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排序方式: 共有255条查询结果,搜索用时 31 毫秒
11.
Pavel A. Tikhonov Nataliya G. Vasilenko Marat O. Gallyamov Georgii V. Cherkaev Viktor G. Vasilev Nina V. Demchenko Mikhail I. Buzin Sergey G. Vasilev Aziz M. Muzafarov 《Molecules (Basel, Switzerland)》2021,26(11)
New multiarm stars have been synthesized based on polylithium derivatives of high-generation carbosilane dendrimers. In the synthesis of multiarm stars based on the eighth-generation dendrimer, steric hindrances were observed even during the synthesis of a polylithium initiator. Subsequently, this led to chain transfer reactions between growing arms, as well as other side effects. As a result, dense nanogel formations with a higher tendency of ordering than in classical objects of this type were isolated from the reaction mixture. The study of the rheology of multiarm stars based on sixth-generation dendrimers made it possible to determine the activation energies of viscous flow in these objects, which makes it possible to consider them as objects with a macromolecular nature and a reptation flow mechanism. 相似文献
12.
A. P. Kozachenko O. V. Shablykin A. N. Vasilenko V. S. Brovarets 《Russian Journal of General Chemistry》2010,80(1):127-132
Reactions of accessible 5-alkylamino- and 5-arylamino-1,3-oxazole-4-carbonitriles with hydrazine hydrate on heating involved
a complex transformation sequence resulting in the formation of 3,4,5-triaminopyrazole derivatives. The structure of the products
was confirmed by their cyclocondensation with acetylacetone, leading to 2-alkyl(aryl)amino-3-acylamino-5,7-dimethylpyrazolo[1,5-a]pyrimidines which were identified by NMR spectroscopy using COSY, NOESY, HMQC, and HMBC techniques. 相似文献
13.
A method is proposed to solve the contact problem for laminated anisotropic shells of revolution. The method is based on a two-dimensional model that accounts for transverse shears and reduction. Also the method is based on the method of successive approximations, the generalized pseudo-force method, and a numerical-analytical method of solving boundary-value problems. The results obtained for a cylindrical shell of complex thickness structure are compared with those obtained in three-dimensional formulation__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 5, pp. 68–75, May 2005. 相似文献
14.
15.
Alexei V. Radchenko Sergei V. Kostjuk Irina V. Vasilenko François Ganachaud Fyodor N. Kaputsky Yohann Guillaneuf 《Journal of polymer science. Part A, Polymer chemistry》2008,46(20):6928-6939
A kinetic study of the living cationic polymerization of p‐methoxystyrene using 1‐(4‐methoxyphenyl)ethanol ( 1 )/B(C6F5)3 initiating system in a mixture of CH3CN with CH2Cl2 1:1 (v/v) at room temperature was carried out utilizing a wide variety of conditions. The polymerization proceeded in a living fashion even in the presence of a large amount of water ([H2O]/[B(C6F5)3] ratio up to 20) to afford polymers whose Mn increased in direct proportion to monomer conversion with fairly narrow MWDs (Mw/Mn ≤ 1.3). The investigation revealed that the rate of polymerization was first‐order in B(C6F5)3 concentration, while a negative order in H2O concentration close to ?2 was obtained. It was also found that the rate of polymerization decreased with lowering temperature, which could be attributed to a decreased concentration in free Lewis acid, the true coinitiator of polymerization. A mechanistic scheme to explain the kinetic behavior of living p‐methoxystyrene polymerization is proposed, which has been validated by PREDICI simulation on multiple‐data curves obtained by 1H NMR in situ polymerization experiment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6928–6939, 2008 相似文献
16.
I. V. Vasilenko S. V. Kostjuk K. V. Zaitsev P. M. Nedorezova D. A. Lemenovskii S. S. Karlov 《Polymer Science Series B》2010,52(3-4):136-143
The syndiospecific polymerization of styrene is studied in the presence of titanium complexes with dialkanolamines—bistitanocanes and titanocane—activated by individual MAO or the combined cocatalyst MAO/TIBA. It is shown that these catalysts are more active and stereospecific after their activation with the combined cocatalyst ([TIBA]: [MAO] ≤ 0.13) than that in the case of the activation with MAO: The activities of the catalysts are ≤18 and 9 kg PS/(mol Ti h), and the syndiotacticities of PS are ≤76 and 60%, respectively. Polymers synthesized in the presence of bistitanocanes are characterized by M n ≤ 4.5 × 104 and T m ≤ 268°C and a narrow molecular-mass distribution (≤2.5). 相似文献
17.
Yu. B. Bolkhovityanov A. P. Vasilenko A. K. Gutakovskii A. S. Deryabin M. A. Putyato L. V. Sokolov 《Physics of the Solid State》2011,53(10):2005-2011
Heterostructures of the “strained Ge film/artificial InGaAs layer/GaAs substrate” type have been grown by molecular beam epitaxy.
A specific feature of these structures is that the plastically relaxed (buffer) InGaAs layer has the density of threading
dislocations on a level of 105–106 cm−2. These dislocations penetrate into the strained Ge layer to become sources of both 60° and 90° (edge) misfit dislocations
(MDs). Using the transmission electron microscopy, both MD types have been found at the Ge/InGaAs interface. It has been shown
that the presence of threading dislocations inherited from the buffer layer in a tensile-strained Ge film favors the formation
of edge dislocations at the Ge/InGaAs interface even in the case of small elastic deformations in the strained film. Possible
mechanisms of the formation of edge MDs have been considered, including (i) accidental collision of complementary parallel
60° MDs propagating in the mirror-tilted {111} planes, (ii) induced nucleation of a second 60° MD and its interaction with
the primary 60° MD, and (iii) interaction of two complementary MDs after a cross-slip of one of them. Calculations have demonstrated
that a critical layer thickness (h
c
) for the appearance of edge MDs is considerably smaller than h
c
for 60° MDs. 相似文献
18.
Solomyannyi R. N. Slivchuk S. R. Vasilenko A. N. Rusanov E. B. Brovarets V. S. 《Russian Journal of General Chemistry》2012,82(2):317-322
A method for the synthesis of a new 4-phenylsulfonyl-substituted 3-aminopyrrole was developed and related pyrrolo[3,2-d]pyrimidine derivatives were synthesized. 相似文献
19.
I. V. Vasilenko O. Cador L. Ouahab V. V. Pavlishchuk 《Theoretical and Experimental Chemistry》2010,46(5):322-327
It was shown that the reaction of the trinuclear complex [FeFe2O(CH3CO2)6(H2O)3]·2H2O with thiourea in tetraethylene glycol leads to the formation of nanoparticles of thiospinel Fe3S4, the size of which depends on the reaction conditions. It was established that the formed thiospinel particles exhibit superparamagnetic
characteristics. It was shown that the size of the nanoparticles has an effect on their magnetic characteristics. 相似文献
20.