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Set-Valued and Variational Analysis - In this paper we consider a class of infinite horizon variational problems resulting from a transformation of singular variational problems. Herein we assume... 相似文献
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Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used as a powerful multielement analytical method
for trace analysis of geological glasses which are useful as reference materials for geochemical in-situ microanalytical work.
The quantification of the analytical results was carried out using the BCR-2G and NIST 612 glass standard reference material
(SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most
of the elements, with increasing mass an increasing of relative sensitivity coefficients was observed. The relative standard
deviation (RSD) for determination of trace element concentration of most elements (N=3) are between 2 and 10%. The determination
of trace elements in various geological glasses by LA-ICP-MS yielded a good agreement with the reference values and those
results of other trace analytical methods.
Received October 15, 1999. Revision April 14, 2000. 相似文献
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Taking the regio‐ and chemoselectivities of our iron complex precursors with pyridine core in aerobic oxidations into account, we envisioned a more effective influence on catalytic properties by the introduction of different substituents in 4‐position of the pyridine moiety. The synthesis of these novel 4‐substituted (pyridine‐2,6‐diyl)dipropanoic acids 4 is described. Analogously to the unsubstituted derivative, ligands 4 reacted with Fe(ClO4)3 to form trinuclear Fe3(μ3‐O) complexes 3 , which were tested in the aerobic Gif‐type oxidation of α‐pinene to myrtenol, verbenone, myrtenal, and pinene oxide. The electronic nature of the substituents was found to slightly effect the ratio of allylic oxidation/epoxidation, whereas its influence on the oxidation preference of secondary to primary C? H bonds is negligible as compared to the unsubstituted complex. 相似文献
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Alessandra Basso Sabine L. Flitsch Ian Brazendale Paolo Linda Lucia Gardossi 《Tetrahedron》2005,61(4):971-976
Hydrolytic yields as high as 80% were obtained by using penicillin G amidase (PGA) on substrates anchored on optimized positively charged PEGA polymers. By increasing the amount of permanent charges inside the polymer, electrostatic interactions between the positively charged PEGA+ and the negatively charged PGA (pI=5.2-5.4) were strengthened, thus favouring the accessibility of the bulky enzyme (MW=88 kDa) inside the pores. The effect of different amounts of charges on polymer swelling and protein retention inside the polymer was investigated and correlated to the enzyme efficiency demonstrating that electrostatic interactions predominate over swelling properties in determining enzyme accessibility. 相似文献
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