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61.
In this note, we discuss the flexibility of Schubert classes in homogeneous varieties. We give several constructions for representing multiples of a Schubert class by irreducible subvarieties. We sharpen [22, Theorem 3.1] by proving that every positive multiple of an obstructed class in a cominuscule homogeneous variety can be represented by an irreducible subvariety. 相似文献
62.
The behavior of Mn overlayers on Fe(0 0 1) under the influence of external magnetic fields is investigated. The electronic charge distribution, local magnetic moments as well as their couplings are determined as a function of the external field by solving self-consistently a tight binding Hamiltonian, parameterized to ab initio TBLMTO calculations. Our method allows to trace back the field-dependent average magnetization of the system to its electronic structure and magnetic configuration. We show how in the non-collinear framework the response of the system is markedly different to what is found in the collinear framework. If metastable magnetic configurations exist, the external field can be used for tuning the system between some of them because the system stays in some of those metastable states even after switching off the external field. 相似文献
63.
Stephanie Giraldo Irma Robles Luis A. Godínez Nancy Acelas Elizabeth Flrez 《Molecules (Basel, Switzerland)》2021,26(15)
Chemical and thermochemical transformations were performed on orange peel to obtain materials that were characterized and further tested to explore their potential as adsorbents for the removal of methylene blue (MB) from aqueous solutions. The results show the high potential of some of these materials for MB adsorption not only due to the surface area of the resulting substrate but also to the chemistry of the corresponding surface functional groups. Fitting of the kinetic as well as the equilibrium experimental data to different models suggests that a variety of interactions are involved in MB adsorption. The overall capacities for these substrates (larger than 192.31 mg g−1) were found to compare well with those reported for activated carbon and other adsorbents of agro-industrial origin. According to these results and complementary with theoretical study using Density Functional Theory (DFT) approximations, it was found that the most important adsorption mechanisms of MB correspond to: (i) electrostatic interactions, (ii) H-bonding, and (iii) π (MB)–π (biochar) interactions. In view of these findings, it can be concluded that adsorbent materials obtained from orange peel, constitute a good alternative for the removal of MB dye from aqueous solutions. 相似文献
64.
Munoz RC García JP Henríquez R Moncada AM Espinosa A Robles M Kremer G Moraga L Cancino S Morales JR Ramírez A Oyarzún S Suárez MA Chen D Zumelzu E Lizama C 《Physical review letters》2006,96(20):206803
We report measurements of the Hall effect performed on 4 gold films evaporated onto mica substrates where the signal arises primarily from electron-surface scattering. The measurements were performed at low temperatures T (4 K < or = T < or = 50 K) under high magnetic field strengths B (1.5 T < or = B < or = 9 T), with B oriented perpendicular to the films. 相似文献
65.
G. Guzmán-Ramírez F. Aguilera-Granja J. Robles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(1):49-60
We report a study on small copper clusters
\textCunn\text{Cu}_n^{\nu} (ν= ±1,0,2; n=3-13) where the minimum energy structures were computed through a joint gradient embedded genetic algorithm
(GEGA) technique, and further density functional theory (DFT) geometry reoptimization of the best GEGA cluster structures
for each size and charge. Our results are compared to previous ab initio and DFT calculations, when available in the literature,
and it is shown than a number of never reported structures for some clusters have been found. From an extensive calibration
of some of the DFT commonly used approximate functionals and basis sets, a discussion on its performance and efficiency for
Cu cluster calculations is provided. All GEGA found structures are subject to a second step DFT reoptimization process, at
the final reported level of theory, BLYP/6-311+G(d), and it is observed that the symmetry found initially by GEGA for almost
all of the 66 clusters studied is kept during the DFT reoptimization, which shows the reliability of the initial search algorithm
employed. Several geometry-related-properties of these clusters are discussed and compared with some results available in
the literature. 相似文献
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