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排序方式: 共有256条查询结果,搜索用时 15 毫秒
101.
Garazi Urgoitia Maria Teresa Herrero Ftima Churruca Nerea Conde Raul SanMartin 《Molecules (Basel, Switzerland)》2021,26(14)
Direct arylation is an atom-economical alternative to more established procedures such as Stille, Suzuki or Negishi arylation reactions. In comparison with other palladium sources and ligands, the use of palladium pincer complexes as catalysts or pre-catalysts for direct arylation has resulted in improved efficiency, higher reaction yields, and advantageous reaction conditions. In addition to a revision of the literature concerning intra- and intermolecular direct arylation reactions performed in the presence of palladium pincer complexes, the role of these remarkably active catalysts will also be discussed. 相似文献
102.
Cristian Conde Mohammad Sal Moslehian Ameur Seddik 《Linear algebra and its applications》2012,436(9):3008-3017
We prove some refinements of an inequality due to X. Zhan in an arbitrary complex Hilbert space by using some results on the Heinz inequality. We present several related inequalities as well as new variants of the Corach–Porta–Recht inequality. We also characterize the class of operators satisfying under certain conditions. 相似文献
103.
104.
J.?C.?Conde P.?González F.?Lusqui?os B.?León 《Applied Physics A: Materials Science & Processing》2009,95(2):465-471
A theoretical approach and qualitative analysis of the changes induced on the surface morphology and the formation of microstructures
on silicon targets irradiated by excimer laser are presented. This study is based on theoretical principles of the laser ablation
process, in particular, on the analysis of the contribution of the laser energy density, which involves the laser beam parameters
and also the physical properties of the target material. For different laser incident angles, the formation of micro-columns
oriented towards the laser incident direction is explained. Moreover, numerical simulations and ablation experiments carried
out with an excimer laser corroborate the theoretical analysis. 相似文献
105.
Ji?í Pinkas Ana Conde Michal Horá?ek Karel Mach 《Journal of organometallic chemistry》2009,694(13):1971-2586
Elimination of methane during thermolysis of title compounds results in the formation of σ-Ti-C bond to t-butyl or benzyl group. The t-butyl-containing titanocene methyl compound [Ti(III)Me(η5-C5Me4t-Bu)2] (5) eliminates methane at 110 °C to give cleanly [Ti(III)(η5:η1-C5Me4CMe2CH2)(η5-C5Me4t-Bu)] (6). The methyl derivative of analogous benzyl-containing titanocene [Ti(III)Me(η5-C5Me4CH2Ph)2] was not isolated because it eliminated methane at ambient temperature to give [Ti(III)(η5:η1-C5Me4CH2-o-C6H4)(η5-C5Me4CH2Ph)] (7) with one phenyl ring linked to titanium atom in ortho-position. The corresponding titanocene dimethyl compound [TiMe2{η5-C5Me4t-Bu)}2] (9) eliminates two methane molecules at 110 °C to give the singly tucked-in 1,1-dimethylethane-1,2-diyl-tethered titanocene [Ti{η5:η1:η1-C5Me3(CH2)(CMe2CH2)}(η5-C5Me4t-Bu)] (11). In distinction, the analogous benzyl derivative [TiMe2(η5-C5Me4CH2Ph)2] (10) eliminates at 110 °C only one methane molecule to afford [TiMe(η5:η1-C5Me4CH2-o-C6H4)(η5-C5Me4CH2Ph)] (12) containing one phenyl group attached to titanium in o-position and one methyl group persisting on the titanium atom. This compound is stable at 150 °C for at least 3 h. The crystal structures of 5, 6, 7, and 10 were determined. 相似文献
106.
Influence of Mn addition on the microstructure and hyperfine parameters of amorphous and nanocrystalline Co60(FeMn)18Nb6B16 alloys has been studied. Although Mn addition does not yield significant differences in crystallization kinetics and in the phases formed after each transformation, it seriously affects the partitioning of Co during nanocrystallization. Whereas for Mn free alloy Co is homogeneously distributed throughout the amorphous matrix and the nanocrystals, in Mn containing alloy Co is enriched in the α-FeCo nanocrystals. This fact prevents the exhaustion in Fe of the amorphous matrix and the crystalline volume fraction achieved at the end of nanocrystallization in the case of Mn containing alloy is ∼20% higher than in the Mn free alloy. 相似文献
107.
α-Haloketones and -dibromides are converted to the corresponding ketones and alkenes respectively with nickel boride generated from sodium borohydride and nickel chloride. 相似文献
108.
109.
The planar point-objective location problem has attracted considerable interest among Location Theory researchers. The result has been a number of papers giving properties or algorithms for particular instances of the problem. However, most of these results are only valid when the feasible region where the facility is to be located is the whole space 2, which is a rather inaccurate approximation in many real world location problems.In this paper, the feasible region is allowed to be any closed, not necessarily convex, setS in 2. The special structure of this nonconvex vector-optimization problem is exploited, leading to a geometrical resolution procedure when the feasible regionS can be decomposed into a finite number of (not necessarily disjoint) polyhedra. 相似文献
110.
Protective Properties of a Sol-Gel Coating on Zinc Coated Steel 总被引:3,自引:0,他引:3
A. Conde J. De Damborenea A. Durán M. Menning 《Journal of Sol-Gel Science and Technology》2006,37(1):79-85
Galvanised and galvannealed steels are widely used due to their good corrosion resistance in aqueous solutions. However, when
additional protection is required, organic coatings, corrosion inhibitors or conversion coatings are used to improve their
corrosion protection. In this work, sol-gel coating was used to improve the corrosion behaviour of these two materials. This
paper analyses the final protective properties of a sol-gel coating prepared by basic catalysis and its dependence on the
sintering temperature and time of treatment. The influence of the sintering conditions on the galvanised and galvannealed
substrates is a decisive factor for the coating quality and for the barrier affect against the aggressive media. While heat
treatment time is the controlling factor for the galvannealed steels, the temperature is determining in the case of the galvanised.
Corrosion mechanisms for sol-gel galvanised steels did not changed with respect to the uncoated steel. However for galvannealed
steel, after coating the mechanism is not purely cathodic. 相似文献