for the second model. 相似文献
87.
In this work, the authors introduce the concept of
$(p,q)$-quasi-contraction mapping in a cone metric space. We prove
the existence and uniqueness of a fixed point for a
$(p,q)$-quasi-contraction mapping in a complete cone metric space.
The results of this paper generalize and unify further fixed point
theorems for quasi-contraction, convex contraction mappings and
two-sided convex contraction of order $2$. 相似文献
88.
This work presents the characteristics of a high frequency ion source operating on a low energy, 150 keV accelerator. The
latter is to be used as a neutron generator and its design is based on a theoretical analysis which shows that if the axial
potential in an electrostatic electrode system is made to increase with four thirds the power of axial distance, inward electric
forces will compensate space charge forces tending to blow up the beam. This results in a simplified acceleration tube much
shorter and of higher gradient than the conventional acceleration columns. The ion source itself is an ordinary type using
axial extraction of the beam, and its main properties investigated are the beam current and beam quality (or emittance). Dependence
of the two on different parameters is investigated in a series of tests. 相似文献
89.
Zakaria Benzekri Sara Sibous Houda Serrar Ali Ouasri Said Boukhris Ali Rhandour Abdelaziz Souizi 《Journal of the Iranian Chemical Society》2018,15(12):2781-2787
In this work, the condensation of aromatic aldehydes with different two-substituted aniline catalyzed by NH3(CH2)5NH3BiCl5 as heterogeneous and recyclable catalyst was reported. It was demonstrated that NH3(CH2)5NH3BiCl5 can act as an efficient and active catalyst and is reusable for six runs without a significant loss of their catalytic activity. Simple preparation of the catalyst, high catalytic activity and good reusability are noteworthy advantages of this catalytic system in the synthesis of benzoxazole, benzimidazole and benzothiazole heterocycles at room temperature under solvent-free conditions. 相似文献
90.
Soraa Bouattour Taher Mhiri Abdelwaheb W. Kolsi Abdelaziz Daoud 《Journal of chemical crystallography》1998,28(5):335-338
The structure of Rb0.7(NH4)0.3HSO4 has been determined by X-ray analysis. The mixed compound crystallizes in the monoclinic space group P21/n with unit cell parameters a = 14.374(6) Å, b = 4.618(6) Å, c = 14.412(2) Å, = 118.03(2)°, V = 844.4(4) Å3, and D
cal = 1.536 g cm–3 for Z = 8. The mixed compound Rb0.7(NH4)0.3HSO4 is a chain-based structure. The Rb+ and NH4
+ cations are intercalated between chains, formed of HSO4
- groups linked with OHO hydrogen-bonding. Rb0.7(NH4)0.3HSO4 presents a new type of structural arrangement different from those of pure RbHSO4 and NH4HSO4. 相似文献