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991.
Jinzhang Gao Haifeng Fan Wu Yang Xiangli Sun Chongyang Li Xuefeng Mao Jie Wang Rong Wang Zhengping Jia 《Central European Journal of Chemistry》2008,6(4):617-621
A rapid, simple and reliable capillary electrophoresis method for the separation and quantitation of inorganic cations with
indirect UV detection at 214 nm was developed. The electrolyte was: 12 mM imidazole as background absorbance provider; 5 mM
malic acid and 1.0 mM 18-crown-6 ether as complexing agents; and 20% D2O (v/v) to improve ion mobility. The pH was 4.25. The applied voltage was 22 kV at 22°C. Nine ions were completely separated
and determined with correlation coefficients of 0.9979-0.9992. The relative standard deviations (RSD) were less than 0.5%
for migration time and less than 5.2% for peak area (n=8). The detection limits (S/N=3) were from 0.08 mg L−1 (for Na+) to 0.51 mg L−1 (for Cu2+). To assess the reliability atomic absorption (AA) was also used to determine the same samples. Satisfactory results were
obtained for real samples of jasmine tea drink and coconut milk.
相似文献
992.
Wang X Li Z Zeng X Luo Q Evans DJ Pickett CJ Liu X 《Chemical communications (Cambridge, England)》2008,(30):3555-3557
Infrared data for mono-iron complexes possessing two cis-CO together with M?ssbauer data for the enzyme and a model complex support the assignment that the iron centre of the cluster-free hydrogenase Hmd is low-spin Fe(II). 相似文献
993.
Yan J Zhou Y Yu P Su L Mao L Zhang D Zhu D 《Chemical communications (Cambridge, England)》2008,(36):4330-4332
A new electrochemical sensor was demonstrated for selective sensing of 3,4-dihydroxyphenylacetic acid (DOPAC) through a non-oxidative mechanism by using single-walled carbon nanotubes (SWNTs) as the electronic transducer and a synthetic cyclophane electron acceptor as the recognition element. 相似文献
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998.
The readily available and inexpensive new chiral oxazolidine in combination with Ti(O(i)Pr)(4) was found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes to generate chiral propargylic alcohols with high enantioselectivities (up to 95%) and excellent yields (up to 98%). 相似文献
999.
He J Hu P Wang YJ Tong ML Sun H Mao ZW Ji LN 《Dalton transactions (Cambridge, England : 2003)》2008,(24):3207-3214
Two ligands with guanidinium/ammonium groups were synthesized and their copper complexes, [Cu(L1)Cl2](ClO4)2.H2O (1) and [Cu(L2)Cl2](ClO4)2 (2) (L1 = 5,5'-di[1-(guanidyl)methyl]-2,2'-bipyridyl cation and L2 = 5,5'-di[1-(amino)methyl]-2,2'-bipyridyl cation), were prepared to serve as nuclease mimics. X-Ray analysis revealed that Cu(II) ion in 1 has a planar square CuN2Cl2-configuration. The shortest distance between the nitrogen of guanidinium and copper atoms is 6.5408(5) A, which is coincident with that of adjacent phosphodiesters in DNA (ca. 6 A). In the absence of reducing agent, supercoiled plasmid DNA cleavage by the complexes were performed and their hydrolytic mechanisms were demonstrated with radical scavengers and T4 ligase. The pseudo-Michaelis-Menten kinetic parameters (kcat, KM) were calculated to be 4.42 h(-1), 7.46 x 10(-5) M for 1, and 4.21 h(-1), 1.07 x 10(-4) M for 2, respectively. The result shows that their cleavage efficiency is about 10-fold higher than the simple analogue [Cu(bipy)Cl2] (3) (0.50 h(-1), 3.5 x 10(-4) M). The pH dependence of DNA cleavage by 1 and its hydroxide species in solution indicates that mononuclear [Cu(L1)(OH)(H2O)]3+ ion is the active species. Highly effective DNA cleavage ability of is attributed to the effective cooperation of the metal moiety and two guanidinium pendants with the phosphodiester backbone of nucleic acid. 相似文献
1000.
Nitrogen-doped CeO2 nanoparticles were synthesized through a wet-chemical route. Nitrogen has been successfully incorporated into CeO2 nanoparticles and the nitrogen-doping level was also successfully controlled. The optical properties due to the different N-doping levels in CeO2 nanoparticles were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), which showed a visible-light absorbance shift. The resulting nanoparticles show enhanced visible-light sensitivity and photocatalytic activity compared to undoped CeO2 nanoparticles. DFT calculations were performed to explore the effect of nitrogen doping versus oxygen vacancies. The calculations show that the change of the electronic structure upon N-doping CeO2 is quite different from that of N-doped TiO2, which has been studied extensively. 相似文献