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991.
Ren Yanru Liu Hanpeng Lin Mingzhu Tu Qingyun Sang Lihua Lin Zhenjin Meng Xianren Liu Zhenxing 《Physica C: Superconductivity and its Applications》1988,156(5)
The TlBaCaCuO superconductors with zero resistance at temperatures in the range of 100–123 K have been sintered by solid state reactions. Electron microscopy and X-ray diffraction studies reveal that they are multiphased, containing both Tl2Ba2CaCu2O8 and Tl2Ba2Ca2Cu3O10 superconducting phases. Infrared spectra have been measured at room temperature for the multiphase samples. The spectra display structures at 590 cm-1 (P1) and 530 cm-1 (P2) which seem characteristic to Cu-O stretching modes. The difference ΔP between P1 and P1 has been found to be related to the superconducting transition temperature. Smaller ΔP corresponds to a higher Tc. The electron-like excitation of0.1 eV and the phonon-like structure at 850 cm-1 are also found to be important for high Tc. 相似文献
992.
在合成BCPDA基础上 ,对甲胎蛋白抗体与BCPDA连接及与铕离子螯合条件进行了研究。BCPDA与甲胎蛋白抗体反应后 ,分离纯化最佳淋洗液为pH 9.1的 0 .1mol/L碳酸盐缓冲溶液 ,BCPDA用量为甲胎蛋白抗体量 (mol)的 12 0~ 16 0倍 ;反应时间为 30min。讨论了Eu3 + BCPDA AFP抗体螯合物的荧光光谱 ,最佳温育时间为6 0min ,体系pH值为 7.8的Tris HCl溶液。当Eu3 + 浓度为 10 -6mol/L时 ,BCPDA的检出限为 4 .3× 10 -11mol/L。 相似文献
993.
铕苯丙氨酸配合物与DNA相互作用的循环伏安法和紫外光谱法研究 总被引:3,自引:2,他引:3
运用循环伏安法和紫外光谱法研究了Eu(phe)3^3+与DNA的相互作用。Eu(phe)3^3+与DNA作用后,循环伏安曲线的峰电流密度减小,峰电位差稍有增中,扩散系数减小,紫外光谱的特征吸收峰呈明显的减色效应,这可能是Eu(phe)3^3+与DNA因静电引力形成加合物以及Eu(phe)3^3+有很强的遮蔽负电荷 作用,促使碱基面与碱基面的进一步堆积所致。 相似文献
994.
995.
Guoliang He Xianguo Geng Lihua Wu 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2016,67(4):90
Resorting to the characteristic polynomial of Lax matrix for the Mikhailov–Shabat–Sokolov hierarchy associated with a \({3 \times 3}\) matrix spectral problem, we introduce a trigonal curve, from which we deduce the associated Baker–Akhiezer function, meromorphic functions and Dubrovin-type equations. The straightening out of the Mikhailov–Shabat–Sokolov flows is exactly given through the Abel map. On the basis of these results and the theory of trigonal curve, we obtain the explicit theta function representations of the Baker–Akhiezer function, the meromorphic functions, and in particular, that of solutions for the entire Mikhailov–Shabat–Sokolov hierarchy. 相似文献
996.
A high performance liquid chromatography method using an efficient extraction method was developed for the determination of astaxanthin in eight kinds of animal feed. The chromatographic separation was achieved using a C18 reversed-phase column, using methanol and acetonitrile as the mobile phases with a flow rate of 1 mL/min. The feeds containing astaxanthin were first treated with maxatase, to cause enzymatic hydrolysis, and then extracted with dichloromethane. The optimized method produced recoveries of between 82.4% and 100% for all eight kinds of feed, and the coefficients of variation were lower than 4.28%. The limit of detection, defined as the concentration that gave a signal-to-noise ratio of 3, for astaxanthin was estimated to be 0.1 µg/g. The limit of quantification, defined as the lowest spiked concentration that gave an appropriate level of precision and accuracy, was 0.3 µg/g. Finally, the method developed was used to determine astaxanthin in real, commercially sourced, feed samples. The method met the requirements for the determination of astaxanthin in feed, providing satisfactory recoveries of 70–110%. 相似文献
997.
Limei Dai Wansheng You Lihua Chen Liqiang Chen Lihong Liu Honghui Gai 《Transition Metal Chemistry》2016,41(8):909-915
Two new hybrids based on Keggin polyoxometalates have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single-crystal X-ray diffraction. The crystal structure analyses reveal that complex 1 has an infinite 1D chain structure, constructed from [Cu(2,2′-bpy)(4,4′-bpy)(H2O)] fragments and [H2PMo11VO40]2? building blocks. Complex 2 has a 2D molecular ladder structure, with a basic structural unit composed of one bis(µ-OH) dicopper(II) [Cu2(OH)2(H2O)2(4,4′-bpy)3] fragment, one [HPMo12O40], and four water molecules. The [Cu2(OH)2(H2O)2(4,4′-bpy)3] units connect alternately to form edge rails. The [HPMo12O40] clusters act as rungs of the ladder, linking pairs of Cu atoms from the two adjacent edge rails. The electrochemical behavior of the complexes in modified carbon paste electrodes and their electrocatalytic reduction of nitrite were investigated. 相似文献
998.
Yingwu Yao Lihua Cui Limiao Jiao Xin Chen Naichuan Yu Haishu Dong 《Journal of Solid State Electrochemistry》2016,20(3):725-731
PbO2-CeO2 nanocomposite electrodes were prepared by pulse electrodeposition in the lead nitrate solution containing CeO2 nanoparticles with different duty cycles. The effects of duty cycle on the morphology and phase structure were investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the decrease of duty cycle can reduce the grain size of PbO2-CeO2 nanocomposite electrodes and make the electrodes more compact. The CeO2 content in composite electrodes increases with the decrease of duty cycle. The steady-state polarization curves and accelerated life tests demonstrate that the oxygen evolution overpotential and service life of PbO2-CeO2 nanocomposite electrodes increase with the decrease of duty cycle. The service life of PbO2-CeO2 nanocomposite electrodes prepared with 25 % duty cycle reaches 218 h which is 1.8 times longer than that of PbO2-CeO2 nanocomposite electrodes prepared by direct electrodeposition. The bulk electrolysis shows that the degradation of malachite green (MG) on the PbO2-CeO2 nanocomposite electrodes is the pseudo-first-order reaction and the MG and chemical oxygen demand (COD) removal efficiency on PbO2-CeO2 nanocomposite electrodes increases with the decrease of duty cycle, which can be attributed to the higher oxygen evolution overpotentials, electrochemical active surface area, and CeO2 content in the composite electrodes. 相似文献
999.
Yunxia Yang Lihua Li Li Zhang Wenjing Dong Keying Ding 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(12):981-989
Polymorphism is the ability of a solid material to exist in more than one form or crystal structure and this is of interest in the fields of crystal engineering and solid‐state chemistry. 2,2′‐(Disulfanediyl)dibenzoic acid (also called 2,2′‐dithiosalicylic acid, DTSA) is able to form different hydrogen bonds using its carboxyl groups. The central bridging S atoms allow the two terminal arene rings to rotate freely to generate various hydrogen‐bonded linking modes. DTSA can act as a potential host molecule with suitable guest molecules to develop new inclusion compounds. We report here the crystal structures of three new polymorphs of the inclusion compound of DTSA and trimethylamine, namely trimethylazanium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate 2,2′‐(disulfanediyl)dibenzoic acid monosolvate, C3H10N+·C14H9O4S2−·C14H10O4S2, (1), tetrakis(trimethylazanium) bis{2‐[(2‐carboxyphenyl)disulfanyl]benzoate} 2,2′‐(disulfanediyl)dibenzoate 2,2′‐(disulfanediyl)dibenzoic acid monosolvate, 4C3H10N+·2C14H9O4S2−·C14H8O4S22−·C14H10O4S2, (2), and trimethylazanium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate, C3H10N+·C14H9O4S2−, (3). In the three polymorphs, DTSA utilizes its carboxyl groups to form conventional O—H…O hydrogen bonds to generate different host lattices. The central N atoms of the guest amine molecules accept H atoms from DTSA molecules to give the corresponding cations, which act as counter‐ions to produce the stable crystal structures via N—H…O hydrogen bonding between the host acid and the guest molecule. It is noticeable that although these three compounds are composed of the same components, the final crystal structures are totally different due to the various configurations of the host acid, the number of guest molecules and the inducer (i.e. ancillary experimental acid). 相似文献
1000.
Rapid extraction and determination of 25 bioactive constituents in Alpinia oxyphylla using microwave extraction with ultra high performance liquid chromatography with tandem mass spectrometry 下载免费PDF全文
Zhi Sun Xiangzhen Kong Lihua Zuo Jian Kang Lei Hou Xiaojian Zhang 《Journal of separation science》2016,39(3):603-610
A novel and rapid microwave extraction and ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of 25 bioactive constituents (including two new constituents) in Fructus Alpinia oxyphylla. The optimized conditions of the microwave extraction was a microwave power of 300 W, extraction temperature of 80°C, solvent‐to‐solid ratio of 30 mL/g and extraction time of 8 min. Separation was achieved on a Waters ACQUITY UPLC® HSS C18 column (2.1 mm× 50 mm, 1.8 μm) using gradient elution with a mobile phase consisting of acetonitrile and 1 mM ammonium acetate at a flow rate of 0.2 mL/min. This is the first report of the simultaneous determination of 25 bioactive constituents in Fructus Alpinia oxyphylla by ultra high performance liquid chromatography with tandem mass spectrometry. The method was validated with good linearity, acceptable precision and accuracy. The validated method was successfully applied to determine the contents of 25 bioactive constituents in Fructus Alpinia oxyphylla from different sources and the analysis results were classified by hierarchical cluster analysis, which indicated the effect of different cultivation regions on the contents of constituents. This study provides powerful and practical guidance in the quality control of Alpinia oxyphylla and lays the foundation for further research of Alpinia oxyphylla. 相似文献