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131.
Leonardo P. Bonorino Eduardo H.M. Brietzke Carlos A. Taschetto 《Journal of Differential Equations》2005,214(1):156-175
In this work we study the period function T of solutions to the conservative equation x″(t)+f(x(t))=0. We present conditions on f that imply the monotonicity and convexity of T. As a consequence we obtain the criterium established by C. Chicone and find conditions easier to apply. We also get a condition obtained by Cima, Gasull and Mañosas about monotonicity and, following some of their calculations, present results on the period function of Hamiltonian systems where H(x,y)=F(x)+n-1|y|n. Using the monotonicity of T, we count the homogeneous solutions to the semilinear elliptic equation Δu=γuγ-1 in two dimensions. 相似文献
132.
133.
Friedhelm C Hummel Bernhard Voller Pablo Celnik Agnes Floel Pascal Giraux Christian Gerloff Leonardo G Cohen 《BMC neuroscience》2006,7(1):73-10
Background
Previous studies showed that anodal transcranial DC stimulation (tDCS) applied to the primary motor cortex of the affected hemisphere (M1affected hemisphere) after subcortical stroke transiently improves performance of complex tasks that mimic activities of daily living (ADL). It is not known if relatively simpler motor tasks are similarly affected. Here we tested the effects of tDCS on pinch force (PF) and simple reaction time (RT) tasks in patients with chronic stroke in a double-blind cross-over Sham-controlled experimental design. 相似文献134.
Daniel A. Krzyzanowski Socrates Kypreos Leonardo Barreto 《Computational Management Science》2008,5(3):207-231
Steadily growing prices of oil and emissions coming from conventional vehicles, might force a switch to an alternative and
less polluting fuel in the coming future. In this article we analyze the potential influence of selected factors for successful
market penetration of hydrogen fuel cell vehicles in hydrogen based private transportation economy. Using a world scale, full
energy system, bottom-up, optimization model (Global MARKAL Model—GMM) we address the possibility of supporting the fuel cell
vehicle technology to become competitive in the markets. In a series of optimizations we evaluate the potential influence
of governmental supports and the internalization of externalities related to CO2 and local pollution emissions originating from the transportation sector, as well as preferential crediting options and demonstration
projects promoting fuel cell vehicles. The results suggest that the crucial element is the price of fuel cells and their further
potential to reduce costs. This reduction of costs may be triggered by governmental support such as direct subsidies to fuel
cells, preferential crediting options for the buildup of hydrogen infrastructure as well as penalization of emitters of CO2 and/or local pollutants. 相似文献
135.
Raymundo Cruz-Almanza Francisco Prez-Flores Leonardo Brea Eva Tapia Reyna Ojeda Aidee Fuentes 《Journal of heterocyclic chemistry》1995,32(1):219-222
Mexican Bentonitic earth (Tonsil) catalyzed the Claisen rearrangement of aryl 1,1-dimethylpropargyl ethers under mild conditions to provide 2,2-dimethyl-2H-1-benzopyrans. The synthesis of encecalin 2f and desmethoxyencecalin 2i , two biologically active products among other natural products ( 2b, 2e ) was performed by this procedure. 相似文献
136.
The application of a Fourier spectrometer to the study of the electronic structure in the far infrared of some intermediate valence or heavy fermion materials or of highT
c
superconductors showed that FT-reflectivity is a powerful tool of investigation at very low energies. A very careful control of the experimental conditions and of the reference measurements is necessary to eliminate spurious reflectivities.The results show optical transitions at very low energy and permit to evaluate the electronic structures and the effective mass of the carriers in the vicinity of the Fermi level. 相似文献
137.
138.
Pyrazole elimination and vinyl bromide were found as products in the Flash Vacuum Pyrolysis of (β-Bromo ethyl)-pyrazole. To obtain kinetic parameters (Ea) we carried out competitive reactions using (β-chloro ethyl)-pyrazole as an internal standard. A thermochemical study to calculate Δ(ΔH ) for this reaction was carried out. 相似文献
139.
Manzoni L Arosio D Belvisi L Bracci A Colombo M Invernizzi D Scolastico C 《The Journal of organic chemistry》2005,70(10):4124-4132
[reaction: see text] An efficient and operationally simple method for the synthesis of functionalized azaoxobicyclo[X.3.0]alkane amino acids has been devised. The key step is an intramolecular nitrone cycloaddition on 5-allyl- or 5-homoallylproline that was found to be completely regio- and stereoselective. 相似文献
140.
Andresa JS Reis RM Gonzalez EP Santos LS Eberlin MN de Paula Nascente PA Tanimoto ST Machado SA Rodrigues-Filho UP 《Journal of colloid and interface science》2005,286(1):303-309
The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N-propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with "on-spot" MALDI-TOF MS detection. 相似文献