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121.
Inna P. Tsypysheva Alexander N. Lobov Alena V. Kovalskaya Polina R. Petrova Sergey P. Ivanov Shamil A. Rameev 《Natural product research》2015,29(2):141-148
The first example of aza-Michael reaction of 12-N-carboxamide of quinolizidine alkaloid (–)-cytisine with α,β-unsaturated ketones, dimethyl acetylenedicarboxylate and β-nitrostyrene under high pressure condition has been described. It has been shown that the [4+2]-cycloaddition takes place in the case with N-phenylmaleimide. 相似文献
122.
Sergey A. Chesnokov Marya Yu. Zakharina Alexander S. Shaplov Elena I. Lozinskaya Inna A. Malyshkina Gleb A. Abakumov Frederic Vidal Yakov S. Vygodskii 《Journal of polymer science. Part A, Polymer chemistry》2010,48(11):2388-2409
The photo‐initiated polymerization of poly(ethylene glycol)dimethacrylates [PEGDM(n)] in the presence of various ionic liquids (ILs) is reported. The influence of ILs concentrations as well as of their nature upon the photopolymerization kinetics was studied in detail. It was found that according to reactive ability in bulk and in solution photopolymerization, the investigated monomers can be divided into two groups: PEGDM(1)–PEGDM(2)–PEGDM(3) and PEGDM(4)–PEGDM(7‐8). ILs slightly influence the photopolymerization of monomers from the first group and greatly change kinetics of those from the second. Such behavior was explained by the theory of “kinetically favorable or unfavorable monomer associations.” It was demonstrated that certain ILs accelerate the photopolymerization of the highest PEGDMs and offer access to the polymers derived from low reactive monomers. Relying on the obtained data, the attempt to predict the structure of the “best” ionic additive for the given monomer photopolymerization was performed and proved. Finally, the influence of both residual and specially added ILs quantities upon the properties of obtained polymer materials was investigated. It was revealed that ILs can physically interact with polymer networks increasing their thermal stability, plasticizing films, and blocks, imparting ionic conductivity equal up to 3.62 × 10?3 Sm/cm at 25 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2388–2409, 2010 相似文献
123.
Edelman I 《The Journal of the Acoustical Society of America》2003,114(1):90-97
The propagation of the Biot slow wave in a fluid-saturated porous medium at low frequencies is investigated by asymptotic methods. It is proven that the Biot wave has a bifurcation behavior depending on its wave number. The bifurcation occurs in a neighborhood of the critical value k(cr), which depends on the permeability of a medium and the viscosity of a fluid. The P2 wave is fully attenuated if its wave number is smaller than k(cr) and it becomes propagatory with wave numbers bigger than k(cr). Asymptotic formulas for the phase velocity and attenuation of the Biot wave are derived. 相似文献
124.
A. V. Abramova E. V. Slivinskii Yu. Ya. Goldfarb A. A. Panin E. A. Kulikova G. A. Kliger 《Kinetics and Catalysis》2005,46(5):758-769
The role of various technologies in oil refining and petrochemistry changes due to amendments to the requirements for fuel quality. The development of these technologies requires the improvement of catalysts. This paper outlines main procedures for the production of dealuminated zeolites, as well as the advantages and drawbacks of these procedures. Catalysts with a high desulfurizing ability for the hydrocracking of vacuum gas-oil to gasoline and diesel fractions and catalysts for the isomerization of fuel hydrocarbons can be prepared using ultrastable Y-type zeolites. The results of testing of zeolite-containing binary catalytic systems in Fischer-Tropsch synthesis are presented. 相似文献
125.
M. M. Solov’ev B. S. Turov M. E. Solov’ev T. E. Abramova N. S. Mineeva 《Polymer Science Series B》2007,49(5-6):123-127
The influence of the type of crosslinks and oligomer microstructure on the local mobility of crosslinked epoxidized 1,4-oligobutadienes was studied by molecular dynamics simulation. Distribution histograms and time autocorrelation functions of distances between oxygen and carbon atoms from different chains were examined. The chain microstructure has a substantial effect on all types of molecular motion. After crosslinking via double bonds, crosslinked oligomer molecules with the trans configuration of the double bonds turn out to be more flexible than their cis counterparts. 相似文献
126.
Yatluk Yu. G. Chernyak S. V. Suvorov A. L. Khrustaleva E. A. Abramova V. I. 《Russian Journal of General Chemistry》2001,71(6):965-967
Chelates of titanium, zirconium, and hafnium with -dicarbonyl compounds react with butyl, amyl, and octyl alcohols to give metal alkoxides. The reaction is accompanied by retro-Claisen cleavage of the ligand. The reactivity of the chelates was studied in relation to the ligand structure, nature of the metal, and reaction temperature. The reaction mechanism is discussed. 相似文献
127.
Nikolaus Kocher Carola Selinka Dirk Leusser Daniel Kost Inna Kalikhman Dietmar Stalke 《无机化学与普通化学杂志》2004,630(12):1777-1793
The homologous series of parent octamethylcyclotetrasilazane (c‐NH‐SiMe2‐)4, ( 1 ), the lithium complex [(THF)2Li2(c‐N‐SiMe2‐NH‐SiMe2‐)2]2, ( 2 ), containing the cyclic dianion, and [(THF)2LiAl(c‐N‐SiMe2‐)4]2, ( 3 ), accommodating the unprecedented tetraanion [Me2SiN]4‐ was synthesized to investigate the nature of the covalent Si‐N single bond in the presence of various metals. These model compounds show a wide diversity of Si‐N(H), Si‐N(M), Si‐N(H, M) and M‐N bonds and serve as bench‐mark systems to study polar bonds by high‐resolution low‐temperature X‐ray structure analysis. Experimental charge density studies reveal highly polar Si‐N bonds with remarkable ionic contribution, even in the non‐metallated starting material 1 . The Li‐N and Li‐O bonds have to be classified as almost purely ionic bonds with topological properties not far from those determined for NaCl. 相似文献
128.
L. I. Fridman A. L. Suvorov E. A. Khrustaleva M. I. Kodess V. I. Abramova 《Russian Chemical Bulletin》1987,36(4):813-816
Conclusions Linear polydialkylsiloxanes undergo cleavage upon heating with alkyl orthotitanates containing primary and secondary alkyl radicals, and the reactions are independent of the structure of radicals attached to the Si atoms, molecular weight, and the nature of the end groups. The factor which seems to determine the reactivity of polydialkysiloxanes with respect to cleavage at room temperature is the presence of CH end groups. The rate and degree of conversion in these reactions is decreased by increasing steric hindrance at the Si or Ti atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 886–890, April, 1987. 相似文献
129.
This paper proposes a linear constrained model predictive control (MPC) to solve the path following problem for quadrotor unmanned aerial vehicles. In the controller, an augmented model is employed to completely eliminate the tracking error due to external disturbances imposed on the quadrotor. The proposed controller is capable of improving the trade-off between feasibility and performance of the system. By approximating the control input sequence in MPC with Laguerre function, the computational burden significantly decreases and the closed-loop performance improves. In addition, a prescribed stability procedure is applied to guarantee the asymptotic stability of the quadrotor error dynamics. Besides, the proposed method improves the numerical ill-conditioning problem in solving MPC, by modifying the position of the closed-loop system poles to lie inside the unit circle. In the simulation results, two scenarios for the quadrotor tracking problem are considered. The results demonstrate the capability and the effectiveness of the proposed control strategy in disturbance rejection, fast trajectory tracking and the quadrotor stability, while a desired performance is achieved. 相似文献
130.
N. A. Pavlycheva N. Sh. Lebedeva A. I. V’yugin V. E. Maizlish G. P. Shaposhnikov S. A. Znoiko I. G. Abramov M. B. Abramova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(11):1847-1850
The interaction of benzotriazolyl derivatives of phthalodinitriles with copper(II) acetate was studied thermogravimetrically and spectroscopically. Electron acceptor properties of peripheral substituents had a predominant influence on the enthalpy parameter of formation of copper(II)phthalocyanines. 相似文献