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991.
Permanent binary phase masks with planar surfaces and high tolerance to laser radiation are recorded in the volume of photo-thermo-refractive glass using the contact copying technique and binary amplitude master masks. Conversion of a Gaussian beam to higher order modes is shown. 相似文献
992.
We present a simple technique for measuring coherence times for stationary light fields using a single detector with tunable time resolution. By measuring the equal-time second-order correlation function at varying instrument response functions it is possible to determine the coherence time and also the shape of the temporal decay without the need to record time-resolved data. The technique is demonstrated for pseudothermal light. Possible applications for dynamic light scattering and photon statistics measurements are discussed. 相似文献
993.
P Orlandi C Ferrari M John Strain A Canciamilla F Morichetti M Sorel P Bassi A Melloni 《Optics letters》2012,37(17):3669-3671
We present the design and the fabrication of compact tunable silicon-on-insulator bandpass filters based on the integration of a Mach-Zehnder interferometer with ring resonators and activated via thermo-optic phase shifters. The proposed architecture provides wide filter bandwidth tunability from 10% to 90% of the free spectral range preserving the filter off-band rejection. Possible applications are channel subset selection in wavelength division multiplexing optical systems, adaptive filtering to signal bandwidth, and reconfigurable filters for gridless networking. 相似文献
994.
Zwergel C Gaascht F Valente S Diederich M Bagrel D Kirsch G 《Natural product communications》2012,7(3):389-394
Aurones [2-benzylidenebenzofuran-3(2H)-ones] are either natural or synthetic compounds, belonging to the flavonoid family. They are isomeric to flavones and provide a bright yellow color to the plants in which they occur. Today, a literature survey indicates that the related flavonoids have been studied not only for their physiological properties and effects on Nature, but also for their therapeutic potential. Aurones are recently attracting the interest of an increasing number of research groups, and, since the last review, some interesting advances have been made in understanding the aurones. In this review, we report the recent advances made on the synthetic routes towards aurones. We also highlight their activity in different biological areas, as well as applied genetic plant modifications to produce these colored compounds. Their synthesis, structure-activity relationships and the importance of the substitution pattern will also be mentioned. Finally, some aspects regarding the possible development of aurones will be discussed briefly. 相似文献
995.
996.
For every closed orientable hyperbolic Haken 3-manifold and, more generally, for any orientable hyperbolic 3-manifold M which is homeomorphic to the interior of a Haken manifold, the number 0.286 is a Margulis number. If H 1(M;ℚ) ≠ 0, or if M is closed and contains a semi-fiber, then 0.292 is a Margulis number for M. 相似文献
997.
B Tangeysh M Fryd MA Ilies BB Wayland 《Chemical communications (Cambridge, England)》2012,48(71):8955-8957
The mean diameter of palladium metal particles produced by citrate reduction of the (H(+))(n) PDMAEMA/[PdCl(4)](2-) aqueous system increases from 1.4 nm to 5.0 nm as the pH decreases from 6.3 to 3.3 and the (H(+))(n) PDMAEMA/[PdCl(4)](2-) species undergo conversion from a cross linked polymer network to a single chain structure. 相似文献
998.
J Alliot E Gravel F Pillon DA Buisson M Nicolas E Doris 《Chemical communications (Cambridge, England)》2012,48(65):8111-8113
A novel approach for the asymmetric synthesis of the active (1S,2R)-enantiomer of the antidepressant milnacipran is reported. The two stereogenic centers borne by the cyclopropane ring were sequentially installed starting from phenylacetic acid. 相似文献
999.
Dr. Etienne Borré Dr. Mathieu Rouen Isabelle Laurent Magaly Magrez Dr. Fréderic Caijo Dr. Christophe Crévisy Dr. Wladimir Solodenko Loic Toupet René Frankfurter Prof. Dr. Carla Vogt Prof. Dr. Andreas Kirschning Dr. Marc Mauduit 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(51):16369-16382
In this study, a new pyridinium‐tagged Ru complex was designed and anchored onto sulfonated silica, thereby forming a robust and highly active supported olefin‐metathesis pre‐catalyst for applications under batch and continuous‐flow conditions. The involvement of an oxazine–benzylidene ligand allowed the reactivity of the formed Ru pre‐catalyst to be efficiently controlled through both steric and electronic activation. The oxazine scaffold facilitated the introduction of the pyridinium tag, thereby affording the corresponding cationic pre‐catalyst in good yield. Excellent activities in ring‐closing (RCM), cross (CM), and enyne metathesis were observed with only 0.5 mol % loading of the pre‐catalyst. When this powerful pre‐catalyst was immobilized onto a silica‐based cationic‐exchange resin, a versatile catalytically active material for batch reactions was generated that also served as fixed‐bed material for flow reactors. This system could be reused at 1 mol % loading to afford metathesis products in high purity with very low ruthenium contamination under batch conditions (below 5 ppm). Scavenging procedures for both batch and flow processes were conducted, which led to a lowering of the ruthenium content to as little as one tenth of the original values. 相似文献
1000.
Antoine Leydier Yi Lin Guilhem Arrachart Raphaël Turgis Delphine Lecerclé Alain Favre-Reguillon Frédéric Taran Marc Lemaire Stéphane Pellet-Rostaing 《Tetrahedron》2012,68(4):1163-1170
Synthesis of modified EDTA and DTPA ligands and determination of their binding affinities for the uranyl cation are described.Thanks to a screening method, based on a chromophoric complex displacement procedure, chelating properties were studied in aqueous media under various pH conditions for evaluation of their in vivo uranyl-removal efficacy. Each ligand showed a more or less pronounced affinity for uranium. Specific ligands based on EDTA or DTPA analogues containing sulfocatecholamide (CAMS) were found to exhibit a significant affinity towards uranyl ion in acidic, neutral or basic conditions. 相似文献