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61.
The rates of thermal decomposition of 1-methacryloyl-3-phenylthiourea (1a), 1-methacryloyl-3-(4-nitrophenyl)thiourea (1b), 1-methacryloyl-3-(4-chloro phenyl)thiourea (1c), 1-methacryloyl-3-(4-methylphenyl)thiourea (1d), 1-methacryloyl-3-(4-methoxyphenyl)thiourea (1e), poly-1-methacryloyl-3-phenylthiourea (2) and 1-acryloyl-3-phenylthiourea (3) have been measured between 390 and 465 K. The reactions were homogeneous and unimolecular with log A = 11.48, 11.48, 11.81, 11.43, 11.11, 11.21 and 11.87s−1 and Ea = 119.7, 111.93, 120.07, 121.94, 120.84, 124.64 and 122.68 kJ mol−1, respectively. Product analysis was used to outline feasible pathways for the elimination reaction of the compounds under study. 相似文献
62.
Maher Arar Abbas Yongacoglu 《Communications Letters, IEEE》2006,10(12):819-821
We propose an efficient 2Ntimes2N MIMO detection algorithm where the transmit signals are grouped in pairs and separately coded using the standard Alamouti space-time code. At the receiver, one or more QR decompositions are performed and the upper triangular property of the R matrices so obtained is exploited in order to successively decode the transmitted symbols starting with those interference-free symbols corresponding to the last two rows and columns of R. Bit-error-rate simulation results, for a 4times4 MIMO system and a bandwidth efficiency of 8 bits/s/Hz, show that the proposed technique, while less complex than ordered MMSE V-BLAST, outperforms the latter by 2-6 dB at a BER of 10-4 相似文献
63.
64.
A. Maher 《Journal of sound and vibration》1980,70(2):213-220
A simple approximation, with allowance for rigid body motion, is presented for the lowest non-zero frequency of a discrete system. The procedure is an extension and modification of that previously used to obtain a bound formula [1]. Illustrative examples and comparisons with known results are presented. 相似文献
65.
The occurrence, distribution and speciation of selenium in Australian marine biota is discussed. Biochemical pathways for the accumulation of selenium by marine organisms are also postulated. Comparison of the levels of selenium in macroalgae, fish, crustaceans and molluscs indicates that preferential accumulation of selenium by particular taxa does not occur. Phaeophyta have significantly lower selenium concentrations than Rhodophyta and Chlorophyta. Fish have lower selenium contents in muscle tissues than molluscs and crustaceans. Marine animals with different dietary intake (planktonic vs herbivorous vs carnivorous) are not observed to have significantly different levels of selenium (P>0.05). Selenium in all the organisms studied was predominantly associated with free amino-acids or protein residues and was not present as characterizable inorganic selenium species (SeO32?, SeO42?). These results indicate that selenium is probably only incorporated into biota for specific biochemical purposes with any exces selenium being excreted or eliminated. 相似文献
66.
In this paper we investigate the stability of the index, the nullity and the deficiency of normally solvable linear relations in paracomplete spaces under perturbation by strictly singular and T-strictly singular linear relations. This study led us to generalize some well-known results for operators and extend some results of small perturbation of normally solvable linear relations given by T. Alvarez (2012) [3]. 相似文献
67.
Nabeil A. Abujnah R. Letizia Mohamed Farhat O. Hameed Maher Abdelrazzak S. S. A. Obayya 《Optical and Quantum Electronics》2013,45(6):503-515
In this paper, slotted microcavity ring resonators based optical storage devices are proposed and analyzed by means of multiresolution time domain technique. The effect of the structure geometrical parameters on the coupling efficiency, normalized transmission spectra and quality factor has been thoroughly investigated and compared to that of the conventional no-slot microring resonator. The suggested slotted configurations increase the quality factor at a fixed gap size between the central ring and input/output waveguides. In addition, the desired compromise between the coupling efficiency and resonance effect inside the ring can be achieved by mere optimization of the slot geometrical characteristics. 相似文献
68.
We introduce the concept of numerical range approximant which is related to that of a spectral approximant. We obtain a variant of Bouldin result on spectral approximation of normal operators [3] and an analogous result for numerical range approximation . We also extend Maher's result on partially isometric approximation [9] and Halmos' on positive approximation [6]. 相似文献
69.
引言
把语音服务、高分辨率相机模块、MP3或PMP播放器功能整合在单个移动电话设计中,已成为未来中高端电话市场的发展趋势。除了超高的功率(〉700mW)立体声音频功能外,视频输出功能也出现在手机应用中,其输出仍主要是CVBS格式,而某些电话甚至提供S视频或模拟RGB输出。 相似文献
70.
Maher HM 《Journal of fluorescence》2008,18(5):909-917
Binary mixtures of naproxen and diflunisal can be resolved by using zero-crossing first derivative emission spectrofluorimetry,
first derivative constant wavelength synchronous luminescence spectrometry and first derivative constant energy synchronous
luminescence spectrometry. These methods do not require any previous separation steps. The lowest quantitation limits for
both drugs were obtained with first derivative constant wavelength synchronous luminescence spectrometry (0.002 and 0.015 μg
ml−1 for naproxen and diflunisal, respectively). The measurements were performed in 40% methanolic aqueous medium at pH 8.0 provided
by adding 0.02 M phosphate buffer solution. The proposed methods were successfully applied to the simultaneous determination
of naproxen and diflunisal in pharmaceuticals and human serum samples with high precision and accuracy. Linearity, accuracy,
precision, limits of detection, limits of quantitation, and other aspects of analytical validation are included in the text. 相似文献