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151.
将二维人工脑模型推广到三维,并给出了一个实际应用算例,还将二、三维模型的计算结果进行了对比,发现三维模型的计算效果明显优于二维模型。  相似文献   
152.
The preparation of Ni–SiC coatings using magnetic field-assisted jet electrodeposition under various plating settings is described in this study. A RBF-BP composite neural network with 4 × 4 × 4 × 7 × 10 × 1 was used to predict the corrosion resistance of Ni–SiC coatings prepared by employing different plating parameters. The results show that the fitting degree between the expected value and the actual value of the RBF-BP composite neural network is 0.97497. Moreover, the hybrid neural network can accurately predict the corrosion resistance of Ni–SiC coatings prepared under different process parameters. The corrosion weight loss of the coating is the lowest at the current density of 4 A/dm2, a jet rate of 3 m/s, a SiC particle concentration of 8 g/L, and at a magnetic field intensity of 0.8 T, demonstrating its corrosion resistance under these conditions. According to the coating characterization analysis, the coating's grain size was significantly refined, and the surface was smoother with a high amount of uniformly sized SiC nanoparticles.  相似文献   
153.
Poly[(R)-3-hydroxybutyrate] (PHB) was blended with an aliphatic copolyester, which was synthesized by the esterification of adipic acid, ethylene glycol, and lactic acid. The blend showed a single Tg, which varied systematically but convexly upwards with the composition. The growth rate of PHB spherulites, the crystallization temperature, and the equilibrium melting temperature of the blend were decreased as the amount of the copolyester was increased. Therefore, the blend system was determined to be compatible. However, the degree of crystallinity, and the enthalpies of crystallization and fusion of PHB in the blend remained almost constant, regardless of the compositional change, although the crystallization rate was decreased upon blending. No chemical change such as transesterification was observed as a result of the blending, yet there was a slight change in the crystalline morphology of PHB. The rate of fungal degradation was lowered with an increase in the copolyester content of the blend. © 1996 John Wiley & Sons, Inc.  相似文献   
154.
This study examined the pharmacokinetic disposition, oral absorption and hepatic extraction of itraconazole and its active metabolite, hydroxyitraconazole, in rats. After i.v. injection, serum itraconazole concentrations decreased biexponentially, with an average terminal elimination half-life, volume of distribution and systemic clearance of 4.9 h, 6.0 l/kg and 14.2 ml/min/kg, respectively. When given orally, its absorption was low, with a mean absolute bioavailability of 16.6%. The metabolite to parent drug area under the curve (AUC) ratio was higher after oral administration compared with i.v. injection (mean ratio, 2.7 vs. 0.9). The hepatic drug extraction ratio determined after femoral and portal vein administration averaged 18.5%. When hydroxyitraconazole was injected i.v., the elimination half-life, volume of distribution and systemic clearance of itraconazole averaged 10.0 h, 2.4 l/kg and 3.4 ml/min/kg, respectively. The fraction of the systemically available itraconazole that was metabolized to hydroxyitraconazole was 21.0% and 76.0% after i.v. and oral administration, respectively. In summary, this study is the first reporting the hepatic extraction of itraconazole and the i.v. disposition characteristics of hydroxyitraconazole in rats. Itraconazole is a drug with a low hepatic extraction ratio and its systemic clearance appears to be largely accounted for by hepatic metabolism.  相似文献   
155.
A de novo preparation of alpha-keto-imides via ynamide oxidation is described. With a number of alkyne oxidation conditions screened, a highly efficient RuO2-NaIO4 mediated oxidation and a DMDO oxidation have been identified to tolerate a wide range of ynamide types. In addition to accessing a wide variety of alpha-keto-imides, the RuO2-NaIO4 protocol provides a novel entry to the vicinal tricarbonyl motif via oxidation of push-pull ynamides, and imido acylsilanes from silyl-substituted ynamides. Chemoselective oxidation of ynamides containing olefins can be achieved by using DMDO, while the RuO2-NaIO4 protocol is not effective. These studies provide further support for the synthetic utility of ynamides.  相似文献   
156.
We report the room-temperature ferromagnetism in transition metals (Co, Ni)-doped 8-hydroxy-quinoline aluminum (Alq3) by thermal coevaporation of high purity metal and Alq3 powders. For 5% Co-doped Alq3, a maximum magnetization of approximately 0.33 microB/Co at 10 K was obtained and ferromagnetic behavior was observed up to 300 K. The Co atoms interact chemically with O atoms and provide electrons to Alq3, forming new states acting as electron trap sites. From this, it is suggested that ferromagnetism may be associated with the strong chemical interaction of Co atoms and Alq3 molecules.  相似文献   
157.
158.
Hydrophobic bacteria, like colloidal solids, can spontaneously adsorb onto fluid-fluid interfaces and modify their mechanical properties. In this study, two strains of bacteria--Acinetobacter venetianus RAG-1 and Rhodococcus erythropolis 20S-E1-c--were prepared in their stationary (i.e. non-dividing) phase in the absence of biosurfactants; the cells were then used as emulsifiers to stabilize n-hexadecane droplets in aqueous environments. Using the micropipette technique, colloidal stability of the bacteria-coated droplets was examined through direct-contact experiments. Both types of bacteria were seen to function as effective stabilizers, although the Acinetobacter venetianus RAG-1 film provided stronger resistance to droplet-droplet coalescence. In addition to creating steric barriers, the adsorbed bacteria also interacted with one another at the interface, giving rise to higher order rheological properties. A technique of directly probing the mechanical properties of the emulsion drop surfaces (i.e. the adsorbed films) on the micrometre-scale revealed that (a) the films behaved as purely elastic sheets, and (b) with a reduction in cell concentration in the aqueous phase, less oil was emulsified, but the elastic moduli of the adsorbed films remained unchanged (suggesting an "all or none" adsorption process). These results are in contrast to a previous macroscopic (i.e. millimetre-scale) study, which showed that the absorbed films were viscoelastic, with the apparent elastic moduli depending strongly on cell concentration. The rheological properties of these bacteria-adsorbed interfaces appeared therefore to be length scale-dependent.  相似文献   
159.
The Ag nanoprisms with controlled arrangements show distinct optical, crystallographic, and surface-enhanced Raman scattering properties depending on their orientation in the assemblies, demonstrating that the controlled assembly of anisotropic nanostructures can be utilized as a powerful tool for studying their physicochemical properties and for the creation of new classes of functional materials.  相似文献   
160.
The controllable preparation of metal nanoclusters in high yield is an essential prerequisite for their fundamental research and extensive application. Here a synthetic approach termed “dual-level kinetic control” was developed to fabricate a family of new silver nanoclusters. The introduction of secondary ligands was first exploited to retard the reduction rate and accomplish the first-level kinetic control. And the cooling of the reaction was performed to further slow the reduction down and accomplish the second-level kinetic control. A family of atomically precise silver nanoclusters (including [Ag25(SR)18], [Ag34(SR)18(DPPP)3Cl4]2+, [Ag36(SR)26S4]2+, [Ag37(SR)25Cl1]+, and [Ag52(SR)28Cl4]2+) were controllably prepared and structurally determined. The developed “dual-level kinetic control” hopefully acts as a powerful synthetic tool to manufacture more nanoclusters with unprecedented compositions, structures, and properties.

A dual-level kinetic control was exploited to fabricate a family of atomically precise silver nanoclusters.  相似文献   
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