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排序方式: 共有262条查询结果,搜索用时 15 毫秒
91.
Siebert JM Baier G Musyanovych A Landfester K 《Chemical communications (Cambridge, England)》2012,48(44):5470-5472
A facile method to produce nanocapsules by copper-free interfacial "click"-polymerization as orthogonal reaction for the encapsulation of functional molecules is successfully performed using stable miniemulsion droplets. Difunctional azides and alkynes have been used for polymerization around the miniemulsion droplets, leading to the formation of nanocapsules. The results were compared with copper-catalyzed systems. 相似文献
92.
Jacquot de Rouville HP Garbage R Ample F Nickel A Meyer J Moresco F Joachim C Rapenne G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(29):8925-8928
The future's wheel: A new class of wheels, based on subphthalocyanine fragments, for future incorporation in functional nanovehicles is reported (see figure). The syntheses of a symmetric wheel, a nitrogen-tagged wheel, and their ethynyl-bridged homodimers are presented. Theoretical calculations and STM imaging demonstrate the advantage of a bowl-shaped structure and the efficiency of the tag for STM imaging. 相似文献
93.
Hoffmann K Mix R Friedrich JF Buschmann HJ Resch-Genger U 《Journal of fluorescence》2009,19(2):229-237
Polypropylene supports were functionalized by plasma-deposition of polymeric allylamine layers. The surface amino groups generated
were wet-chemically reacted with xanthene dyes resulting in fluorescent polymer films. The effect of polymer-attachment of
the dyes on their emission features was studied fluorometrically and different methods were tested to improve the fluorescence
properties of the films. Modification with cucurbit[6]uril (CB6) yields a moderately enhanced fluorescence as well as an improved
photostability. The observed effect is most likely due to CB6-induced rigidization of the linker molecules which seems to
reduce fluorescence quenching dye–dye and fluorophore–surface interactions. 相似文献
94.
With the development of high power ultrafast laser passively mode-locked by a semiconductor saturable absorber mirror (SESAM), the damage threshold and degeneration mechanism of the SESAM become more and more important. One way to reduce the maximum electric field inside the active part of the SESAM is the use of a dielectric coating on the top of the semiconductor structure. With Presnel formula, optical transfer matrix, and optical thin film theory, the electric field distribution and reflectance spectrum can be simulated. We introduce the design principles of SESAM including the dependence of reflectance spectrum on dielectric function of absorber, and investigate the dependences of the electric field distribution, modulation depth, reflectance spectrum, and the relative value of incident light power at the top quantum well of SESAM on the number of SiO2/Ta2O5 layers. 相似文献
95.
Transitory starch plays a central role in the life cycle of plants. Many aspects of this important metabolism remain unknown; however, starch granules provide insight into this persistent metabolic process. Therefore, monitoring alterations in starch granules with high temporal resolution provides one significant avenue to improve understanding. Here, a previously established method that combines LCSM and safranin-O staining for in vivo imaging of transitory starch granules in leaves of Arabidopsis thaliana was employed to demonstrate, for the first time, the alterations in starch granule size and morphology that occur both throughout the day and during leaf aging. Several starch-related mutants were included, which revealed differences among the generated granules. In ptst2 and sex1-8, the starch granules in old leaves were much larger than those in young leaves; however, the typical flattened discoid morphology was maintained. In ss4 and dpe2/phs1/ss4, the morphology of starch granules in young leaves was altered, with a more rounded shape observed. With leaf development, the starch granules became spherical exclusively in dpe2/phs1/ss4. Thus, the presented data provide new insights to contribute to the understanding of starch granule morphogenesis. 相似文献
96.
Frank Katzenberg Joerg C. Tiller 《Journal of polymer science. Part A, Polymer chemistry》2016,54(14):1381-1388
Charles Goodyear discovered the vulcanization of natural rubber (NR) 170 years ago and transferred the gooey natural compound into the first representative of an entirely new class of materials; the elastomers. Thenceforth, NR was intensively explored and was used for countless products to date. All the more surprising, it was found recently that NR exhibits superior and unexpected properties whenever it is cross-linked to a degree smaller than 0.4% which is fairly below the commonly used 1%–2%. This article gives a brief overview on the exceptional properties of lightly cross-linked NR, named shape memory natural rubber (SMNR), including the cold programmable shape memory effect, storing of extremely large strain, energy and cold, and its capability to sense and memorize environmental parameters. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1381–1388 相似文献
97.
98.
V. Hejny J. Weiß P. Achenbach J. Ahrens J.R.M. Annand R. Beck M. Kotulla B. Krusche V. Kuhr R. Leukel I.J.D. MacGregor V. Metag R. Novotny V. Olmos de León F. Rambo A. Schmidt M. Schumacher U. Siodlaczek H. Ströher F. Wissmann M. Wolf 《The European Physical Journal A - Hadrons and Nuclei》2002,13(4):493-499
The photoproduction of η-mesons from 2H and 4He has been studied for energies close to the production thresholds. The experiments were carried out with the tagged photon
beam of the Mainz MAMI accelerator. The η-mesons were detected via their two photon decays with the electromagnetic calorimeter
TAPS. Total cross-sections, angular and momentum distributions of the η-mesons have been determined for both reactions. The
total cross-sections in the threshold region show a large enhancement over the predictions of a participant-spectator model,
indicating significant final-state interaction effects. The results are compared to recent model calculations taking into
account nucleon-nucleon and nucleon-η final-state interaction effects on different levels of sophistication.
Received: 23 November 2001 / Accepted: 11 February 2002 相似文献
99.
Hybrids of silver nanoparticles with amphiphilic hyperbranched macromolecules exhibiting antimicrobial properties 总被引:1,自引:0,他引:1
Aymonier C Schlotterbeck U Antonietti L Zacharias P Thomann R Tiller JC Mecking S 《Chemical communications (Cambridge, England)》2002,(24):3018-3019
Hybrids of silver particles of 1 to 2 nm in size with highly branched amphiphilically modified polyethyleneimines adhere effectively to polar substrates providing environmentally friendly antimicrobial coatings. 相似文献
100.
TMQ is an important precursor in industrial vitamin E synthesis. We report a "green chemistry approach" with respect to the highly selective and environmentally friendly oxidation of 2,3,6-trimethylphenol (TMP) to trimethyl-1,4-benzoquinone (TMQ) with molecular oxygen as oxidant and a copper catalyst immobilized in a molten salt. n-Butanol as co-solvent has a positive effect on the activity and selectivity. The structurally characterized catalyst, a 1-n-butyl-3-methylimidazolium oxotetracuprat, is formed in situ via hydrolysis of CuCl2 in the presence of imidazolium chloride. We propose a mechanism of oxidative phenolate activation at a [Cu4(mu4-O)]6+ core as electronically coupled electron acceptor, formation of a copper-bound phenolate radical anion, spin delocalization into the aromatic ring, and attack by triplet oxygen at the para position. Attack of Cu(I) as reduction equivalent at the peroxy radical, proton-mediated elimination of a copper(II)-hydroxo species, will either substitute a copper(I) site in the reduced oxo cluster or take up an electron from the reduced mixed valent cluster [Cu4(mu4-O)]6+ to regenerate the oxidized cluster as the active electron acceptor. 相似文献