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51.
时间分辨与偏振红外光谱研究电场诱导下手性反铁电液晶的 … 总被引:1,自引:0,他引:1
手性反铁电液晶分子中的各个不同片段、不同基团在电场诱导下展现不同的取向与取向分布。在交变电场的作用下,分子中各个部分的翻转动力学行为也表现的不同。 相似文献
52.
53.
H. R. Adam C. W. Davis K. L. Graham Isaburo Wada und Shoichiro Saito 《Fresenius' Journal of Analytical Chemistry》1930,82(8-9):325-326
Ohne Zusammenfassung 相似文献
54.
Methyl, benzyl, methoxymethyl, methylthiomethyl, methoxyethoxymethyl, and β-(trimethylsilyl)ethoxymethyl esters could be cleaved readily under mild conditions on treatment with AlCl3-N,N-dimethylaniline in CH2Cl2 to give parent carboxylic acids in high yields. 相似文献
55.
Takahiro Hirai Daiki Kato Dr. Binh Khanh Mai Shoichiro Katayama Shoko Akiyama Dr. Haruki Nagae Prof. Dr. Fahmi Himo Prof. Dr. Kazushi Mashima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10735-10742
A catalyst system of mononuclear manganese precursor 3 combined with potassium alkoxide served as a superior catalyst compared with our previously reported manganese homodinuclear catalyst 2 a for esterification of not only tertiary aryl amides, but also tertiary aliphatic amides. On the basis of stoichiometric reactions of 3 and potassium alkoxide salt, kinetic studies, and density functional theory (DFT) calculations, we clarified a plausible reaction mechanism in which in situ generated manganese–potassium heterodinuclear species cooperatively activates the carbonyl moiety of the amide and the OH moiety of the alcohols. We also revealed details of the reaction mechanism of our previous manganese homodinuclear system 2 a , and we found that the activation free energy (ΔG≠) for the manganese–potassium heterodinuclear complex catalyzed esterification of amides is lower than that for the manganese homodinuclear system, which was consistent with the experimental results. We further applied our catalyst system to deprotect the acetyl moiety of primary and secondary amines. 相似文献
56.
A poly(L ‐histidine) (PLH)‐carbohydrate conjugate has been synthesized as a new macromolecule extracting pH‐dependent properties of PLH with imidazole groups. Because of poor water solubility at physiological pH, the application of PLH with a pKa around 6.0 has been limited in spite of the native possession of the pH‐dependent property change at endosomal pH. Although the PLH modified with aliphatic primary amino groups suddenly precipitated out of the aqueous medium above pH 6.0 as a result of the deprotonation of the imidazole groups, the water solubility of PLH was improved at physiological pH by the conjugation of the aminated PLH with hydrophilic maltopentaose. The resulting PLH‐maltopentaose conjugates and metalloporphyrins formed the complexes which varied their assembling structure below pH 6.0. The PLH‐maltopentaose would be the fundamental compound for designing various drug carriers with the pH sensitivity at endosomal pH. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
57.
Shoichiro Fukusako Masahiko Yamada Hisashi Morizane Myoung-Hwan Kim 《Experimental Thermal and Fluid Science》1993,6(4):353-359
An experimental study was performed to determine the melting heat transfer characteristics along a horizontal heated circular tube immersed in a solid-air-liquid three-phase fluidized liquid ice bed. A mixture of fine ice particles and ethylene glycol acqueous solution was adopted as the liquid ice for the test. Measurements were carried out for a range of parameters such as airflow rate, heated tube diameter, and initial concentration of acqueous binary solution. It was found that the heat transfer coefficient for the fluidized liquid ice bed might be more than 20 times as large as that for the fixed liquid ice bed. 相似文献
58.
The effects of suction or blowing at the surface of a rotating cone in a quiet fluid on the skin friction and heat transfer are described. The equations which govern the fluid motion and thermal energy transfer are transformed by the boundary layer approximations and the resulting equations are solved under the condition that the suction or blowing velocity varies as x
n
(x: distance measured from the apex of the cone, n: arbitrary constant). The solutions are obtained as a perturbation from the basic laminar flow of an incompressible viscous fluid over the impermeable rotating cone. Detailed numerical calculations are performed for the case of an isothermal rotating cone with uniform blowing or suction, i.e. n=0, the Prandtl number being 0.72. Results are given for the shear stress, heat transfer and velocity and temperature fields. It is shown from the analysis that suction sharply increases the circumferential shear stress and the heat transfer at the surface.Nomenclature
c
proportional constant
-
C
fx
dimensionless skin friction factor,
x
/(V
2)
-
C
fx0
dimensionless skin friction factor for an impermeable cone
-
C
fy
dimensionless circumferential skin friction factor,
y
/(V
2)
-
C
fy0
dimensionless circumferential skin friction factor for an impermeable cone
-
c
p
specific heat at constant pressure
-
f
k
function of
-
g
k
function of
-
h
heat transfer coefficient, q/(T
w–T
)
-
k
thermal conductivity of fluid
-
n
arbitrary constant
-
Nu
x
local Nusselt number, hx/k
-
Nu
x0
local Nusselt number for an impermeable cone
-
Pr
Prandtl number
-
q
heat transfer rate
-
r
radius of a circular cross section of the cone, x sin
-
R
x
Reynolds number, Vx/
-
T
temperature
-
T
w
surface temperature of the cone
-
T
temperature of the surrounding fluid
-
u
fluid velocity in x-direction
-
v
fluid velocity in y-direction
-
V
circumferential velocity at the cone surface, r
-
w
fluid velocity in z-direction
-
x
coordinate along meridional section
-
y
coordinate along a circular cross section
-
z
coordinate perpendicular to both x and y
-
perturbation parameter, cx
n
/(x sin )1/2
-
dimensionless z-coordinate, z( sin /)1/2
-
k
function of
-
kinematic viscosity
-
density of fluid
-
x
skin friction in x-direction
-
y
circumferential skin friction
-
stream function
-
angular speed of the cone 相似文献
59.
Thedibenzyldiisopropylphosphoramidite"',whichcouldbecleavedbyreduction(hydrogenolysis),isaveryusefulreagentforthephosphorylationofhydroxygroupespeciallyvicinalhydroxygroup.Itisusedveryoftenforthesynthesisofnucleotideandmyo-inositolpolyphosphates.However,itcannotbeusedforthephosphorylationofthecompoundshavinganolefinicgroupwhichwouldalsobereducedtoparaffininthereductioncleavingofthebenZylgroup.Now,WereportthesynthesisofanewphosphorylatingreagentN,N-di-isopropyl-O,O-di-P-methox1.Sincep-methox… 相似文献
60.
Shoichiro Tanigawa 《Hyperfine Interactions》1993,79(1-4):575-589
The origin of the effect of defects on positron annihilation in semiconductors has been studied. The electron-positron momentum densities in elemental semiconductors (Si and Ge), III-V compound semiconductors (GaAs, InP and GaSb), diamond and the proton irradiated Si were investigated by a full-scale use of the two-dimensional angular correlation of positron annihilation radiations (2D-ACAR). The obtained results showed, as a whole, good agreement with the electron momentum distribution of the fully occupied Jones zone with a small exception for the fact that the low density channels are running along the three principal axes. This anisotropy was strong in elemental semiconductors, while it was weakened in compound semiconductors. This anisotropy and its dependence on the material were found to be generally understood by the incorporation of crystal symmetry. The anisotropy will be discussed by group theory in conjunction to the effect of defects on positron annihilation. 相似文献