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排序方式: 共有209条查询结果,搜索用时 15 毫秒
21.
Semion I. Kuchanov Konstantin V. Tarasevich Timur V. Zharnikov 《Journal of statistical physics》2006,122(5):875-908
The statistical theory of gelation in the simplest process of the non-random polycondensation (S. I. Kuchanov, T. V. Zharnikov,
J. Stat. Phys., 111(5/6), 1273 (2003)) has been refined as to be able to take into account the effect of a monomer configuration
on topological characteristics of the polymer network of the gel. Proceeding from the kinetic analysis of such a polycondensation,
we rigorously prove that it can be described in terms of some stochastic branching process. The parameters of the process
depend on the overall number of functional groups in the monomer as well as on the pattern of their mutual arrangement. Examples
of some model systems illustrate the effect of kinetic and configurational factors on the topology of a polymer network formed
in the course of non-random polycondensation. 相似文献
22.
Igor Rodin Timur Baygildiev Andrey Stavrianidi Arcady Braun Igor Rybalchenko Oleg Shpigun 《Chromatographia》2015,78(7-8):585-591
23.
Galeev TR Romanescu C Li WL Wang LS Boldyrev AI 《The Journal of chemical physics》2011,135(10):104301
The structures and the electronic properties of two aluminum-doped boron clusters, AlB(7)(-) and AlB(8)(-), were investigated using photoelectron spectroscopy and ab initio calculations. The photoelectron spectra of AlB(7)(-) and AlB(8)(-) are both broad, suggesting significant geometry changes between the ground states of the anions and the neutrals. Unbiased global minimum searches were carried out and the calculated vertical electron detachment energies were used to compare with the experimental data. We found that the Al atom does not simply replace a B atom in the parent B(8)(-) and B(9)(-) planar clusters in AlB(7)(-) and AlB(8)(-). Instead, the global minima of the two doped-clusters are of umbrella shapes, featuring an Al atom interacting ionically with a hexagonal and heptagonal pyramidal B(7) (C(6v)) and B(8) (C(7v)) fragment, respectively. These unique umbrella-type structures are understood on the basis of the special stability of the quasi-planar B(7)(3-) and planar B(8)(2-) molecular wheels derived from double aromaticity. 相似文献
24.
Imre Miklós Szilágyi Eero Santala Mikko Heikkilä Marianna Kemell Timur Nikitin Leonid Khriachtchev Markku Räsänen Mikko Ritala Markku Leskelä 《Journal of Thermal Analysis and Calorimetry》2011,105(1):73-81
This article demonstrates how important it is to find the optimal heating conditions when electrospun organic/inorganic composite
fibers are annealed to get ceramic nanofibers in appropriate quality (crystal structure, composition, and morphology) and
to avoid their disintegration. Polyvinylpyrrolidone [PVP, (C6H9NO)
n
] and ammonium metatungstate [AMT, (NH4)6[H2W12O40]·nH2O] nanofibers were prepared by electrospinning aqueous solutions of PVP and AMT. The as-spun fibers and their annealing were
characterized by TG/DTA-MS, XRD, SEM, Raman, and FTIR measurements. The 400–600 nm thick and tens of micrometer long PVP/AMT
fibers decomposed thermally in air in four steps, and pure monoclinic WO3 nanofibers formed between 500 and 600 °C. When a too high heating rate and heating temperature (10 °C min−1, 600 °C) were used, the WO3 nanofibers completely disintegrated. At lower heating rate but too high temperature (1 °C min−1, 600 °C), the fibers broke into rods. If the heating rate was adequate, but the annealing temperature was too low (1 °C min−1, 500 °C), the nanofiber morphology was excellent, but the sample was less crystalline. When the optimal heating rate and
temperature (1 °C min−1, 550 °C) were applied, WO3 nanofibers with excellent morphology (250 nm thick and tens of micrometer long nanofibers, which consisted of 20–80 nm particles)
and crystallinity (monoclinic WO3) were obtained. The FTIR and Raman measurements confirmed that with these heating parameters the organic matter was effectively
removed from the nanofibers and monoclinic WO3 was present in a highly crystalline and ordered form. 相似文献
25.
Sawyer BC Stuhl BK Yeo M Tscherbul TV Hummon MT Xia Y Kłos J Patterson D Doyle JM Ye J 《Physical chemistry chemical physics : PCCP》2011,13(42):19059-19066
Cold molecules promise to reveal a rich set of novel collision dynamics in the low-energy regime. By combining for the first time the techniques of Stark deceleration, magnetic trapping, and cryogenic buffer gas cooling, we present the first experimental observation of cold collisions between two different species of state-selected neutral polar molecules. This has enabled an absolute measurement of the total trap loss cross sections between OH and ND(3) at a mean collision energy of 3.6 cm(-1) (5 K). Due to the dipolar interaction, the total cross section increases upon application of an external polarizing electric field. Cross sections computed from ab initio potential energy surfaces are in agreement with the measured value at zero external electric field. The theory presented here represents the first such analysis of collisions between a (2)Π radical and a closed-shell polyatomic molecule. 相似文献
26.
Tutueva Aleksandra V. Karimov Timur I. Moysis Lazaros Nepomuceno Erivelton G. Volos Christos Butusov Denis N. 《Nonlinear dynamics》2021,104(1):727-737
Nonlinear Dynamics - One of the widely-used ways in chaos-based cryptography to generate pseudo-random sequences is to use the least significant bits or digits of finite-precision numbers defined... 相似文献
27.
Nazym K. Korbozova Nataliya O. Kudrina Nataliya A. Zhukova Alexander E. Grazhdannikov Irina V. Blavachinskaya Gulnaz A. Seitimova Timur E. Kulmanov Tatyana G. Tolstikova Nina V. Terletskaya 《Molecules (Basel, Switzerland)》2022,27(21)
In terms of prevalence, thyroid pathology, associated both with a violation of the gland function and changes in its structure, occupies one of the main places in clinical endocrinology. The problem of developing low-toxic and highly effective herbal preparations for the correction of thyroid hypofunction and its complications is urgent. Salidroside is a glucoside of tyrosol, found mostly in the roots of Rhodiola spp., and has various positive biological activities. The purpose of this study was to study the antihypothyroid potential of salidrosid-containing extract from R. semenovii roots, which was evaluated on a mercazolyl hypothyroidism model. We showed that extract containing salidroside is a safe and effective means of hypothyroidism correction, significantly reducing (p ≤ 0.001) the level of thyroid-stimulating hormone and increasing the level of thyroid hormones. The combined use of R. semenovii extract with potassium iodide enhances the therapeutic effect of the extract by 1.3-times. 相似文献
28.
We prove that a C
*-algebra A or a predual N
* of a von Neumann algebra N has the Daugavet property if and only if A (or N) is non-atomic. We also prove a similar (although somewhat weaker) result for non-commutative L
p-spaces corresponding to non-atomic von Neumann algebras. 相似文献
29.
Timur Oikhberg 《Archiv der Mathematik》2006,86(4):356-364
We construct a “universal space” for 1-exact finite dimensional operator spaces (an analogue of the Gurarii space).
Received: 20 June 2005 相似文献
30.