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排序方式: 共有872条查询结果,搜索用时 31 毫秒
71.
Manuela Martín‐Zarco Santiago Toribio Joaquín C. García‐Martínez Julián Rodríguez‐López 《Journal of polymer science. Part A, Polymer chemistry》2009,47(23):6409-6419
A series of polyamido amine (PAMAM) dendrimers (Generations 2, 3, 4, and 6) fully functionalized at their periphery with first‐ and second‐generation poly (phenylenevinylene) (PPV) dendrons have been efficiently prepared. MALDI‐TOF mass spectrometry proved to be particularly useful for the characterization of the new hybrid dendrimers as well as for the estimation of the average number of PPV dendrons attached to the surface. The optical absorption and emission properties of these systems were studied. The materials display extremely high molar extinction coefficients and emit blue light with only slightly lower fluorescence quantum yields than the corresponding free dendrons. Self‐quenching interactions between PPV units were not observed in THF. However, the luminescence properties underwent a dramatic change when toluene was used as the solvent. The lower polarity of toluene caused shrinkage of the PAMAM structure and brought the PPV chromophores closer together, leading to self‐quenching interactions and excimer formation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6409–6419, 2009 相似文献
72.
An eco-friendly tandem tosylation/Ferrier N-glycosylation of amines catalyzed by Er(OTf)3 in 2-MeTHF
Monica Nardi Natividad Herrera Cano Antonio De Nino Maria Luisa Di Gioia Loredana Maiuolo Manuela Oliverio Ana Santiago Diletta Sorrentino Antonio Procopio 《Tetrahedron letters》2017,58(18):1721-1726
Er(OTf)3 in 2-MeTHF provides a new and eco-friendly process for Ferrier glycosylation of sulfonamides and amino acids with various N-nucleophiles.The stereoselective synthesis of 2,3-unsaturated-N-pseudoglycals was carried out with 3,4,6-tri-O-acetyl-d-glucal and different nucleophiles affording good results in a short time. 相似文献
73.
Giuseppe Cirillo Francesco Puoci Manuela Curcio Ortensia Ilaria Parisi Francesca Iemma Umile Gianfranco Spizzirri Nevio Picci 《Colloid and polymer science》2010,288(6):689-693
The aim of this study is the preparation of molecularly imprinted polymers by employing a redox pair as initiator system.
Bulk molecularly imprinted polymers were synthesized by using Fenton reagents as initiator system. Theophylline, methacrylic
acid, and ethylene glycol dimethacrylate were employed as model template, functional monomer, and crosslinking agent, respectively.
Conventional imprinted polymers were also prepared by using 2,2′-azoisobutyronitrile in order to evaluate the efficiency of
the proposed initiator system. Redox molecularly imprinted polymers and conventional molecularly imprinted polymers were characterized
by water uptake measurement, while the imprinting effect of synthesized polymers were evaluated by performing binding experiments
in organic (acetonitrile) and in water (buffered water solution at pH = 7.4) media. 相似文献
74.
Three new compounds bearing furyl, aryl, or thienyl moieties linked to an imidazo-crown ether system (1, 2, and 3) were synthesized and fully characterized by elemental analysis, infrared, UV-vis absorption, and emission spectroscopy, X-ray crystal diffraction, and MALDI-TOF-MS spectrometry. The interaction toward metal ions (Ca(2+), Cu(2+), Ni(2+), and Hg(2+)) and F(-) has been explored in solution by absorption and fluorescence spectroscopy. Mononuclear and binuclear metal complexes using Cu(2+) or Hg(2+) as metal centers have been synthesized and characterized. Compounds 2 and 3 show a noticeable enhancement of the fluorescence intensity in the presence of Ca(2+) and Cu(2+) ions. Moreover compound 3 presents a dual sensory detection way by modification of the fluorimetric and colorimetric properties in the presence of Cu(2+) or Hg(2+). EPR studies in frozen solution and in microcrystalline state of the dinuclear Cu(II)3 complex revealed the presence of an unique Cu(2+) type. 相似文献
75.
Subhendu Naskar Priyankar Paira Rupankar Paira Shyamal Mondal Arindam Maity Abhijit Hazra Krishnendu B. Sahu Pritam Saha Sukdeb Banerjee Peter Luger Manuela Webe Nirup B. Mondal 《Tetrahedron》2010,66(27-28):5196-5203
An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives. 相似文献
76.
Manuela L.Q.A. Kaneko 《European Polymer Journal》2010,46(5):881-444
Rubber composites were obtained from natural (MT) or organomodified (O-MT) montmorillonite clay masterbatches and high molar mass poly(dimethylsiloxane)-gum (PDMS). The masterbatches were prepared by compounding MT or O-MT with a siloxane-polyether surfactant. The rubber composites were characterized by X-ray diffraction, small angle/wide angle X-ray scattering, scanning and transmission electron microscopies and tensile tests. The results showed that masterbatch compounding with O-MT improved the dispersion of this clay into the PDMS matrix. The morphology of the resulting composite showed a combination of intercalated and partially exfoliated clay layers with occasional clay aggregates. The addition of only 5 phr of O-MT into the PDMS matrix, via masterbatch compounding, improved the tensile strength as much as that obtained with the composite filled with 30 phr of O-MT clay prepared by the direct addition of the clay to PDMS. Moreover, the elongation at break was improved by at least 126%. 相似文献
77.
Bright red crystals of [Mn(H2O)6][BiI4]2 · 2H2O are obtained from a solution of MnI2, BiI3, and I2 in absolute ethanol, which is exposed to humid air. Reversible dehydratization sets in at about 50 °C. Added water decomposes the hydrate by irreversible precipitation of BiOI. The optical bandgap is about 1.9(1) eV. X‐ray diffraction on a single‐crystal revealed a monoclinic lattice (space group P21/c) with a = 760.39(4) pm, b = 1315.6(1) pm, c = 1398.37(7) pm, and β = 97.438(4)°. In the crystal structure zigzag chains of edge‐sharing [BiI2/1I4/2]– octahedra and linear strings of H2O‐bridged [Mn(H2O)6]2+ octahedra run parallel [100]. 相似文献
78.
79.
Quantum dots (QDs) are inorganic semiconductor nanocrystals that have unique optoelectronic properties responsible for bringing
together multidisciplinary research to impel their potential bioanalytical applications. In recent years, the many remarkable
optical properties of QDs have been combined with the ability to make them increasingly biocompatible and specific to the
target. With this great development, QDs hold particular promise as the next generation of fluorescent probes. This review
describes the developments in functionalizing QDs making use of different bioconjugation and capping approaches. The progress
offered by QDs is evidenced by examples on QD-based biosensing, biolabeling, and delivery of therapeutic agents. In the near
future, QD technology still faces some challenges towards the envisioned broad bioanalytical purposes.
相似文献
80.
Ester Sagristà Estelle Larsson Maryam Ezoddin Manuela Hidalgo Victòria Salvadó Jan Åke Jönsson 《Journal of chromatography. A》2010,1217(40):6153-6158
In this study, a three-phase hollow fiber liquid-phase microextraction (HF-LPME) method combined with liquid chromatography–mass spectrometry was developed for direct determination of four non-steroidal anti-inflammatory drugs (ketoprofen, naproxen, diclofenac and ibuprofen) in sewage sludge. The drugs were extracted from non-spiked and spiked slurry samples with different amounts of sludge into an organic phase and then back-extracted into an aqueous phase held in the lumen of the hollow fiber. High enrichment factors ranging from 2761 to 3254 in pure water were achieved. In sludge samples, repeatability and inter-day precision were tested with relative standard deviation values between 10–18% and 7–15%, respectively. Average concentrations of 29 ± 9, 138 ± 2, 39 ± 5 and 122 ± 7 ng/g were determined in dried sludge from Källby sewage treatment plant (Sweden) for ketoprofen, naproxen, diclofenac and ibuprofen, respectively. 相似文献