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81.
Dry Reforming of Methane on a Highly‐Active Ni‐CeO2 Catalyst: Effects of Metal‐Support Interactions on C−H Bond Breaking 下载免费PDF全文
B. Sc. Zongyuan Liu Dr. David C. Grinter Dr. Pablo G. Lustemberg Dr. Thuy‐Duong Nguyen‐Phan Dr. Yinghui Zhou B. Sc. Si Luo Dr. Iradwikanari Waluyo Dr. Ethan J. Crumlin Dr. Dario J. Stacchiola Prof. Jing Zhou Dr. Javier Carrasco Prof. H. Fabio Busnengo Dr. M. Verónica Ganduglia‐Pirovano Dr. Sanjaya D. Senanayake Prof. José A. Rodriguez 《Angewandte Chemie (International ed. in English)》2016,55(26):7455-7459
Ni‐CeO2 is a highly efficient, stable and non‐expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO2 at temperatures as low as 300 K, generating CHx and COx species on the surface of the catalyst. Strong metal–support interactions activate Ni for the dissociation of methane. The results of density‐functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV on Ni/CeO2?x(111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CHx or C species are detected in the C 1s XPS region. The reforming of methane proceeds in a clean and efficient way. 相似文献
82.
Old and New Morrey Spaces with Heat Kernel Bounds 总被引:1,自引:0,他引:1
Given p ∈ [1,∞) and λ ∈ (0, n), we study Morrey space
of all locally integrable complex-valued functions f on
such that for every open Euclidean ball B ⊂
with radius rB there are numbers C = C(f ) (depending on f ) and c = c(f,B) (relying upon f and B) satisfying
and derive old and new, two essentially different cases arising from either choosing
or replacing c by
—where tB is scaled to rB and pt(·, ·) is the kernel of the infinitesimal generator L of an analytic semigroup
on
Consequently, we are led to simultaneously characterize the old and new Morrey spaces, but also to show that for a suitable
operator L, the new Morrey space is equivalent to the old one. 相似文献
83.
Normal mode calculations for two alternating sequence dodecamers in A, B, and Z conformations have been performed in dihedral angle space extended to endocyclic valence angles to account for sugar ring flexibility. Normal modes are analyzed in terms of helicoidal and backbone parameter variations with special attention being paid to global deformations of the double helix such as bending, twisting, or stretching. Results show that the allomorphic form of DNA has the largest influence on the flexibility of the sugar-phosphate backbone. Amplitudes of these vibrations follow the order: B > Z > A. In contrast, the amplitudes of helicoidal parameter variations are much more dependent on the base sequence. Global deformations of the double helix occur with characteristic times in the range of 1 to 10 ps and can be of mixed character, the strongest bending mode being at the same the time strongest stretching mode. © 1997 by John Wiley & Sons, Inc. J Comput Chem 18: 796–811, 1997 相似文献
84.
Duong Sang Phu Chang Hyun Lee Chi Hoon Park So Young Lee Young Moo Lee 《Macromolecular rapid communications》2009,30(1):64-68
With a view towards direct methanol fuel cell applications, novel sulfonated poly(phenylene sulfide sulfone nitrile) (sPPSSfN) has been prepared and subsequently crosslinked by a Friedel‐Craft reaction using 4,4′‐oxybis(benzoic acid) as a crosslinker to achieve lower water swelling and lower methanol permeability. The dimensional change of SPPSSfN40 is 43.7% in 90 °C liquid water but that of the crosslinked membrane, XsPPSSfN40, is 23.3% while maintaining proton conductivity at 0.22 S · cm−1. These results show that the Friedel‐Craft crosslinking of the novel sPPSSfN membrane effectively reduces water uptake and the degree of swelling while improving the dimensional stability and maintaining high proton conductivity.
85.
Dinh Quang Khieu Duong Tuan Quang Tran Dai Lam Nguyen Huu Phu Jae Hong Lee Jong Seung Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(1-2):73-81
Raman spectroscopy has been successfully employed in order to investigate the formation of β-cyclodextrin host–guest inclusion molecular complexes with several different azo-dye structures. The Raman pattern of the carbohydrate framework results negligible when neared to the magnificent intensity of the highly polarisable guest systems and a complete and feasible comparison of the spectral features between the free and the complexed situation of the guest molecule is allowed. In general, with respect to the free guest state, it was found within the complex that a hampering of Raman intensity displays, accompanied by a levelling directed variation of the relative peak intensities, and peculiar Raman peak broadening with shifts occur, relatable to the host–guest settling of inclusive intermolecular interactions. Supportively to the other commonly established characterising methods, or in valid alternative, Raman technique has proved astoundingly useful under the perspective of the diagnostic evaluation of cyclodextrin host–guest molecular inclusion for azo-dyes and, more generally, for a highly polarisable guest structure. It features sample non-destructivity, handiness, fastness and sensitive reproducibility, occasionally providing useful suggestions about the complexation topology. 相似文献
86.
In this paper, we use a simple discrete dynamical model to study integer partitions and their lattice. The set of reachable configurations of the model, with the order induced by the transition rule defined on it, is the lattice of all partitions of a positive integer, equipped with a dominance ordering. We first explain how this lattice can be constructed by an algorithm in linear time with respect to its size by showing that it has a self-similar structure. Then, we define a natural extension of the model to infinity, which we compare with the Young lattice. Using a self-similar tree, we obtain an encoding of the obtained lattice which makes it possible to enumerate easily and efficiently all the partitions of a given integer. This approach also gives a recursive formula for the number of partitions of an integer, and some informations on special sets of partitions, such as length bounded partitions. 相似文献
87.
Duong Quoc Viet 《Journal of Pure and Applied Algebra》2009,213(11):2104-2116
Let A be a Noetherian local ring with the maximal ideal m and an m-primary ideal J. Let S=?n≥0Sn be a finitely generated standard graded algebra over A. Set S+=?n>0Sn. Denote by FJ(S)=?n≥0→(Sn/JSn) the fiber cone of S with respect to J. The paper characterizes the multiplicity and the Cohen-Macaulayness of FJ(S) in terms of minimal reductions of S+. 相似文献
88.
89.
Hong Van Nguyen Duong Thuy Tran Hung Khac Pham 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(2):37
Network structure as well as structural and compositional heterogeneities in aluminosilicate (Al2O3-2SiO2) under compression is investigated by analysis and visualization of simulation data. Structural and compositional heterogeneities are clarified through analysis of topology structure and size distribution of TO x -clusters (T = Si, Al; x = 3, 4, 5, 6) as well as OT y -clusters (y = 2, 3, 4). The TO x -cluster can be considered as TO x -grains. It appears that the structure of aluminosilicate is the mixture of TO x -grains with a different short-range order structure and this is the origin of structural heterogeneity. Regarding their composition, the OSi y - and OAl y -clusters can be considered as silica- and alumina-grains respectively, and the structure of aluminosilicate can thus be considered to be formed from silica- and alumina-grains. This results in compositional heterogeneity. Moreover, the degree of polymerization and polyamorphism as well as dynamic heterogeneity is also discussed in detail. 相似文献
90.
Ruan HD Frost RL Kloprogge JT Duong L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(5):967-981
Fourier transform infrared microscopy has been used to investigate in situ dehydroxylation of goethite to form hematite. The characterisation was based on the behaviour of hydroxyl units, which were observed in the hydroxyl stretching and hydroxyl deformation and water bending regions, and the Fe-O vibrations of the newly formed hematite during the thermal dehydroxylation process. Two hydroxyl stretching modes (v1 and v2), and three bending (V(bending-1, 2, 3)) and two deformation (V(deformation-1, 2)) modes were observed for goethite. The characteristic vibration at 916 cm(-1) was observed together with the residuals of the v1 and v2 bands in hematite spectrum. The structural transformation between goethite and hematite through thermal dehydroxylation was interpreted in order to provide criteria that can be used for the characterisation of thermally activated bauxite and their conversion to activated alumina phases. 相似文献