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51.
(±)-5,2′-Dihydroxy-6,7,6′-trimethoxyflavanone, (-)-5,2′-dihydroxy-6,7,8,6′-tetramethoxyflavanone, chrysin, wogonin, apigenin, isoscutellarein, scutellarein, cosmosiin, and the new flavonoid wogonin-7-O-β-D-glucopyranoside, the structure of which was established using chemical transformations and spectral data, were isolated from Scutellaria immaculata roots.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 26–28, January–February, 2005. 相似文献
52.
A stereoselective synthesis of the ABCD ring framework of azaspiracid-1 and azaspiracid-3 has been achieved using a tandem bis-spiroketalization protocol in the presence of a mild proton source from 1,4-diketone precursor. A tetrahydrofuran intermediate with the correct stereochemistry for the D ring of azaspiracids-1 and 3 was then taken through a linear sequence of reactions to afford the desired diketone precursor. The D-ring of azaspiracid-1 was then constructed by employing a Sharpless asymmetric dihydroxylation followed by etherification using a homoallyl derivative. The structure of the ABCD ring framework with four contiguous rings was established by extensive NMR analysis. 相似文献
53.
Study on the Phase Diagram of CsCl-CeCl3-HCl(11%)-H2O System and the Properties of the Compounds 总被引:2,自引:0,他引:2
The equilibrium solubility of CsCl-CeCl3-HCl(11%)-H2O qua-ternary system at 25℃ has been determined by the physicchemical analysis method ,and the phase diagram was plotted, Two new double salts 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O obtained from the complicated system were identified and characterized by XRD,TG-DTA ,DSC,UV and fluorescence spectroscopy, Studies on the fluorescence excitation and emission show that 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O have upconversion luminescence of infrared-visible range,and the upconversion emission intensity increases with the increase of ratio of CeCl3 in CsCl. 相似文献
54.
55.
Joon Myong Song 《Analytica chimica acta》2004,507(1):115-121
In this work, we report Escherichia coli O157:H7 detection using antibody-immobilized capillary reactors, enzyme-linked immunosorbent assay (ELISA), and a biochip system. ELISA selective immunological method to detect pathogenic bacteria. ELISA is also directly adaptable to a miniature biochip system that utilizes conventional sample platforms such as polymer membranes and glass. The antibody-immobilized capillary reactor is a very attractive sample platform for ELISA because of its low cost, compactness, reuse, and ease of regeneration. Moreover, an array of capillary reactors can provide high-throughput ELISA. In this report, we describe the use of an array of antibody-immobilized capillary reactors for multiplex detection of E. coli O157:H7 in our miniature biochip system. Side-entry laser beam irradiation to an array of capillary reactors contributes significantly to miniaturized optical configuration for this biochip system. The detection limits of E. coli O157:H7 using the ELISA and Cy5 label-based immunoassays were determined to be 3 and 230 cells, respectively. This system shows capability to simultaneously monitor multifunctional immunoassay and high sensitive detection of E. coli O157:H7. 相似文献
56.
报道从中国南海网胰藻Hydroclathrus clathratus中分离得到3个单体化合物,经过MS,IR,1HNMR,13CNMR(DEPT),HMQC和HMBC等波谱技术鉴定为:(6R,7aS)-6-羟基-4,4,7a-三甲基-2,4,5,6,7,7a-六氢苯并呋喃-2-酮(1),1-(2-脱氧-β-D-呋喃核糖)-5-甲基-1,2,3,4-四氢嘧啶-2,4-二酮(2),尿嘧啶(3),并通过X射线单晶衍射实验确定化合物1的立体结构,其中化合物1是首次从自然界中分离得到. 相似文献
57.
5-Amino-4-cyano-8-isobutyl-7-isopropyl-6-thiocarbamoyl-2-azabicyclo[2.2.2]oct-5-en-3-thione was synthesized by the condensation of isovaleryl aldehyde with cyanothioacetamide. The structure of the product was established by X-ray crystallography. 相似文献
58.
《Journal of separation science》2005,28(13):1457-1466
Comprehensive 2‐D size‐exclusion chromatography (SEC×SEC) has been realized. SEC×SEC is not a useful technique for characterizing complex polymers. However, it is potentially an elegant tool to study band‐broadening phenomena. If narrow fractions can be collected from the first dimension, the band broadening in the second dimension is only due to chromatographic dispersion. This would allow a clear distinction to be made between chromatographic band broadening (column and extra‐column) and SEC selectivity (band broadening due to sample polydispersity). In comparison with MALDI‐MS, SEC×SEC allows the study of polymers across a much broader molar‐mass range. 相似文献
59.
A new synthetic route for the preparation of the betain-like compound (CH3N)6P4F8 from (CH3NPF3)2,N-methyl-hexamethyldisilazane andN,N-dimethyl-urea has been found. The steps of this multi-stage reaction could be rationalized to a far extent.
10. Mitteilung:Kubjacek M., Utvary K., Mh. Chem.112, 305 (1981). 相似文献
60.
《Arabian Journal of Chemistry》2022,15(7):103900
Emerging pharmaceutical ingredients (APIs) like sulfamethoxazole (SMX), metronidazole (MNZ) and ciprofloxacin (CIP) are biopersistent and toxic to the environment and public health. In this study, UV/TiO2 photodegradation was applied in the degradation of SMX, MNZ and CIP individually and in a mixture. For a 5 mg/L SMX solution, about 97% of SMX was degraded within 360 min, which was reduced to 80% for 80 mg/L of SMX solution at the same TiO2 dosage and photodegradation time. The maximum removals of MNZ and CIP as individual components were 100% and 89%, respectively at 600 min of photodegradation reaction time. For binary mixtures, the highest removal (100%) was achieved for MNZ and CIP ([MNZ] = [CIP] = 40 mg/L) mixture at 120 min whereas the degradations were 97% and 96% for SMX and MNZ, and SMX and CIP binary mixtures, respectively, even after 600 min of experimental time at the same concentrations. For tertiary mixture, the maximum degradation 99% was observed for (SMX = CIP] = 20 mg/L and [MNZ] = [40 mg/L) at 600 min. The observed reaction rate was 0.01085 min?1 when SMX concentration was 5 mg/L, which decreased to 0.00501 min?1 for SMX concentration of 80 mg/L, indicating decreasing of reaction rate at higher concentration. The results indicate that the UV/TiO2 process is promising to apply for the treatment of pharmaceutical wastewaters. 相似文献