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41.
Dietrich Estel Manfred Mohnke Frans Biermans Harald Rotzsche 《Journal of separation science》1995,18(7):403-412
This paper deals with the separation of alkanes, naphthenes, and aromatic compounds in naphtha and reformate, on a newly developed apolar high resolution GC column. The selectivity of this apolar phase has been compared with those of squalane, DB-1, and SE-30. A total of 95 hydrocarbons were reliably identified, mostly by GC-MS. Repeated measurements of Kováts retention indices are presented as evidence for the reproducible manufacture of fused silica columns coated with this phase. 相似文献
42.
Hans-Detlev?GilsingEmail author Jürgen?Angerer Dietrich?Prescher 《Monatshefte für Chemie / Chemical Monthly》2005,136(5):795-801
Summary. The synthesis of an oxidative major metabolite of bis(2-ethylhexyl) phthalate is described. The target molecule and its ring-deuterated isomer were obtained via acylation of the appropriate -hydroxy benzyl ester or the corresponding carboxylate with phthalic anhydride or phthalic anhydride-d4. All transformation steps proceed with high yields. 相似文献
43.
Cosper MM Jameson GN Davydov R Eidsness MK Hoffman BM Huynh BH Johnson MK 《Journal of the American Chemical Society》2002,124(47):14006-14007
The combination of resonance Raman, electron paramagnetic resonance and M?ssbauer spectroscopies has been used to investigate the effect of S-adenosyl-l-methionine (SAM) on the spectroscopic properties of the [4Fe-4S]2+ cluster in biotin synthase. The results indicate that SAM interacts directly at a unique iron site of the [4Fe-4S]2+ cluster in BioB and support the hypothesis of a common inner-sphere mechanism for the reductive cleavage of SAM in the radical SAM family of Fe-S enzymes. 相似文献
44.
Alessandro B. Tossi Helmut Görner Dietrich Schulte-Frohlinde 《Photochemistry and photobiology》1989,50(5):585-597
The reactions of polyuridylic acid [poly(U)] with Ru(bpy)3(3+) [Ru(III)] and SO4.-, following UV and visible light irradiation of Ru(bpy)3(2+) [Ru(II)] in the presence of S2O8(2-), were studied in an argon-saturated aqueous solution using time-resolved absorption and conductivity methods. The kinetics of the Ru(III) conversion to Ru(II) in the presence of poly(U) was monitored spectroscopically either in the absence of SO4.- [rapid mixing with Ru(III)] or in its presence (after laser flash excitation, lambda exc = 353 nm). The conversion of Ru(III) to Ru(II) is complete at a [nucleotide]/[sensitizer] (N/S) ratio greater than or equal to 10 (rate constant k = 12 s-1) for rapid mixing and at N/S greater than or equal to 6 (k = 15 s-1 at N/S = 10) after laser pulsing. Conductivity measurements following the laser pulse revealed a fast conductivity increase (risetime less than 10 micros), due to the formation of charged species and protons. A slower increase in the 0.1-0.5 s range was observed for poly(U) but it is considerably smaller for poly(dU) and absent in uracil containing monounits. The slow increase is unaffected by pH changes in the 3.5-7 range, markedly reduced in the 7-9 range and is replaced by a slight decrease in conductivity in buffered solutions. An explanation is that poly(U)-bound excited Ru(II) reacts with S2O8(2-) forming Ru(III) and SO4.- as oxidizing species both of which react with poly(U) bases. The resulting base radicals react with Ru(III) or the ligands in the ruthenium complex, producing protons which give rise to the slow conductivity increase (k = 15 s-1 at N/S = 10). The formation of single-strand breaks and the ensuing release of condensed counterions does not appear to contribute significantly to the slow conductivity signal. At N/S less than 10 the observed rate and extent of Ru(III)--Ru(II) conversion and of the slow proton production vary markedly with the N/S ratio. 相似文献
45.
46.
We report the synthesis and physical studies of a novel porphyrazine (pz) dimer [1[Ni,Cu]]2, which has Ni(II) ions incorporated into the pz cores and is linked by two Cu(II) ions coordinated to bis(picolinamide) chelates attached to the pz periphery. [1[Ni,Cu]]2 was prepared from precursor pz 2 with a selenodiazole ring fused to the pz core. This ring was deprotected to form the diamino-pz 3, which reacted with 2 mol of picolinoyl chloride hydrochloride to form pz 1[2H,2H], with peripheral bis(picolinamide) chelates; this was metalated to form [1[Ni,Cu]]2. The crystal structures of 1[2H,2H] and [1[Ni,Cu]]2 are presented. The latter is a dimer in which parallel, face-to-face pz's with an average separation of 3.30 angstroms are linked through the peripheral picolinamide ligands by a pair of peripheral Cu(II) ions. Each Cu(II) is coordinated with distorted square-planar geometry by a picolinamide from each pz. In this report, we focus on the interaction of these two peripheral Cu(II) ions. We discuss the preparation and magnetic properties of the pz dimer complex [1[Ni,Cu]]2 with two Cu(II) ions in the peripheral chelate but a diamagnetic metal ion Ni(II) in the pz core. Although [1[Ni,Cu]]2 contains two Cu(II) ions (S = 1/2), we could detect no electron paramagnetic resonance signal, which suggests very strong antiferromagnetic exchange between those two Cu(II) ions. Temperature-dependent magnetic susceptibility measurement gives an exchange splitting between the S = 0 ground state and the excited triplet state of delta = 660 cm(-1). 相似文献
47.
Abe K Akagi T Anthony PL Antonov R Arnold RG Averett T Band HR Bauer JM Borel H Bosted PE Breton V Button-Shafer J Chen JP Chupp TE Clendenin J Comptour C Coulter KP Court G Crabb D Daoudi M Day D Dietrich FS Dunne J Dutz H Erbacher R Fellbaum J Feltham A Fonvieille H Frlez E Garvey D Gearhart R Gomez J Grenier P Griffioen KA Hoibraten S Hughes EW Hyde-Wright C Johnson JR Kawall D Klein A Kuhn SE Kuriki M Lindgren R Liu TJ Lombard-Nelsen RM Marroncle J Maruyama T Maruyama XK McCarthy J Meyer W 《Physical review letters》1995,74(3):346-350
48.
Adams MR Aïd S Anthony PL Averill DA Baker MD Baller BR Banerjee A Bhatti AA Bratzler U Braun HM Breidung H Busza W Carroll TJ Clark HL Conrad JM Davisson R Derado I Dhawan SK Dietrich FS Dougherty W Dreyer T Eckardt V Ecker U Erdmann M Faller F Fang GY Figiel J Finlay RW Gebauer HJ Geesaman DF Griffioen KA Guo RS Haas J Halliwell C Hantke D Hicks KH Hughes VW Jackson HE Jancso G Jansen DM Jin Z Kaufman S Kennedy RD Kinney ER Kirk T Kobrak HG Kotwal AV Kunori S Lancaster S Lord JJ Lubatti HJ 《Physical review letters》1995,74(9):1525-1529
49.
van den Brand JF Ent R Anthony PL Arnold RG Arrington J Beise EJ Belz JE Bosted PE Bulten H Chapman MS Coulter KP Dietrich FS Epstein M Filippone BW Gao H Gearhart RA Geesaman DF Hansen J Holt RJ Jackson HE Jones CE Keppel CE Kinney ER Kuhn S Lee K Lorenzon W Lung A Makins NC Margaziotis DJ McKeown RD Milner RG Mueller B Napolitano J Nelson J O'Neill TG Papavassiliou V Petratos GG Potterveld DH Rock SE Spengos M Szalata ZM Tao LH van Bibber K Wasson DA White JL Zeidman B 《Physical review D: Particles and fields》1995,52(9):4868-4871
50.
Makins NC Ent R Chapman MS Hansen J Lee K Milner RG Nelson J Arnold RG Bosted PE Keppel CE Lung A Rock SE Spengos M Szalata ZM Tao LH White JL Coulter KP Geesaman DF Holt RJ Jackson HE Papavassiliou V Potterveld DH Zeidman B Arrington J Beise EJ Belz E Filippone BW Gao H Lorenzon W Mueller B McKeown RD O'Neill TG Epstein M Margaziotis DJ Napolitano J Kinney E Anthony PL van Bibber K Dietrich FS Gearhart RA Patratos GG Kuhn SE van den Brand JF Bulten H Jones CE 《Physical review letters》1994,72(13):1986-1989