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排序方式: 共有325条查询结果,搜索用时 15 毫秒
51.
Development and validation of methods for the trace determination of phthalates in sludge and vegetables 总被引:1,自引:0,他引:1
Sablayrolles C Montréjaud-Vignoles M Benanou D Patria L Treilhou M 《Journal of chromatography. A》2005,1072(2):233-242
A routine method which is simple, quick and precise has been set up and validated for phthalate analysis in environmental samples (tomato plants and sewage sludges). Six phthalates have been studied simultaneously: dimethylphthalate, diethylphthalate, di-n-butylphthalate, n-butylbenzylphthalate, di-2-ethyl-hexyl phthalate (DEHP) and di-n-octylphthalate. Optimization of sample, solvent extraction uses a Soxtec apparatus and extract purification with an a solid-phase extraction cartridge allows between 90 and 110% recovery of phthalates. Precise, sensitive and selective identification and quantifying of analytes is by GC-MS in the single ion monitoring mode. This protocol allows analytes with concentrations as low as 10 microg/kg dry matter (DM) to be determined from small (1-2 g DM) samples. This analytical method has been applied to the phthalate transfer study for agricultural recycling of sludges, where phthalate bioavailability has been studied in aquiculture using two types of experiments. Tomatoes have been grown in containers where the trace organics have been directly introduced as pure substances, and in a second experiment under the same growth conditions, sewage sludge has replaced the pure substances. Transfer of these trace organics has been followed into the various parts of the tomato plant and in general only the DEHP is worthy of note although its percentage transfer remains very low even in an experiment designed to maximize this. 相似文献
52.
Mireille Richard-Plouet Jean-Louis Guille Yves Frere Louis Danicher 《Journal of Sol-Gel Science and Technology》2002,25(3):207-213
A new process to control the distribution of metal nanoparticles is proposed. It involves the use of complexing microcapsules obtained by interfacial polycondensation. The latter are hollow spheres constituted of a polymer membrane, containing an insoluble active ingredient, such as a polyacrylic acid, which can complex Co2+ ions. These capsules are dispersed in a silica sol followed by thermal treatments and reduction under H2 which results in metallic Co nanoparticles confined in the capsules domains. The particles do not diffuse in the matrix. 相似文献
53.
Pascal Thebault Mireille Starita-Geribaldi Serge Geribaldi 《Journal of fluorine chemistry》2007,128(3):211-218
New semi-fluorinated amidosulfobetaines, homologs of hydrocarbon amidosulfobetaines (ASB) commonly used in two-dimensional gel electrophoresis (2DE), were prepared in three steps from 2-F-alkylethyl iodide or F-alkyl iodide. Their synthesis was described and their air-water interface properties were investigated and compared with their perhydrogenated counterpart properties. The influence of the relative lengths of the perfluorinated and hydocarbonated moieties was discussed. 2DE of a rat testicular membrane fraction was performed comparatively using one of these fluorinated sulfobetaines and its hydrocarbon homolog; these preliminary results showed the great potential of the semi-fluorinated sulfobetaines in proteomic analysis. 相似文献
54.
Mireille Bourhis René Golse Michel Goursolle Philippe Picard 《Tetrahedron letters》1985,26(29):3445-3448
Amino norbornenonecarboxylates were synthesized from methyl acrylate and amino butadienecarboxylates. This result is equivalent of amino cyclopentadienones Diels-Alder reaction. Amino butadienecarboxylates were prepared by prototropic transposition of the β-allenic aminoesters. 相似文献
55.
Novikov A Caroff M Della-Negra S Depauw J Fallavier M Le Beyec Y Pautrat M Schultz JA Tempez A Woods AS 《Rapid communications in mass spectrometry : RCM》2005,19(13):1851-1857
A Au-Si liquid metal ion source which produces Au(n) clusters over a large range of sizes was used to study the dependence of both the molecular ion desorption yield and the damage cross-section on the size (n = 1 to 400) and on the kinetic energy (E = 10 to 500 keV) of the clusters used to bombard bioorganic surfaces. Three pure peptides with molecular masses between 750 and 1200 Da were used without matrix. [M+H](+) and [M+cation](+) ion emission yields were enhanced by as much as three orders of magnitude when bombarding with Au(400) (4+) instead of monatomic Au(+), yet very little damage was induced in the samples. A 100-fold increase in the molecular ion yield was observed when the incident energy of Au(9) (+) was varied from 10 to 180 keV. Values of emission yields and damage cross-sections are presented as a function of cluster size and energy. The possibility to adjust both cluster size and energy, depending on the application, makes the analysis of biomolecules by secondary ion mass spectrometry an extremely powerful and flexible technique, particularly when combined with orthogonal time-of-flight mass spectrometry that then allows fast measurements using small primary ion beam currents. 相似文献
56.
Mireille?Bousquet-MélouEmail author Einar?Steingrímsson 《Journal of Algebraic Combinatorics》2005,22(4):383-409
In a recent paper, Backelin, West and Xin describe a map φ* that recursively replaces all occurrences of the pattern k... 21 in a permutation σ by occurrences of the pattern (k−1)... 21 k. The resulting permutation φ*(σ) contains no decreasing subsequence of length k. We prove that, rather unexpectedly, the map φ* commutes with taking the inverse of a permutation.
In the BWX paper, the definition of φ* is actually extended to full rook placements on a Ferrers board (the permutations correspond to square boards), and the construction
of the map φ* is the key step in proving the following result. Let T be a set of patterns starting with the prefix 12... k. Let T′ be the set of patterns obtained by replacing this prefix by k... 21 in every pattern of T. Then for all n, the number of permutations of the symmetric group
n that avoid T equals the number of permutations of
n that avoid T′.
Our commutation result, generalized to Ferrers boards, implies that the number of involutions of
n that avoid T is equal to the number of involutions of
n avoiding T′, as recently conjectured by Jaggard.
Both authors were partially supported by the European Commission's IHRP Programme, grant HPRN-CT-2001-00272, “Algebraic Combinatorics
in Europe” 相似文献
57.
Michle Fontaine Joseph Delhalle Mireille Defranceschi Grard Lcayon Jacques Boissel 《International journal of quantum chemistry》1993,46(1):171-181
3-21G RHF calculations on (CF3)2O and (CF3)2OH+ molecules are carried out to assess the changes induced in the molecular properties of ether links in poly (perfluoro ethers) interacting with acid sites at contact surfaces. Geometry of the species, vibrational frequencies, proton affinity, and energetics of the (CF3)2OH+ fragmentation provide a preliminary basis to understand problems raised by lubricant degradation. © 1993 John Wiley & Sons, Inc. 相似文献
58.
Koudia M Abel M Maurel C Bliek A Catalin D Mossoyan M Mossoyan JC Porte L 《The journal of physical chemistry. B》2006,110(20):10058-10062
The adsorption and ordering of zinc phthalocyanine (ZnPc) and octachloro zinc phthalocyanine (ZnPcCl(8)) on an Ag(111) surface is studied in situ by scanning tunneling microscopy under ultrahigh vacuum. Two-dimensional self-assembled supramolecular domains are observed for these two molecules. We show how substituting chlorine atoms for half of the peripheral hydrogen atoms on ZnPc influences the self-assembly mechanisms. While intermolecular interactions are dominated by van der Waals forces in ZnPc molecular networks, ZnPcCl(8) molecular packing undergoes a sequential phase evolution driven by the creation of C-Cl...H-C hydrogen bonds between adjacent molecules. At the end of this evolution, the final molecular assembly involves all possible hydrogen bonds. Our study also reveals the influence of molecule-substrate interactions through the presence of fault lines generating a stripe structure in the molecular film. 相似文献
59.
Tomato pericarp tissue was studied by low-field nuclear magnetic resonance (NMR) relaxometry. Two kinds of experiments were
performed to investigate the correlation between multi-exponential NMR relaxation and the subcellular compartments. The longitudinal
(T
1) versus transverse (T
2) relaxation times were first measured on fresh samples and then the transverse relaxation time was measured on samples exposed
to water stress. Four signal components were found in all experiments. The results showed that all signal components corresponded
to the water in different cell compartments, and that no signal from non-exchangeable protons was present. Moreover, we demonstrated
that NMR relaxation is suitable for the continuous monitoring of water rebalancing between subcellular compartments of plant
tissues. 相似文献
60.