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71.
嵇英华  赖慧芳  蔡十华  王资生 《中国物理 B》2010,19(3):30310-030310
A scheme is proposed to controll the decoherence of three-level rf-SQUID qubit with asymmetric potential by designing an external electric circuit for superconductive flux qubit. The results show that it may not only raise the gate speed but also extend decoherence time for a three-level structure.  相似文献   
72.
陈东阁  唐新桂  贾振华  伍君博  熊惠芳 《物理学报》2011,60(12):127701-127701
采用传统的固相反应法,在1400–1500 ℃下烧结,制备得到Al2O3-Y2O3-ZrO2三相复合陶瓷.样品的结构、形貌和电性能分别用X射线衍射(XRD)、扫描电子显微镜(SEM)及介电谱表征.XRD表明此三相复合体系无其他杂相,加入Y2O3及ZrO2后使得Al2O3成瓷温度降低;SEM表明此体系晶粒直径为200–500 nm,并且样品随烧结温度的升高而变得更加致密,晶界更加清晰;介电损耗谱中出现峰值弛豫现象,根据Cole-Cole复阻抗谱得出其为非德拜弛豫. 关键词: 2O3-Y2O3-ZrO2三相陶瓷')" href="#">Al2O3-Y2O3-ZrO2三相陶瓷 介电弛豫 阻抗谱 热导率  相似文献   
73.
Polyphenols are classified as an organic chemical with phenolic units that display an array of biological functions. However, polyphenols have very low bioavailability and stability, which make polyphenols a less bioactive compound. Many researchers have indicated that several factors might affect the efficiency and the metabolism (biotransformation) of various polyphenols, which include the gut microbiota, structure, and physical properties as well as its interactions with other dietary nutrients (macromolecules). Hence, this mini-review covers the two-way interaction between polyphenols and gut microbiota (interplay) and how polyphenols are metabolized (biotransformation) to produce various polyphenolic metabolites. Moreover, the protective effects of numerous polyphenols and their metabolites against various gastrointestinal disorders/diseases including gastritis, gastric cancer, colorectal cancer, inflammatory bowel disease (IBD) like ulcerative colitis (UC), Crohn’s disease (CD), and irritable bowel syndrome (IBS) like celiac disease (CED) are discussed. For this review, the authors chose only a few popular polyphenols (green tea polyphenol, curcumin, resveratrol, quercetin), and a discussion of their proposed mechanism underpinning the gastroprotection was elaborated with a special focus on clinical evidence. Overall, this contribution would help the general population and science community to identify a potent polyphenol with strong antioxidant, anti-inflammatory, anti-cancer, prebiotic, and immunomodulatory properties to combat various gut-related diseases or disorders (complementary therapy) along with modified lifestyle pattern and standard gastroprotective drugs. However, the data from clinical trials are much limited and hence many large-scale clinical trials should be performed (with different form/metabolites and dose) to confirm the gastroprotective activity of the above-mentioned polyphenols and their metabolites before recommendation.  相似文献   
74.
The steering control of a ship during a course-changing maneuver is formulated as a Bolza optimal control problem, which is solved via the sequential gradient-restoration algorithm (SGRA). Nonlinear differential equations describing the yaw dynamics of a steering ship are employed as the differential constraints, and both amplitude and slew rate limits on the rudder are imposed. Two performance indices are minimized: one measures the time integral of the squared course deviation between the actual ship course and a target course; the other measures the time integral of the absolute course deviation. Numerical results indicate that a smooth transition from the initial set course to the target course is achievable, with a trade-off between the speed of response and the amount of course angle overshoot.  相似文献   
75.
In this paper, we propose some decision logic languages for rule representation in rough set-based multicriteria analysis. The semantic models of these logics are data tables, each of which is comprised of a finite set of objects described by a finite set of criteria/attributes. The domains of the criteria may have ordinal properties expressing preference scales, while the domains of the attributes may not. The validity, support, and confidence of a rule are defined via its satisfaction in the data table.  相似文献   
76.
Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain structures constituted by domains with the same (or identical) crystal structure and chemical composition, including anti-phase domain structures, twinning domain structures, inversion domain structures, and translationtwinning domain structures; (ⅱ) domain structures constituted by two or more than two kinds of domains with the same chemical composition but different crystal structures; and (ⅲ) domain structures constituted by two kinds of compositional and structural different domains, including exsolution-induced and polysomatic reaction-induced domain structures. Different types of domain structures may display different phenomena in their TEM images and SAED patterns, due to different crystallographic characteristics of different domain structures. The domain structures in minerals  相似文献   
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The first examples of the unknown pyrazino[2,3-e]-as-triazine ring system, that is, the 6,7-dihydroxy-5,6,7,8-tetrahydropyrazino[2,3-e]-as-triazines, have been prepared by ring closure of selected 5,6-diamino-as-triazines with 40% aqueous glyoxal. These 4-azapteridines experience a novel exchange process with alcohols at the C(7)-position. When dissolved in alcohol and stirred at room temperature, the 7-alkoxy, 6-hydroxy analogues are formed and isolated. In fact, during ring closure, if alcohols are used as the solvent, only the latter compounds are obtained. Initially, cyclization of the ortho-diamino-as-triazines with glyoxal proceeds in a stereoselective manner giving rise to both the cis and trans adducts. A single-crystal X-ray diffraction study has determined the predominant and most stable adduct to be the trans (R,R or S,S) isomer. Spectroscopy (nmr) has verified the intermediacy of the cis adduct, but because of the aforementioned exchange process only the trans isomer is isolated. The site of exchange on these σ-adducts has been rigorously established as C(7). A plausible reaction mechanism by which this exchange process occurs is presented.  相似文献   
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