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排序方式: 共有8143条查询结果,搜索用时 15 毫秒
61.
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Mathiazhagan C Molzon WR Cousins RD Konigsberg J Kubic J Melese P Rubin P Slater WE Wagner D Hart GW Kinnison WW Lee DM McKee RJ Milner EC Sanders GH Ziock HJ Arisaka K Knibbe P Urheim J Axelrod S Biery KA Irwin GM Lang K Margulies J Ouimette DA Ritchie JL Trang QH Wojcicki SG Auerbach LB Buchholz P Highland VL McFarlane WK Sivertz M Chapman MD Eckhause M Ginkel JF Hancock AD Joyce D Kane JR Kenney CJ Vulcan WF Welsh RE Whyley RJ Winter RG 《Physical review letters》1989,63(20):2181-2184
63.
Summary The complexestrans-[Ru(NH3)4(H2O)PPh3](PF6)2 and [Ru(NH3)5L](PF6)2, (L=AsPh3 or SbPh3) have been isolated and characterized by microanalysis, cyclic voltammetry and ultraviolet-visible spectroscopy. The specific rate constants for the aquation of [Ru(NH3)5L]2+ totrans-[Ru(NH3)4L(H2O)]2+ are (2.5±0.1)×10–5s–1 and (1.8±0.1)×10–5s–1 for L=AsPh3 and SbPh3, respectively, at 25.0±0.1°C; =0.10 mol dm–3, NaO2CCF3. Under the same conditions, the second-order rate constants for the substitution of water intrans-[Ru(NH3)4(H2O)L]2+ by isonicotinamide (isn) are 1.2±0.1, (6.3±0.3)×10–2 and (3.8±0.2)×10–2
m
–1s–1 for L=PPh3, AsPh3, and SbPh3, respectively, suggesting that the order of decreasingtrans-effect is: PPh3AsPh3>SbPh3. The formation constants for thetrans-[Ru(NH3)4L(isn)]2+ complexes are 75±3, (1.40±0.01)×103 and (1.80±0.02)×103M–1 for L=PPh3, AsPh3, and SbPh3, respectively, suggesting that the order of increasingtrans-influence is: SbPh33PPh3. 相似文献
64.
BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-X. SYNTHESES AND ANALYSES OF SULFONATED PHTHALOCYANINES 总被引:5,自引:0,他引:5
Hasrat Ali Réjean Langlois J. Richard Wagner Nicole Brasseur Benoit Paquette Johan E. VAN Lier 《Photochemistry and photobiology》1988,47(5):713-717
Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono- to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous-methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments. 相似文献
65.
The natural products cis-p-menthane-1,7-diol (cis-IV), cis-p-menth-8-ene-1,7-diol (cis-I) and cis-p-menthane-1,7,8-triol (cis-II) are obtained starting from the corresponding cis-cyanohydrins, cis-2 and cis-7, respectively, by chemical transformation of the cyano into the hydroxymethyl group. The key step of the synthesis is the very high cis-selectivity (> or = 96 %) of the MeHNL-catalyzed HCN addition to 4-alkylcyclohexanones. From 4-isopropylcyclohexanone (1) the cyanohydrin cis-2 and from 4-(1-methylvinyl)cyclohexanone (6) the cyanohydrin cis-7 result almost quantitatively. Regioselective hydroxylation of cis-I affords the triol cis-II. X-ray crystal structure determinations of the final products confirm their cis-configuration. 相似文献
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68.
Silvio De Bernardini Georg Graf Colin A. Leach Peter Bühlmayer Felix Waldmeier Christoph Tamm 《Helvetica chimica acta》1983,66(2):639-651
The modified nucleoside Πd (1) was used in the synthesis of the oligonucleotide d (TpTpΠpCpGpTpCpApApApApTpC). Diester methodology being unsatisfactory, the triester synthesis was investigated with the unnatural nucleoside. An improved method of nucleoside phosphorylation was developed for the synthesis of the fully-protected nucleotide 2e. This molecule could be cleanly and selectively deprotected, and allowed the efficient synthesis of the desired oligonucleotide. 相似文献
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70.
Azidomethyl–polystyrene, obtained by nucleophilic substitution of chloromethyl–polystyrene, undergoes a Schmidt rearrangement when treated with trifluoromethanesulfonic acid, affording amino–polystyrene. To assess its loading and reactivity the resin is used as a support for the preparation of triazene-linked amine. 相似文献