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321.
研究了直流电场对含LiClO4的聚氧化乙烯(PEO)400与环氧树脂形成的液晶态互穿网络高分子忆禽子导体的电导率的影响。在室温至90℃范围内,电导率随外加电压增加面降低。外加电压越高,对电导率变化的影响越大。 相似文献
322.
高效液相色谱与原子荧光光谱联用分析汞化合物形态的研究 总被引:15,自引:2,他引:15
建立了高效液相色谱与原子荧光光谱联用测定汞化合物形态的分析方法。实验对淋洗液组分浓度、氧化剂和还原剂浓度、载气流速及紫外消解管长度等操作条件进行了优化,获得了令人满意的分析结果。在优化的分离检测条件下,20μg/L的汞化合物标准溶液平行7次进样分析,甲基汞、无机汞和乙基汞的色谱峰高的相对标准偏差(RSD)分别为2.0%、2.9%和2.4%;3种汞化合物的线性范围为10~1000μg/L,25μL进样检出限分别为3、2和4μg/L。用建立的方法测定了脉红螺样品中甲基汞的含量,甲基汞和乙基汞的加标回收率分别为90%和92%。 相似文献
323.
PdH2、YH2分子的结构与势能函数 总被引:6,自引:0,他引:6
用密度泛函理论的B3LYP方法,对钯和钇原子采用SDD收缩价基函数,氢原子采用6-311++G**全电子基函数,对PdH2和YH2体系的结构进行优化计算,得到PdH2分子最稳态为C2v构型,电子组态为1A1,平衡核间距RPdH=0.1692 nm,键角∠HPdH=29.4°,离解能De=5.5212 eV,基态简正振动频率:ν1(b2)=1470.1 cm-1、ν2(a1)=1007.9 cm-1、ν3(a1)=2907.0 cm-1.YH2分子最稳态也为C2v构型,电子组态2A1,RYH=0.1962 nm,∠HYH=114.3°,De=5.6691 eV,基态简正振动频率:ν1(b2)=1457.9 cm-1、ν2(a1)=476.0 cm-1、ν3(a1)=1506.3 cm-1.由微观过程的可逆性原理分析了分子的可能离解极限.并用多体项展式理论方法分别导出基态PdH2和YH2分子的势能函数,其等值势能面图准确地再现了PdH2和YH2分子的结构特征和离解能,由此讨论了Pd + H2和Y + H2分子反应的势能面静态特征. 相似文献
324.
A simple, rapid and sensitive high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of oxytetracycline, doxycycline, tetracycline and chlortetracycline was developed, and successfully applied to the analysis of commercial tetracycline antibiotics. The separation was performed on a reverse-phase C18 column with a gradient elution composed of methanol and sodium acetate buffer (containing disodium ethylenediaminetetraacetate and calcium chloride, pH 8.10) as the mobile phase, and fluorescence detection at 532 nm (excitation at 380 nm). The detection limits for oxytetracycline, doxycycline, tetracycline and chlortetracycline were 0.1, 0.5, 0.3 and 0.4 g L–1, respectively. Data with respect to precision and accuracy were reported and discussed. 相似文献
325.
Colorless [Au[C(NHMe)(2)](2)]X.H(2)O (X = Cl or Br) crystallize as dimers with Au.Au separations of 3.1231(3) A (Cl salt) and 3.1297(4) A (Br salt) between the linear, two-coordinate cations, and there is no direct interaction of Au(I) with the halide ions which are hydrogen bonded to ligand N-H groups and the water molecules. The luminescence of these dimers occurs at higher energy than that observed in extended chains of the same cation in the corresponding (PF(6))(-) and (BF(4))(-) salts and shows the important effects of aggregation on the observed luminescence. 相似文献
326.
Xiao Ying Xu Feng Cheng Jian Hua Shen Xiao Min Luo Li Li Chen Li Duo Yue Yi Du Fei Ye Shan Hao Jiang Da Yuan Zhu Hua Liang Jiang Kai Xian Chen 《International journal of quantum chemistry》2003,93(6):405-410
Docking simulation of 18 agonists with the ligand binding pocket (LBP) of PPARγ has been performed. The binding conformations and binding affinities of these agonists were obtained by use of the flexible docking protocol FlexX. Test compound calculations indicated that FlexX can reproduce the binding conformation of the crystal structure (root mean square deviation = 1.43 Å); moreover, the predicted binding affinities correlate well with the activities of these agonists. The interaction model and pharmacophore of PPARγ agonists were derived and the difference in biologic activities of these agonists can be well explained. The PPARγ agonists must have both polar head and the hydrophobic tail, which form hydrogen bonds and hydrophobic contacts with hydrophilic and hydrophobic regions of the LBP of PPARγ, respectively. In addition, a suitable linker is also necessary. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 405–410, 2003 相似文献
327.
328.
The use of poly(maleic acid–styrene)-encapsulated silica for the determination of monovalent and divalent cations is well accepted in ion chromatography. The separation of Mn2+, alkali and alkaline earth metal cations is obtained under the same chromatographic conditions. The influences of pH and the concentration of eluent on the retention of cations have been studied. The preparation conditions of packings were studied. The metal ions in the boiler water samples from a thermal power plant were quantitatively determined using this column. The results are in agreement with those determined by ICP and Volumetric analysis methods. 相似文献
329.
A method for the determination of the major serotonin metabolite — 5-hydroxyindole-3-acetic acid (5-HIAA) in human gastric juice by cyclic voltammetry was described. The measurement conditions were investigated. The potential window was chosen from +0.1 to +0.9 V, the supporting electrolyte was 0.025 M PBS solution (pH 2.0). The method allowed determination in the concentration range from 2.0 ×10−7 to 2.0 ×10 −5 M and a detection limit of 80 nM. When samples of gastric juice were analyzed with the method, we obtained the mean content of 5-HIAA in the gastric juice. Meanwhile, interference from other ions and substances were examined. The experimental results indicate that the method for the determination of gastric juice samples is successful. 相似文献
330.
Ting Wang Yan-Qiang Wang Yan-Lei Su Zhong-Yi Jiang 《Journal of membrane science》2006,280(1-2):343-350
A new random copolymer was synthesized by reacting hydrophilic N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) (DMMSA) with hydrophobic butyl methacrylate (BMA) through a conventional radical polymerization. The as-prepared sulfobetaine copolymer (DMMSA–BMA) was blended with polyethersulfone (PES) to fabricate antifouling ultrafiltration membrane for BSA separation. The X-ray photoelectron spectroscopy analysis of blend membranes revealed concentration of sulfobetaine groups at the membrane surfaces that endowed the membrane with higher hydrophilicity and better antifouling property. For the membrane with 8.0 wt% DMMSA–BMA copolymer concentration (No. 5), irreversible fouling has been considerably reduced and the flux recovery rate of the blend membrane reached as high as 82.8%. Furthermore, the blend membrane could effectively resist BSA fouling in a wide pH range from 4.0 to 8.0. 相似文献