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991.
The existence of periodic solutions for the nonlinear asymmetricoscillator x' + x+ rßx = h(t),(' =d/dt (is discussed, where , rß are positive constantssatisfying for some positive integer n N and h(t) L (0,2) is 2-periodic with x±= max {±x,0}. 2000 Mathematics Subject Classification34C10, 34C25. 相似文献
992.
993.
A linear comprehensive adsorption model of hydrogen on super activated carbon under supercritical conditions 总被引:1,自引:0,他引:1
Zhan L Li KX Wang YL Meng QH Lv CX Ling LC 《Journal of colloid and interface science》2002,250(1):63-66
The adsorption isotherms of hydrogen on super activated carbon were measured systematically, covering a temperature range of 93-293 K at 20 K intervals and pressures up to 7 MPa. All the experimental data were linearized by adopting the coordinates ln ln(n) vs 1/(ln P). The results indicate that the adsorption limit (P(lim), n(lim)) exists virtually at high pressure and has a certain physical meaning. Based on the adsorption limit, further analyses were carried out by modeling the adsorption isotherms in the coordinates ln(n(lim)/n) vs ln(RT(ln(P(lim)/P) and a linear comprehensive adsorption model was proposed in the form n (lim)=n.exp(psi T+lambda/T-c/) (beta).[RT ln( P (lim)P )] (b) which can predict the adsorption isotherm of hydrogen on activated carbon in supercritical conditions. 相似文献
994.
Diode-pumped self-Q-switched single-frequency 946-nm Nd(3+), Cr(4+):YAG microchip laser 总被引:3,自引:0,他引:3
Lv L Wang L Fu P Chen X Zhang Z Gaebler V Li D Liu B Eichler HJ Zhang S Liu A Zhu Z 《Optics letters》2001,26(2):72-74
A stable low-threshold self-Q-switched diode-pumped 946-nm Nd(3+), Cr(4+):YAG microchip laser operating in single frequency and fundamental transverse mode is reported. The output characteristics of the microchip laser were investigated under cw and pulsed pumping. By combination of the infrared microchip and an external frequency doubler, 473-nm pulses with a conversion efficiency of 18% were achieved. 相似文献
995.
996.
Haifeng Yang Jun Zhu Chun Sheng Xiaojing Sun Jiahua Ji Xiaoling Ma 《Journal of Raman spectroscopy : JRS》2007,38(7):890-895
Monolayers of N‐acetylalanine on a metallic surface can serve as a biocompatible functional interface to construct biosensors. In the present paper, the surface‐enhanced Raman scattering (SERS) spectra of N‐acetylalanine monolayers self‐assembled on a silver surface under different pH were recorded. Assignments of the obtained spectra were carried out by density functional theory (DFT) calculations (BLYP/6‐311G). On the basis of the SERS effect, the nature of adsorption of N‐acetylalanine on a silver surface was deduced. It can be concluded that the fully protonated N‐acetylalanine is adsorbed on the silver surface via the imine group together with the carboxylate group, while it anchored onto the surface not only through both the imine and the carboxylate groups but also through the amide group after being completely deprotonated in the basic solution. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
997.
Liang Sun Fengyun Guo Qiang Lv Haitao Yu Hongtao Li Wei Cai Yuheng Xu Liancheng Zhao 《Crystal Research and Technology》2007,42(11):1117-1122
Zr: LiNbO3 crystals has been grown. The crystal composition and phase are analyzed by X‐ray diffration. The optical damage resistance ability of Zr: LiNbO3 crystals is studied by the Sénarmont compensation method and the transmitted beam pattern distortion method. The saturated value of the birefringence change of 6 mol% Zr: LiNbO3 crystal is 1.01×10‐4, which is seven times smaller than that of congruent pure LiNbO3 crystal. The results of UV‐Visible and IR absorption spectra of Zr: LiNbO3 crystals powerfully confirm that the optical damage resistance threshold concentration of the Zr4+ ions doped in LiNbO3 crystals is about 6 mol% in the melt. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
Liang Sun Haitao Yu Qiang Lv Fengyun Guo Hongtao Li Wei Cai Yuheng Xu Liancheng Zhao 《Crystal Research and Technology》2007,42(7):730-736
Mg: Er: LiNbO3 crystals were grown by the Czochralski technique with various concentrations of MgO = 2 mol%, 4 mol%, 6 mol% and the fixed concentration of Er2O3= 1 mol% in the melt, and the 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was fabricated by the Czochralski technique with special technology process. The crystals were treated by polarization, reduction and oxidation. The segregation coefficients of Mg2+ and Er3+ in Mg: Er: LiNbO3 crystals were measured by X‐ray fluorescence spectrograph, as well as the crystal's defect structure and optical properties were analyzed by the UV‐Vis, IR and fluorescent spectroscopy. The pump wavelength and the surge wavelength were determined. Using m‐line method tested optical damage resistance of those crystals, the results show that photodamage threshold of Mg: Er: LiNbO3 crystals are higher than that of Er: LiNbO3 crystal, and the oxidation treat could enhance the photodamage resistant ability of crystals while the reduction treat could depress the ability. The optical damage resistance of 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was the strongest among the samples, which was two orders magnitude higher than that of 1 mol%Er: LiNbO3 crystal. The dependence of the optical properties on defect structure of Mg: Er: LiNbO3 crystals was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
Synchronization between two different chaotic systems with nonlinear feedback control 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper presents chaos synchronization between two different chaotic
systems by using a nonlinear controller, in which the nonlinear functions of
the system are used as a nonlinear feedback term. The feedback controller is
designed on the basis of stability theory, and the area of feedback gain is
determined. The artificial simulation results show that this control method
is commendably effective and feasible. 相似文献
1000.
胶束电动毛细管色谱快速测定化妆品中的防腐剂 总被引:7,自引:0,他引:7
重氮烷基脲和对羟基苯甲酸酯(甲酯、乙酯和丙酯)是目前化妆品中较常添加的防腐剂。卫生部《化妆品卫生规范》对上述4种防腐剂均限定了用量,其中重氮烷基脲的含量(质量分数,下同)应不大于0.5%,对羟基苯甲酸酯的含量应不大于0.4%。因此有必要建立一个快速、简便的同时测定这4种防腐剂的方法。 相似文献