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排序方式: 共有1269条查询结果,搜索用时 265 毫秒
1.
Jean-Pierre Birat 《钢铁》2004,39(Z1):25-27
连铸技术是钢铁工业的关键技术,将来钢水仍将通过连铸机凝固,连铸技术有很强的适应性. 相似文献
2.
S Arold P Franken MP Strub F Hoh S Benichou R Benarous C Dumas 《Canadian Metallurgical Quarterly》1997,5(10):1361-1372
BACKGROUND: Human immunodeficiency virus (HIV) Nef protein accelerates virulent progression of acquired immunodeficiency syndrome (AIDS) by its interaction with specific cellular proteins involved in signal transduction and host cell activation. Nef has been shown to bind specifically to a subset of the Src family of kinases. The structures of free Nef and Nef bound to Src homology region 3 (SH3) domain are important for the elucidation of how the affinity and specificity for the Src kinase family SH3 domains are achieved, and also for the development of potential drugs and vaccines against AIDS. RESULTS: We have determined the crystal structures of the conserved core of HIV-1 Nef protein alone and in complex with the wild-type SH3 domain of the p59fyn protein tyrosine kinase (Fyn), at 3.0 A resolution. Comparison of the bound and unbound Nef structures revealed that a proline-rich motif (Pro-x-x-Pro), which is implicated in SH3 binding, is partially disordered in the absence of the binding partner; this motif only fully adopts a left-handed polyproline type II helix conformation upon complex formation with the Fyn SH3 domain. In addition, the structures show how an arginine residue (Arg77) of Nef interacts with Asp 100 of the so-called RT loop within the Fyn SH3 domain, and triggers a hydrogen-bond rearrangement which allows the loop to adapt to complement the Nef surface. The Arg96 residue of the Fyn SH3 domain is specifically accommodated in the same hydrophobic pocket of Nef as the isoleucine residue of a previously described Fyn SH3 (Arg96-->lle) mutant that binds to Nef with higher affinity than the wild type. CONCLUSIONS: The three-dimensional structures support evidence that the Nef-Fyn complex forms in vivo and may have a crucial role in the T cell perturbating action of Nef by altering T cell receptor signaling. The structures of bound and unbound Nef reveal that the multivalency of SH3 binding may be achieved by a ligand induced flexibility in the RT loop. The structures suggest possible targets for the design of inhibitors which specifically block Nef-SH3 interactions. 相似文献
3.
4.
Water quality assessment of a recently refilled reservoir: The case of Bütgenbach Reservoir, Belgium
Anna Lourantou Jean-Pierre Thomé Anne Goffart 《Lakes & Reservoirs: Research and Management》2007,12(4):261-274
Bütgenbach Reservoir is situated in the High Ardennes plateau in eastern Belgium (50°25′N; 6°13′E). It is used principally for flood control and for production of hydroelectric energy. It has been subjected to a previous series of studies because of its eutrophication problems and their impacts on the local economy. Bütgenbach Reservoir was emptied during spring 2004 for dam restoration, being refilled in mid‐September of the same year. Selected physicochemical and biological parameters (temperature, dissolved oxygen, pH, inorganic and organic nutrients, chlorophyll‐a) were measured fortnightly during the lake's productive season (mid‐April to mid‐October 2005) at three sampling sites throughout the water column. The water quality conditions after refilling of the lake were compared to previous studies accomplished at the same sampling sites (prior to emptying the lake). The actual trophic status was mesotrophic to eutrophic, based on the combination of total phosphorous and chlorophyll‐a concentrations, as well as water transparency. Bütgenbach Reservoir generally exhibits good water quality, based on the French water quality system SEQ‐eau. A longitudinal decrease in water quality was observed from upstream to downstream, because mainly of the differences in lake bottom morphology and water residence time, and their impacts on nutrient distribution in the lake. 相似文献
5.
Jean-Pierre Mon 《电信纪事》1985,40(11-12):565-571
In order to evaluate the possibility of using frequency diversity to counteract selective effects due to multipath propagation, the signal amplitude behavior has been investigated on a 1 GHz — wide frequency band. The analysis shows a great variability accross the band-width and suggests a possible improvement of the availability of a line of sight link by implementing frequency diversity devices. 相似文献
6.
De Fruyt Filip; Van Leeuwen Karla; Bagby R. Michael; Rolland Jean-Pierre; Rouillon Frédéric 《Canadian Metallurgical Quarterly》2006,18(1):71
Structural, mean- and individual-level, differential, and ipsative personality continuity were examined in 599 patients treated for major depression assigned to 1 of 6 forms of a 6-month pharmaco-psychotherapy program. Covariation among traits from the Five Factor model remained invariant across treatment, and patients described themselves as slightly more extraverted, open to experience, agreeable and conscientious, and substantially more emotional stable after treatment. Trait changes were only to a small extent explained by changes in depression severity. There was evidence for differential, individual-level, and ipsative stability, with stable personality profiles in terms of shape and to a lesser extent in terms of scatter and elevation. Traits remain relatively stable, except for emotional stability, despite the depressive state and the psychopharmacological interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Phase-change thermal energy storage using spherical capsules: performance of a test plant 总被引:1,自引:0,他引:1
J.P Bédécarrats F Strub B Falcon J.P Dumas 《International Journal of Refrigeration》1996,19(3):187-196
The aim of this paper is the study of an industrial process of energy storage usable for air conditioning or refrigeration, investigating a test plant which is a tank with a reduced size, filled with randomly dispersed commercial nodules, placed in a refrigeration loop. The nodules are spherical capsules in which phase change materials (PCM) are encapsulated. This test plant permits the study at length of the behaviour of the tank with, in particular, the charge mode taking into account the undercooling and the discharge mode. A simulation program that considers aspects of both the surrounding heat transfer fluid and the phase-change material packed inside the nodules is developed here in the cases of the charge and the discharge processes. The simulation results are then compared with experimental observations. 相似文献
8.
DG Avode B Bouteille F Houngbe C Adjien C Adjide D Houinato A Hountondjl M Dumas 《Canadian Metallurgical Quarterly》1998,39(1):60-61
Retroperitoneal extravasation is an extremely uncommon complication of duodenal ulcer perforation. The preoperative diagnosis is difficult and may even by missed at operation. There were 25 cases reported in the literature. Only one patient was correctly diagnosed preoperatively and only seven patients survived. We describe the first case of retroperitoneal extravasation from perforated duodenal ulcer presenting as scrotal sepsis. 相似文献
9.
Jean-Pierre Montheard Bernard Boinon Ahmed Belfkira Abderahim Sadel Quang-Tho Pham 《Polymer Bulletin》1992,28(6):615-620
Summary Vinylidene cyanide has been copolymerized in solution by radical reaction with equal initial mole fraction of para substituted acetoxystyrenes. The copolymers have been characterized by means of DSC, TGA and GPC. These products are stable up to 220° and have no visible glass transition temperature. The microstructure of these new copolymers has been studied by 13CNMR; they have an alternating structure and monomers units are arranged in head-to-tail placements. 相似文献
10.
This note considers the problem of local stability of bilinear systems with aperiodic sampled-data linear state feedback control. The sampling intervals are time-varying and upper bounded. It is shown that the feasibility of some linear matrix inequalities (LMIs), implies the local asymptotic stability of the sampled-data system in an ellipsoidal region containing the equilibrium. The method is based on the analysis of contractive invariant sets, and it is inspired by the dissipativity theory. The results are illustrated by means of numerical examples. 相似文献