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191.
为了研究白血病骨髓移植病人全血微量元素铜的变化及其意义 ,用原子吸收光谱法检测了正常对照组与白血病骨髓移植患者预处理前及移植后骨髓空虚期全血微量元素铜的含量。结果表明 ,正常对照组全血铜浓度与白血病骨髓移植患者预处理前全血铜浓度差异无显著性 (P >0 0 5 ) ,而与骨髓空虚期全血铜浓度有显著性差异 (P <0 0 5 ) ,说明白血病缓解后血铜接近正常对照组水平 ,而白血病骨髓移植患者预处理后骨髓空虚期全血铜含量高于正常对照组 ,说明预处理影响微量元素铜的代谢 ,本文就其影响机理进行了研究 相似文献
192.
Meng Wang 《European Polymer Journal》2007,43(11):4613-4618
In this study the optical property and film morphology of a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,5-dihexyloxybenzene) (PF6OC6), are investigated. It is found that the intensity of the 0-1 emission relative to the 0-0 emission in the PL spectra and the full width at the half-maximum (fwhm) of PL spectra of the PF6OC6 films decrease firstly and then increase with increasing the annealing temperature. The polymer films also exhibit different morphological features after annealing at different temperatures. The optical and morphological results suggest that the vibronic structure of PF6OC6 is closely related to the film morphology, and its formation is enhanced in the amorphous (or less ordered) films and inhibited in the ordered films. 相似文献
193.
194.
Xiangke Wang Jinzhou Du Zuyi Tao Zhongxiu Fan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(1):133-138
The migration of radionuclides 85+89Sr2+, 134Cs+, 125I- and 75SeO3
2- in calcareous soil from Yuzhong county of Gansu Province (China) at pH 7.8±0.2 and 152+154Eu(III) in red earth from Yingtan county of Jiangxi Province (China) at pH 4.6±0.2, in presence of CaCl2 was studied using column experiments. Results indicate that the negative anions, iodide and selenide are mobile nuclides while the migration of positive cations is related to the sorption capacity for the element. Iodide can be assumed to be non-reactive in calcareous soil. The breakthrough curves (BTCs) were fitted to the analytical solution or numerical solution of one-dimensional convection-dispersion transport models. Good agreements were obtained between the measured and predicted concentration profiles. 相似文献
195.
196.
A new type of dendritic 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN)-derived Schiff-base ligands have been synthesized and applied to the titanium-catalyzed hetero-Diels-Alder reaction of Danishefsky's diene with aldehydes. These reactions afforded the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-ones in quantitative yields and with excellent enantioselectivities (up to 97.2 % ee). The disposition of the dendritic wedges and the dendron size in the ligands were found to have significant impact on the enantioselectivity of the reaction. The recovered dendritic catalyst could be reused without further addition of the Ti source or a carboxylic acid additive for at least three cycles, retaining similar activity and enantioselectivity. The high stability of this type of assembled dendritic titanium catalyst may be attributed to the stabilization effect of large-sized dendron units in the catalyst molecule. The other important phenomenon observed with this catalyst system is that a higher degree of asymmetric amplification has been achieved by attachment of the dendron unit to the chiral ligand, which represents a new advantage of dendrimer catalysts for asymmetric reactions using chiral ligands of lower optical purity. 相似文献
197.
198.
L—半胱氨酸(L—Cys)是蛋白质的降解产物之一,在体内除参与蛋白质的合成外,还参与毒物的解毒过程。本文用pH电位滴定法测定L—Cys同Fe~(2+)、Ni~(2+)、Zn~(2+)、Pb~(2+)形成配合物的稳定常数,以温度系数法获得配位反应的焓变,根据所得的热力学参数,对配位反应的推动力和配合物的结构进行讨论,并进一步用红外光谱和电子光谱对Pb~(2+)、Ni~(2+)两体系所得的结果予以证实。 相似文献
199.
An enzymatic assay for glucose based on the use of the fluorescent probe for hydrogen peroxide, europium(III) tetracycline (EuTc), is described. The weakly fluorescent EuTc and enzymatically generated H2O2 form a strongly fluorescent complex (EuTc–H2O2) whose fluorescence decay profile is significantly different. Since the decay time of EuTc–H2O2 is in the microseconds time domain, fluorescence can be detected in the time-resolved mode, thus enabling substantial reduction of background fluorescence. The scheme represents the first H2O2-based time-resolved fluorescence assay for glucose not requiring the presence of a peroxidase. The time-resolved assay (with a delay time of 60 s and using endpoint detection) enables glucose to be determined at levels as low as 2.2 mol L–1, with a dynamic range of 2.2–100 mol L–1. The method also was adapted to a kinetic assay in order to cover higher glucose levels (mmol L–1 range). The latter was validated by analyzing spiked serum samples and gave a good linear relationship for glucose levels from 2.5 to 55.5 mmol L–1. Noteworthy features of the assay include easy accessibility of the probe, large Stokes shift, a line-like fluorescence peaking at 616 nm, stability towards oxygen, a working pH of approximately 7, and its suitability for both kinetic and endpoint determination. 相似文献
200.