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901.
Chromatographic behavior of small organic compounds in low‐temperature high‐performance liquid chromatography using liquid carbon dioxide as the mobile phase 下载免费PDF全文
Tomohiro Motono Takashi Nagai Shinya Kitagawa Hajime Ohtani 《Journal of separation science》2015,38(14):2381-2386
Low‐temperature high‐performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at –35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low‐temperature high‐performance liquid chromatography at temperatures from –35 to –5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl‐silica (C18) column provided reversed phase mode separation, and a bare silica‐gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately –15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high‐performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns. 相似文献
902.
Skeletal Rearrangement of O‐Propargylic Formaldoximes by a Gold‐Catalyzed Cyclization/Intermolecular Methylene Transfer Sequence 下载免费PDF全文
Prof. Dr. Itaru Nakamura Shinya Gima Yu Kudo Prof. Dr. Masahiro Terada 《Angewandte Chemie (International ed. in English)》2015,54(24):7154-7157
Skeletal rearrangement of O‐propargylic formaldoximes, in the presence of gold catalysts, afforded 4‐methylene‐2‐isoxazolines in good to excellent yields by an intermolecular methylene transfer. In addition, the cascade reaction with maleimide in the presence of a gold catalyst afforded isoxazole derivatives by cyclization/methylene transfer and a subsequent ene reaction, whereas that using a copper catalyst gave oxazepines through a 2,3‐rearrangement. 相似文献
903.
Shinya Harusawa Hiroki YoneyamaDaiki Fujisue Masayoshi NishiuraMihoyo Fujitake Yoshihide UsamiZheng-yun Zhao Scott A. McPheeTimothy J. Wilson David M.J. Lilley 《Tetrahedron letters》2012,53(44):5891-5894
Novel C5-linked C0- and C2-tetrazole ribonucleoside phosphoramidites were designed and synthesized via tetrazole C-nucleosides. Pivaloyloxymethyl (POM) and methyl-substituted POM (MePOM) groups were introduced as N-protecting groups in the tetrazole ring that can be readily removed under mild basic conditions. The phosphoramidites were successfully incorporated into the VS ribozyme substrate and hence providing a chemogenetic approach to determine which nucleobases of ribozymes function as the acid or base, in the studies of ribozyme general acid and base catalysis. 相似文献
904.
905.
Abstract It was found that each of the tetrakis(n-alkyldithiolato)dinickel(II), (Cn-DTA)4-Ni2, complexes where n-alkyl is n-pentyl through n-dodecyl, exhibits a broken-fan texture on cooling from an isotropic liquid, and that the phase gave a characteristic lamella structure X-ray diffraction powder pattern. Furthermore, the infrared spectrum of this phase is more similar to that of the isotropic liquid than that of the crystal. Therefore, the phase can be described as a monotropic lamella mesophase. Interestingly, each of the complexes of bis(n-alkylxanthato)nickel(II), (Cn-Xan)2Ni, (n = 5, 7, 9, 11) exhibits double (triple) melting behavior via the isotropic liquid, whereas each of the complexes of (Cn-Xan)2Ni (n = 4, 6, 8, 10, 12) shows ordinary single melting behavior. Such unique double melting accompanied by an even-odd effect appears to be the first example of this in the long chain substituted compounds. Each of the complexes of (Cn-Xan)2 Ni (n = 9, 11, 12) has a monotropic lamella mesophase exhibiting a large broken fan texture. 相似文献
906.
Shinya Harusawa Shuji Nakamura Sayoko Yagi Takushi Kurihara Yasumasa Hamada Takayuki Shioiri 《合成通讯》2013,43(14):1365-1371
A simple and convenient procedure for the syntheses of some nonsteroidal anti-inflammatory agents, ibuprofen, rac-naproxen, clidanac and loxoprofen, is described. 相似文献
907.
908.
Hiroki Bessho Sunao Iwakami Naoshi Hiramatsu Akihiko Hara Shinya Hashimoto 《International journal of environmental analytical chemistry》2013,93(3):155-166
Abstract Vitellogenin is a sensitive biomarker used to study the effects of artificial estrogens in aquatic environments. We developed and optimized a luminometric immunoassay that was able to detect trace amounts of vitellogenin in the serum of male flounder collected from an uncontaminated reference site. The lowest measurable concentration of vitellogenin in the serum was approximately 0.08 ng/ml with purified protein diluted in buffer. The reproducibility of the vitellogenin measurements was determined by the analysis of triplicate samples and found to be about 5.3%, based on serum samples containing vitellogenin at 2.0 ng/ml. This method was successfully applied to samples collected from an uncontaminated reference site for the monitoring of baseline levels of serum vitellogenin in male flounder. 相似文献
909.
Muon transfer from proton to deuteron was examined with muonic X-rays. The parameter q
1s was determined directly and the time spectra of the X-rays were analyzed for effects of the muon transfer reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
910.