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11.
Adiran deAguirre Ignacio Funes‐Ardoiz Feliu Maseras 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3938-3942
The computational characterization of the full catalytic cycle for the synthesis of indoline from the reaction between iodoacetanilide and a terminal alkene catalyzed by a nickel complex and a photoactive ruthenium species is presented. A variety of oxidation states of nickel, Ni0, NiI, NiII, and NiIII, is shown to participate in the mechanism. Ni0 is necessary for the oxidative addition of the C?I bond, which goes through a NiI intermediate and results in a NiII species. The NiII species inserts into the alkene, but does not undergo the reductive elimination necessary for C?N bond formation. This oxidatively induced reductive elimination can be accomplished only after oxidation to NiIII by the photoactive ruthenium species. All the reaction steps are computationally characterized, and the barriers for the single‐electron transfer steps calculated using a modified version of the Marcus Theory. 相似文献
12.
Hernandez J Solla-Gullón J Herrero E Aldaz A Feliu JM 《The journal of physical chemistry. B》2005,109(26):12651-12654
The surface structure of gold nanorods has been determined by studying the behavior of electrochemical reactions sensitive to the structure and compared to that obtained by other structure characterization techniques. Lead underpotential deposition (UPD) reveals that the surface of the nanorods is composed by (111) and (110) domains, while (100) domains are practically absent from the surface. In the case of the oxygen reduction reaction, the formation of hydrogen peroxide as a final product of the reaction in the whole potential range also indicates that (100) domains are absent on the surface of the nanoparticles, corroborating the previous result. These results are compared with other surface structure information provided by other techniques. 相似文献
13.
An unprecedented alpha-C-C agostic interaction in a cyclopropyl tris(pyrazolyl)boratoniobium complex
Jaffart J Etienne M Reinhold M McGrady JE Maseras F 《Chemical communications (Cambridge, England)》2003,(7):876-877
Structural, spectroscopic and theoretical evidence indicate that an unusual alpha-C-C agostic interaction is preferred over both alpha- and beta-C-H agostic alternatives in the title compound, TpMe2NbCl(c-C3H5)(MeCCMe). 相似文献
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15.
Alexander Björling Elisabet Ahlberg Juan M. Feliu 《Electrochemistry communications》2010,12(3):359-361
Electrochemical oxygen adsorption/desorption below monolayer level leads to a disordering of platinum single-crystal surfaces vicinal to the (1 1 1) plane. The kinetics can be described by means of a consecutive reaction from (1 1 1)-terrace sites to (1 1 0)-defect sites, in which (1 0 0)-defects act as intermediates. The first oxidation of the electrode reflects independent contributions from terrace and step sites, the latter being structure sensitive. Oxygen adsorption charges amount to a mean value of one electron per step site. 相似文献
16.
Sebastián Feliu Jr. C. MaffiotteA. Samaniego Juan Carlos GalvánVioleta Barranco 《Applied Surface Science》2011,257(20):8558-8568
The purpose of this study has been to advance in knowledge of the chemical composition, structure and thickness of the thin native oxide film formed spontaneously in contact with the laboratory atmosphere on the surface of freshly polished commercial AZ31 and AZ61 alloys with a view to furthering the understanding of protection mechanisms. For comparative purposes, and to more fully describe the behaviour of the native oxide film, the external oxide films formed as a result of the manufacturing process (as-received condition) have been characterised. The technique applied in this research to study the thin oxide films (thickness of just a few nanometres) present on the surface of the alloys has basically been XPS (X-ray photoelectron spectroscopy) in combination with ion sputtering. Corrosion properties of the alloys were studied in 0.6 M NaCl by measuring charge transfer resistance values, which are deduced from EIS (electrochemical impedance spectroscopy) measurements after 1 h of exposure. Alloy AZ61 generally showed better corrosion resistance than AZ31, and the freshly polished alloys showed better corrosion resistance than the alloys in as-received condition. This is attributed to a combination of (1) higher thickness of the native oxide film on the AZ61 alloy and (2) greater uniformity of the oxide film in the polished condition. The formation of an additional oxide layer composed by a mixture of spinel (MgAl2O4) and MgO seems to diminish the protective properties of the passive layer on the surface of the alloys in as-received condition. 相似文献
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18.
The electrochemistry of platinum single crystals is historically reviewed. After a brief revision of historical results dating before the publication of the landmark experiment by J. Clavilier of the flame annealing in 1980, the controversy introduced by this experiment into the surface electrochemistry community is described. Questions about the structure and composition of the platinum surface after the flame annealing and their implications on the characteristic voltammetry of platinum single crystal electrodes were slowly answered in the years that followed the first introduction of this methodology. One of the last questions to be solved was that about the nature of the chemical species responsible for the charge transfer process that leads to the so-called unusual features in the voltammogram. This was solved with the charge displacement experiment. Nowadays, a great deal of knowledge has been gathered about the structure of the interphase between platinum electrodes and electrolytic solutions and also about the electrocatalytic behaviour of platinum surfaces. State-of-the-art information about platinum electrochemistry is provided, with emphasis on results from our group, especially those obtained with a thermodynamic analysis, involving either constant or variable temperatures and with the laser-induced temperature jump method. 相似文献
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20.
E. B. Molodkina I. G. Botryakova A. I. Danilov J. Souza-Garcia J. M. Feliu 《Russian Journal of Electrochemistry》2012,48(3):302-315
Kinetics and mechanism of nitrate anion reduction on the Pt(100) electrode in perchloric and sulfuric acid solutions are studied.
Analysis of the results of electrochemical measurements (combination of potentiostatic treatment and cyclic voltammetry) and
the data of in situ IR spectroscopy allow suggesting the following scheme of the nitrate reduction process on Pt(100) differing
from that in the literature. If the potential of 0.85 V is chosen as the starting potential for a clean flame-annealed electrode
surface and negativegoing (cathodic) potential sweep is applied, then an NO adlayer with the coverage of about 0.5 monolayer
is formed on Pt(100) in the nitrate solution already at 0.6 V. The further decrease in the potential results in NO reduction
to hydroxylamine or/and ammonia, desorbing products vacate the adsorption sites for nitrate and hydrogen adatoms. At E < 0.1 V, adsorbed hydrogen is mostly present on the surface. During positive-going (anodic) potential sweep, the process
of nitrate reduction starts after partial hydrogen desorption, the cathodic peak of nitrate reduction to hydroxylamine or
ammonia is observed at 0.32 V on cyclic voltammograms. The process of nitrate anion reduction continues up to 0.7 V; at higher
potentials, the surface redox process with participation of hydroxylamine or ammonia (the anodic peak at 0.78 V) and nitrate
(the cathodic peak at 0.74 V is due to nitrate reduction to NO on the vacant adsorption sites) occurs. 相似文献