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971.
Tomás Moya-Pizarro Roger Salmon Léopold Fournes Gilles Le Flem Barbara Wanklyn Paul Hagenmuller 《Journal of solid state chemistry》1984,53(3):387-397
Single crystals of the high-temperature form of NaFeP2O7 have been grown by a flux technique. II-NaFeP2O7 crystallizes in the monoclinic space group with lattice parameters: a = 7.298(2) Å, b = 7.874(2) Å, c = 9.536(3) Å, β = 111.85(2)°. The structure refined from 1481 independent reflections leads to R = 0.044 and confirms the work previously published by M. Gabelica-Robert, M. Goreaud, P. Labbe, and B. Raveau (J. Solid State Chem.45, 389, 1982). Magnetic Mössbauer resonance studies have shown the existence of antiferromagnetic ordering with a weak ferromagnetic component below 30 K. The FeO bond is markedly ionic in character due to the highly polarizing power of phosphorus in tetrahedral site. 相似文献
972.
A. V. Guttsait S. V. Belyakov A. F. Mishnev Ya. Ya. Bleidelis é. Yu. Gudrinietse 《Chemistry of Heterocyclic Compounds》1987,23(9):986-989
4-Trifluoromethyl-6-phenyl-2-chloro-3-cyanopyridine was synthesized, and its molecular-crystal structure was established. The chlorine atom was replaced by amino, mercapto, thiocyanato, and azido groups. The possibility of the direct amination of 4-trifluoromethyl-6-phenyl-3-cyano-2-pyridone by the action of hexamethylphosphoric triamide (HMPT) was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1233–1237, September, 1987. 相似文献
973.
Zh. Bo J. H. Yan X. D. Li Y. Chi K. F. Cen B. G. Chéron 《Plasma Chemistry and Plasma Processing》2007,27(5):546-558
The combined effects of oxygen and water vapor on three typical volatile organic compounds, i.e. tetrachloromethane, n-butane and toluene, decomposition efficiency under gliding arc gas discharge conditions are studied. The electron density
and the density of the reactive radicals such as O and OH are modified by addition of oxygen and water vapor. Consequently,
the decomposition process can be enhanced or suppressed, depending on the involved chemical structures and reaction channels.
The addition of oxygen and water vapor suppresses the tetrachloromethane decomposition which indicates that this process is
mainly controlled by the electron dissociation reactions. By contrast, the n-butane and toluene decompositions are enhanced, which shows that they can be mainly ascribed to the radical induced reactions.
Especially, in a moist atmosphere the OH radicals are supposed to play the most important role in the n-butane decomposition process. 相似文献
974.
Development of an analytical procedure for determination of selected estrogens and progestagens in water samples 总被引:1,自引:0,他引:1
An analytical procedure has been developed for determination of eight selected natural and synthetic hormonal steroids in surface water and in effluent samples. Several methodological points have been investigated and are discussed; they include the choice of the solid-phase extraction sorbent, the influence of flow rate on recovery, the breakthrough volume for a given sorbent (Env+ and Oasis HLB), sample clean up, and sample storage. As regards the latter point, it was found that when no preservative was added to effluent from a sewage-treatment plant, severe loss of steroids occurred—85% of progesterone and about 30% of both estrone and estradiol were found to be degraded in 24 h. The procedure developed was applied to samples from the Seine river estuary. Sex steroids were not detected in surface water; estrone was the most commonly detected steroid in sewage-treatment plant effluent, with levels ranging from 1.8 to 8.3 ng L–1. Synthetic estrogens (ethynylestradiol and mestranol) and progestagens (levonorgestrel and norethindrone) were never detected, whatever the sampling season. Overall, for 162 out of 168 measurements levels were below the detection limits of the developed procedure. 相似文献
975.
Alain H. Roux Daniel Hétu Gérald Perron Jacques E. Desnoyers 《Journal of solution chemistry》1984,13(1):1-25
Mixed micelles can be formed in water between various pairs of hydrophobic solutes such as surfactants, alcohols and hydrocarbons. These systems can often be studied through the thermodynamic functions of transfer of one of the solutes, usually kept near infinite dilution, from water to an aqueous solution of the other solute. When mixed micelles are formed, these functions change significantly, and often go through extrema, in the region where the binary system micellizes or undergoes some microphase transition.Three main effects are responsible for the observed trends: pair-wise interactions between both solutes in the monomeric form, a distribution of the reference solute between the aqueous and micellar phases and a shift in the monomer-micelle equilibrium in the vicinity of the reference solute. Simple equations can be derived for these three effects which can account for the sign and magnitude of the observed trends using parameters which are derived for the most part from the two binary systems. 相似文献
976.
Ru-based catalysts can be used in E-selective cross metathesis (CM) reactions to synthesise various functionalised internal allylic monofluorides. 相似文献
977.
Petra Spitzer Bruno Rossi Yves Gaignet Stéphane Mabic Uwe Sudmeier 《Accreditation and quality assurance》2005,10(3):78-81
There is currently a major issue with the calibration of conductivity meters used for high purity water: the lack of availability of a reference material or reference methods for low conductivity ranges (conductivity below 1 S cm–1 at 25.0 °C, resistivity >1 M cm at 25.0 °C). This paper describes the current status of conductivity measurements in high purity water. A new and improved approach, currently being investigated, should allow us to make the calibration of conductivity meters used for low conductivity ranges traceable to the SI.Milipore, Milli-Q and Elix are registered trademarks of Millipore Corporation. 相似文献
978.
Summary An extension of the multiconfigurational SCF approach for the resolution of the vibrational problem is presented; it follows the philosophy of the CASSCF method developed in Quantum Chemistry. The new method allows a more complete treatment of anharmonic mode couplings, converges much faster and gives a clearer physical insight of vibrational interactions. This is exemplified by the calculation of infrared transition moments in the H2O and D2O isotopomers of the water molecule. It is shown how this property varies with the quality of the wave function when vibrational resonances occur. A detailed analysis by means of this new VCASSCF method demonstrates the crucial importance of excited bending oscillators in the intensity of some pure stretching transitions.Boursier F.R.I.A. 相似文献
979.
Pandya SU Garçon C Chavant PY Py S Vallée Y 《Chemical communications (Cambridge, England)》2001,(18):1806-1807
The vinylzinc reagents derived from hydrozirconation of alkynes and transmetallation add readily to nitrones to yield pure (E)-N-allylhydroxylamines; some of these rearrange into O-allylhydroxylamines. 相似文献
980.
Jean-Pierre Labbé 《Mikrochimica acta》1964,52(2-4):298-316
Résumé L'auteur reprend et complète la méthode de dosage microgravimétrique du germanium à l'état de germanimolybdate de tétraphénylarsonium (F
Ge=0,02137). Dans une deuxième partie, il décrit une méthode de préparation des heptagermanates alcalins et de métagermanates de métaux bivalents à partir des solutions d'oxyde GeO2 et d'acétates métalliques. Les courbes de thermolyse et les spectres d'absorption infrarouge sont présentés. Aucun orthogermanate ne précipite des solutions aqueuses.
Mémoire en l'honneur du professeurA. A. Benedetti-Pichler. 相似文献
Summary The author resumes and completes the method for the microgravimetric determination of germanium as the germanium molybdate of tetraphenylarsonium (F Ge=0.02137). In a second part he describes a method for preparing some heptagermanates of divalent metals from solutions of the oxide GeO2 and metal acetates. The thermolysis curves and the infrared absorption curves are given. No orthogermanate precipitates from aqueous solutions.
Zusammenfassung Der Verfasser berichtet über die mikrogravimetrische Bestimmung des Germaniums als Tetraphenylarsonium-Germanium-Molybdat (F Ge=0,02137). Im zweiten Teil der Arbeit wird die Herstellung von Alkaliheptagermanat sowie von Metagermanaten bivalenter Metalle aus Germaniumoxidlösungen und Metallacetaten beschrieben. Die Thermolysekurven und IR-Absorptionsspektren werden vorgelegt. Aus wäßrigen Lösungen fällt kein Orthogermanat aus.
Mémoire en l'honneur du professeurA. A. Benedetti-Pichler. 相似文献