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91.
Nathalie Laronze Jean-François Moisan Catherine Roch-Marchal Feng-Xian Liu Gilbert Hervé 《Journal of Cluster Science》2002,13(3):355-368
Transition metal salts of heteropolyacids have been prepared taking into account the strong acidic and cation exchanging properties of the solid heteropolyacids. The exchange between protons and the transition metal cation is carried out by stirring a suspension of the hydrated heteropolyacid in a solution of the metal acetylacetonate complex in toluene. The exchange occurs on the surface of the solid particles and diffusion of protons and metal cations into the hydrated lattice leads to the substitution of all the protons. The method can be utilized in order to prepare supported vanadyl and copper molybdophosphates from supported heteropolyacids and they have been studied in the catalysis of the oxidative dehydrogenation of isobutyric acid. The effect of vanadyl counter-ions on the catalytic behavior is the same as observed with bulk catalysts but, on the contrary, copper supported molybdophosphate shows an acid catalytic activity not observed with bulk catalysts. 相似文献
92.
Zouhair Asfari Rym Abidi Françoise Arnaud Jacques Vicens 《Journal of inclusion phenomena and macrocyclic chemistry》1992,14(2):163-169
The template synthesis of copper(II) phthalocyanine by the condensation of dicyanobenzene within the supercages of Cu(II) exchanged X and Y type zeolites was studied using differential scanning calorimetry. The exotherms for intrazeolite and surface complexation have been resolved. These thermal events exhibit a dependence on the copper loading and hydration level which has been interpreted as a pressure effect. 相似文献
93.
Cantat T Jaroschik F Nief F Ricard L Mézailles N Le Floch P 《Chemical communications (Cambridge, England)》2005,(41):5178-5180
New samarium carbene complexes have been synthesized and characterized by X-ray diffraction analysis; the carbenic nature was assessed by reactivity studies. 相似文献
94.
A laboratory information management system (LIMS) can make a major contribution to the quality and therefore to the efficiency
and competitiveness of a laboratory. Since it can impact all aspects of a laboratory's organization it must be the key if
not the principal player of the laboratory's quality system. It should support the laboratory in establishing, maintaining
and applying quality procedures thereby enabling the laboratory to achieve its quality goals. As a tool, LIMS permits the
laboratory to input and use its own know-how and experience to optimize the total organization (internal and external) and
workflow of generated information. However, perceived "quality" in the context of an LIMS, can be viewed as being made up
of different facets such as the security, reliability and accessibility of information as well as its turn around time and
production cost. This paper reviews the role of a LIMS in the laboratory and the contribution that both system design and
functionality can have on "building quality ".
Received: 5 October 1998 · Accepted: 20 October 1998 相似文献
95.
Menezes PH Gonçalves SM Hallwass F Silva RO Bieber LW Simas AM 《Organic letters》2003,5(10):1601-1604
[reaction: see text] Several (77)Se NMR experiments were performed by titrating a sample of selenides with the chiral shift reagent methylbenzylamine (MBA), followed by acquisition of (77)Se NMR spectra. Eventually, we observed the appearance of two anisochronous resonances, with a relatively large separation, from 37 to 56 Hz, corresponding to the formation of the diastereomeric complexes. This methodology avoids derivatization processes, and the studied compound can be easily recovered from the NMR tube. 相似文献
96.
Françoise Maugé Jean-Paul Gallas Jean-Claude Lavalley Guido Busca Gianguido Ramis Vincenzo Lorenzelli 《Mikrochimica acta》1988,95(1-6):57-61
In the far IR region at low molybdenum loadings, Mo-SiO2 catalysts present a pseudomolybdate or a polymolybdate species, while bulk-like MoO3 appears at loadings close to the geometrical monolayer coverage. W-SiO2 and V-SiO2 spectra show bands close to those observed on the corresponding bulk oxides.In the case of TiO2, Al2O3, ZrO2 supported catalysts, a band is observed near 1000 cm–1 which is assigned to the Mo=O stretching vibration of coordinatively unsaturated Mo
n+ ions showing a stronger interaction with the support than one observed on silica. 相似文献
97.
The scope of catalytic enantioselective tandem carbonyl ylide formation-intramolecular [3 + 2] cycloadditions 总被引:1,自引:0,他引:1
Hodgson DM Labande AH Pierard FY Expósito Castro MA 《The Journal of organic chemistry》2003,68(16):6153-6159
Catalytic enantioselective tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reactions of 2-diazo-3,6-diketoesters show promising scope in terms of asymmetric induction as the tethered alkene/alkyne dipolarophile component is varied. Cycloadditions were found to occur in moderate to very good yields, with a difference in ee exhibited by the electronically different 2-diazo-3,6-diketoesters 1, 25 and 33, 34. Values for ee of up to 90% for alkene dipolarophiles and up to 86% for alkyne dipolarophiles were obtained. 相似文献
98.
A new selenite ion selective electrode using solid salts of Ag(2)Se and Cu(2)S has been developed. Detailed information is provided concerning the composition, working pH and conditioning of the electrode. The change of potential with concentration is found to be linear in the range of 10(-5)-10(-2) M, the slope of the linear portion is 28 mV/10-fold change in selenite concentration. The effect of other ions on selenite response is evaluated and selenium content of anodic slime is determined. 相似文献
99.
Development of quantitative vitellogenin-ELISAs for fish test species used in endocrine disruptor screening 总被引:5,自引:0,他引:5
Nilsen BM Berg K Eidem JK Kristiansen SI Brion F Porcher JM Goksøyr A 《Analytical and bioanalytical chemistry》2004,378(3):621-633
The yolk protein precursor vitellogenin (Vtg) in plasma has proved to be a simple and sensitive biomarker for assessing exposure of fish to environmental estrogens. Within international bodies such as the Organization for Economic Cooperation and Development (OECD) work is ongoing to develop screening and testing programmes for endocrine disrupting effects of new chemicals, and in the focus of this development are the fish test species common carp (Cyprinus carpio), fathead minnow (Pimephales promelas), zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes). In this study we have developed quantitative enzyme linked immunosorbent assays (ELISAs) for Vtg in common carp/fathead minnow, zebrafish and Japanese medaka. The assays were developed using a combination of monoclonal and polyclonal fish Vtg antibodies in a sandwich format, using stabilized Vtg from the test species as a standard. The carp Vtg ELISA has a working range of 1–63 ng/mL, a minimal detection limit of 0.6 ng/mL, and may also be used for quantification of Vtg in fathead minnow. In fathead minnow whole-body homogenate samples, the practical detection limit is 400 ng/mL due to the matrix effect. The zebrafish Vtg ELISA has a working range of 0.5–63 ng/mL, a minimal detection limit of 0.4 ng/mL, and a practical detection limit of 200 ng/mL in whole-body homogenate samples. The medaka Vtg ELISA has a working range of 0.25–16 ng/mL, a minimal detection limit of 0.1 ng/mL, and a practical detection limit of 125 ng/mL in whole-body homogenate samples. The intra- and inter-assay variations were below 20% for all assays. The assays were evaluated with sets of representative samples spanning the wide dynamic range of Vtg-levels found in fish exposed to environmental estrogens, and all three assays are currently undergoing international inter-laboratory validation. 相似文献
100.
Eupatorium cannabinum subsp. corsicum (L.), an aromatic plant, is an endemic subspecies from Corsica. The essential oil from aerial parts of E. cannabinum subsp. corsicum was studied by GC, GC/MS and 13C NMR. One hundred and forty-seven components were identified representing 93.6% of the total amount. The main constituents are germacrene D (28.5%), alpha-phellandrene (19.0%) and para-cymene (5.2%). A particularity of this essential oil is the presence of monoterpene esters derived from nerol, lavandulol, borneol, thymol and 8,9-dehydrothymol. These compounds have been investigated using GC/MS in different ionization modes like electron impact (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI). 相似文献