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排序方式: 共有149条查询结果,搜索用时 15 毫秒
11.
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
12.
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
13.
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
14.
15.
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
16.
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
17.
18.
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
19.
José Ángel Cid 《International Journal of Mathematical Education in Science & Technology》2013,44(5):659-662
In many statistical discussions, especially in data analysis, the idea of polynomials plays a key role. For example, Dwyer [1] employed polynomials to express factorial moments of discrete distribution in terms of cumulative totals. Traditionally, polynomials are derived using the difference operator method (see [2], p. 134]). In this article, using the differential equation approach as an alternative method, we obtain generalized exponential and logarithmic polynomials, and find their special cases appearing in statistical signal‐noise models. 相似文献
20.