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91.
One new 1,3-diphenylpropane, viscolin (1), and one new flavanone, (2S)-7,4'-dihydroxy-5,3'-dimethoxyflavanone (2), together with thirty-nine known compounds, which included eleven known flavanones, two chromones, fourteen benzenoids, one inositol, two pyrimidines, four triterpenoids and five steroids, were isolated and characterized from Viscum coloratum. Structures of new compounds were determined by spectral analysis. Among them, viscolin (1) showed the most significant inhibition on superoxide anion generation by human neutrophils in response to fMLP (formyl-L-methionyl-L-leucyl-L-phenylalanine). 相似文献
92.
93.
研究了光折变晶体钛酸钡中相向传输的二波混频的温度效应,得到在 BaTiO3中增益耦合系数随温升而增加、并在85℃左右反向.说明其主要载流子的类型在此温度时发生改变.给出了有效陷阱浓度N(T)的温升模型,其理论预期值与实验数据符合较好. 相似文献
94.
In this paper we generalize to unbounded convex subsets C of hyperbolic spaces results obtained by W.A. Kirk and R. Espínola on approximate fixed points of nonexpansive mappings in product spaces (C×M)∞, where M is a metric space and C is a nonempty, convex, closed and bounded subset of a normed or a CAT(0)-space. We extend the results further, to families (Cu)u∈M of unbounded convex subsets of a hyperbolic space. The key ingredient in obtaining these generalizations is a uniform quantitative version of a theorem due to Borwein, Reich and Shafrir, obtained by the authors in a previous paper using techniques from mathematical logic. Inspired by that, we introduce in the last section the notion of uniform approximate fixed point property for sets C and classes of self-mappings of C. The paper ends with an open problem. 相似文献
95.
An unequally spaced fractal interpolation method is developed to reconstruct the low data rate laser Doppler velocimetry (LDV)
signal for better spectral results. The reconstructed result not only augments the data points to improve the statistics but
also retains the turbulent fractal dimension of the flow. In other words, the interpolated data are flow turbulence-correlated
data which are physically reasonable. This method is demonstrated on the LDV spectral measurements in the shear layer of a
jet flow and the results are compared against the hot-wire spectral data. When the data rate of the LDV signal is low, the
fractal interpolation method can suitably restore the major spectral peaks while the conventional sample-and-hold fails. Effects
of the data rate, data record length, sampling rate and the fractal dimension on the accuracy of the spectral reconstruction
are also discussed.
A version of this paper was presented at the 4th International Symposium on Transport Phenomena in Heat and Mass Transfer,
July 14–18, 1991, Sydney, Australia 相似文献
96.
Hsin-Ling Hsu Cheng-Fang Tien Jihperng Leu 《Journal of Solid State Electrochemistry》2014,18(6):1665-1671
This study develops a simple method to change the distribution of the pore size in a TiO2 layer, using polyethylene glycol (PEG), while maintaining nearly the same surface area and porosity to clarify how large pores affect the performance of dye-sensitized solar cells (DSSCs). Specifically, a heating step at 100 °C for a specific duration is added prior to PEG removal and TiO2 sintering at 400 °C. This process transforms the role of the PEG from a surfactant to a pore generator (porogen) and forms larger pores, depending on the loading and aggregation time for the PEG to gain larger pores. The effect of larger pores in TiO2 films under 30 % PEG loading, on the performance of an agarose gel electrolyte-based DSSC, was further investigated using the ionic liquid, 1-allyl-3-ethylimidazolium iodide (AEII). The I–V characteristic and the electrochemical impedance spectroscopy analysis show that larger pores readily improve redox couple diffusion in a TiO2 porous electrode and modify the interface between electrolyte and TiO2. Using the optimized TiO2 film with larger pores (30 % PEG loading, 100 °C/60 min), an efficiency of 7.43 % is achieved for the agarose gel electrolyte-based DSSC, which represents a 26.1 % improvement over TiO2 without the addition of PEG. 相似文献
97.
Tian‐Shung Wu Yann‐Ln Leu Yao‐Lung Tsai Fu‐Wen Lin Yu‐Yi Chan Chia‐Yu Chiang 《中国化学会会志》2001,48(1):109-112
Continuing our investigation on the bioactive compounds from the plant of the Aristolochia genus in Taiwan, we isolated one new sesquiterpene, aristololide, from the stem and roots of A. elegans, eleven known compounds from the fruits of A. elegans and nine known compounds from the fresh leaves of A. zollingeriana. Their structures were elucidated according to the 1D and 2D NMR spectroscopic analyses or by comparison with literature values. 相似文献
98.
Ching Hsuan Lin Sheng Xiong Cai Tsu Shang Leu Ting Yu Hwang Hao Hsin Lee 《Journal of polymer science. Part A, Polymer chemistry》2006,44(11):3454-3468
We propose three approaches to obtain flame‐retardant benzoxazines. In the first approach, we synthesize a novel benzoxazine (dopot‐m) from a phosphorus‐containing triphenol (dopotriol), formaldehyde, and methyl amine. Dopot‐m is copolymerized with a commercial benzoxazine [6′,6‐bis(3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazineyl)methane (F‐a)] or diglycidyl ether of bisphenol A (DGEBA). The thermal properties and flame retardancy of the F‐a/dopot‐m copolymers increase with the content of dopot‐m. As for the dopot‐m/DGEBA curing system, the glass‐transition temperature of the dopot‐m/DGEBA copolymer is 252 °C, which is higher than that of poly(dopot‐m). The 5% decomposition temperature of the dopot‐m/DGEBA copolymer increases from 323 to 351 °C because of the higher crosslinking density caused by the reaction of phenolic OH and epoxy. In the second approach, we incorporate the element phosphorus into benzoxazine via the curing reaction of dopotriol and F‐a. After the curing, the thermal properties of the F‐a/dopotriol copolymers are almost the same as those of neat poly(F‐a), and this implies that we can incorporate the flame‐retardant element phosphorus into the polybenzoxazine without sacrificing any thermal properties. In the third approach, we react dopo with electron‐deficient benzoxazine to incorporate the element phosphorus. After the curing, the glass‐transition temperatures of polybenzoxazines decrease slightly with the content of dopo, mainly because of the smaller crosslinking density of the resultant polybenzoxazines. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3454–3468, 2006 相似文献
99.
Laurenťiu Leuštean 《Central European Journal of Mathematics》2003,1(3):382-397
In this paper we study the prime and maximal spectra of a BL-algebra, proving that the prime spectrum is a compact T
0 topological space and that the maximal spectrum is a compact Hausdorff topological space. We also define and study the reticulation
of a BL-algebra. 相似文献
100.
Abstract. An MV-convergence is a convergence on an MV-algebra which renders the operations continuous. We show that such
convergences on a given MV-algebra A are exactly the restrictions of the bounded -convergences on the abelian -group in which A appears as the unit interval. Thus the theory of -convergence and Cauchy structures transfers to MV-algebras.?We outline the general theory, and then apply it to three particular
MV-convergences and their corresponding Cauchy completions. The Cauchy completion arising from order convergence coincides
with the Dedekind-MacNeille completion of an MV-algebra. The Cauchy completion arising from polar convergence allows a tidy
proof of the existence and uniqueness of the lateral completion of an MV-algebra. And the Cauchy completion arising from α-convergence
gives rise to the cut completion of an MV-algebra.
Received August 8, 2001; accepted in final form October 18, 2001. 相似文献