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991.
Kai-Hui Sun Xin-Hua Ma Xian-Ming Zeng Zhong-Yue Lin Yu-Mei Cai Hai-Tao Zhang 《Natural product research》2019,33(20):2925-2931
One new indole-type alkaloid, α-L-rhamnopyranosyl-(1→6)-β-D- glucopyranosyl 6-methoxy-3-indolecarbonate (1), together with three known alkaloids (2–4), one aromatic acid (5) and five known saponins (6–10), was isolated from the roots of Clematis florida var. plena. Their structures were established by NMR spectroscopic analysis and acid hydrolysis. In in vivo anti-inflammatory activity, n-butanol extract was found to be potent against ear edema in mice, with inhibition rate of 48.7% at a dose of 800?mg/kg. Furthermore, compounds 8 and 9 obtained from the n-butanol extract exhibited significant anti-inflammatory activities with inhibition rates of 50.9% and 54.7% at a dose of 200?mg/kg. 相似文献
992.
Wang Yue Wang Yadi Huang Lina Liu Xiangyong Hu Jun Lü Junhong 《Analytical and bioanalytical chemistry》2019,411(27):7157-7164
Analytical and Bioanalytical Chemistry - Endothelial damage is a major manifestation in many forms of heart and lung injuries induced by lipopolysaccharide (LPS), but the biochemical responses and... 相似文献
993.
Based on the anomaly cancellation method, initiated by Robinson and Wilczek, we investigate Hawking radiation from the event horizon and cosmological horizon of the higher dimensional Reissner–Nordström–de Sitter black hole via covariant gauge and gravitational anomalies. Unlike in black hole space-time, to describe the observable physics, the effective field theory here is constructed between the event horizon and cosmological horizon. Our result shows that to restore the underlying gauge covariance and diffeomorphism covariance at the quantum level, the covariant compensating fluxes of gauge and energy–momentum tensor, which are shown to equal to those of Hawking radiation, should be radiated from the event horizon and absorbed from the cosmological horizon, respectively. 相似文献
994.
Yi-Wen Han Xiao-Xiong Zeng Shu-Zheng Yang 《International Journal of Theoretical Physics》2008,47(7):2011-2020
The recent work of Robinson and Wilczek that Hawking radiation can be determined by the compensating fluxes is extended to the charged and magnetized Reissner-Nordström de Sitter black hole. We reconstruct the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge and gauge potential. We construct the effect field theory between the event horizon and cosmological horizon to respectively determine the compensating fluxes from them, which are shown to exactly equal to those of Hawking radiation, by the covariant anomaly cancellation conditions. 相似文献
995.
Yu-jun Quan Pei-de Han Qi-jiang Ran Fan-ping Zeng Li-peng Gao Chun-hua Zhao 《Optics Communications》2008,281(11):3105-3110
A photonic wire-based directional coupler based on SOI was fabricated by e-beam lithography (EBL) and the inductively coupled plasma (ICP) etching method. The size of the sub-micron waveguide is 0.34 μm × 0.34 μm, and the length in the coupling region and the separation between the two parallel waveguides are 410 and 0.8 μm, respectively. The measurement results are in good agreement with the results simulated by 3D finite-difference time-domain method. The transmission power from two output ports changed reciprocally with about 23 nm wavelength spacing between the coupled and direct ports. The extinction ratio of the device was between 5 and 10 dB, and the insertion loss of the device in the wavelength range 1520-1610 nm was between 22 and 24 dB, which included an about 18.4 ± 0.4 dB coupling loss between the taper fibers and the polished sides of the device. 相似文献
996.
We investigate numerically the effects of scatterer sizes on backscattered polarization patterns using the third-order scattering model developed. The calculated results show that both parallel and cross polarization patterns from water suspensions of polystyrene spheres have four-lobe structures of the azimuth dependence of intensities. Particularly, the parallel polarization pattern is sensitive to scatterer sizes, exhibiting good agreement with prior experimental measurements. Furthermore, the polarization patterns from the dysplastic and normal cells with different size distribution widths are calculated and analyzed. The results show that the polarization patterns of dysplastic and normal cells have distinct differences, which might be used for identification of the morphological structure changes of cancer, dysplasia, and regeneration cells. 相似文献
997.
Zheng Y Zeng Z Li X Chen X Liu P Xiong H Lu H Zhao S Wei P Zhang L Wang Z Liu J Cheng Y Li R Xu Z 《Optics letters》2008,33(3):234-236
We experimentally demonstrate the generation of an extreme-ultraviolet (XUV) supercontinuum in argon with a two-color laser field consisting of an intense 7 fs pulse at 800 nm and a relatively weak 37 fs pulse at 400 nm. By controlling the relative time delay between the two laser pulses, we observe enhanced high-order harmonic generation as well as spectral broadening of the supercontinuum. A method to produce isolated attosecond pulses with variable width and intensity is proposed. 相似文献
998.
The implementation of the angular spectrum approach based on the two-dimensional fast Fourier transform is evaluated for near-field pressure simulations of square ultrasound transducers, where the three-dimensional pressure field is calculated from the normal velocity distribution on the transducer surface. The pressure field is propagated in the spatial frequency domain with the spatial propagator or the spectral propagator. The spatial propagator yields accurate results in the central portion of the computational grid while significant errors are produced near the edge due to the finite extent of the window applied to the spatial propagator. Likewise, the spectral propagator is inherently undersampled in the spatial frequency domain, and this causes high frequency errors in the computed pressure field. This aliasing problem is alleviated with angular restriction. The results show that, in nonattenuating media, the spatial propagator achieves smaller errors than the spectral propagator after the region of interest is truncated to exclude the windowing error. For pressure calculations in attenuating media or with apodized pistons as sources, the spatial and spectral propagator achieve similar accuracies. In all simulations, the angular spectrum calculations with the spatial propagator take more time than calculations with the spectral propagator. 相似文献
999.
Using a periodic expansion by means of the Bloch theorem, the flexural vibration band gaps are studied in a thin plate with two-dimensional ternary locally resonant structures, i.e. a thin epoxy plate containing a periodic square array of lead discs hemmed around by rubber. The full band gaps of flexural vibration in the thin plate are obtained within which sound and vibration will be forbidden. The numerical results are used to show how the width of the first full band gap depends on the radius ratio of lead disc to hemmed disc, filling fraction, lattice constant (distance between the centers of the nearest lead discs) and thickness of the thin plate. It is observed that the gap width can be changed a lot by modulating these physical parameters. 相似文献
1000.
Guochao Qi Sam Zhang Khiam Aik Khor Xianting Zeng Chunming Liu Lwin Lwin Ma 《Applied Surface Science》2008,255(2):304-307
Magnesium is one of the most important bivalent ions associated with biological apatite. A series of magnesium-substituted calcium apatite coatings (Ca10−xMgx)(PO4)6(OH)2, where x = 0, 0.50, 1.00, 1.50 and 2.00, are synthesized onto Ti6Al4V substrate by sol-gel dip-coating method to determine how magnesium influences the synthesis and the resulting structural and biological properties. X-ray diffraction (XRD) analysis shows that the incorporation of magnesium helps formation of Mg-containing β-TCP (β-TCMP) phase. X-ray photoelectron spectroscopy (XPS) is used to study the chemical composition and the results show that the apatite structure can only host magnesium less than ∼2.4 wt.% beyond which magnesium aggregates on the surfaces. The incorporation of magnesium slows down the dissolution of Ca2+ from the coating. The in vitro behavior of the coatings is evaluated with human osteosarcoma MG63 cells for cell morphology and proliferation. Similar cell morphologies are observed on all coatings. The cell proliferation results show that the incorporation of magnesium up to x = 2 has no adverse effect on cell growth. 相似文献