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101.
102.
Kato N Sakayanagi M Nakayama T Nishimura H Ogamo A 《Journal of chromatography. A》2002,973(1-2):159-166
A novel detection method for 21 different anions by thin-layer chromatography is presented. Anions on the target plate form salts with amine in a developing solvent and are visualized after staining with citric acid-acetic anhydride reagent as white spots contrasting against a pale red-pink background. This method has particularly high sensitivity for anions of chlorate, sulfate, phosphate, chromate and dichromate (0.02-0.05 microg). The method is demonstrated to efficiently detect toxic arsenite in curry sauce as an example application. The proposed method offers highly efficient indirect detection for a wide range of anions, and serves as a purification procedure for the preparation of anionic sample solutions for other analytical methods. 相似文献
103.
Treatment of O-tert-butyldimethylsilyloximes having olefin moieties in the molecules with BF3.OEt2 results in efficient generation of N-borano-nitrones, which undergo intramolecular cycloaddition at room temperature to afford N-nonsubstituted cycloadducts after work-up. 相似文献
104.
[reaction: see text] A combined system of boron trifluoride and molecular sieves is an efficient promoter for the carbonyl-ene reaction of alpha-methylsyrenes with paraformaldehyde. The coexistence of BF3 x OEt2 and molecular sieves 4A is essential for obtaining high yields of ene products. 相似文献
105.
Shimizu Y Shiokawa N Yamamoto N Kozuma M Kuga T Deng L Hagley EW 《Physical review letters》2002,89(23):233001
Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally. With less than ten cold rubidium atoms launched into an optical microcavity, up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminal) are observed. Comparison of the experimental data with numerical simulations as well as future experiments are discussed. 相似文献
106.
Wave propagation in laminated plates with delaminations was calculated using the semi-analytical finite element method. The visualization results and deeper numerical analyses revealed the following phenomena on the fundamental Lamb modes at delamination regions of laminated plates. First, Lamb wave propagates toward the delamination, and then splits into two independent waves at the "Entrance" of the delamination with no significant reflections. These two waves reach the "Exit" of the delamination with the different phases and arrival time. Thus reflected and transmitted waves are excited at the Exit. The repetition of such reflections at the Exit causes the multiple reflections at regular intervals corresponding to the delamination size. 相似文献
107.
Manabu Yamamoto Tadashi Shohji Takahiro Kumamaru Yuroku Yamamoto 《Fresenius' Journal of Analytical Chemistry》1981,305(1):11-14
Summary The masking effect of potassium iodide with or without hydroxylamine on the interferences in the atomic-absorption spectrophotometric determination of antimony via its hydride by sodium borohydride tablet reduction has been studied. It has been well known in the conventional colorimetric method [21] that both potassium iodide and stannous chloride completely suppress the evolution of stibine. However, in this sodium borohydride tablet reduction, potassium iodide plays a role in masking the interferences of not only stannous chloride but also other numerous ions. By the procedure established here, the calibration curve was linear up to a concentration of 0.04g/ml of antimony with the coefficient of variation of 2.4 %. The method was successfully applied to the determination of antimony in a river sediment.
Maskierende Wirkung von Kaliumiodid auf Störungen bei der AAS-Bestimmung von Antimon durch Stibinerzeugung mit Hilfe der Natriumborhydridreduktion
Zusammenfassung Es ist bekannt, daß bei der colorimetrischen Bestimmungsmethode [21] sowohl KI als auch SnCl2 die Entwicklung von Stibin vollständig verhindern. Bei der hier beschriebenen Reduktion mit Hilfe einer NaBH4-Tablette maskiert jedoch KI (mit oder ohne Hydroxylaminzusatz) Störungen durch SnCl2 sowie durch zahlreiche andere Ionen. Die Eichkurve verläuft bis zu 0,04 g Sb/ml linear. Der Variationskoeffizient beträgt 2,4 %. Als Anwendungsbeispiel wird die Antimonbestimmung in Flußsedimenten erwähnt.相似文献
108.
Kenji Sumiya Tsunetaka Matsumoto Seiji Watatani Fumttada Hayama 《Journal of Physics and Chemistry of Solids》1979,40(12):1097-1102
Highly coercive magnetic powder was obtained by growing cobalt ferrite on the surface of γ-Fe2O3 particles in highly alkaline suspensions containing cobalt and ferrous ions in a Co/Fe molar ratio = . The mechanism of the growth and the structure of cobalt ferrite on γ-Fe2O3 were studied by X-ray diffraction and electron diffraction techniques. Results show that crystals of cobalt ferrite CoFe2O4 with a spinel type crystal structure of lattice constant 8.415 Å grew epitaxially on γ-Fe2O3. The acicular direction of the epitaxially grown Co-γ-Fe2O3 as well as γ-Fe2O3 was in the [01] direction. It was found that from the lattice constant value and the half width of X-ray diffraction peaks, the lattice constant epitaxially grown Co γ-Fe2O3 may be attributed to two kinds of crystals, viz., seed γ-Fe2O3 () which was partly reduced to Fe3O4, and surface layer CoFe2O4 (). The crystal growth in the interface between the seed crystals and the growth layer was affected by the crystal structure of the seed crystals. The lattice constant of CoFe2O4 which was located in the vicinity of the interface was almost equal to that of the seed crystals. 相似文献
109.
Kouichi Sugihara Hiroshi Kamiya Mieko Yamaguchi Takahiro Kaneda Soichi Misumi 《Tetrahedron letters》1981,22(17):1619-1622
Two quinones bridged with a polyether chain and the corresponding hydroquinones were synthesized, and their redox reaction and complexations with sodium and potassium ions were observed. 相似文献
110.
Ultrathin, large nylon capsules whose porous membranes were corked with charged, synthetic bilayer-forming amphiphiles (cationic, anionic, zwitterionic bilayers) were prepared. The chemically stable, bilayer-corked capsules can selectively retain 0.1 M aqueous acidic (HCl, HNO3, H2SO4, HClO4 and p-toluenesulfonic acid) and alkaline solutions (NaOH, Ba(OH)2, NH4 OH, and N(Et)4OH) in the inner aqueous phase depending on the surface charge of corking bilayers: the capsule corked with positively and negatively charged bilayers could selectively store alkalies and acids, respectively, and could keep a selective pH-gradient across the membrane. The zwitterionic bilayer-corking could retain neither acids nor alkalies in the inner aqueous phase. The permeation of these acids and alkalies to the outer phase (pH gradient decreasing across the capsule membrane) could be reversibly controlled by the phase transition of corking bilayers from gel to liquid crystalline state. The selective storage and permeation of acids and alkalies could be explained by the process of permeation of H+ or OH- counter ions across the charged bilayer-corking. 相似文献