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91.
一维双极粘滞量子流体力学模型解的存在性 总被引:1,自引:0,他引:1
研究了一类一维稳态双极半导体方程的粘滞量子流体力学模型.该模型包含关于粒子浓度和电流密度的连续方程以及电势Poisson方程的耦合方程组,其中含有三阶量子修正项和二阶粘滞项.该问题在有界区间(0,1)中讨论,并通过边界条件的假设将原方程组变形为常见的形式,得到原问题的等价问题.用截断方法将等价问题正则化,并得到正则化问题解的先验估计.利用Leray-Schauder不动点定理证明正则化问题解的存在性,最后通过L∞估计证明正则化问题的解即为原问题的解,从而证明了原双极粘滞量子流体力学模型存在稳态解. 相似文献
92.
Zhang F.Wu Q.Zeng G. 《复杂系统与复杂性科学》2017,(1):81-87
We consider an SIRS epidemic model with a general direct immunization rate on networks. By constructing suitable Lyapunov functions, we find that the dynamical behvaior of the model is completely determined by the epidemic threshold λc. When λ≤λc, the disease-free equilibrium is globally asymptotically stable; when λ>λc, the endemic equilibrium is globally asymptotically stable. In addition, we propose a uniform direct immunization and a targeted direct immunization. The results show that under the same average immunization rate s there exists a critical immunization-lost rate δc so that the epidemic threshold of the targeted direct immunization is smaller (larger) than that of the uniform direct immunization if δ<δc(δ>δc). © 2017, The Journal of Agency of Complex Systems and Complexity Science. All right reserved. 相似文献
93.
Large intergenic non-coding RNA-RoR modulates reprogramming of human induced pluripotent stem cells 总被引:1,自引:0,他引:1
94.
Pan Q Qiao F Gao C Norman B Optican L Zelenka PS 《Cellular and molecular life sciences : CMLS》2011,68(20):3425-3436
The non-receptor tyrosine kinase Src is a critical regulator of cytoskeletal contraction, cell adhesion, and migration. In
normal cells, Src activity is stringently controlled by Csk-dependent phosphorylation of Src(Y530), and by Cullin-5-dependent
ubiquitinylation, which affects active Src(pY419) exclusively, leading to its degradation by the proteosome. Previous work
has shown that Src activity is also limited by Cdk5, a proline-directed kinase, which has been shown to phosphorylate Src(S75).
Here we show that this phosphorylation promotes the ubiquitin-dependent degradation of Src, thus restricting the availability
of active Src. We demonstrate that Src(S75) phosphorylation occurs in vivo in epithelial cells, and like ubiquitinylation,
is associated only with active Src. Preventing Cdk5-dependent phosphorylation of Src(S75), by site-specific mutation of S75
or by Cdk5 inhibition or suppression, increases Src(Y419) phosphorylation and kinase activity, resulting in Src-dependent
cytoskeletal changes. In transfected cells, ubiquitinylation of Src(S75A) is about 35% that of wild-type Src-V5, and its half-life
is approximately 2.5-fold greater. Cdk5 suppression leads to a comparable decrease in the ubiquitinylation of endogenous Src
and a similar increase in Src stability. Together, these findings demonstrate that Cdk5-dependent phosphorylation of Src(S75)
is a physiologically significant mechanism of regulating intracellular Src activity. 相似文献
95.
F.A.Zhang L.Chen J.Q.Ma X.Yang 《复旦学报(自然科学版)》2007,46(5)
1 Results Nanocomposite has attracted more and more interest all over the world.Polystyrene (PS) is a commercialized and mass-productive polymer,continuous research efforts have been devoted to the development of polystyrene/montmorillonite (PS/MMT) nanocomposites[1-2].But the polarity of styrene (St) is too small to intercalate the space between the clay layers.The polarity of hydrophilic monomer is so strong that it can intercalate the MMT easily,the intercalated smectic clays maybe exfoliated by usin... 相似文献
96.
Q.Xia Y.P.Wu 《复旦学报(自然科学版)》2007,46(5)
1 Results In order to overcome the inherent incompatibility of PC with graphite in the lithium ion battery system, improve their electrochemical performance at low temperature,phenyl tris-2-methoxydiethoxy silane (PTMS) has been studied as an additive to the PC-based electrolyte of lithium ion batteries with graphite anode. From the cyclic voltammogram for the graphite anode in the PC-based electrolyte,we find that in the case of the electrolyte without the additive,there is a large irreversible peak ne... 相似文献
97.
Lei Jiang ChunFang Cai YongDong Zhang ShengYi Mao YongGe Sun KaiKai Li Lei Xiang ChunMing Zhang 《科学通报(英文版)》2012,57(11):1311-1319
U-bearing sandstones from the Dongsheng deposit in Ordos Basin contain abundant C15-C18 fatty acids. The fatty acids may have been derived from modern and ancient organisms including organisms from the intervals of U mineralization. A certain amount of i15:0, a15:0, a17:0 fatty acids coexist with small amounts of i17:1ω7c and 10me16:0, characteristic biomarkers of Desulfovibrio and Desulfobacter sp., respectively. This indicates the existence of sulfate-reducing bacteria (SRB) in the sandstones. The presence of sulfur-oxidizing bacteria (SOB), such as Beggiatoa and Thioploca, is indicated by significant amounts of 16:1ω7c and 18:1ω7c fatty acids. The existence of the SRB in the deposit, as inferred from the fatty acids, is consistent with results from fossilized microorganisms and isotopic compositions of ore-stage pyrite. This suggests that the environment may have been favorable for the SRB to grow since ore formation (9.8-22 Ma). The bacteria may have degraded hydrocarbons directly, or indirectly utilized hydrocarbons degraded by oxic microbes in the deposits. This process may have produced 12C-rich calcite and prominent baseline humps of unresolved complex mixtures (UCM), and 25-demethylated hopanes and tricyclic terpanes. The existence of sulfur-oxidizing bacteria and sulfate-reducing bacteria in the deposit may have resulted in bacterial sulfate reduction to sulfide, re-oxidization of the sulfide to sulfate and subsequent reduction of the sulfate to sulfide. This assertion is supported by ore-stage pyrite with δ34S values as low as-39.2‰, and the lightest sulfate (about 11‰) measured during the Phanerozoic, a difference of more than 46‰. 相似文献
98.
文章论述了掘进机电气系统所采用的控制方式以及保护方式,结合掘进机电气系统原理,提出电气系统故障点分布,进行分析,使维修人员能够快捷地判断和处理故障。 相似文献
99.
Mao Jinliang 《科学之友》2012,(15)
文章介绍了人机界面的性能、参数,并分析了其在掘进机中的应用和在提高电气系统性能上的重要作用. 相似文献
100.
In this paper, CdS quantum dots sensitized TiO2 composite powders (QD-CdS/TiO2) were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern (XRD) shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD- CdS/TiO2 powder samples; the crystal size of CdS in QD- CdS/TiO2 is about 3-7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1∶2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B (RhB) is up to 92.2% within 60 min. 相似文献