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991.
A reliable and rapid method based on rapid-resolution liquid chromatography-diode array detection (RRLC-DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) has been developed for the isolation and characterization of multiple constituents in the root of Stellera chamaejasme L., which was extracted by sonication with methanol in an optimized procedure. Separation of the multiple constituents was achieved on an Agilent Zorbax XDB-C18 (50x3.0 mm i.d.; 1.8 microm) column using a gradient elution at a flow rate of 0.4 mL/min. The detection wavelength was 210 nm. Mass spectra were acquired in both positive and negative modes. A formula database of the known chemical constituents in the root of Stellera chamaejasme L. was established by an Agilent software. Twenty-two obvious peaks appeared in the total ion chromatogram and nine of them were characterized by TOF/MS. The RRLC-DAD and ESI-TOF/MS method with ultrasonic extraction would be useful for rapid and effective characterization of chemical constituents in the root of Stellera chamaejasme L. 相似文献
992.
Two new copper(II) complexes of [Cu(Ofloxacin)(phen)(H2O)] · (NO3) · 2H2O and [Cu(Levofloxacin)(phen)(H2O)] · (NO3) · 2H2O were obtained and their structures were studies. Both ligands and complexes were assayed against gram-positive and gram-negative
bacteria by the in vitro doubling dilutions method. The inhibitory effect of the ligands and complexes on the leukemia HL-60
cell line were measured with the MTT assay method and the liver cancer HePG-2 cell line measured by the SRB method. The results
indicated that the complexes have stronger inhibitory effect on HL-60 than on HePG-2. The complex [Cu(Levofloxacin)(phen)(H2O)] · (NO3) · 2H2O (I) has stronger effect on HL-60 than the complex (Cu(Ofloxacin)(phen)(H2O)] · (NO3) · 2H2O (II).
The text was submitted by the authors in English. 相似文献
993.
建立在食品及环境样品中特丁硫磷残留量的气相色谱检测及气质联用确证法。样品采用乙酸乙酯提取、活性炭-酸性氧化铝复合小柱净化,丙酮-正己烷混合溶液(体积比为1:9)洗脱,样液浓缩后经GC—FPD检测.外标法定量,GC—MS定性。GC—FPD法分析时,特丁硫磷在不同样品、不同水平的加标回收率为74.5%~103.3%.RSD为2.1%~11.7%(n=5),方法的检出限为0.001mg/kg.气质联用法确证时,特丁硫磷的SIM离子为186、231(Q,100)、288. 相似文献
994.
A novel enzyme immobilization technique based on thionine‐bovine serum albumin conjugate (Th‐BSA) and gold colloidal nanoparticles (nano‐Au) was developed. Thionine was covalently bound onto the BSA film with glutaraldehyde(GA) as cross‐linker to achieve Th‐BSA conjugate. The free amino groups of thionine were then used to attach nano‐Au for the immobilization of horseradish peroxidase (HRP). Such nano‐Au/Th‐BSA matrix shows a favorable microenvironment for retaining the native activity of the immobilized HRP and thionine immobilized in this way can effectively shuttle electrons between the electrode and the enzyme. The proposed biosensor displays excellent catalytic activity and rapid response for H2O2. The linear range for the determination of H2O2 is from 4.9×10?7 to 1.6×10?3 M with a detection limit of 2.1×10?7 M at 3σ and a Michaelies‐Menten constant K value of 0.023 mM. 相似文献
995.
996.
Dr. Fei-ze Li Jun-shan Geng Dr. Kong-qiu Hu Li-wen Zeng Jing-yang Wang Xiang-he Kong Prof. Ning Liu Prof. Zhi-fang Chai Dr. Lei Mei Prof. Wei-qun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(34):8730-8736
We present here the synthesis of a novel fluorescent actinide polyrotaxane compound URCP1 through the utilization of an end-cutting pseudorotaxane precursor with only the cucurbit[6]uril (CB[6]) macrocyclic components acting as linking struts. The non-coordinating guest motif in the obtained polyrotaxane, with increased freedom and structural flexibility, can display intriguing temperature-triggered conformational variations inside the cavity of CB[6], which was clearly evidenced by crystallographic snapshots at different temperatures. Notably, this observation of temperature-triggered structural dynamics in URCP1 represents the first report of actinide polyrotaxane with such feature in solid-state. Moreover, URCP1 has a high photoluminescence quantum yield (PLQY) of 49.8 %, comparable to other luminescent uranyl compounds, and can work as a fluorescent probe to selectively detect Fe3+ over other eight competing cations in aqueous solution, with the limit of detection being as low as 4.4×10−3 ppm. 相似文献
997.
Jiazhuang Chen Yuke Zhong Dr. Yalan Liu Dr. Lei Zhang Dr. Mei Li Dr. Wei Han Prof. Zhifang Chai Prof. Weiqun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(42):e202200443
AlCl3-NaCl was utilized as an electrolyte in this work due to its low melting point and Lewis acidity, in which samarium exists in two oxidation states, Sm(III) and Sm(II), resulting in unique electrochemical behaviours. Sm metal dissolves in AlCl3-NaCl melt to form SmCl2, which is verified by electrochemical and spectroscopic techniques. As the Lewis acidity of the melt increases, the diffusion coefficient of Sm(II) gradually increases, and the activation energy of diffusion decreases. Moreover, an additional co-reduction peak of Sm3+ and AlCl4− is observed to be more positive than that of Al(0)/Al(III) in Lewis basic melt, which may be tightly correlated with the variation of Sm(II) coordination in AlCl3-NaCl melt and ligand variation from Cl− to AlCl4− and Al2Cl7− as the Lewis acidity of the AlCl3-NaCl melt increases, according to the in situ electronic absorption spectra of Sm in this melt. 相似文献
998.
999.
聚碳酸酯(PC)与聚酯做成合金后可发生酯交换反应,影响材料的性能及稳定性,采用几种不同的手段去量化这二者之间的反应,为阻燃合金配方的设计提供指导作用。利用差式扫描量热仪(DSC)和静态热分析仪(TMA)对PC与聚酯之间的反应程度进行判别及量化。结果表明,酯交换反应程度越小时,DSC和TMA测试结果是DSC测得?t_m和?t_c越小,TMA测得的平均线性膨胀系数越大。 相似文献
1000.