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61.
Henrique E. Toma Tulio E. Chavez-Gil Reginaldo C. Rocha Hercílio R. Rechenberg 《Journal of inclusion phenomena and macrocyclic chemistry》1999,34(1):57-68
A novel multibinding species has been obtained by attaching four aliphatic polyamine chains to an iron(II)-polyimine centre, derived from 2,6-diacetylpyridine. Molecular simulations for the complex corroborate the evidence from 1H NMR spectroscopy of a symmetric structure, with the four polyamines displaying a tetrahedral arrangement around the metal centre. The protonated polyamine complex interacts with hexacyanoferrate(II) ions, leading to an inclusion compound which has been characterized based on vibrational and Mössbauer spectroscopy, and on cyclic voltammetry. 相似文献
62.
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64.
Cláudia M. Morais Valérie Montouillout Michael Deschamps Dinu Iuga Franck Fayon Filipe A. A. Paz João Rocha Christian Fernandez Dominique Massiot 《Magnetic resonance in chemistry : MRC》2009,47(11):942-947
From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving 31P and 27Al, we show that the structure of microporous alumino‐phosphate AlPO4‐40 contains at least four times more sites than expected, and we attribute two types of AlIV sites. The newly described 27Al‐31P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
65.
This work proposes a Progressive Assisted Sorting Algorithm (PASA) based on a multicriteria evaluation ELECTRE-type method.
The purpose of the PASA is to aid a decision maker to progressively sort a set of alternatives into a set of categories, which
we considered are ordered (ordinal sorting), following a consistency principle. We consider the principle that if an alternative
outranks (is as good as) a second one, then it must belong to the same category or to a better category. The set of alternatives
already sorted by the decision maker will implicitly define the categories, and will constrain the range of categories where
other alternatives may be sorted. We show how the same idea may be used in an aggregation/disaggregation approach, considering
some parameters of ELECTRE are not fixed a priori, but are constrained only by the examples provided. In this context, we
establish a “convex-shape property” stating that the range of possible categories for an alternative is always an interval
of categories. A discussion contrasting this approach with ELECTRE TRI is included in the conclusions. 相似文献
66.
Thales R. de Moura Sahra L. Cavalcanti Paulo R. D. V. de Godoy Elza T. Sakamoto-Hojo Fillipe V. Rocha Eduardo T. de Almeida Victor M. Deflon Antonio E. Mauro Adelino V. G. Netto 《Transition Metal Chemistry》2017,42(6):565-574
Complexes of the type cis-[PdX2(imzt)(PPh3)] {imzt = imidazolidine-2-thione; PPh3 = triphenylphosphine; X = Cl (1), Br (2), I (3), SCN (4)} have been synthesized and characterized by elemental analyses, molar conductance, IR and 1H NMR spectroscopies. The complex 1·MeOH was obtained from the reaction of [PdCl2(CH3CN)2], imidazolidine-2-thione and triphenylphosphine in CHCl3/CH3OH. Complexes 2·MeOH, 3 and 4 were prepared by metathesis of the chlorido ligands in 1 with bromide, iodide and thiocyanate, respectively. Elemental analyses showed good agreement with the expected mononuclear compositions, while the molar conductivities of the complexes in DMF were consistent with their nonelectrolytic nature. NMR spectra confirmed coordination of the imidazolidine-2-thione and triphenylphosphine ligands. Single-crystal X-ray diffraction determination of 1·CH3OH showed that the coordination geometry around PdII is nearly square planar, with the chlorido ligands in a cis configuration. All four complexes have been tested in vitro by XTT assay for their cytotoxicity against human glioblastoma cell line (U87MG). The binding of 1 with guanosine was studied by 1H NMR spectroscopy, revealing that the coordination takes place via N7. 相似文献
67.
Application of X-ray diffraction, micromagnetic and hole drilling methods for residual stress determination in a ball bearing steel ring 总被引:1,自引:0,他引:1
C. O. D. Martins Ph.D. T. R. Strohaecker A. S. Rocha T. K. Hirsch 《Experimental Mechanics》2005,45(4):344-350
A basic understanding of distortion problems requires the analysis of a complete manufacturing process including an almost
complete overview of residual stress states in the component during each production step. To reduce the measurement time in
the future, three measurements methods (X-ray diffraction, micromagnetic and blind hole drilling methods) have been used to
analyze residual stress states in machined AISI 52100 ball bearing rings. X-ray diffraction was used as a state-of-the-art
method for machining induced residual stresses with pronounced gradients. The ring exhibited a complex residual stress state
with high tensile residual stresses at the surface, a strong gradient in depth, and also showed some variation along the outer
circumference due to a superimposition of machining induced residual stresses and effects from the clamping device process.
Due to this surface state, micromagnetic signals depend on the analyzing frequency. A calibration of the signals was only
possible with the X-ray diffraction data. The results of the three different measurement methods correlate reasonably well. 相似文献
68.
Dalva E. C. Ferreira Wagner B. De Almeida Ademir Neves Willian R. Rocha 《International journal of quantum chemistry》2010,110(5):1048-1055
Density functional theory (DFT) calculations with different exchange‐correlation functionals were performed for a mixed valence Fe(II)/Fe(III) binuclear complex with μ‐methoxo and two μ‐carboxylate bridging ligands, (1) with geometry optimizations being performed for all possible spin multiplicities (MS = 2, 4, 6, 8, and 10). Within the exchange‐correlation functionals studied, only the hybrid GGA functionals B3P and B3LYP and also the pure GGA functional RPBE, predicts the geometry with high spin (S = 9/2) to be more stable than the geometry with low spin state (S = 1/2) by 20 kcal/mol, in agreement with the experimental findings. These functionals also predict the same stability order for the different spin states, being MS = 10>8>6>2>4. The meta‐GGA functionals TPSS and TPSSh and also the pure GGA functionals BLYP and BP86 predict different stability orders. The computed average EPR g‐tensor, gav, of 2.03, at the B3LYP level, is in good agreement with the experimental findings. Heisenberg exchange coupling constants, J, were calculated within the broken‐symmetry formalism, at the B3LYP level, showing that the two iron centers are antiferromagnetic coupling, with a very weak coupling constant of about ?7 cm?1, in good agreement with the experimental value. Additionally, the effect of using different multiplicities of the reference geometries on the computed J value is discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
69.
Bruna Cláudia Lourenção Roberta Antigo Medeiros Romeu C. Rocha‐Filho Orlando Fatibello‐Filho 《Electroanalysis》2010,22(15):1717-1723
A cathodically pretreated boron‐doped diamond electrode was used for the simultaneous anodic determination of ascorbic acid (AA) and caffeine (CAF) by differential pulse voltammetry. Linear calibration curves (r=0.999) were obtained from 1.9×10?5 to 2.1×10?4 mol L?1 for AA and from 9.7×10?6 to 1.1×10?4 mol L?1 for CAF, with detection limits of 19 μmol L?1 and 7.0 μmol L?1, respectively. This method was successfully applied for the determination of AA and CAF in pharmaceutical formulations, with results equal to those obtained using a HPLC reference method. 相似文献
70.
Christoph Rameshan Werner Stadlmayr Christian Weilach Simon Penner Harald Lorenz Michael Hvecker Raoul Blume Tulio Rocha Detre Teschner Axel Knop‐Gericke Robert Schlgl Norbert Memmel Dmitry Zemlyanov Günther Rupprechter Bernhard Kltzer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(18):3292-3296