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NIKITIN S.; PR?TZEL-WOLTERS D. 《IMA Journal of Mathematical Control and Information》1991,8(4):431-439
In 1983 Morse proved, for unknown scalar one-dimensional linearsystems, the nonexistence of rational or polynomial universalstabilizers (UAS). In 1983, Nussbaum gave an example of an analyticUAS. In our paper, it is shown that there exist time-invariantpolynomial UAS's with multidimensional gain adaptation. Thedesign procedure is developed for linear, minimum-phase systemsof relative degree one. Convergence of the closed-loop systemis proved. Some numerical simulations are provided. 相似文献
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Xiao Chi Ma Bao Jing Zhang Sha Deng Shan Shan Huang Ke Xin Liu Jing Ming Jia 《中国化学快报》2009,20(3):317-319
A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR. 相似文献
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Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
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Poly(trimethylene terephthalate)(PTT) is an excellent fiber material.Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis(TGA),thermogravimetric analysis-Fourier transform infrared spectroscopy(TGA-FTIR) analysis,differential scanning calorimetry(DSC) and X-ray diffraction(XRD).The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle.The PTTwithintrinsicviscosity(Ⅳ) of 0.74 dL/g has a maximum crystallinity... 相似文献
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Nuclear magnetization storage in biologically-relevant molecules opens new possibilities for the investigation of metabolic pathways, provided the lifetimes of magnetization are sufficiently long. Dissolution-dynamic nuclear polarization-based spin-order enhancement, sustained by long-lived states can measure the ratios between concentrations of endogenous molecules on a cellular pathway. These ratios can be used as meters of enzyme function. Biological states featuring intracellular amino-acid concentrations that are depleted or replenished in the course of in-cell or in-vivo tests of drugs or radiation treatments can be revealed. Progressing from already-established long-lived states, we investigated related spin order in the case of amino acids and other metabolites featuring networks of coupled spins counting up to eight nuclei. We detail a new integrated theoretical approach between quantum chemistry simulations, chemical shifts, J-couplings information from databanks, and spin dynamics calculations to deduce a priori magnetization lifetimes in biomarkers. The lifetimes of long-lived states for several amino acids were also measured experimentally in order to ascertain the approach. Experimental values were in fair agreement with the computed ones and prior data in the literature. 相似文献
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An alternative approach to synthesize pedamide,a key building block of pederin was described.Iodine-induced asymmetric heterocyclization was used as the key step to construct the skeleton,a tetrahydropyran ring with three chiral centers.Brown's asymmetric allylation and Lewis acid-mediated allylation were investigated to introduce chains and chiral alcohols.Sharpless dihydroxylation decorated the side chain.And high optically pure target was obtained by removing the epimers formed in these reactions on c... 相似文献
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A convenient route for the synthesis of 3,4-dihydrocoumarin derivates from salicylaldehyde derivates and 1,3-dicarbonyl compounds under solvent-free microwave irradiation conditions was described. In this way, a range of compounds was obtained in moderate to good yields in a short reaction time. 相似文献
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Highly effective direct synthesis of DMC from CH_3OH and CO_2 using novel Cu-Ni/C bimetallic composite catalysts 总被引:1,自引:0,他引:1
Novel Cu-Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2. 相似文献