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排序方式: 共有1349条查询结果,搜索用时 15 毫秒
1.
A. V. Timofeev 《Plasma Physics Reports》2003,29(8):683-687
The conditions under which the energy of the electron Langmuir oscillations can escape from the plasma into vacuum are determined in the simplest model of a plane slab of an inhomogeneous cold magnetized plasma in a uniform magnetic field. 相似文献
2.
A A Timofeev O A Azizova G V Chernysheva 《Biulleten' eksperimental'no? biologii i meditsiny》1985,99(3):301-303
Using the method of spin labels it was shown that in hypercholesterolemia (HCh), the following parameters decreased: the velocity of maleimide spin label binding to sarcoplasmic reticulum (SR) Ca-ATPase of rabbit skeletal muscles, the accessibility of spin-labeled thiol groups of the enzyme to potassium ferricyanide and sodium ascorbate, and the mobility of the Ca-ATPase molecule fragment to which the spin label was attached. In addition, intensification of lipid peroxidation was demonstrated in SR membranes. Supplementation of the high-cholesterol diet with alpha-tocopherol resulted in the decreased rates of lipid peroxidation in SR membranes and increased values of the above parameters relative to the values found under HCh. It is concluded that the effect of alpha-tocopherol in vivo on the structure of the Ca-ATPase proteolipid complex in HCh is due mainly to antioxidant properties of the diet-supplementing substance. 相似文献
3.
A V Martynikhin I V Poliakov A A Timofeev E V Rubakhina 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1985,35(2):232-237
The influence of spatio-temporal factors (spatial heterogeneity of distribution of the numbers sought for in the matrix of data, processes of learning and development of fatigue, periodic attention oscillations) of the character of solving the task of searching the numbers in a matrix of 176 three-figure numbers (16 lines, 11 columns) was studied in 39 operators. The possibility was shown to use the characteristics obtained for evaluation of professionally important abilities of an operator working at the display. 相似文献
4.
A. V. Timofeev 《Plasma Physics Reports》2009,35(11):912-923
A previously developed method for analyzing the plasma processing of spent nuclear fuel is generalized to a plasma containing
multicharged fuel ions. In such a plasma, ion cyclotron resonance heating of nuclear ash ions should be carried out in two
monochromatic RF fields of different frequencies, provided that the fraction of ξ multicharged ions is small, ξ ≤ 0.1, a condition
that substantially restricts the productivity of systems for processing spent nuclear fuel. Ways of overcoming this difficulty
are discussed. 相似文献
5.
I L Kuz'mina A A Timofeev S V Germanov L V Levchenko M A Kulish 《Biulleten' eksperimental'no? biologii i meditsiny》1986,101(2):163-165
The effect of antioxidant--alpha-tocopherol--on Ca2+-transporting system in sarcoplasmic reticulum (SR) of the rabbit skeletal muscles was studied in hypercholesterolemia (HC). alpha-tocopherol administration to animals with HC produced a break on the curve of temperature dependence of Ca-ATPase activity at about 20 degrees C, that disappeared in HC, increased the rate of "rapid" SH-group binding by thiol reagents, and normalized the level of unsaturated fatty acids in SR membranes without altering phospholipid content. It is suggested that the damage of Ca-ATPase in HC is mainly due to activation of lipid peroxidation. 相似文献
6.
7.
Segmental mobility dynamic peculiarities of poly(U), poly(A) and poly(C) synthetic polymers and their complexes were investigated by spin-label method. Imidazolide spin-label was introduced into 2'-oxi-groups of polymer ribose in correlation: one spin-label on 18-20 bases. Formation of complexes was observed by ESR spectra at two pH: 4.2 and 7.2. Segmental mobility of only single strand spin-labelled polymer segment and in the complex was evaluated by measuring rotational correlation time (tau) determined by dependence of distances between outer wide extrema in ESR spectra from solvent viscosity at different temperatures. It turned out that correlation time tau of single strand structures in a high degree depend on pH and temperature. For three strand structures abrupt increase of tau because of appearance of rigidity was observed. It is possible to evaluate part of triple complexes poly(U.A.A) and poly(U.U.A) existing in dynamic equilibrium depending on pH and temperature by the form of outer wide extrema. Adding of dye to complex of poly(U).poly(A) causes an increase of rigidity of the supermolecular structure. Quantitative characteristics of formed complexes were obtained by simulation of ESR spectra on computer. 相似文献
8.
Darja Fer
ej-Temeljotov Matev Kmet Darko Kocjan Sonja Kotnik Aleksander Resman Uro Urleb Katarina Verhnjak Igor Zver Janko
mitek 《Chirality》1993,5(4):288-292
Structure–interaction relationships, stereoselectivity, and solubility enhancement in inclusion compexation of β-cyclodextrins (CDs) with some racemic and enantiomerically pure 1,4-dihydropyridine derivatives (DHPs) were investigated. 1:1 and 1:2 (mole ratio) complexes were prepared and characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), MS-FAB spectrometry, 1H-NMR spectroscopy, water and phase solubility. The solubility studies have revealed different complexation equilibria for optically pure DHP enantiomers, and corresponding racemic mixtures in water solutions. By means of 1H-NMR chemical shift measurements, the inclusion of aromatic fragments of racemic and enantiomerically pure DHP molecules within the cavities of different CDs was elucidated. Considerable stereoselectivity in complexation interactions was observed. The results indicate the potential use of cyclodextrins as chiral selectors for enantiomeric resolution of 1,4-DHP calcium antagonists. © 1993 Wiley-Liss, Inc. 相似文献
9.
Katarina Jansson Gunnar Kratz Anders Haegerstrand 《In vitro cellular & developmental biology. Animal》1996,32(9):534-540
Summary Reepithelialization of artificial partial thickness wounds made in biopsies of human skin was determined after 3, 5, or 7
d of incubation, submerged or elevated to the air-liquid interface. The biopsies were reepithelialized within 5–7 d, with
a more complete epidermal healing in wounds exposed to air. Both types of wounds showed similar time-course in deposition
of basement membrane components, as detected by immunofluorescence labeling. Laminin and collagen type VII were deposited
underneath the migrating tips, whereas collagen type IV was detected after reepithelialization. Markers of terminal differentiation
showed a pattern close to normal in the air-liquid incubated wounds after reepithelialization. Involucrin was detected in
the suprabasal regions of the migrating epidermis and thereafter in the upper half of neo-epidermis in the air-liquid incubated
wound. Filaggrin could not be detected in the submerged wounds at any time during healing, whereas wounds exposed to air showed
a well-differentiated epidermis by Day 7. Tritiated thymidine-incorporation indicated proliferation of epidermal and dermal
cells during reepithelialization and a maintained viability, as shown by cultivation of endothelial- and fibroblast-like cells
obtained from the dermis 7 d after wounding.
Reepithelialization in this humanin vitro model is supported by a matrix close to normal with the possibility of extracellular influences and cell-cell interactions
and, in addition, the technique is simple and reproducible. Therefore, we suggest this model for studies of regeneration in
culture and as a complement toin vivo studies on epidermal healing. 相似文献
10.
Janet Katarina Nordqvist Christopher Tilmann Robin Lovell-Badge Blanche Capel 《Current biology : CB》1997,7(12)
Background: The gene Sry acts as a developmental switch, initiating a pathway of gene activity that leads to the differentiation of testis rather than ovary from the indifferent gonad (genital ridge) in mammalian embryos. The early events following Sry expression include rapid changes in the topographical organization of cells in the XY gonad. To investigate the contribution of mesonephric cells to this process, gonads from wild-type mice (CD1), and mesonephroi from a transgenic strain ubiquitously expressing β-galactosidase (ROSA26), were grafted together in vitro. After culture, organs were fixed and stained for β-galactosidase activity to identify cells contributed from the mesonephros to the male or female gonad.Results: Migration of mesonephric cells occurred into XY but not XX gonads from 11.5–16.5 days post coitum (dpc). Somatic cells contributed from the mesonephros were distinguished by their histological location and by available cell-specific markers. Some of the migrating cells were endothelial; a second population occupied positions circumscribing areas of condensing Sertoli cells; and a third population lay in close apposition to endothelial cells.Conclusions: Migration from the mesonephros to the gonad is male specific at this stage of development and depends on an active signal that requires the presence of a Y chromosome in the gonad. The signals that trigger migration operate over considerable distances and behave as chemoattractants. We suggest that migration of cells into the bipotential gonad may have a critical role in initiating the divergence of development towards the testis pathway. 相似文献