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1.
Veličković Jelena Đ. Andrić Deana Roglić Goran Tešic Živoslav Lj. Milojković-Opsenica Dušanka M. 《平面色谱法杂志一现代薄层色谱法》2004,17(4):255-260
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica... 相似文献
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Isoflavonoids are a class of organic compounds that act primarily as antioxidants. They are produced almost exclusively by various members of the bean family including soybeans, tofu, peanuts, chick peas, and alfalfa. The antioxidant characteristics that isoflavonoids exhibit help hinder the progression of certain cancers, primarily breast, prostate, and colon cancer. We have developed a three-five step synthesis for obtaining a suite of isoflavonoid derivatives. The synthesis involves an enamine formation, a ring closure and halogenation, a Suzuki coupling, and finally a global deprotection to obtain the respective isoflavonoid derivatives. 相似文献
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Methyl 3-0-benzyl-2,4,6-trideoxy-6-iodo-α-D--hexopyranoside was prepared from D-glucose and demonstrated to have potential utility as a chiral synthon for the elaboration of HMG-CoA reductase inhibitors. 相似文献
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Deana Desa 《Advances in Data Analysis and Classification》2018,12(4):841-865
This study examined how a non-linear modeling of ordered categorical variables within multiple-group confirmatory factor analysis supported measurement invariance. A four-item classroom disciplinary climate scale used in cross-cultural framework was empirically investigated. In the first part of the analysis, a separated categorical confirmatory factor analysis was initially applied to account for the complex structure of the relationships between the observed measures in each country. The categorical multiple-group confirmatory factor analysis (MGCFA) was then used to conduct a cross-country examination of full measurement invariance namely the configural, metric, and scalar levels of invariance in the classroom discipline climate measures. The categorical MGCFA modeling supported configural and metric invariances as well as scalar invariance for the latent factor structure of classroom disciplinary climate. This finding implying meaningful cross-country comparisons on the scale means, on the associations of classroom disciplinary climate scale with other scales and on the item-factor latent structure. Application of the categorical modeling appeared to correctly specify the factor structure of the scale, thereby promising the appropriateness of reporting comparisons such as rankings of many groups, and illustrating league tables of different heterogeneous groups. Limitations of the modeling in this study and future suggestions for measurement invariance testing in studies with large numbers of groups are discussed. 相似文献
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Milman G Barnes AJ Schwope DM Schwilke EW Goodwin RS Kelly DL Gorelick DA Huestis MA 《Analytical and bioanalytical chemistry》2011,401(2):599-607
Oral fluid (OF) is an increasingly accepted matrix for drug testing programs, but questions remain about its usefulness for
monitoring cannabinoids. Expectorated OF specimens (n = 360) were obtained from 10 adult daily cannabis smokers before, during, and after 37 20-mg oral Δ9-tetrahydrocannabinol (THC) doses over 9 days to characterize cannabinoid disposition in this matrix. Specimens were extracted
and analyzed by gas chromatography–mass spectrometry with electron-impact ionization for THC, 11-hydroxy-THC, cannabidiol,
and cannabinol, and negative chemical ionization for 11-nor-9-carboxy-THC (THCCOOH). Linear ranges for THC, 11-hydroxy-THC,
and cannabidiol were 0.25–50 ng/mL; cannabinol 1–50 ng/mL; and THCCOOH 5–500 pg/mL. THCCOOH was the most prevalent analyte
in 344 specimens (96.9%), with concentrations up to 1,390.3 pg/mL. 11-hydroxy-THC, cannabidiol, and cannabinol were detected
in 1, 1, and 3 specimens, respectively. THC was detected in only 13.8% of specimens. The highest THC concentrations were obtained
at admission (median 1.4 ng/mL, range 0.3–113.6) from previously self-administered smoked cannabis. A total of 2.5 and 3.7%
of specimens were THC-positive at the recommended Substance Abuse and Mental Health Services Administration (2 ng/mL) and
Driving Under the Influence of Drugs, Alcohol and Medicines (DRUID) (1 ng/mL) confirmation cutoffs, respectively. THC is currently
the only analyte for monitoring cannabis exposure in OF; however, these data indicate chronic therapeutic oral THC administration
and illicit oral THC use are unlikely to be identified with current guidelines. Measurement of THCCOOH may improve the detection
and interpretation of OF cannabinoid tests and minimize the possibility of OF contamination from passive inhalation of cannabis
smoke. 相似文献
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Harbron EJ Vicente DA Hadley DH Imm MR 《The journal of physical chemistry. A》2005,109(48):10846-10853
We report fluorescence studies of phototriggered changes in spectral position and shape for two azobenzene-functionalized poly(p-phenylenevinylene) derivatives, poly(2-methoxy-5-(4-phenylazophenyl-4'-(1,10-dioxydecyl))-1,4-phenylenevinylene) (MPA-10-PPV) and poly(2-hexyloxy-5-(4-phenylazophenyl-4'-(1,10-dioxydecyl))-1,4-phenylenevinylene) (HPA-10-PPV). Upon trans --> cis azobenzene photoisomerization, small (ca. 1 nm) blue shifts in spectral position are observed for MPA-10-PPV in 100% toluene, a good solvent for this polymer. These shifts are reversed upon visible irradiation and can be cycled many times. To probe the dependence of these shifts on initial polymer conformation, a dichloromethane-methanol cosolvent study was performed in which the solvent quality was decreased incrementally to induce a reduction in polymer coil dimensions. Unirradiated dichloromethane solutions of both MPA-10-PPV and HPA-10-PPV showed a red shift and reduction in quantum yield with increasing methanol concentration as expected based on literature results for other poly(p-phenylenevinylene) derivatives. These changes have been attributed to a dramatic conformational collapse by others and occur for these azo polymers over the 30-60% (v/v) methanol range. While little or no light-induced spectral shifting was observed at low (or=70%) methanol concentrations, significant spectral shifts were observed for both polymers upon azobenzene photoisomerization in solutions with 30-60% methanol, the same range over which the polymer undergoes collapse to a highly coiled state. The largest shifts are visible to the eye, with a 65:35 (v/v) dichloromethane-methanol solution of HPA-10-PPV showing yellow-orange fluorescence when the azobenzenes are trans, green fluorescence when they are cis, and yellow-orange again after the azobenzenes are returned to the trans state. We attribute these color changes to a reversible UV-phototriggered expansion of polymer coil dimensions that occurs as a result of trans --> cis azobenzene side chain isomerization and provide temperature data to support this conclusion. 相似文献
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Rose KG Jaber DM Jaber DA Gondo CA Hamilton DG 《The Journal of organic chemistry》2008,73(10):3950-3953
Heating of the solid ammonium salts obtained from treatment of mellitic acid with 3 equiv of a primary amine yields trisubstituted mellitic triimides via dehydration and imide ring closure. This surprisingly simple synthetic approach is amenable to incorporation of alkyl, aryl, and amino acid ester substituents, thereby opening broad access to a family of C(3)-symmetric organic electron acceptors. 相似文献