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51.
Barone V Bloino J Monti S Pedone A Prampolini G 《Physical chemistry chemical physics : PCCP》2011,13(6):2160-2166
Classical all-atom molecular dynamics (MD) simulations and quantum mechanical (QM) time-dependent density functional theory (TD-DFT) calculations are employed to study the conformational and photophysical properties of the first emitter excited state of tetramethyl-rhodamine iso-thiocyanate fluorophore in aqueous solution. For this purpose, a specific and accurate force field has been parameterised from QM data to model the fluorophore's first bright excited state. During the MD simulations, the consequences of the π→π* electronic transition on the structure and microsolvation sphere of the dye has been analysed in some detail and compared to the ground state behaviour. Thereafter, fluorescence has been calculated at the TD-DFT level on configurations sampled from the simulated MD trajectories, allowing us to include time dependent solvent effects in the computed emission spectrum. The latter, when compared with the absorption spectrum, reproduces well the experimental Stokes shift, further validating the proposed multilevel computational procedure. 相似文献
52.
V. Barone M. Genovese N. N. Nikolaev E. Predazzi B. G. Zakharov 《Zeitschrift fur Physik C Particles and Fields》1996,70(1):83-88
We discuss the latest CCFR determination of the strange sea density of the proton. We comment on the differences with a previous,
leading-order, result and point out the relevance of quark mass effects and current non-conservation effects. By taking them
into account it is possible to solve the residual discrepancy with another determination of the strange-quark distribution.
Two important sources of uncertainties are also analysed. 相似文献
53.
G. Barone L. H. Böttger J. A. Wolny H. Paulsen A. X. Trautwein A. Silvestri I. Sergueev G. LaManna 《Hyperfine Interactions》2005,165(1-4):299-302
Nuclear inelastic scattering (NIS) of synchrotron radiation has been used to investigate the dynamics of tin ions chelated
by DNA. Theoretical NIS spectra have been simulated with the help of density functional theory (DFT) calculations using 12
models for different binding sites of the tin ion in (CH3)Sn(DNAPhosphate)2. The simulated spectra are compared with the measured spectrum of the tin–DNA complex. 相似文献
54.
Antonino Lauria Ilenia Abbate Noemi Gambino Giampaolo Barone 《Tetrahedron letters》2008,49(35):5125-5128
Derivatives of the new ring system pyrazolo[3,4-d][1,2,3]triazolo[1,5-a]pyrimidine were synthesized from the corresponding angular isomers, through a Dimroth rearrangement, in quantitative yields. Preliminary computational studies demonstrated that this class of compounds could be a good candidate as DNA intercalating agents. 相似文献
55.
F. Bergsma J. Dorenbosch C. Nieuwenhuis J. V. Allaby U. Amaldi G. Barbiellini A. Capone Y. Eisenberg W. Flegel M. Jonker L. Lanceri M. Metcalf J. Panman D. Perret-Gallix R. Plunkett C. Santoni K. Winter I. Abt J. Aspiazu F. W. Büsser H. Daumann P. D. Gall T. Hebbeker F. Niebergall P. Schütt P. Stähelin P. Gorbunov E. Grigoriev V. Kaftanov V. Khovansky A. Rosanov L. Barone B. Borgia M. Diemoz U. Dore F. Ferroni E. Longo L. Luminari P. Monacelli F. de Notaristefani E. Valente CHARM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,40(2):171-192
We present here the final results of experiments searching for neutrino oscillations, carried out by the CHARM Collaboration. The data — taking took place in 1983. The first experiment was performed by exposing two detectors simultaneously to the CERN PS low energyv µ beam. In the second experiment the full CHARM detector was exposed to the wide-band horn-focusedv µ beam of the CERN SPS. Complete details of the experiments and data reduction are presented. No statistically significant signals for neutrino oscillations were observed. Our 90% CL limits in the appearance experiment (v µ→v e ) exclude Δm 2≧0.19 eV2 for complete mixing (sin22θ=1), and sin22θ≧0.008 for the region Δm 2≧30 eV2. These results, and the limits observed for (v µ→v x ) (disappearance of (v µ), are in agreement with those of most other experiments but exclude part of the region previously reported as a possible indication ofv µ→v e oscillations. 相似文献
56.
Summary A comprehensive study of the binary association complexes B2H6 and AlBH6 has been performed by ab initio molecular orbital theory. Reliable formation enthalpies can be computed only be extended basis sets and a reasonably complete account of correlation. The greater stability towards neutral dissociation of AlBH6 with respect to B2H6 obtained at the Hartree-Fock level employing the 6-21G* basis set ( 10 kcal/mol) is reduced to only 2 kcal/mol when the basis set is sufficiently saturated and correlation energy properly included. The value of the activation energy for hydrogen scrambling in AlBH6 is much less sensitive to the method used, although correlation still plays a significant rôle reducing the potential energy barrier from 11.4 to 7.7 kcal/mol. 相似文献
57.
58.
Enthalpies of sublimation and fusion for N-acetyl substituted glycine,L-alanine,and D-leucine amides
Enthalpies and entropies of sublimation for N-acetylglycine amide (NAGA), N-acetyl-L-alanine amide (L-NAAA), and N-acetyl-D-leucine amide (D-NALA) were determined from the dependence of their vapour pressures on temperature, as measured by the torsion-effusion method. Enthalpies and temperatures of fusion were measured by differential scanning calorimetry (DSC) and entropies of fusion were derived. No solid-to-solid transitions were detected from r.t. to fusion. Enthalpies of sublimation and fusion were combined to evaluate enthalpies of vaporization of the melts. The experimental results decreased inversely to the molecular mass. An interpretation of this trend in terms of the crystalline structure of these compounds is proposed. 相似文献
59.
Guido Barone Giuseppina Castronuovo Pompea Del Vecchio Vittorio Elia Maria Teresa Tosto 《Journal of solution chemistry》1988,17(10):925-936
The excess enthalpies of ternary aqueous solutions of biuret with four aliphatic alcohols or four isomeric pentoses have been determined by flow microcalorimetry at 25°C. The coefficients of the virial expansion of the excess enthalpies have been evaluated and compared with those already reported for urea and thiourea with the same alcohols and pentoses used here. For biuret-alcohol systems, the cross coefficients are positive and depend on the length and branching of the alkyl chain of the alcohols. On the contrary, they are negative for biuret-pentose systems. Hence, biuret, as urea and thioura, is able to differentiate the behavior of families of solutes characterized by the same functional groups. The results are interpreted in terms of the relative stabilities of the hydration cospheres of predominantly hydrophobic or predominantly hydrophilic cosolutes. However, hypotheses about the hydration cospheres of the saccharides, which are more complex than those used previously, seem to be necessary to rationalize their complete behavior in water. 相似文献
60.
We prove the existence and uniqueness of a continuous solution F = φ + w of the initial-value problem for vehicular traffic according to the nonlinear Prigogine-Herman model, where φ is a suitable t- and x-independent car distribution.We then show that the perturbation w is strongly continuous and strongly differentiable any number of times with respect to the probability of not passing q. Moreover, the derivatives (in the strong sense) satisfy linear systems.We finally investigate the behavior of w(t) as t → + ∞ and, under the assumption that the probability of not passing remains unchanged after the instant t = 0, we prove that lim ∥w(t)∥ = 0 as t → + ∞. 相似文献