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11.
Cid MB Alfonso F Martín-Lomas M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(3):928-938
The stereochemical outcome of glycosylations with 2-azido-2-deoxy-D-gluco- and D-galactopyranosyl trichloroacetimidates as glycosyl donors has been investigated by using a series of chiro-inositol derivatives as glycosyl acceptors. The influence of the absolute configuration, the conformation and the conformational flexibility of the glycosyl acceptor has been studied by using different glycosyl donors under similar pre-established experimental conditions. Although the structure of the acceptor may play a role in governing the stereochemistry of these glycosylations, the results show that, in general terms, the relative influence of these factors is difficult to evaluate. For a given set of experimental conditions, the stereochemical course of these glycosylations depends on structural features of both glycosyl donor and glycosyl acceptor. It is a balance of these factors, where the structure of the glycosyl donor always plays a major role, which determines the stereochemistry of the coupling reaction. Therefore, the examples reported in the literature in which the structure of the glycosyl acceptor appears to be crucial in determining the stereochemistry of the reaction constitute particularly favorable cases which do not presently allow any further generalization. 相似文献
12.
Serxio I. Arias-Barros Antonio Cid Luis García-Río Juan C. Mejuto Jorge Morales 《Colloid and polymer science》2010,288(2):217-221
The influence of different polyethylene glycol (PEG) on the percolation of the ternary system composed by sodium bis(2-ethylhexyl)
sulfosuccinate (AOT) + isooctane + water has been studied. The additives used were chosen on the basis of its chain length
(the number of polymeric units). In all cases, we observed a decrease in the percolation threshold on increasing the amount
of PEG added to the AOT microemulsions. We observed a correlation between the effect exerted by the additive upon the percolation
temperature and its chain length. Moreover, a relationship between the percolation temperature and the additive partition
coefficient between 1-octanol and water (logP) was found. Both of them proved the importance of the inclusion of the additives into the microemulsion interface to explain
their influence upon the percolative phenomenon. Such inclusion modified the properties of the AOT film, facilitating the
exchange of matter between droplets. 相似文献
13.
G. Astray A. Cid J. A. Manso J. C. Mejuto O. Moldes J. Morales J. Quintás 《Journal of solution chemistry》2011,40(12):2072-2081
Aggregation numbers of micelles based on N-alkylamines and mixed systems CTACl/N-alkylamines have been determined using fluorescence
techniques. The values of aggregation number are compared as a function of hydrocarbon chain length and as a function of the
molar fraction in the mixed systems. 相似文献
14.
Interband absorption change dispersions due to the filling of the trapping states are measured in commercial semiconductor doped glasses. The corresponding refractive index changes are obtained through the Kramers-Kronig transformation. Our results indicate a large deep-trapping-states nonlinearity in this material. 相似文献
15.
16.
Duce S Jorge M Alonso I García Ruano JL Cid MB 《Organic & biomolecular chemistry》2011,9(24):8253-8260
The presence of a p-nitrophenyl group converts acetone into an excellent and versatile nucleophile in organocatalytic processes, able to react with α,β-unsaturated aldehydes affording β-substituted α-arylcyclohexenones via a Michael reaction/aldol reaction/dehydration sequence, which occurs in good yields, ee up to 96% and complete diastereoselectivity. The resulting compounds are excellent synthons for the diastereoselective preparation of a variety of synthetically useful polysubstituted cyclohexanones and derivatives. 相似文献
17.
Rodrigo E Morales S Duce S Ruano JL Cid MB 《Chemical communications (Cambridge, England)》2011,47(40):11267-11269
Heteroarylvinyl sulfone 1 has been successfully used as a new sulfonyl Michael acceptor in aminocatalytic reactions with branched aldehydes. Subsequent one-pot Julia-Kocienski olefination allows the challenging preparation of enantiomerically pure α-allylated aldehydes bearing C-α quaternary carbons. 相似文献
18.
19.
This paper presents a study on the deformation of anisotropic fibrous porous media subjected to moistening by water in the liquid phase. The deformation of the medium is studied by applying the concept of effective stress. Given the structure of the medium, the displacement of the solid matrix is not taken into account with respect to the displacement of the liquid phase. The transport equations are derived from the model proposed by Narasimhan. The transport coefficients and the relation between the variation in apparent density and effective stress are obtained by test measurements. A numerical model has been established and applied for studying drip moistening of mineral wool samples capable or incapable of deformation.Nomenclature
D
mass diffusion coefficient [L2t–1]
-
e
void fraction
-
g
gravity acceleration [Lt–2]
-
J
mass transfer density [ML–2t–1]
-
K
hydraulic conductivity [Lt–1]
-
K
s
hydraulic conductivity of the solid phase [Lt–1]
-
K
*
hydraulic conductivity of the deformable porous medium [Lt–1]
-
P
pressure of moistening liquid [ML–1 t–2]
-
S
degree of saturation
-
t
time [t]
-
V
speed [Lt–1]
-
X
horizontal coordinate [L]
-
Z
vertical coordinate measured from the bottom of porous medium [L]
-
z
z-coordinate [L]
Greek Letters
porosity
- 1
total hydric potential [L]
-
g
gas density [ML–3]
-
1
liquid density [ML–3]
-
0
apparent density [ML–3]
-
s
density of the solid phase [ML–3]
-
density of the moist porous medium [ML–3]
-
external load [ML–1t–2]
-
effective stress [ML–1t–2]
-
bishop's parameter
-
matrix potential or capillary suction [L]
Indices g
gas
- 1
moistening liquid
- p
direction perpendicular to fiber planes
- s
solid matrix
- t
direction parallel to fiber planes
- v
pore
Exponent *
movement of solid particles taken into account 相似文献
20.
S.M. Rezende Cid.B. de Araujo E. Montarroyos V. Jaccarino 《Solid State Communications》1980,35(8):627-630
A study of the local magnon mode in FeF2 crystals with Mn2+ impurities by inelastic Raman light scattering is presented. Though the interaction between the radiation and the Mn spins is negligible the scattering by the s0 local mode is very strong. The data of the frequency and the scattering intensity are analyzed in terms of a magnetization coupled mode approach. 相似文献