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EP Sheretov VS Gurov MV Dubkov OV Korneeva 《Rapid communications in mass spectrometry : RCM》1999,13(16):1699-1702
In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Umberto Vettori Giordano Lesma Micaela Nali Giovanni Palmisano 《Journal of mass spectrometry : JMS》1984,19(6):280-284
The fragmentation pathways of some 4,5-dihydro-1,2,4-benzothiadiazepine-1,1-dioxide derivatives are discussed on the basis of metastable transition data, exact mass measurements and labelling experiments. These compounds show several primary fragmentation processes: M ? SO2, M ? OH and one involving an intramolecular oxygen migration (M ? CH3NO). 相似文献
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DC magnetization, neutron depolarization and neutron diffraction (with both polarized and unpolarized neutrons) measurements
have been reported for the Co1.1−x
Zn
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Ge0.1Fe1.2O1 spinels with x=0.5, 0.6 and 0.7. Neutron depolarization and neutron diffraction measurements confirm the presence of a long range ferrimagnetic
ordering of the local canted spins in these ferrite samples. The observed features of low field magnetization have been explained
under the framework of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins. An important
role of magnetic anisotropy (due to the presence of Co2+ ions) in establishing the magnetic ordering and domain kinetics in these ferrites has been observed. 相似文献
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Gianni Podda Antonio Maccioni Umberto Vettori Sergio Daolio Pietro Traldi 《Journal of mass spectrometry : JMS》1983,18(7):275-277
The reaction of catechol with 2,4-dimethyl-2,3-pentadiene, carried out in the chemical ionization chamber of a VG ZAB2F mass spectrometer, has been studied with respect to the partial pressure of the reacting species. The structure of the reaction product, 2,2-diisopropyl-1,3-benzodioxole, has been proved by exact mass measurements, B/E linked scans, labelling experiments and collisionally activated dissociation mass analysed ion kinetic energy spectra. 相似文献
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Annarella Costanzo Fabrizio Bruni Gabriella Auzzi Silvia Selleri Lorenzo Pecori Vettori 《Journal of heterocyclic chemistry》1990,27(3):695-697
Reaction of 5-ethylamino-3-phenylpyrazole with dicarboxylic acid anhydrides in tetrahydrofuran in the presence of 1,3-dicyclohexylcarbodiimide, afforded bicyclic and tricyclic derivatives of pyrazolo[1,5-a][1,3]-diazepines. The tricyclic derivatives constitute a new class of compounds. Characterisation of these products was effected with ir, pmr, and 13C nmr spectral data. 相似文献
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Pietro Traldi Umberto Vettori Franco Dragoni 《Journal of mass spectrometry : JMS》1982,17(11):587-592
Commercial direct insertion probes generally do not operate under ideal conditions required for direct inlet systems, with the consequence of large decomposition effects for thermolabile compounds. Instrumental parameters for two different probes are given which indicate that under the best conditions a molecular distillation occurs with drastic reduction of pyrolysis processes. 相似文献