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排序方式: 共有248条查询结果,搜索用时 15 毫秒
191.
Marine Frezza 《Tetrahedron letters》2005,46(38):6495-6498
The Baylis-Hillman reaction between 2-(tert-butyldimethylsilyloxy)ethanal and 3-buten-2-one followed by desilylation gave rise to the corresponding α-methylene-β,γ-dihydroxy ketone further converted by reductive ozonolysis of the carbon-carbon double bond into racemic 4,5-dihydroxy-2,3-pentanedione (DPD), a significant molecule in bacterial cell-cell communication systems. The same sequence applied to other substrates allowed the preparation of chain elongated analogues and 5-O-acylated derivatives of DPD. 相似文献
192.
Le Moigne M Dufour E Bertrand D Maury C Seraphin D Jourjon F 《Analytica chimica acta》2008,621(1):8-18
The potential of front-face spectroscopy for grape ripening dates discrimination was investigated on Cabernet Franc grapes from three parcels located on the Loire Valley and for six ripening dates. The 18 batches were analysed by front-face fluorescence spectroscopy and visible spectroscopy. The excitation spectra (250-310 nm, emission wavelength = 350 nm) were characterised by a shoulder at 280 nm. Grapes spectra were classified by factorial discriminant analysis (FDA). Ripening dates were well predicted by fluorescence spectra: grapes before veraison were separated from grapes after veraison and almost every ripening date was identified. The common spectroscopic space obtained by CCSWA showed that wavelengths corresponding to anthocyanin absorption in the visible were correlated to fluorescence wavelengths around the starting and ending points of the shoulder (263 and at 292 nm). Then, regression models were investigated to predict total soluble solids (TSS), total acidity, malvidin-3G, total anthocyanins and total phenolics content from visible and fluorescence spectra. To predict technological indicators (TSS and total acidity), the PLS model with visible spectra (RMSECV = 0.82°Brix or 0.96 g L−1 H2SO4) was better than those with fluorescence one (RMSECV = 1.39°Brix or 2.06 g L−1 H2SO4). For malvidin-3G and total anthocyanins, all and were superior to 0.90 and RMSECV were low. Visible and fluorescence spectroscopies succeeded in predicting anthocyanin content. Concerning total phenolic, the best prediction was provided by fluorescence spectroscopy. 相似文献
193.
Iwona Nierengarten Michel Holler Marine Rmy Uwe Hahn Aurlien Billot Robert Deschenaux Jean-Franois Nierengarten 《Molecules (Basel, Switzerland)》2021,26(8)
With their ten peripheral substituents, pillar[5]arenes are attractive compact scaffolds for the construction of nanomaterials with a controlled number of functional groups distributed around the macrocyclic core. This review paper is focused on the functionalization of pillar[5]arene derivatives with small dendrons to generate dendrimer-like nanomaterials and bioactive compounds. Examples include non-viral gene vectors, bioactive glycoclusters, and liquid-crystalline materials. 相似文献
194.
195.
Yael Juarez-Martinez Dr. Pablo Labra-Vázquez Dr. Alejandro Enríquez-Cabrera Andrés F. Leon-Rojas Diego Martínez-Bourget Dr. Pascal G. Lacroix Marine Tassé Sonia Mallet-Ladeira Dr. Norberto Farfán Dr. Rosa Santillan Dr. Gabriel Ramos-Ortiz Dr. Jean-Pierre Malval Prof. Isabelle Malfant 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(62):e202201692
One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl-substituted terpyridine ligand, and bpy the 2,2’-bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF-CC-TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis-RuNO2 and bis-RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one-photon absorption (OPA) correlates well with the TD-DFT computations. A spectacular effect is observed at two-photon absorption (TPA) with a large enhancement of the molecular cross-section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA-based drug delivery. 相似文献
196.
Demeter Sandor Szweda Roman Patterson Judy Grigoryan Marine 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):619-627
Journal of Radioanalytical and Nuclear Chemistry - Given potential worldwide shortages of fission sourced 99Mo/99mTc medical isotopes there is increasing interest in alternate production... 相似文献
197.
Thomas Body Andreas Stegmeir Wladimir Zholobenko David Coster Frank Jenko 《等离子体物理论文集》2020,60(5-6):e201900139
Advanced divertor configurations modify the magnetic geometry of the divertor to achieve a combination of strong magnetic flux expansion, increased connection length and higher divertor volume—to improve detachment stability, neutral/impurity confinement and heat-channel broadening. In this paper, we discuss the modification of the flux-coordinate independent (FCI) turbulence code GRILLIX to treat generalized magnetic geometry, to allow for the investigation of the effect of magnetic geometry on turbulent structures in the edge and scrape-off layer (SOL). The development of grids and parallel operators from numerically defined magnetic equilibria is discussed, as is the application of boundary conditions via penalization, with the finite-width method generalized to treat complex non-conformal boundaries. Initial testing of hyperbolic (advection) and parabolic (diffusion) test cases are presented for the Snowflake scenario. 相似文献
198.
Extremes - Storm processes constitute prototype models for spatial extremes. They are classically simulated on a finite number of points within a given domain. We propose a new algorithm that... 相似文献
199.
Marine Cotte Victor Gonzalez Frederik Vanmeert Letizia Monico Catherine Dejoie Manfred Burghammer Loïc Huder Wout de Nolf Stuart Fisher Ida Fazlic Christelle Chauffeton Gilles Wallez Núria Jimnez Francesc Albert-Tortosa Nati Salvad Elena Possenti Chiara Colombo Marta Ghirardello Daniela Comelli Ermanno Avranovich Clerici Riccardo Vivani Aldo Romani Claudio Costantino Koen Janssens Yoko Taniguchi Joanne McCarthy Harald Reichert Jean Susini 《Molecules (Basel, Switzerland)》2022,27(6)
The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes as an alternative to standard proposals for access to beamtime, in particular via the “block allocation group” (BAG) mode. Here, we present the recently implemented “historical materials BAG”: a community proposal giving to 10 European institutes the opportunity for guaranteed beamtime at two X-ray powder diffraction (XRPD) beamlines—ID13, for 2D high lateral resolution XRPD mapping, and ID22 for high angular resolution XRPD bulk analyses—with a particular focus on applications to cultural heritage. The capabilities offered by these instruments, the specific hardware and software developments to facilitate and speed-up data acquisition and data processing are detailed, and the first results from this new access are illustrated with recent applications to pigments, paintings, ceramics and wood. 相似文献
200.
L. Patrone D. Nelson V.I. Safarov S. Giorgio M. Sentis W. Marine 《Applied Physics A: Materials Science & Processing》1999,69(7):S217-S221
We show that conventional pulsed laser ablation (PLA) of Si and Ge targets in inert buffer gases is an efficient method of nanocluster synthesis. From a photoluminescence study of Si and Ge nanoclusters produced by PLA we have demonstrated the possibility of tuning the luminescence band from the near infrared to the near ultraviolet regions. The stabilization of the properties of Si nanoclusters by reactive (H2 gas) PLA synthesis was proved by photoluminescence measurements. Finally, we report a photoluminescence study of gas-suspended Ge nanoclusters during their preparation. They exhibit a broad luminescence spectrum extended from UV to the blue-green region and modulated by a molecule-like structure. We propose an interpretation of the vibronic structure involving Ge-O-Ge vibrations at the surface of photo-excited clusters. To the best of our knowledge, we report here the first observation of vibrational effects from gas-suspended Ge nanoclusters. 相似文献