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661.
José Sanabria Ennis Rosas Carlos Carpintero 《Rendiconti del Circolo Matematico di Palermo》2009,58(3):453-465
We introduce and study two new notions of sets called (Λ, mn)-closed sets and gΛ
mn
-sets, which are defined on a nonempty set with two minimal structures. These sets enables us to unify modifications of λ-closed sets [1] and generalized Λ-sets [15], respectively. Moreover, we give a new characterization of the class of mn-T
1/2 [17] by using gΛ
mn
-sets. 相似文献
662.
In order to elucidate the presence of non-localized states in doped graphene, a scaling analysis of the wavefunction moments, known as inverse participation ratios, is performed. The model used is a tight-binding Hamiltonian considering nearest and next-nearest neighbors with random substitutional impurities. Our findings indicate the presence of non-normalizable wavefunctions that follow a critical (power-law) decay, which show a behavior intermediate between those of metals and insulators. The power-law exponent distribution is robust against the inclusion of next-nearest neighbors and growing the system size. 相似文献
663.
Marcos Pérez Francisco Mu?oz José Mejía-López Gerardo Martínez 《Journal of nanoparticle research》2012,14(6):1-15
The aim of this work is to investigate the influence of the preparation method on the surface charge and electrokinetic properties of poly-??-caprolactone-based particles using poloxamer 188 as stabilizing agent. To target such objective, two processes (the nanoprecipitation and the emulsification-diffusion) are used to prepare well-defined nanospheres ranging in hydrodynamic diameters from 100 to 200?nm. The effect of the materials used on the particle zeta potential is systematically studied to compare the two preparation methods. The polarity of the organic solvent directly affects the zeta potential of particles prepared via the emulsification-diffusion method. The results obtained suggest that the aqueous phase used for preparing particles affects the possible re-arrangement of polymers during the emulsification step. As the aqueous phase is saturated with the organic solvent, the polar and the non-polar moieties of the polymer chains might be re-conformed following organic solvent diffusion from the particle core to the continuous phase. Regarding the nanoprecipitation process, the electrokinetic properties of the particles were found to be organic solvent independent, but principally affected by the pH and the salinity of the aqueous phase used during the particle preparation. 相似文献
664.
Rita Prosmiti Alexei A. Buchachenko Pablo Villarreal Gerardo Delgado-Barrio 《Theoretical chemistry accounts》2001,106(6):426-433
Ab initio molecular electronic structure calculations are performed for H5
+ at the QCISD(T) level of theory, using a correlation-consistent quadruple-zeta basis set. Structures, vibrational frequencies
and thermochemical properties are evaluated for ten stationary points of the H5
+ hypersurface and are compared with previous calculations. The features of the H3
+…H2 interaction at intermediate and large intermolecular distances are also investigated. Furthermore, an analytical functional
form for the potential-energy surface of H5
+ is derived using a first-order diatomics-in-molecule perturbation theory approach. Its topology is found to be qualitatively
correct for the short-range interaction region.
Received: 15 March 2001 / Accepted: 5 July 2001 / Published online: 11 October 2001 相似文献
665.
666.
Javier E. Alfonso-Ramos Ruben Van Lommel David Hernández-Castillo Prof. Frank De Proft Roy González-Alemán Prof. Erik V. Van der Eycken Gerardo M. Ojeda-Carralero 《European journal of organic chemistry》2023,26(3):e202201028
1,3-Dipolar cycloadditions are the preferred method to generate five-membered heterocyclic rings. Surprisingly, cycloadditions based on acyl-isocyanide ylides have remained underexplored by the chemical community. Acyl-isocyanide ylides readily react with dipolarophiles, such as substituted alkenes, to yield Δ1-pyrroline derivatives. As an explanation for the observed reactivity of this reaction is lacking, extensive density functional theory calculations were performed to scrutinize the mechanistic features of the transformation. Herein we explain the experimental outcome of the reaction using a variety of reactivity theories and predict opposed regioselectivity for electron-poor and electron-rich dipolarophiles. With the insights obtained, we hope to incentivize the design of new cycloaddition reactions based on the acyl-isocyanide ylides motif. 相似文献
667.
Farouil Léa Duchaudé Yolène Zozo Léa Sylvestre Muriel Lafay Florent Marote Pedro Cebrián-Torrejón Gerardo 《Journal of Solid State Electrochemistry》2023,27(5):1249-1259
Journal of Solid State Electrochemistry - Today, pest control by chemical treatment is the main strategy against pest insects. This article proposes to show how cyclic voltammetry of immobilized... 相似文献
668.