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61.
62.
Forward degenerate four-wave mixing (DFWM) processes are investigated with a femtosecond pulsed laser in lithium niobate crystal doubly-doped with magnesium and iron (LiNbO3:Fe, Mg). The pulse energy dependence reveals a pure third-order nonlinear response, and the third-order nonlinear susceptibility x^(3) in the material is evaluated to be 4.96 × 10^-13 esu. The time-resolved DFWM process shows a response time of x^(3) shorter than 100fs, which is due to the nonresonant electronic nonlinearities. Our results indicate that LiNbO3 crystals have potentials for ultrafast real-time optical processing systems, which require a large and fast x^(3) optical nonlinearity. 相似文献
63.
64.
Jia‐Yuh Sheu Yeh‐Long Chen Cherng‐Chyi Tzeng Shu‐Lin Hsu Kuo‐Chang Fang Tai‐Chi Wang 《Helvetica chimica acta》2003,86(7):2481-2489
Certain 1‐ethyl‐ and 1‐aryl‐6‐fluoro‐1,4‐dihydroquinol‐4‐one derivatives were synthesized and evaluated for antimycobacterial and cytotoxic activities. Preliminary results indicated that, for 1‐aryl‐6‐fluoroquinolones, both 7‐(piperazin‐1‐yl)‐ and 7‐(4‐methylpiperazin‐1‐yl) derivatives, 9b and 11a , are able to completely inhibit the growth of M. tuberculosis at a concentration of 6.25 μg/ml, while the 7‐[4‐(2‐oxo‐2‐phenylethyl)piperazin‐1‐yl] derivative 13 exhibits only 31% growth inhibition at the same concentration. For 1‐ethyl‐6‐fluoroquinolones, both 7‐[4‐(2‐oxopropyl)piperazin‐1‐yl]‐ and 7‐[4‐(2‐oxo‐2‐phenylethyl)piperazin‐1‐yl]‐derivatives, 2a and 2b , respectively, show complete inhibition, while their 2‐iminoethyl and substituted phenyl counterparts 3a and 2c are less active. In addition, the 6,8‐difluoro derivative was a more‐favorable inhibitor than its 6‐fluoro counterpart ( 2b vs. 2d ). These results deserve full attention especially because 2a, 2b, 9b , and 11a are non‐cytotoxic at a concentration of 100 μM . Furthermore, compound 9b proved to be a potent anti‐TB agent with selective index (SI)>40 and an EC90 value of 5.75 μg/ml. 相似文献
65.
Chun-Wei Hsu 《Journal of Non》2008,354(34):4037-4042
A sol-gel method has been used to fabricate a cholesterol MIP for application in polar solutions. In this study, (cholesteryl propylcarbamate)triethoxysilane and tetraethyl orthosilicate were used as the hydrophobic monomer and crosslinker, respectively. The MIP had a larger pore volume when formation of the polymer was catalyzed at a higher pH than when it was formed at lower pH values, with the pore diameters being 3.5 nm and 2 nm, respectively for materials formed at high and low pH values. Both of these pore volumes were greater than those found for the respective control polymers formed without template. However, only the polymers formed at low pH values showed an imprinting effect. Compared with other methods explored, the sol-gel procedure gave only a small amount of non-specific binding for both the MIP and NIP when synthesized at low pH values. The largest imprinting-induced promotion of binding (IPB) value of the MIP (13 650%) was obtained with [HCl] = 0.01 M in the sol-gel solution. The MIP showed high selectivity towards cholesterol in comparison with other steroid hormones, and also to a lesser extent recognized vitamin D3 in methanol solution containing 5 vol.% water. 相似文献
66.
67.
This paper investigates regression quantiles (RQ) for unstable autoregressive models. The uniform Bahadur representation of the RQ process is obtained. The joint asymptotic distribution of the RQ process is derived in a unified manner for all types of characteristic roots on or outside the unit circle. It involves stochastic integrals in terms of a sequence of independent and identically distributed multivariate Brownian motions with correlated components. The related L-estimator is also discussed. The asymptotic distributions of the RQ and the L-estimator corresponding to the nonstationary componentwise arguments can be transformed into a function of a normal random variable and a sequence of i.i.d. univariate Brownian motions. This is different from the analysis based on the LSE in the literature. As an auxiliary theorem, a weak convergence of a randomly weighted residual empirical process to the stochastic integral of a Kiefer process is established. The results obtained in this paper provide an asymptotic theory for nonstationary time series processes, which can be used to construct robust unit root tests. 相似文献
68.
In this paper, some new uniform frames with block size four and index one or three are obtained. The known existence results for (4,1)‐frames and (4,3)‐frames are both improved to the extent that only a finite number of possible exceptions remain. © 2003 Wiley Periodicals, Inc. 相似文献
69.
热喷涂技术的现状和发展 总被引:4,自引:0,他引:4
介绍了热喷涂工艺的特点,喷涂方法的种类及其技术以及热喷涂技术的应用概况,并对热喷涂技术的发展方向给予了展望。 相似文献
70.
Here proposed are certain asympotic expansion formulas for L
n
(∞-1)
(λz) and C
n
(∞)
(λz) in which 0<w=0(λ) and Cn/(w)(λz), z being a complex number. Also presented are certain estimates for the remainders (error bounds) of the asymptotic
expansions within the regions D1(-∞<Rez<=1/2(ω/λ) and D2(1/2(ω/λ)<=Rez<∞), respectively.
Supported by NSERC (Canada) and also by the National Natural Science Foundation of China. 相似文献