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排序方式: 共有78条查询结果,搜索用时 31 毫秒
41.
We study the action of an electric field on a Bingham fluid from the point of view of existence and uniqueness of solutions. We also give an upper bound for the stopping time. 相似文献
42.
We consider a nonlinear homogenization problem for a Ginzburg–Landau functional with a (positive or negative) surface energy term describing a nematic liquid crystal with inclusions. Assuming that sizes and distances between inclusions are of the same order ?, we obtain a limiting functional as . We generalize the method of mesocharacteristics to show that a corresponding homogenized problem for arbitrary, periodic or non-periodic geometries is described by an anisotropic Ginzburg–Landau functional. We give computational formulas for material characteristics of an effective medium. To cite this article: L. Berlyand et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
43.
Doina Dimonie M. Dimonie V. Munteanu H. Iovu J. Couve M. J. Abadie 《Polymer Degradation and Stability》2000,70(3):319-324
A DSC and TGA study of linear polydicyclopentadiene (L-PDCPD) shows that the thermal behaviour of this polymer is characterized by an endothermic and two exothermic processes. In previous work it was demonstrated that the endothermic process is a glass transition and the second exotherm represents the thermo-oxidation of the polymer. In this work the first exothermic process is shown to be a possible thermal polymerization of the double bonds in the polymer chains. 相似文献
44.
Identification and specificity profiling of protein prenyltransferase inhibitors using new fluorescent phosphoisoprenoids 总被引:4,自引:0,他引:4
Dursina B Reents R Delon C Wu Y Kulharia M Thutewohl M Veligodsky A Kalinin A Evstifeev V Ciobanu D Szedlacsek SE Waldmann H Goody RS Alexandrov K 《Journal of the American Chemical Society》2006,128(9):2822-2835
Posttranslational modification of proteins with farnesyl and geranylgeranyl isoprenoids is a widespread phenomenon in eukaryotic organisms. Isoprenylation is conferred by three protein prenyltransferases: farnesyl transferase (FTase), geranylgeranyl transferase type-I (GGTase-I), and Rab geranylgeranyltransferase (RabGGTase). Inhibitors of these enzymes have emerged as promising therapeutic compounds for treatment of cancer, viral and parasite originated diseases, as well as osteoporosis. However, no generic nonradioactive protein prenyltransferase assay has been reported to date, complicating identification of enzyme-specific inhibitors. We have addressed this issue by developing two fluorescent analogues of farnesyl and geranylgeranyl pyrophosphates {3,7-dimethyl-8-(7-nitro-benzo[1,2,5]oxadiazol-4-ylamino)-octa-2,6-diene-1}pyrophosphate (NBD-GPP) and {3,7,11-trimethyl-12-(7-nitro-benzo[1,2,5]oxadiazo-4-ylamino)-dodeca-2,6,10-trien-1} pyrophosphate (NBD-FPP), respectively. We demonstrate that these compounds can serve as efficient lipid donors for prenyltransferases. Using these fluorescent lipids, we have developed two simple (SDS-PAGE and bead-based) in vitro prenylation assays applicable to all prenyltransferases. Using the SDS-PAGE assay, we found that, in contrast to previous reports, the tyrosine phosphatase PRL-3 may possibly be a dual substrate for both FTase and GGTase-I. The on-bead prenylation assay was used to identify prenyltransferase inhibitors that displayed nanomolar affinity for RabGGTase and FTase. Detailed analysis of the two inhibitors revealed a complex inhibition mechanism in which their association with the peptide binding site of the enzyme reduces the enzyme's affinity for lipid and peptide substrates without competing directly with their binding. Finally, we demonstrate that the developed fluorescent isoprenoids can directly and efficiently penetrate into mammalian cells and be incorporated in vivo into small GTPases. 相似文献
45.
Muresan Emil Ioan Lutic Doina Lisa Gabriela Pui Aurel 《Journal of Sol-Gel Science and Technology》2017,81(3):934-944
Journal of Sol-Gel Science and Technology - Porous aluminosilicate macrospheres were prepared by spray gelling technique using chitosan, chitosan and yeast cells and respectively chitosan, yeast... 相似文献
46.
Gina Lupașcu Elena Pahonțu Sergiu Shova Ștefania Felicia Bărbuceanu Diana Carolina Ilieș Mihaela Badea Codruța Paraschivescu Cătălin Ducu Johny Neamțu Mihaela Dinu Robert Viorel Ancuceanu Doina Drăgănescu Cristina Elena Dinu-Pîrvu 《应用有机金属化学》2020,34(11):e5931
A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)imino)methyl) phenol ( HL 1 ) and its complexes [Co(L1)2(H2O)2] ( 1 ), [Cu(L1)2] ( 2 ), [Mn(L1)2(H2O)2] ( 3 ), [Ni(L1)2(H2O)2] ( 4 ), [Pd2(L1)2(OAc)2·1.16H2O] ( 5 ), [Pt(L1)2] ( 6 ) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, 1H-NMR, 13C-NMR, UV–Vis, mass spectroscopies and X-ray powder diffraction (XRD). The molecular structures of ligand HL 1 and two complexes ( 2 and 5 ) were confirmed by X-ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square-planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R-3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells. 相似文献
47.
Maria-Cristina Popescu Cornelia Vasile Daniela Filip Doina Macocinschi Gh. Singurel 《光散射学报》2005,17(3):231-233
pacc:7855K Physicalblendscontainingmacromolecular compoundsandlowmolecularweightliquidcrys tals(LCs)haveimportantapplications.LCsare usedasreinforcementsforamorphouspolymersor indisplaydevices.TheadditionofLCstoamor phouspolymersdeterminesimprovementsin… 相似文献
48.
Abstract The pointwise gradient constrained homogenization process, for Neumann and Dirichlet type problems, is analyzed by means of
the periodic unfolding method recently introduced in [21]. Classically, the proof of the homogenization formula in presence
of pointwise gradient constraints relies on elaborated measure theoretic arguments. The one proposed here is elementary: it
is based on weak convergence arguments in Lp spaces, coupled with suitable regularization techniques.
Keywords: Homogenization, Gradient constrained problems, Periodic unfolding method
Mathematics Subject Classification (2000): 49J45, 35B27, 74Q05 相似文献
49.
Doina Cioranescu João-Paulo Dias 《Journal of Mathematical Analysis and Applications》1980,73(1):252-266
In this paper we prove some results about the existence, uniqueness and regularity of the solutions of a tridimensional variational approximated model for the Leslie's equations of an incompressible nematic liquid crystal (cf. [7]). This model was introduced in [1] where the bidimensional case is studied. Here we use the methods developed in [6], [4] and [8]. 相似文献
50.
Mihaela Homocianu Doina Macocinschi Maria Butnaru 《Journal of Macromolecular Science: Physics》2013,52(4):720-731
In this study the wetting characteristics of untreated and plasma-treated polyurethane thin films were investigated. The degree of wettability was investigated by measuring the contact angle formed between a liquid drop and the solid surface. The work of adhesion, interfacial free energy, spreading coefficient, and Girifalco–Good's interaction parameter changed significantly for plasma-treated polyurethane films. Both complete and partial wetting were analyzed from the spreading coefficient of liquid drops on the solid substrate. 相似文献