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111.
112.
Mikko Kalmi Mohammed Lahcini Pascal Castro Olli Lehtonen Ahmed Belfkira Markku Leskel Timo Repo 《Journal of polymer science. Part A, Polymer chemistry》2004,42(8):1901-1911
The use of tetrakis Sn(IV) alkoxides as highly active initiators for the ring‐opening polymerization of D ,L ‐lactide is reported. The activities of prepared Sn(IV) tetra‐2‐methyl‐2‐butoxide, Sn(IV) tetra‐iso‐propoxide, and Sn(IV) tetra‐ethoxide were compared to a well‐known ring‐opening polymerization initiator system, Sn(II) octoate activated with n‐butanol. All polymerizations were conducted at 75 °C in toluene. The activities of tetrakis Sn(IV) alkoxides grew in order of increasing steric hindrance, and the bulky Sn(IV) alkoxides showed higher activity than the Sn(II) octoate/butanol system. The living character of the polymerization was demonstrated in homopolymerization of D ,L ‐lactide and in block copolymerization of L ‐lactide with ?‐caprolactone. 1H, 13C, and 119Sn NMR were used to characterize the prepared Sn(IV) alkoxides and the polymer microstructure, and size exclusion chromatography was used to determine the molar masses as well as the molar‐mass distributions of the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1901–1911, 2004 相似文献
113.
Pihlaja K Martiskainen O Stájer G 《Rapid communications in mass spectrometry : RCM》2007,21(5):653-660
The electron ionization mass spectrometric behavior of pyrroloquinazolinones (1-6) and isoindoloquinazolinones (7-14) was studied. These compounds were further classified as partly saturated pyrroloquinazolinones (1-3), benzologues (7-11), methylene-bridged derivatives (4-6, 12, 13) and a bisacyl compound (14). The mass spectra of the pyrrolo- and isoindoloquinazolinones did not exhibit stereospecific retro-Diels-Alder (RDA) fragmentations. The cyclohexane-fused compounds 7 (cis annelated) and 8 (trans annelated) did display some other ions differing in their abundances that could be used to differentiate this pair of stereoisomers. Also the cyclohexene-fused compounds 2, 3, 9 and 10 exhibited somewhat different ion abundances pairwise that could be utilized for isomeric differentiation. Earlier hypothesis of pyrrolo ring cleavage via the loss of C(3)H(5)O(.) was strengthened by the fragmentation of compounds 1-4. RDA(+/-H) fragmentation is more favorable than the formation of [M-R](+) ions (R=H, C(6)H(4)CH(3), or C(6)H(4)Cl) when an unsaturated bicyclic group is present but both RDA fragmentation and [M-R](+) formation occur for cyclohexene-fused compounds, possibly because of the lower ring strain than with norbornene-fused compounds. The [M-H](+) ion was abundant for compounds 7 and 8 as was [M-Ar](+) for 1-4 and 11. Although the compounds studied might participate in amide-imidol tautomerism, no indication of such tautomerism was detected. 相似文献
114.
Local behaviour of a K-quasiconformal mapping f at a point z0of maximal stretching is studied. A sufficient condition forthe existence of the finite limit lim(f(z) f(z0))/(z z0)|z z0|1/K1 as z z0, and a criterionfor z0 to be a point of maximal stretching are given. 相似文献
115.
Abstract We study Harnack type properties of quasiminimizers of the
-Dirichlet integral on metric measure spaces equipped with a doubling measure and supporting a Poincaré inequality. We show
that an increasing sequence of quasiminimizers converges locally uniformly to a quasiminimizer, provided the limit function
is finite at some point, even if the quasiminimizing constant and the boundary values are allowed to vary in a bounded way.
If the quasiminimizing constants converge to one, then the limit function is the unique minimizer of the
-Dirichlet integral. In the Euclidean case with the Lebesgue measure we obtain convergence also in the Sobolev norm.
Keywords: Metric space, doubling measure, Poincaré inequality, Newtonian space, Harnack inequality, Harnack convergence theorem
Mathematics Subject Classification (2000): 49J52, 35J60, 49J27 相似文献
116.
Risto Pöykiö Kati Manskinen Juha Oksanen Hannu Nurmesniemi Olli Dahl 《Chemical Papers》2014,68(11):1546-1554
The main impetus for utilising the biosludge from the neutral sulphite semi-chemical pulping process is the Finnish legislation which from 1st January 2016 prohibits the deposition of this residue in landfills in Finland. The dry matter content of the biosludge in this case study was low (12.1 mass %), meaning that incineration of this residue is uneconomical. The biosludge was rich in P (6260 mg kg?1). This, together with the high total organic carbon value of 459 g kg?1 and the metal concentrations (As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) lower than the Finnish permissible limits for land application, supports wide and various end-uses for this residue. Except for S (27600 mg kg?1) and Cd (1.4 mg kg?1), the other heavy metal concentrations in the biosludge were lower than the maximum values for heavy metal concentrations in a non-contaminated soil referred to the literature. From the utilisation perspective, and in view of the high levels of S and Na, this residue could efficiently be used, for example, to landscape landfills. 相似文献
117.
118.
Martin T. Söderström Raimo A. Ketola Olli Kostiainen 《Fresenius' Journal of Analytical Chemistry》1995,352(6):550-556
GC-FTIR spectra of 55 nerve agent homologues and dialkyl methylphosphonates have been analyzed. Infrared spectral library searches together with retention index searches have been used for identification of nerve agent homologues and dialkyl methylphosphonates. 相似文献
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120.