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71.
综述了锌在小儿神经系统疾病和内分泌代谢性疾病中的作用及临床意义,尤其是对癫痫的发病起重要作用,大量资料证明高锌与癫痫发作有关,其血锌值明显高于健康儿童,因此在治疗中不要轻易补锌。还综述了锌与智能发育障碍、生长发育障碍、多动症、胎儿畸形、遗传性感音神经性聋等疾病的关系及在治疗糖尿病、肝豆状核变性等内分泌和代谢性疾病时要注意维持锌的正常动态平衡。 相似文献
72.
反相液相色谱用球形共聚物柱填料 总被引:2,自引:0,他引:2
采用新颖聚合工艺制备用于反相高效液相色谱柱填料的乙基苯乙烯-二乙烯苯球形共聚物,不需使用备有高速搅拌的混匀器和特殊的筛析设备,聚合物粒径的95%在3~7μm之间,测算了渗透性、柱效和峰不对称性等柱参数,并通过分离实例说明该填料对胺类、酚类和芳烃类具有优良分离性能。 相似文献
73.
A simple method has been developed to produce SERS-active metal surfaces. Six metal surfaces (cadmium, nickel, gold, iron, copper, and silver) have been prepared on an aluminum foil underlayment by chemical reduction and strong surface-enhanced Raman signals have been observed for pyridine species on these surfaces. This permits the direct comparison of pyridine spectra on different metal surfaces prepared by the same chemically clean method. The differences among the SER spectra of the aqueous pyridine species using different metals generally follow the trend of silver, cadmium, nickel, iron, gold, and copper, which can be explained by the selective formation of alpha-pyridyl species and the equilibria between end-on adsorbed pyridines and edge-on adsorbed alpha-pyridyl species on the different metal surfaces. 相似文献
74.
A pure calcium borate Ca2[B2O4(OH)2]·0.5H2O has been synthesized under hydrothermal condition and characterized by XRD, FT-IR and TG as well as by chemical analysis. The molar enthalpy of solution of Ca2[B2O4(OH)2]·0.5H2O in HC1·54.582H2O was determined. From a combination of this result with measured enthalpies of solution of H3BO3 in HC1·54.561H2O and of CaO in (HCl + H3BO3) solution, together with the standard molar enthalpies of formation of CaO(s), H3BO3(s) and H2O(l), the standard molar enthalpy of formation of −(3172.5 ± 2.5) kJ mol−1 of Ca2[B2O4(OH)2]·0.5H2O was obtained. 相似文献
75.
交联聚丙烯酰胺吸水凝胶的强度 总被引:1,自引:0,他引:1
高吸水材料是一类新型的功能高分子材料,已有广泛开发和应用。本文讨论了含大量无机填料膨润土的阴离子型交联聚丙烯酰胺(JSWAM)吸水凝胶的强度及其形态结构。 吸水材料JSWAM的制备:将填料搅拌分散于丙烯酰胺水溶液中,同时加入规定量的甲叉基双丙烯酰胺、过硫酸铵、碱,而后聚合并水解。将聚合物胶块造粒、烘干、粉碎。凝胶强度 相似文献
76.
Crystal growth of calcium oxalate (CaC2O4) in bulk aqueous solution, reverse microemulsion of p-octyl polyethylene glycol phenylether (OP)/iso-octyl alcohol (IOA)/cydohexane/water and above microemulsions containing different kinds of amino acids, such as aspartic acid (Asp), tyrosine (Tyr) and tryptophan (Trp) were studied. The results indicated that different crystallization types of the crystals, which were calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD) and calcium oxalate trihydrate (COT), existed in bulk aqueous solution. But CaC2O4 growth mainly paralleled with (1 01) plane of COM in reverse microemulsion because of the induction of surfactant at water/oil interface. After adding amino acids into microemulsions, the growth of CaC2O4 crystals mainly influenced by the varieties of amino acids and the pH values of the amino acid aqueous solution. When pH values of the solutions was higher than isoelectric points of amino acids, CaC2O4 crystal paralleled with (1 01) plane of COM more easily with the addition of Trp, Tyr, Asp in turn; however, when pH of the solutions was lower than isoelectric points of Trp, CaC2O4 crystal growth paralleled with (020) face of COM. It is obviously that amino acids, pH values of the solutions and surfactant played important roles in the process of crystal growth of CaC2O4 in the microemulsions. The formation mechanism of CaC2O4 was also discussed in different microemulsions at last. 相似文献
77.
PengZHANG JiCunREN ZuoJunSHEN 《中国化学快报》2004,15(9):1091-1094
In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma. 相似文献
78.
Detailed EPR and ENDOR experiments on the cocrystalline complex of 1-methyluracil:9-Ethyladenine (MUEA) have revealed that the major radiation-induced products observed at 10 K on MU are: MUEA1, a radical formed by net hydrogen abstraction from the N1-CH3 methyl group, MUEA2, the MU radical anion, and MUEA3, the C5 H-addition radical. The following four products were observed on the adenine moiety at 10 K, MUEA4, the N3 protonated adenine anion, MUEA5, the native adenine cation, MUEA6, the amino deprotonated adenine cation, and MUEA7, the C8 H-addition radical formed by net H-addition to C8 of the adenine base. The geometries, energetics, and hyperfine properties of all possible radicals of MU and EA, the native anions and cations, as well as radicals formed via net hydrogen atom abstraction (deprotonated cations) or addition (protonated anions) were investigated theoretically. All systems were optimized using the hybrid Hartree–Fock–density functional theory functional B3LYP, in conjunction with the 6-31G(d,p) basis set of Pople and co-workers. Calculations of the anisotropic hyperfine couplings for all the radicals observed in MUEA are presented and are shown to compare favorably with the experimentally measured hyperfine couplings. The calculated ionizations potentials indicate that EA would be the preferred oxidation site. In MUEA, both the adenine cation and its N4-deprotonated derivative were observed. The calculated electron affinities indicate that MU would be the preferred reduction site. In MUEA radical, MUEA2 is a uracil reduction product, however the protonation state of this radical could not be determined experimentally. Calculations suggest that MUEA2 is actually the C4=O protonated anion. 相似文献
79.
80.
The efficiency of fluorescence resonance energy transfer (FRET) between two chromophores positioned at opposite ends of DNA base pair domains has been investigated. The base pair domain serves as a helical scaffold which defines both the distance between chromophores and the dihedral angle between their electronic transition dipole moments, each incremental base pair increasing the distance and stepping the dihedral angle. Fluorescence quantum yields and lifetimes have been determined for both the donor and acceptor chromophores. The experimental data are found to be in excellent accord with an oriented dipole model, rather than with the averaged dipole model conventionally assumed for FRET. 相似文献