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排序方式: 共有537条查询结果,搜索用时 31 毫秒
41.
A. I. Zaitsev N. E. Zaitseva Yu. P. Alekseeva E. M. Kuril'chenko S. F. Dunaev 《Inorganic Materials》2003,39(8):816-825
The vapor composition over and thermodynamic properties of Cu–Zr melts (5.1–85.0 at. % Zr) are studied by Knudsen cell mass spectrometry between 1191 and 1823 K. The data set obtained comprises more than 1100 activity values for various compositions and temperatures. The thermodynamic behavior of Cu–Zr melts is described in terms of the associated-solution approach with an accuracy no worse than the experimental accuracy. The melts are shown to contain two molecular species: CuZr and Cu2Zr. The contributions of different types of chemical bonding to the Gibbs energy and enthalpy of formation of Cu–Zr melts are asymmetrical and shifted from the equiatomic composition in opposite directions: the extremum of covalent bonding is shifted to the Cu-rich side, while metallic bonding is more significant in Zr-rich alloys. The rapid temperature variation of covalent bonding leads to a large excess heat capacity C
p
E of the melts and a negative excess entropy f
S
E, which rapidly drops with decreasing temperature. It is shown that not only C
p
E and f
S
E but also their temperature variations are governed by the parameters of association reactions and depend more strongly on the entropy than on the enthalpy of complex formation. This indicates that, in the general case, the glass-forming capabilities of melts are independent of the interparticle interaction and accounts for the pronounced tendency of Cu–Zr melts toward amorphization. 相似文献
42.
Meshcheriakova VA Plotnikova OA Sharafetdinov KhKh Alekseeva RI Mal'tsev GIu Kulakova SN 《Voprosy pitaniia》2001,70(2):28-31
It was investigated the influence of a diet supplemented with polyunsaturated fatty acids (PUFA) omega-3 on dynamic of basal glycaemia, lipid profile and composition of fatty acids of erythrocytes in type 2 diabetic patients. Traditional 9 diet was supplemented with fish ("Eiconol", 8 grams per day) or vegetable (linseed oil, 17.5 grams per day) PUFA omega-3. The results investigations indicated that a omega-3 PUFA-enriched diet has a beneficial effects on lipid metabolism. But dietary administration of PUFA omega-3 may be used differently for correction of dislipoproteinemia in diabetic patients. 相似文献
43.
44.
We conducted a meta-analysis of age differences in predecisional information search (N = 1,304) that suggests that aging is associated with a small but significant decrease in predecisional information search (Hedges's g = –0.30). In addition, we investigated the consequences of limited information search for decision quality in real-world consumer environments using simulation methods. Overall, the results suggest that the aging decision maker can afford to neglect information because this leads to small losses in decision quality. In other words, less may be enough for the aging consumer. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
I. P. Alekseeva O. V. Atonen V. V. Golubkov A. A. Onushchenko 《Glass Physics and Chemistry》2007,33(6):527-534
The specific features in the structure of nanostructured glass-ceramic materials based on sodium zinc silicate glasses doped with lead sulfide are investigated using small-angle X-ray scattering and X-ray powder diffraction. It is established that a close-to-monodisperse size distribution of PbS nanocrystals is an important structural feature of the system under investigation. An analysis of the X-ray powder diffraction data demonstrates that the shape of the lead sulfide nanocrystals precipitated depends on the heat treatment conditions and can differ from a spherical shape. 相似文献
46.
Yuri S. Lipatov Tatiana T. Alekseeva Lyubov A. Sorochinskaya Galina V. Dudarenko 《Polymer Bulletin》2008,59(6):739-747
Summary Peculiarities of formation kinetics of sequential semi-interpenetrating polymer networks based on crosslinked polyurethane
with different cross-linking density and linear polystyrene and polybutylmethacrylate have been studied. Polyurethane networks
were synthesized differing in molecular mass Mc of the chains between cross-links. Monomeric styrene and butyl methacrylate were introduced into these networks by swelling
them in monomers up to equilibrium. The kinetics of polymerization of monomers in swollen networks was investigated. The experimental
data show the dependence of the kinetic parameters of polymerization on Mc, this dependence being different for various monomers. Sharp discrepancy in molecular mass distribution of polymers formed
in various matrices has been observed. The differences in dependencies of reaction kinetics and molecular mass distribution
are supposed to be connected to various dependence of the chain growth and termination of various monomers on the density
of network, i.e. on the confinements imposed by the intranetwork space. 相似文献
47.
48.
Larisa I. Privalova Boris A. Katsnelson Nadezhda V. Loginova Vladimir B. Gurvich Vladimir Y. Shur Yakov B. Beikin Marina P. Sutunkova Ilzira A. Minigalieva Ekaterina V. Shishkina Svetlana V. Pichugova Ludmila G. Tulakina Svetlana V. Beljayeva 《International journal of molecular sciences》2014,15(11):21538-21553
We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity. 相似文献
49.
50.
Muhammad G. Dastgir Ludmila G. Peeva Andrew G. Livingston 《Chemical engineering science》2005,60(24):7034-7044
This study investigates the possibility of using a composite-supported polymeric liquid membrane (CSPLM) configuration for the Membrane Aromatic Recovery System (MARS). The membrane was prepared by impregnating the liquid membrane phase into the pores of a composite flat sheet membrane consisting of a microporous support and a thin non-porous layer. A polyvinylidenfluoride (PVDF) microporous support coated with a thin non-porous polydimethylsiloxane (PDMS) layer was chosen as a composite membrane due to its superior combination of mass transfer rates and chemical resistance among the membranes tested and polypropylene glycol (PPG) was used as a liquid membrane phase due to its high affinity for phenol. The resulting membrane showed uniform selectivity and operational stability under the continuous MARS operating conditions for more than two months. The mass transfer rates () were 5 times higher than those of the silicone rubber tubing () which is used in commercial scale MARS technology. The CSPLM also exhibited reduced water flux and low sodium ion transfer. The partition coefficient of phenol between PPG/water was measured as 84. A marked effect of ionic strength on partition coefficient of phenol was observed with partition coefficient increase to 134 when measured in the presence of 20 wt% KCl in phenol aqueous solution. 相似文献