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991.
A rapid protocol for the multicomponent microwave-assisted organocatalytic domino Knoevenagel/hetero Diels-Alder reaction (DKHDA) has been developed for the synthesis of 2,3-dihydropyran[2,3-c]pyrazoles. The reported procedure could be used for the fast generation of novel substituted 2,3-dihydropyran[2,3-c]pyrazoles with potential anti-tuberculosis activity. 相似文献
992.
Environmental biodegradation of synthetic polymers I. Test methodologies and procedures 总被引:1,自引:0,他引:1
Jan P. Eubeler Sabine Zok Marco Bernhard Thomas P. Knepper 《Trends in analytical chemistry : TRAC》2009,28(9):1057-1072
Biodegradation of synthetic polymers is an important property that is used in many applications. Evaluation of the extent of biodegradation has used different methods in recent years. For each environmental compartment, different approaches have to be made in order to obtain valuable data on biodegradability.This review describes validated and accepted methods based on standardized biodegradation tests, analytical tests, enzymatic tests or tests of physical properties to evaluate the biodegradability of synthetic polymers for different types of environmental compartments (e.g., soil, compost or aqueous media).Part II of this review will subsequently report on the environmental biodegradation of different groups of synthetic polymers. 相似文献
993.
Benito Alcaide Prof. Dr. Pedro Almendros Dr. Teresa Martínez del Campo Elena Soriano Dr. José L. Marco‐Contelles Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(8):1909-1928
Calculating cyclization : Theoretical work directed towards the elucidation of the mechanisms of the gold‐, palladium‐, and lanthanum‐catalyzed oxycyclizations (5‐exo versus 6‐endo versus 7‐endo) of γ‐allenols has been pursued in close relationship with the experimental study (Part 1, accompanying paper) and has corroborated the bench results to provide a complete study of the reactivity of γ‐allenols under different metal‐catalyzed conditions.
994.
Massimo Stefanoni Marco Luparia Dr. Alessio Porta Dr. Giuseppe Zanoni Dr. Giovanni Vidari Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(16):3940-3944
Rhenium does the job! A readily available rhenium complex efficiently catalyzed the direct Meyer–Schuster‐like rearrangement of different alkyl‐ and aryl‐substituted propargylic secondary and tertiary alcohols to the corresponding α,β‐unsaturated compounds, which were produced with virtually complete E stereoselectivity. The reaction proceeded under neutral conditions and no racemization of potentially enolizable stereocenters was observed.
995.
A novel free-flow electrophoresis glass chip design with two-depth etched structures for the separation and fractionation of proteins is presented. The microfluidic structures etched in two depths enhance the flow characteristics inside the miniaturized device. A novel nine-port outlet interface enables the fractionation of the separated analytes. The separation and focussing of a protein sample mixture demonstrated the ability of the new chip. 相似文献
996.
H. El Shinawi J.F. Marco F.J. Berry C. Greaves 《Journal of solid state chemistry》2009,182(8):2261-2268
The M4+-containing K2NiF4-type phases La0.8Sr1.2Co0.5Fe0.5O4 and La0.8Sr1.2Co0.5Mn0.5O4 have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermal analysis, neutron powder diffraction and Mössbauer spectroscopy. Oxide ion vacancies are created in these materials via reduction of M4+ to M3+ and of Co3+ to Co2+. The vacancies are confined to the equatorial planes of the K2NiF4-type structure. A partial reduction of Mn3+ to Mn2+ also occurs to achieve the oxygen stoichiometry in La0.8Sr1.2Co0.5Mn0.5O3.6. La0.8Sr1.2Co0.5Fe0.5O3.65 contains Co2+ and Fe3+ ions which interact antiferromagnetically and result in noncollinear magnetic order consistent with the tetragonal symmetry. Competing ferromagnetic and antiferromagnetic interactions in La0.8Sr1.2Co0.5Fe0.5O4, La0.8Sr1.2Co0.5Mn0.5O4 and La0.8Sr1.2Co0.5Mn0.5O3.6 induce spin glass properties in these phases. 相似文献
997.
Lara Bianchi Giovanni Petrillo Egon Rizzato Elda Severi Marco Stenta Cinzia Tavani 《Tetrahedron》2009,65(1):336-757
(1E,3Z)-1-Aryl-4-methanesulfonyl-2-nitro-1,3-butadienes (8), derived from the initial ring-opening of 3-nitrothiophene (5), have been found to undergo a facile base-induced cyclization leading to thiopyran S,S-dioxides (9), thus furnishing a further example of effective ring-enlargement from 5- to 6-membered sulfur heterocycles. Compounds 9 are obtained as single racemic mixtures in satisfactory yields; they still contain a nitrovinylic moiety, which can be exploited for further modifications targeted to new derivatives endowed with either synthetic or pharmacological potentialities e.g., in the field of L-type Ca2+-channel blockers. 相似文献
998.
Liuqing Yang Marco Hill Dr. Meitian Wang Dr. Santosh Panjikar Dr. Joachim Stöckigt Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(28):5211-5213
Cutting carbons : The three‐dimensional structure of polyneuridine aldehyde esterase (PNAE) gives insight into the enzymatic mechanism of the biosynthesis of C9‐ from C10‐monoterpenoid indole alkaloids (see scheme). PNAE is a very substrate‐specific serine esterase. It harbors the catalytic triad S87‐D216‐H244, and is a new member of the α/β‐fold hydrolase superfamily. Its novel function leads to the diversification of alkaloid structures.
999.
Kristoffer Haldrup Dr. Morten Christensen Marco Cammarata Dr. Qingyu Kong Dr. Michael Wulff Prof. Simon O. Mariager Klaus Bechgaard Prof. Robert Feidenhans'l Prof. Niels Harrit Prof. Martin M. Nielsen Prof. 《Angewandte Chemie (International ed. in English)》2009,48(23):4180-4184
Molecular movies : Time‐resolved X‐ray scattering provides direct structural information on an electronically excited complex while it is formed in the bimolecular reaction between excited octahydrogen[tetrakis‐μ‐diphosphito‐1κP:2κP′‐diplatinate](4‐) (PtPOP*) and thallium ions. In the exciplex one thallium(I) and two platinum(II) ions are found to be collinear.
1000.
Louis Jeanjean Marco Squassina 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2009,26(5):465
For a general class of autonomous quasi-linear elliptic equations on we prove the existence of a least energy solution and show that all least energy solutions do not change sign and are radially symmetric up to a translation in . 相似文献