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71.
Experimental Techniques - 相似文献
72.
Let F be a field, let A be a vector space over F, and let GL(F, A) be the group of all automorphisms of the space A. If H is a subgroup of GL(F, A), then we set aug dimF (H) = dimF (A(ωFH)), where ωFH is the augmentation ideal of the group ring FH. The number aug dimF (H) is called the augmentation dimension of the subgroup H. In the present paper, we study locally solvable linear groups with minimality condition for subgroups of infinite augmentation
dimension.
__________
Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 57, No. 11, pp. 1476–1489, November, 2005. 相似文献
73.
74.
The First Molybdenum(VI) and Tungsten(VI) Oxoazides MO2(N3)2, MO2(N3)2⋅2 CH3CN, (bipy)MO2(N3)2, and [MO2(N3)4]2− (M=Mo,W) 下载免费PDF全文
Ralf Haiges Juri Skotnitzki Zongtang Fang David A. Dixon Karl O. Christe 《Angewandte Chemie (International ed. in English)》2015,54(33):9581-9585
Molybdenum(VI) and tungsten(VI) dioxodiazide, MO2(N3)2 (M=Mo, W), were prepared through fluoride–azide exchange reactions between MO2F2 and Me3SiN3 in SO2 solution. In acetonitrile solution, the fluoride–azide exchange resulted in the isolation of the adducts MO2(N3)2⋅2 CH3CN. The subsequent reaction of MO2(N3)2 with 2,2′‐bipyridine (bipy) gave the bipyridine adducts (bipy)MO2(N3)2. The hydrolysis of (bipy)MoO2(N3)2 resulted in the formation and isolation of [(bipy)MoO2N3]2O. The tetraazido anions [MO2(N3)4]2− were obtained by the reaction of MO2(N3)2 with two equivalents of ionic azide. Most molybdenum(VI) and tungsten(VI) dioxoazides were fully characterized by their vibrational spectra, impact, friction, and thermal sensitivity data and, in the case of (bipy)MoO2(N3)2, (bipy)WO2(N3)2, [PPh4]2[MoO2(N3)4], [PPh4]2[WO2(N3)4], and [(bipy)MoO2N3]2O by their X‐ray crystal structures. 相似文献
75.
Direct Catalytic Enantio‐ and Diastereoselective Ketone Aldol Reactions of Isocyanoacetates 下载免费PDF全文
Dr. Raquel de la Campa Dr. Irene Ortín Prof. Dr. Darren J. Dixon 《Angewandte Chemie (International ed. in English)》2015,54(16):4895-4898
A catalytic asymmetric aldol addition/cyclization reaction of unactivated ketones with isocyanoacetate pronucleophiles has been developed. A quinine‐derived aminophosphine precatalyst and silver oxide were found to be an effective binary catalyst system and promoted the reaction to afford chiral oxazolines possessing a fully substituted stereocenter with good diastereoselectivities and excellent enantioselectivities. 相似文献
76.
The thermo-stimulated luminescence of γ-irradiated commercial polytetrafluoroethylene (PTFE) was explored. There are up to four intense maxima in the luminescence curves of different formulations of PTFE. The position and number of maxima remain constant at doses up to 30 kGy. The differences of the glow curves in the different copolymers may be the result of impurities capable of reacting with ions or radicals formed under irradiation and by differences in the polymer’s topological structures. 相似文献
77.
A polyvinylidene fluoride film has been bombarded with accelerated (1–5 MeV) helium ions at a fluence of 1015 ion/cm2. Unlike the completely amorphous structure of the unirradiated polymer, the weight fraction of the crystalline modification in the irradiated polymer is 0.86–0.90, which is indicative of the efficient conversion of the amorphous structures of the polymer pseudo-network into the crystalline ones. Irradiation with 1-MeV ions leads to the greatest changes in the fraction of the crystalline modification and the glass-transition and flow temperatures of the polymer. The detachment of fluorine and the surface carbonization of the irradiated polymer occur under the ion beam. 相似文献
78.
Duncan A. Hay Fiona M. AdamGerwyn Bish Frederick CaloRachel Dixon M. Jonathan FrayJames Hitchin Peter JonesMichael Paradowski Gemma C. ParsonsKatie J.W. Proctor David C. PrydeNicholas N. Smith Thien-Duc Tran 《Tetrahedron letters》2011,52(44):5728-5732
A flexible route which enables access to derivatives of 4-amino-1,3-dihydroimidazo[4,5-c]pyridin-2-ones is described. Issues of selectivity, reaction safety, and low yields in original routes are overcome with the key improvements to the route, including a Negishi cross-coupling and use of a carbamate as a protecting group and intrinsic carbonyl source. The new route enables variation of C-6 and N-1 substituents. 相似文献
79.
The role of the ocean in the cycling of oxygenated volatile organic compounds (OVOCs) remains largely unanswered due to a paucity of datasets. We describe the method development of a membrane inlet-proton transfer reaction/mass spectrometer (MI-PTR/MS) as an efficient method of analysing methanol, acetaldehyde and acetone in seawater. Validation of the technique with water standards shows that the optimised responses are linear and reproducible. Limits of detection are 27 nM for methanol, 0.7 nM for acetaldehyde and 0.3 nM for acetone. Acetone and acetaldehyde concentrations generated by MI-PTR/MS are compared to a second, independent method based on purge and trap-gas chromatography/flame ionisation detection (P&T-GC/FID) and show excellent agreement. Chromatographic separation of isomeric species acetone and propanal permits correction to mass 59 signal generated by the PTR/MS and overcomes a known uncertainty in reporting acetone concentrations via mass spectrometry. A third bioassay technique using radiolabelled acetone further supported the result generated by this method. We present the development and optimisation of the MI-PTR/MS technique as a reliable and convenient tool for analysing seawater samples for these trace gases. We compare this method with other analytical techniques and discuss its potential use in improving the current understanding of the cycling of oceanic OVOCs. 相似文献
80.
Polymerization of tetrafluoroethylene and methyl methacrylate has been initiated by active sites arising upon γ-radiolysis
of perfluorinated organic acids and their derivatives. In the low-temperature radiolysis, two types of active sites are formed.
The active sites of the first type (supposedly, -ĊF-COO−), which provide the most efficient polymerization at low temperatures, are accumulated during radiolysis of NaPFNA both at
77 and 300 K. The active sites of the second type, supposedly, of the radical type, are accumulated during radiolysis at 77
K and annealed during heating the sample to room temperature. 相似文献