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991.
Visible-light photolysis of the cheap starting material [FeCp(η6-toluene)][PF6] (Cpη5-C5H5) using a simple 100-W globe in the presence of diphenyldiphosphinoethane (dppe) and terminal alkynes cleanly yields the vinylidene complexes [FeCp(dppe)(CCHR)][PF6] and, upon further deprotonation, the iron-alkynyl complexes; the reaction is extended to ferrocenylacetylene to yield a bimetallic complex. 相似文献
992.
Didier Morvan Frédéric Gloaguen Philippe Schollhammer Jean-Jacques Yaouanc Nelly Kervarec 《Journal of organometallic chemistry》2009,694(17):2801-1091
The ligand exchange reaction of IMe-(CH2)2-PPh2 (IMe = 1-methyimidazol-2-ylidene) and the hexacarbonyl complex [{Fe2{μ-S(CH2)3S}(CO)6] (1) resulted in the formation of the chelated complex [{Fe2{μ-S(CH2)3S}(CO)4(IMe-(CH2)2-PPh2)] (2). The molecular structure of 2 was confirmed by spectroscopic and X-ray analyses. This complex catalyzes proton reduction. Low temperature NMR studies on the protonation of 2 revealed the formation of a terminal hydride intermediate. 相似文献
993.
994.
Caroline Didier Guillermina Forno Marina Etcheverrigaray Ricardo Kratje Héctor Goicoechea 《Analytica chimica acta》2009,650(2):167-174
The optimal blends of six compounds that should be present in culture media used in recombinant protein production were determined by means of artificial neural networks (ANN) coupled with crossed mixture experimental design. This combination constitutes a novel approach to develop a medium for cultivating genetically engineered mammalian cells. The compounds were collected in two mixtures of three elements each, and the experimental space was determined by a crossed mixture design. Empirical data from 51 experimental units were used in a multiresponse analysis to train artificial neural networks which satisfy different requirements, in order to define two new culture media (Medium 1 and Medium 2) to be used in a continuous biopharmaceutical production process. These media were tested in a bioreactor to produce a recombinant protein in CHO cells. Remarkably, for both predicted media all responses satisfied the predefined goals pursued during the analysis, except in the case of the specific growth rate (μ) observed for Medium 1. ANN analysis proved to be a suitable methodology to be used when dealing with complex experimental designs, as frequently occurs in the optimization of production processes in the biotechnology area. The present work is a new example of the use of ANN for the resolution of a complex, real life system, successfully employed in the context of a biopharmaceutical production process. 相似文献
995.
Andr Benattar Didier Barbry Bruno Hasiak Daniel Couturier 《Journal of heterocyclic chemistry》1981,18(1):63-65
Treatment of 1,1-dimethyl-2-tolylpiperidinium halides with sodium amide in liquid ammonia affords derivatives of 2,3,4,5,6,7-hexahydro-1H-2-benzazonine via the Sommelet-Hauser rearrangement. Structures of the reaction products have been established by 13C nmr. In the case of 1,1-dimethyl-2-benzylpiperidinium halide, only an elimination reaction takes place. 相似文献
996.
997.
Schoeller WW Rozhenko A Bourissou D Bertrand G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(15):3611-3617
The concept of through-space versus through-bond interactions on the stabilization of biradical structures with a singlet or triplet ground state is evaluated for the 1,3-diboracyclobutane-1,3-diyls and related congeners. Singlet biradicals are favored when the intermediate units E feature singlet character (PH(2) (+), AsH(2) (+)), while E fragments with triplet character (NH(2) (+)) induce small energy separations between the lowest singlet and triplet states. These considerations are supported by quantum chemical calculations with energy optimization at 1) MCSCF level plus MR-MP2 correction, 2) MR-MP2 level, and 3) two different types of density functional levels for the planar (D(2h)) geometries. The singlet-triplet energy separations in the planar compounds increase with increasing singlet stability of the corresponding E fragments. In addition to this newly developed principal features for singlet stabilization, which primarily occurs in bonded structures with higher main-group elements, the corresponding valence isomers with bicyclobutane, cyclobutene and cis-butadiene structures are investigated. 相似文献
998.
We study the stress response to a steady imposed shear rate in a concentrated suspension of colloidal particles. We show that, in a small range of concentrations and shear rates, stress exhibits giant fluctuations. The amplitude of these fluctuations obeys a power-law behavior, up to the apparition of a new branch of flow, leading to an excess of high amplitude fluctuations which exhibit a well-defined periodicity. 相似文献
999.
The role of various magnetic interchain couplings is investigated by numerical methods in doped frustrated quantum spin chains. A nonmagnetic dopant introduced in a gapped spin chain releases a free spin-1/2 soliton. The formation of a local magnetic moment is analyzed in terms of soliton confinement. A four-spin coupling which might originate from cyclic exchange is shown to produce such a confinement. Dopants on different chains experience an effective space-extended nonfrustrating pairwise spin interaction. 相似文献
1000.
Delabouglise D Marcus B Mermoux M Bouvier P Chane-Tune J Petit JP Mailley P Livache T 《Chemical communications (Cambridge, England)》2003,(21):2698-2699
Grafting of biotin on top of a polycrystalline boron-doped diamond layer was achieved by surface oxidation followed by an esterification reaction and revealed by fluorescently labelled streptavidin. 相似文献