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151.
INTRODUCTIONThe atom transfer radical polymerization (ATRP) has become an important method for preparing well-definedmacromolecules. This technique offers control over the molecular weights, the chain end functionalities, and thechain architectures[1-12]. It has been used extensively for the preparation of homopolymers, block, and randomcopolymers[13-39], for the preparation of organic/inorganic hybrid materials[40-54], as well as for combining variousother living polymerization methods … 相似文献
152.
The intrinsic electrical conductivity of alpha, omega-alkanedithiol increases if both ends of the molecule are covalently bonded to metallic contacts. 相似文献
153.
A detailed study of the paramagnetic to ferromagnetic phase transition in the one-band Hubbard model in the presence of binary-alloy disorder is presented. The influence of the disorder (with concentrations x and 1-x of the two alloy ions) on the Curie temperature T(c) is found to depend strongly on electron density n. While at high densities, n>x, the disorder always reduces T(c); at low densities, n相似文献
154.
The pH sensitivity of conducting polymer films is an important issue from the sensor design point of view. The doping and supporting electrolyte anions effect on the potentiometric sensitivity and response time of polypyrrole (PPy) electrodes towards changes of solution pH were studied. It was found that (i) the response of PPy doped by easily exchangeable common anions (Cl–, NO3
–, ClO4
–) in their solutions (KCl, KNO3, NaClO4) is slow. In contrast, (ii) polypyrrole films deposited in the presence of weak acid anions (phthalates, oxalates, salicylates) were characterised by instantaneous responses in the above mentioned solutions. On the basis of electrochemical experiments (open circuit potential vs. time dependencies, cyclic voltammetry, EQCM), the observed differences were attributed to different mechanisms of pH sensitivity of tested films. The long response times are related to the incorporation of the solution ions into the film in order to compensate charges created due to protonation. On the other hand, if the ion-exchange is hindered as in the case of (ii), instantaneous open circuit responses are observed due to polarisation of the oxidised polymer layer, analogously to the metal electrode. Moreover, for these films the internal pH buffering within the polymer membrane will weaken the pH change effect.The mechanisms were confirmed in the course of studying the pH effect in solutions containing anions easily (KCl, NaClO4, KNO3) or hardly exchangeable with polypyrrole (K2SO4, sodium poly(4-styrenesulphonate) solutions) acidified with H2SO4. 相似文献
155.
Other Index
Key Word Index of Volume 38 – 2003 相似文献156.
[reaction: see text] Vinylsilanes are formed in high yields in the reaction of representative acyl(trimethyl)silanes with anions generated from Kocienski's sulfones. 相似文献
157.
An example of the complementary use of GC-MS. GC-AED and GC-FT-IR is described for efficient structure elucidation of an unknown impurity in pharmaceutical analysis. None of the analytical techniques could solve the structure of the unknown impurity alone; identification was, however, straightforward by combining the available spectroscopic information. GC-MS provided information about structural fragments and molecular mass of the unknown compound. GC-AED was used for confirmation of the occurrence of the individual elements in the structure and to enable calculation of the empirical formula. GC-FT-IR gave valuable information regarding functional groups in the molecule. 相似文献
158.
We consider expansions with respect to the multi-dimensional Hermite functions which are eigenfunctions of the harmonic oscillator L=−Δ+|x|2. For the heat-diffusion and Poisson semigroups corresponding to a self-adjoint extension of L we investigate their boundary behaviour and mapping properties. All this is done for functions from Lp(w), 1?p<∞, w∈Ap. Then Riesz transforms and conjugate Poisson integrals are considered. The Riesz transforms occur to be Calderón-Zygmund operators hence their mapping properties follow by using results from a general theory. 相似文献
159.
Krzysztof Kołodziejczyk 《Journal of Geometry》2000,68(1-2):155-170
Denote by
n
3
,n 2, the lattice consisting of all pointsx in 3 such thatnx belongs to the fundamental lattice 3 of points with integer coordinates. Letl
n be the subset of
n
3
consisting of all points whose coordinates are odd multiples of 1/n. The purpose of this paper is to give several new Pick-type formulae for the volume of three-dimensional lattice polyhedra, that is, polyhedra with vertices in 3. Our formulae are in terms of numbers of only thel
n-points belonging to a lattice polyhedronP in contrast to already known formulae which employ numbers of all the
n
3
-points inP. On our way to establishing the formulae we show that the number of points froml
n belonging to a three-dimensional lattice polyhedronP has some polynomiality properties similar to those of the well-known Ehrhart polynomial expressing the number of points of
n
3
inP. The paper contains also some comments on a problem of finding a volume formula which would employ only the setsl
n and which would be applicable to lattice polyhedra in arbitrary dimensions.Research partially supported by KBN Grant 2 P03A 008 10. 相似文献
160.
For the semiinfinite Ising model with quenched boundary disorder, we prove concavity inequalities for the difference of wall tensions associated with the minus and plus phases. These inequalities generalize phenomenological equalitiesknown as Cassie's law. 相似文献