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排序方式: 共有115条查询结果,搜索用时 15 毫秒
61.
62.
Lukas Scheibler Pascal Dumy Mila Boncheva Kirsten Leufgen Hans-Jrg Mathieu Manfred Mutter Horst Vogel 《Angewandte Chemie (International ed. in English)》1999,38(5):696-699
The combination of self-assembly and regioselective surface chemistry has made it possible to immobilize peptide recognition sites 1 on a template attached to a gold surface. Each of the seven individual reaction steps, including the final functional biomolecular recognition, was controlled in situ with surface-sensitive detection techniques. The presented strategy is of general importance for the formation of complex supramolecular structures with biologically interesting functionalities at the interfaces. 相似文献
63.
64.
M. van den Bossche F.-C. Zhang F. Mila 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):367-370
In order to understand the properties of Mott insulators with strong ground state orbital fluctuations, we study the zero
temperature properties of the SU(4) spin-orbital model on a square lattice. Exact diagonalizations of finite clusters suggest that the ground state is disordered
with a singlet-multiplet gap and possibly low-lying SU(4) singlets in the gap. An interpretation in terms of plaquette SU(4) singlets is proposed. The implications for LiNiO2 are discussed.
Received 6 July 2000 相似文献
65.
J. Choukroun V.A. Pashchenko Y. Ksari J.Y. Henry F. Mila P. Millet P. Monod A. Stepanov J. Dumas R. Buder 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):655-659
The magnetic susceptibility and the electron spin resonance in the X-band of the transition metal oxide compound MgVO3 are reported. We show that this compound, made of weakly coupled infinite chains of VO5 pyramids, behaves as a S
=1/2 one-dimensional Heisenberg antiferromagnet. From the ESR and magnetic experiments we deduce the Néel temperature K, the in-chain coupling constant K and the g-factor values g
x
=
g
z
=1.972(2), g
y
=1.946(1) for V4+ ions in MgVO3.
Received 14 July 1999 相似文献
66.
Tatjana Trtić-Petrović Jelena Ðorđević Nikolina Dujaković Ksenija Kumrić Tatjana Vasiljević Mila Laušević 《Analytical and bioanalytical chemistry》2010,397(6):2233-2243
An optimised extraction and cleanup method for the analysis of pesticide in natural water samples is presented. Sixteen pesticides
of different polarity and from the different chemical classes (organophosphates, triazines, benzimidazoles, carbamates, carbamides,
neonicotinoides, methylureas, phenylureas and benzohydrazides), most frequently used in Serbia, were selected for the analysis.
Liquid-phase microextraction in a single hollow fibre (HF-LPME) has been applied for sample preparation. The concentrations
of pesticides were determined using HPLC-MS/MS method with electrospray ionisation. The extraction behaviour and selection
of the experimental conditions was predicted based on log D and pK
a values of targeted pesticides, which were calculated applying the computer software ACD/Labs PhysChem Suite v12. The influence
of the donor pH and concentration of pesticides, organic phase composition as well as the extraction time on the extraction
efficiency was investigated. Optimum extraction conditions were evaluated with respect to the investigated parameters of the
extraction. The extraction method was validated for 10 out of 16 studied pesticides. Linear range of the pesticides was 0.1–5 μg L−1 with the correlation coefficient from 0.991 to 0.9998, and the relative standard deviation for three standard measurements
was between 0.2 and 11.8%. The limits of detections ranged from 0.026 to 0.237 μg L−1 and the limits of quantifications from 0.094 to 0.793 μg L−1. The optimised two-phase HF-LPME method was successfully applied for determination of moderately polar as well low-polar
pesticides in the environmental water samples. 相似文献
67.
Nikolina Dujakovi? Svetlana Gruji? Marina Radiši? Tatjana Vasiljevi? Mila Lauševi? 《Analytica chimica acta》2010,678(1):63-72
The sensitive multiresidual analytical method for simultaneous analysis of 14 most commonly used agricultural pesticides in Serbia was developed and optimized. The selected insecticides, fungicides and herbicides belong to seven chemical classes (organophosphates, neonicotinoids, carbamates, diacylhydrazines, benzimidazoles, triazines and phenylureas). The method was based on solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The following parameters that may affect the SPE procedure efficiency were optimized: the sorbent type in combination with different elution solvents, the sample pH and the sample volume. For each pesticide, MSn analysis was performed and distinctive ions and transitions were selected for identification and quantification, as well as for confirmation purposes. External matrix-matched calibration method was used to eliminate variable matrix effect and ensure precise quantification. Good recoveries (72-129%), and low limits of detection (0.4-5.5 ng L−1) and quantification (1.1-18.2 ng L−1) were achieved for all selected pesticides. The developed and optimized method was successfully applied in the analysis of several river waters, as well as ground waters in Serbia, influenced by agriculture. The most frequently detected pesticide was carbendazim. Dimethoate, carbofuran and propazine were also found in the investigated samples. 相似文献
68.
Using mean-field theory, exact diagonalizations, and SU(3) flavor theory, we have precisely mapped out the phase diagram of the S = 1 bilinear-biquadratic Heisenberg model on the triangular lattice in a magnetic field, with emphasis on the quadrupolar phases and their excitations. In particular, we show that ferroquadrupolar order can coexist with short-range helical magnetic order, and that the antiferroquadrupolar phase is characterized by a remarkable 2/3 magnetization plateau, in which one site per triangle retains quadrupolar order while the other two are polarized along the field. Implications for actual S=1 magnets are discussed. 相似文献
69.
70.
Formation of a silver selenide layer on silicone coated polyamide cloth was investigated. Fabric samples were selenized in potassium selenotrithionate (K2SeS2O6) solution then treated with AgNO3 solution. Formation of a silver selenide particle layer on the surface was confirmed by a change in appearance, X-ray diffraction, and EDX analysis. XRD revealed two phases: orthorhombic naumannite (Ag2Se) and monoclinic selenium (Se8). SEM showed that the fabric macrostructure and the multifilament yarn microstructure was preserved. The silver selenide particles ranged from 100 nm to more than 20 µm. 相似文献