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51.
Bernardo da Cruz Antonio Gerson Leyva Maria Elena Simão Renata Antoun 《Journal of Solid State Electrochemistry》2018,22(5):1459-1469
Journal of Solid State Electrochemistry - In this work, we report the electrochemical polymerization of novel low bandgap hybrid polymer films based on 3,4-ethylenedioxythiophene containing... 相似文献
52.
Stefan Wild Michael Fickert Aleksandra Mitrovic Vicent Lloret Christian Neiss Jos Alejandro Vidal‐Moya Miguel ngel Rivero‐Crespo Antonio Leyva‐Prez Katharina Werbach Herwig Peterlik Mathias Grabau Haiko Wittkmper Christian Papp Hans‐Peter Steinrück Thomas Pichler Andreas Grling Frank Hauke Gonzalo Abelln Andreas Hirsch 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5820-5826
53.
Hassan Hosseini‐Monfared Rahman Bikas Sakine Mohammadi Teresa Mancilla Percino Serhiy Demeshko Franc Meyer Marco A. Leyva Ramírez 《无机化学与普通化学杂志》2014,640(2):405-411
A 1D coordination polymer of manganese(III) with a hydrazone‐based ligand, [Mn2(L)(μ‐OCH3)2(OHCH3)2]n ( 1 ), was synthesized and characterized by elemental analyses and spectroscopic methods {H4L = bis[(2‐hydroxynaphthalen‐1‐yl)methylene]adipohydrazide}. The crystal structure of 1 was determined by X‐ray crystallography. The two dianionic domains of the ligand adopt trans configuration, and each coordinates in a tridentate mode via the O, N, O′‐donor atoms to a MnIII ion forming a dinuclear compound. The methoxy ligands provide an asymmetric bridge between two central manganese atoms, which lead to the formation of a 1D coordination polymer. A 2D supramolecular structure is formed by hydrogen bonding interactions between the 1D chains. Although the methoxy ligands are labile, the polymer preserves its oligonuclearity in the solution. Temperature‐dependent magnetic susceptibility studies proved the presence of a weak antiferromagnetic interaction between manganese(III) ions with J = –3.2 cm–1, which results from axial distortion of the manganese coordination environment. Compound 1 showed catalase‐like activity in disproportionation of H2O2. 相似文献
54.
55.
María Elena Leyva Guilherme M. O. Barra Ana C. F. Moreira Bluma G. Soares Dipak Khastgir 《Journal of Polymer Science.Polymer Physics》2003,41(23):2983-2997
The conductivity of styrene‐butadiene‐styrene block copolymers containing different amounts of extraconductive carbon black (CB) was investigated as a function of the mold temperature. The composites exhibited reduced percolation thresholds (between 1.0 and 2.0 vol % CB). The dynamic mechanical analysis characterization revealed that the glass‐rubber‐transition temperatures of both segments were not affected by the CB addition, although the damping of the polybutadiene phase displayed a progressive drop with an increase in the CB concentration. The normalized curves of tan δ/tan δmax (where tan δ represents the value of the loss tangent at any measurement temperature and tan δmax represents the loss tangent peak value at the corresponding temperature Tmax) versus T/Tmax (where T is the temperature and Tmax is the maximum temperature), corresponding to both polystyrene and polybutadiene phases as well as the activation energy related to the glass‐rubber‐transition process, did not present any significant change with the addition of CB. The dielectric analysis revealed the presence of two relaxation peaks in the composite containing 1.5 vol % CB, the magnitude of which was strongly influenced by the frequency, being attributed to interfacial Maxwell‐Wagner‐Sillars relaxations caused by the presence of different interfaces in the composite. The mechanical properties were not affected by the presence of CB at concentrations of up to 2.5 vol %. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2983–2997, 2003 相似文献
56.
D. Vega C. Ramos H. Aliaga M. T. Causa B. Alascio M. Tovar G. Polla G. Leyva P. Knig I. Torriani 《Physica B: Condensed Matter》2002,320(1-4):37-39
Structural studies on the electron doped Ca1−xYxMnO3 are presented. At 300 K, orthorhombic O-phase was observed in all cases, associated to low electric resistivity and high Curie–Weiss temperature. For samples with x>0.07, structural phase transitions to more distorted orthorhombic and monoclinic phases were found at T<170K. In these phases only weak ferromagnetic interactions were observed. 相似文献
57.
V. Herrera F. Sendoya I. Pupo D. Hernández P. Leyva 《Journal of Radioanalytical and Nuclear Chemistry》2002,252(1):105-108
For the characterization of deposit layers on AISI 316L surfaces in high purity water systems, operating up to 80 °C Mössbauer spectroscopy (ME), scanning electron microscopy (SEM), X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) are used. Austenitic steel particles were identified on the surfaces of systems not properly cleaned before start-up. Long exposition of austenitic surfaces to high purity water promotes the build-up, composed by trivalent iron and chromium oxidehydroxides and oxide. The oxidehydroxide phase is located mainly at the solid-water interface, whereas oxide phase is in direct contact with metal. Spheroid-like morphology of particles in these layers and the lack of metal attack suggest that coagulation and crystallization processes are the way for oxide production from existing dissolved species. 相似文献
58.
Antonio Leyva 《Tetrahedron》2008,64(10):2348-2358
A new method for the synthesis of dienes and enynes containing chiral 1,2-diols is described. The strategy is based on the Pd-catalysed cross-coupling reactions of a series of vinyl and alkynyl asymmetric butanediacetal-protected building blocks. After the coupling, removal of the protecting group leads to the desired functionalised dienes and enynes. 相似文献
59.
Leyva V Corral I Schmierer T Heinz B Feixas F Migani A Blancafort L Gilch P González L 《The journal of physical chemistry. A》2008,112(23):5046-5053
The experimental UV/vis absorption spectrum of ortho-nitrobenzaldehyde (o-NBA) has been assigned by means of MS-CASPT2/CASSCF, TD-DFT, and RI-CC2 theoretical computations. Additional information on the nature of the absorbing bands was obtained by comparing the o-NBA spectrum with that of related compounds, as, e.g., nitrobenzene and benzaldehyde. For wavelengths larger than approximately 280 nm, the absorption spectrum of o-NBA is dominated by a series of weak n pi* absorptions from the NO2 and CHO groups. These weak transitions are followed in energy by a more intense band, peaking at 250 nm and arising from charge transfer pi pi* excitations involving mainly benzene and nitro orbitals. Finally, the most intense band centered at 220 nm has its origin in the overlap of two different absorptions: the first one localized in the NO2 substituent and the second one arising from a charge transfer excitation involving the NO2 and the CHO fragments, respectively. 相似文献
60.
Migani A Leyva V Feixas F Schmierer T Gilch P Corral I González L Blancafort L 《Chemical communications (Cambridge, England)》2011,47(22):6383-6385
o-Nitrobenzaldehyde is photolabile because of an irreversible phototautomerization, whereas comparable aromatic compounds function as photoprotectors because the tautomerization is reversible. In this experimental and theoretical study we track down the cause of this difference to the electronic changes that occur during the tautomerization. 相似文献