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排序方式: 共有117条查询结果,搜索用时 265 毫秒
61.
62.
A. E. Sobel A. Pearl E. Gerchick B. Kramer E. A. Kocsis S. J. Fainberg L. B. Fligelman J. Wierciski V. Lucas A. Steopoe M. P. Babkin und W. T. Tschuiko 《Fresenius' Journal of Analytical Chemistry》1940,119(1-2):59-61
Ohne Zusammenfassung 相似文献
63.
Vena Pearl Bogolan-Walsh Jinqiao Duan Tamay
zgkmen 《Communications in Nonlinear Science & Numerical Simulation》2008,13(8):1627-1641
The impact of boundary noise on the dynamical evolution of the scalar transport equation in shear flows is studied, taking off from earlier studies in shear-flow dispersion in internal waves, a mechanism for horizontal mixing in the ocean. In particular, we model a gravity current evolving under an assumed shear-flow. The transport equation is deterministic, with a noise term at the inlet boundary. This was motivated by observed seasonal fluctuations in some known sources of salty, dense water in the oceans, like the Red Sea overflow, as well as observed thermal and saline anomalies in the thermohaline circulation.The noises used were: Wiener white, Wiener colored, Lévy white, and Lévy colored noise. Lévy processes form a more general class of processes which are generally non-Gaussian in distribution, and may have infinitely many jumps in finite time. They have been used to model pollutant point-sources, the flight time of particles in vortices, and linear and nonlinear anomalous diffusion.The major finding was that white noises (Wiener and Lévy ) and colored Wiener noise all have the effect of impeding the diffusion process, by as much as 33%. However, colored Lévy noise (non-Gaussian, time-correlated) does not have this effect on diffusion. This would suggest that time-correlation is more important in distinguishing noises than the distribution of the process that produced the noise. This also explains why Lévy colored noise showed great sensitivity to the stability parameter α, while Lévy white noise is unaffected by its stability parameter. 相似文献
64.
GSK-3-selective inhibitors derived from Tyrian purple indirubins 总被引:13,自引:0,他引:13
Meijer L Skaltsounis AL Magiatis P Polychronopoulos P Knockaert M Leost M Ryan XP Vonica CA Brivanlou A Dajani R Crovace C Tarricone C Musacchio A Roe SM Pearl L Greengard P 《Chemistry & biology》2003,10(12):1255-1266
Gastropod mollusks have been used for over 2500 years to produce the "Tyrian purple" dye made famous by the Phoenicians. This dye is constituted of mixed bromine-substituted indigo and indirubin isomers. Among these, the new natural product 6-bromoindirubin and its synthetic, cell-permeable derivative, 6-bromoindirubin-3'-oxime (BIO), display remarkable selective inhibition of glycogen synthase kinase-3 (GSK-3). Cocrystal structure of GSK-3beta/BIO and CDK5/p25/indirubin-3'-oxime were resolved, providing a detailed view of indirubins' interactions within the ATP binding pocket of these kinases. BIO but not 1-methyl-BIO, its kinase inactive analog, also inhibited the phosphorylation on Tyr276/216, a GSK-3alpha/beta activation site. BIO but not 1-methyl-BIO reduced beta-catenin phosphorylation on a GSK-3-specific site in cellular models. BIO but not 1-methyl-BIO closely mimicked Wnt signaling in Xenopus embryos. 6-bromoindirubins thus provide a new scaffold for the development of selective and potent pharmacological inhibitors of GSK-3. 相似文献
65.
Mojtaba Haghighi Yazdi Pearl Lee-Sullivan 《Journal of Thermal Analysis and Calorimetry》2009,96(1):7-14
An inherent challenge with polymer blends is the difficulty in resolving the glass transition, T
g, for the smaller mass fraction component. The objective of this work was to determine the practical scanning conditions for
identifying the dual T
g’s for a 75:25 polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blend using a thermomechanical analyzer (TMA). Scanning
rates up to 20°C min−1 using dilatometer and expansion modes were studied. Heating and cooling rates were found to affect both T
g values but the effects were not simple relationships. T
g values could either increase or decrease depending on the scanning rate applied. Higher rates resulted in large thermal lags
which opened the accuracy of measurements to question. Generally, higher rates tended to display only one T
g but the duality of T
g’s can be detected with scanning rates between 0.5 and 5°C min−1 for both modes. 相似文献
66.
67.
D.R. Taikar C.P. Joshi S.V. Moharil P.L. Muthal S.M. Dhopte 《Journal of luminescence》2012,132(5):1112-1115
A modified synthesis of La2BaZnO5 phosphors activated with rare earths Eu3+, Tb3+, Pr3+ and Sm3+, and ns2 ion Bi3+ is reported. RE2BaZnO5 compounds are conventionally prepared by two step solid state reaction. In the first step, carbonates or similar precursors are intimately mixed and heated at 900 °C to decompose the precursors to oxides. To eliminate the unwanted phases like BaRE2O4, the resulting powders are reheated at 1100 °C for long time. We prepared La2BaZnO5 phosphors activated with various activators by replacing the first step by combustion synthesis. Results on photoluminescence are presented. PL results on Eu3+ and Tb3+ are in good agreement with the literature reports. PL emission from Sm3+, Pr3+ and Bi3+ had not been reported earlier. Excitation spectrum of Eu3+ is dominated by a charge transfer band around 318 nm, while for the other rare earths a band at 240 nm is always present. This is attributed to the host absorption. 相似文献
68.
We consider the possibility that the soft supersymmetry-breaking parameters m1/2 and m0 of the MSSM are universal at some scale Min below the supersymmetric grand unification scale MGUT, as might occur in scenarios where either the primordial supersymmetry-breaking mechanism or its communication to the observable sector involve a dynamical scale below MGUT. We analyze the (m1/2,m0) planes of such sub-GUT CMSSM models, noting the dependences of phenomenological, experimental and cosmological constraints on Min. In particular, we find that the coannihilation, focus-point and rapid-annihilation funnel regions of the GUT-scale CMSSM approach and merge when Min∼1012 GeV. We discuss sparticle spectra and the possible sensitivity of LHC measurements to the value of Min. 相似文献
69.
SrZnO2 phosphors have been synthesized by two new methods viz. carbonate decomposition at 1000 °C and combustion synthesis. Phosphors activated with Pb2+, Sm3+, Tb3+, Bi3+ and Pr3+ could be prepared in one step using the combustion synthesis. Characteristic emission and excitation were observed for Bi3+. For the remaining activators excitation spectra always contained a band at 283 nm. Presence of this band for all these different types of activators was interpreted as host sensitization. 相似文献
70.
K Girish Kumar Sareena John Pearl Augustine Remalakshmy Poduval Beena Saraswathyamma 《Analytical sciences》2007,23(3):291-294
A PVC membrane sensor for the selective determination of mebendazole (MBZ) was fabricated. The sensor is based on an ion association of MBZ with silicotungstic acid (STA) as ion pair and bis(2-ethylhexyl)phthalate (BEP) as the plasticizing agent in a PVC matrix. The sensor showed a linear response for MBZ for a concentration range 1.0x10(-6)-5.0x10(-2) M with a Nernstian slope of 55.8 mV/decade (limit of detection 6.3x10(-7) M) in the pH range 4-7. It has a fast response time of <30 s. The sensor showed a very good selectivity for MBZ with respect to a large number of ions. The direct determination of MBZ in pharmaceutical formulations gave results that compare well with the data obtained from the standard method. 相似文献