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91.
Herbert Muffler Guenter Siegemund Werner Schwertfeger 《Journal of fluorine chemistry》1982,21(2):107-132
4.5-Perfluoro-1.3-dioxolanes are available by reaction of 2(α-chloroalkoxy)perfluoro-carbonyl halides or -ketone with fluoride ions. A mechanism for the intramolecular ring- closure-reaction is proposed. Hydrogen atoms at C-2 in can be exchanged photochemically by chlorine. Starting from the 2-monochloro-derivatives the 2-monofluoro-4.5-perfluoro- 1.3-dioxolanes are formed by reaction with triethylamine- hydrofluoride. 相似文献
92.
9 氯甲基蒽 ( 1 )与 3 ,5 二甲氧基苄醇 ( 2 )在相转移催化剂存在下反应生成 9 ( 3 ,5 二甲氧基苄基氧甲基 )蒽 ( 3 ) .( 3 )的苯溶液在紫外光照射下发生蒽环与苯环间的分子内 [4π + 4π]光致环加成反应 ,定量地生成多环化合物 ( 4 ) .( 4 )在热的作用下发生逆反应 ,定量地转化成原料 ( 3 ) .这种光致可逆反应可应用于制备光开关材料 . 相似文献
93.
Abstract— Escherichia coli cells treated with sublethal doses of acridine plus near-UV light exhibit an effective split-dose recovery response that requires an incubation period of about 30–45 min. Studies of the metabolic requirements for split-dose recovery revealed the following: (a) DNA synthesis is not required for split-dose recovery; (b) inhibition of electron transport or protein synthesis reduces the efficiency of split-dose recovery by about one-half; (c) inhibition of phospholipid synthesis or cell wall synthesis completely eliminates the split-dose recovery response. These results suggest an involvement of membrane repair mechanisms in response to damage by acridine plus near-UV light. Additional evidence for such a process was provided by more direct assays for membrane recovery. It was found that cells treated with sublethal doses of acridine plus near-UV light are sensitive to low concentrations of detergents, and lose that sensitivity upon incubation. Likewise, treated cells are susceptible to lethal osmotic shock, but can recover from this susceptibility if incubated after treatment but prior to exposure to low osmotic conditions. Based on accumulating evidence, we propose that E. coli cells are capable of repairing membrane damage resulting from exposure to acridine plus near-UV light. 相似文献
94.
Substituierte 2-(Thiazol-4-yl)-phenole als Liganden und potentielle Extraktionsmittel für Kupfer(II)
Substituted 2-(Thiazol-4-yl)-phenols as Ligands and Potential Extractants for Copper (II) Substituted 2-(thiazol-4-yl)-phenols are obtained by the HANTZSCH synthesis. Their solubility in toluene is higher than in n-octane depending on the position, the chain length, and the polarity of the substituents. From alcoholic solutions complexes of the type CuL2n are precipitated. According to the substituents their structure is distorted octahedral (CuL22, CuL23) or distorted tetrahedral (CuL28, CuL29). The new complexes are nearly insoluble in toluene and aliphatic hydrocarbons, but CuL28 and CuL29 are soluble in chloroform. Therefore copper(II) may be extracted by HL8 and HL9 using chloroform as a diluent. 相似文献
95.
The 13C NMR spectra of a series of 7-substituted 1,4-dialkylspiro[4.5]decanes and of suitable reference compounds are assigned and the derived substituent effects upon the chemical shifts are discussed. In particular, consideration of γ and δ-effects allows the differentiation between 1,4-cis- and 1,4-trans-compounds. Furthermore, the (relative) configuration of the chiral spiroatom C-5 is determined. 相似文献
96.
Christoph Luef Aloke Paul Jiri Vizdal Ales Kroupa Alexander Kodentsov Herbert Ipser 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):381-395
Summary. The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500°C by a drop calorimetric technique
using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500°C were constructed.
Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well
as the invariant reaction temperature of the ternary eutectic L ⇄ (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found
at 135°C. 相似文献
97.
98.
E. L. Wagner 《Theoretical chemistry accounts》1974,32(4):295-310
Potential surfaces for Li2O and Al2O have been calculated by an ab initio SCF-LCAO-MO method and by the semiempirical CNDO method. For both molecules the semiempirical methods incorrectly imply unreasonable structures with very acute apex angles and very long bond distances — rather more like diatomic Li2 or Al2 molecules with O-atoms attached to their bonds. Our ab initio treatment does correctly predict a symmetrical linear configuration for Li2O with bond distances in excellent agreement with experiment. This method also predicts a linear symmetrical structure for Al2O, in agreement with experimental gas phase measurements but in disagreement with matrix-isolation studies. 相似文献
99.
Rudolf Wagner 《Fresenius' Journal of Analytical Chemistry》1976,282(4):315-321
Summary Problems, techniques and means of water sampling are reviewed. Applicability and performance are discussed with regard to individual and composite samples, and also to automatic sampling. Storage and preservation of samples are dealt with.
Probenahme und Behandlung von ProbenWasser
Zusammenfassung Probleme, Verfahren und Hilfsmittel bei der Probenahme von Wasser werden behandelt. Ausführung und Anwendbarkeit von Einzel und Mischproben sowie der automatischen Probenahme werden diskutiert, ebenso die Aufbewahrung und Konservierung von Proben.
Start of discussion held at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria. 相似文献
100.
A new phase CrTe3 was discovered and its existence was confirmed by differential thermal analysis and X-ray investigations. Symmetry and lattice parameters as well as the temperature of its peritectic decomposition were determined.
Über die PhaseCrTe 3
Zusammenfassung Eine neue Phase CrTe3 wurde entdeckt und ihre Existenz wurde mittels differential-thermoanalytischer und röntgenographischer Untersuchungen sichergestellt. Es wurden Symmetrie und Gitterparameter sowie auch die Temperatur des peritektischen Zerfalls bestimmt.相似文献