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Refat MS Teleb SM Grabchev I 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):205-211
The interaction of iodine as a sigma-acceptor with two derivatives of polyamidoamine dendrimers (donor), 1,8-naphthalimide polyamidoamine (PAM1) and 4-piperidino-1,8-naphthalimide polyamidoamine (PAM2) have been investigated spectrophotometrically at room temperature in chloroform. The results indicate the formation of two CT-complexes [(PAM1)I](+)I(3)(-) and [(PAM2)(2)I](+)I(3)(-) with molar ratios of 1:2 and 1:1, respectively. The formation of these two complexes are in good agreement with their elemental analysis, infrared measurements and photometric titration plots based on the characteristic absorption bands of I(3)(-) ion around 280 and 360 nm. Moreover the formation of triiodide ion, I(3)(-), in both of the two complexes was supported by measuring their spectra in the far-infrared region. Three characteristic bands are observed at 125, 110 and 75 cm(-1) due to nu(as)(I-I), nu(s)(I-I) and delta(I(3)(-)), respectively, with C(2v) symmetry. 相似文献
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Teleb SM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(13):3093-3100
Four complexes are obtained during the reactions of 6-amino-1-methyl-5-nitrosouracil and its 6-methylamine derivative with Co(II) and Cu(II) ions. Theses complexes were characterized through their elemental, thermal analysis, infrared and 1H NMR spectroscopes. The obtained results indicate that, the exocyclic oxygen and nitrogen atoms are the most probable binding sites rather than ring nitrogen atoms. For cobalt complexes, the two pyrimidine bases act as bidentate ligands in the anionic form with the dissociation of iminic or N3 proton depending upon the nature of substituents on the pyrimidine ring. For copper complexes, the pyrimidine bases interact in the neutral form as monodentate ligands. Octahedral geometries are proposed for all of these complexes. 相似文献
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Teleb SM Gaballa AS Elmosallamy MA Nour el-M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2708-2712
The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6) with pi-acceptors such as picric acid (HPA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been studied spectrophotometrically in chloroform at 25 degrees C. The results obtained indicate the formation of 1:4 charge-transfer complexes with the general formula (DD18C6)(acceptor)4. The electronic and infrared spectra of charge-transfer complexes along with the (1)H NMR spectra were recorded and discussed. Based on the data obtained, the complexes were formulated as [(DD18C6H2)(HPA)2](PA)2 and [(DD18C6H2)(DDQ)2](DDQH)2. A general mechanism explaining the formation of the DDQ complex has been suggested. 相似文献
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Simple Zeros of the Riemann Zeta-Function 总被引:1,自引:0,他引:1
Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26. 相似文献
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Teleb SM Refat MS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(7):1579-1586
The reaction of ferric(III) acetylacetonate (donor), Fe(acac)3, with iodine as a sigma-acceptor and with other different pi-acceptors have been studied spectrophotometrically at room temperature in chloroform. The pi-acceptors used in this investigation are 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil and 7,7',8,8'-tetracyanoquinodimethane (TCNQ). The results indicate the formation of 1:1 charge-transfer complexes with a general formula, [Fe(acac)3 (acceptors)]. The iodine complex was shown to contain the triiodide species, [Fe(acac)3]2I(+)I3-, based on the electronic absorptions as well as on the Far-infrared absorption bands characteristic for the non-linear triiodide species, I3-, with C2v symmetry. The proposed structure of this complex is further supported by thermal and middle infrared measurements. 相似文献
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Quantum Zeno and anti-Zeno paradoxes 总被引:1,自引:0,他引:1
Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox).
We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure
change of state: an anti-Zeno paradox. 相似文献
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粉粒体两相流的电容层析成象测量 总被引:4,自引:0,他引:4
粉粒体系统中的固相浓度分布的在线测量是十分困难的问题.电容层析成象技术是一种近年来发展起来的非侵入式快速浓度场测量技术.它不干扰流场,不受流动中颗粒浓度、加速度、不透明等因素的制约.本文讨论其测量原理、应用、近期进展、存在的主要问题及其解决的对策. 相似文献