排序方式: 共有44条查询结果,搜索用时 15 毫秒
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Le Faou JH Suomijärvi T Blumenfeld Y Piattelli P Agodi C Alamanos N Alba R Auger F Bellia G Chomaz P Coniglione R Del Zoppo A Finocchiaro P Frascaria N Gaardhoje JJ Garron JP Gillibert A Lamehi-Rachti M Liguori-Neto R Maiolino C Migneco E Russo G Roynette JC Santonocito D Sapienza P Scarpaci JA Smerzi A 《Physical review letters》1994,72(21):3321-3324
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Akiba Y Beavis D Beery P Britt HC Budick B Chasman C Chen Z Chi CY Chu YY Cianciolo V Cole BA Costales JB Crawford HJ Cumming JB Debbe R Engelage J Fung SY Gonin M Gushue S Hamagaki H Hansen O Hayano RS Hayashi S Homma S Kaneko H Kang J Kaufman S Kehoe WL Kurita K Ledoux RJ Levine MJ Miake Y Morrison DP Morse RJ Moskowitz B Nagamiya S Namboodiri MN Nayak TK Olness J Parsons CG Remsberg LP Roehrich D Rothschild P Sakurai H Sangster TC Seto R Soltz R Stankus P Steadman SG Stephans GS Sung T 《Physical review letters》1996,76(12):2021-2024
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Lenhart JL van Zanten JH Dunkers JP Zimba CG James CA Pollack SK Parnas RS 《Journal of colloid and interface science》2000,221(1):75-86
Silane coupling agents are commonly applied to glass fibers to promote fiber/resin adhesion and enhance durability in composite parts. In this study, a coupling agent multilayer on glass was doped with trace levels of the dimethylaminonitrostilbene (DMANS) fluorophore. The fluorophore was immobilized on the glass surface by tethering the molecule to a triethoxy silane coupling agent, creating the DMANS/silane coupling agent molecule (DMSCA). DMSCA was then diluted with commonly used coupling agents and grafted to a glass microscope coverslip to create a model composite interface. A 53-nm blue shift in fluorescence from the immobilized DMSCA can be followed during cure of an epoxy resin overlayer, giving this technique potential to monitor the properties of the fiber/resin interface during composite processing. Contact angle measurements on these coupling agent layers were similar in the presence or absence of the DMSCA molecule, suggesting that trace levels of the fluorescent probe did not affect the structure of the layer. The immobilized DMSCA molecule behaved similarly to the DMANS precursor in solution. Both showed longer wavelength fluorescence in more polar environments. Copyright 2000 Academic Press. 相似文献
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Garcia Ruano JL Alemparte C Martin Castro AM Adams H Rodriguez Ramos JH 《The Journal of organic chemistry》2000,65(23):7938-7943
The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles. 相似文献
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Cadars S Sein J Duma L Lesage A Pham TN Baltisberger JH Brown SP Emsley L 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,188(1):24-34
The robustness of the refocused INADEQUATE MAS NMR pulse sequence for probing through-bond connectivities has been demonstrated in a large range of solid-state applications. This pulse sequence nevertheless suffers from artifacts when applied to multispin systems, e.g. uniformly labeled (13)C solids, which distort the lineshapes and can potentially result in misleading correlation peaks. In this paper, we present a detailed account that combines product-operator analysis, numerical simulations and experiments of the behavior of a three-spin system during the refocused INADEQUATE pulse sequence. The origin of undesired anti-phase contributions to the spectral lineshapes are described, and we show that they do not interfere with the observation of long-range correlations (e.g. two-bond (13)C-(13)C correlations). The suppression of undesired contributions to the refocused INADEQUATE spectra is shown to require the removal of zero-quantum coherences within a z-filter. A method is proposed to eliminate zero-quantum coherences through dephasing by heteronuclear dipolar couplings, which leads to pure in-phase spectra. 相似文献
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Schmidt KS Filippov DV Meeuwenoord NJ van Der Marel GA van Boom JH Lippert B Reedijk J 《Angewandte Chemie (International ed. in English)》2000,39(2):375-377
Cross-linking ability is possible with the oligonucleotide-tethered, monofunctional trans-Pt(II) complex shown. It was synthesized by a novel solid-phase approach comprising conjugation of immobilized tetrathymidylic acid with a trans-a(2)Pt(II) building unit, ammonolysis, and transformation of the resulting complex (R=1-N-cyclohexylmethylthyminate) into the chloro derivative (R=Cl). a=NH(2)CH(3), T=thymine. 相似文献
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Baltisberger JH Walder BJ Keeler EG Kaseman DC Sanders KJ Grandinetti PJ 《The Journal of chemical physics》2012,136(21):211104
We present an improved and general approach for implementing echo train acquisition (ETA) in magnetic resonance spectroscopy, particularly where the conventional approach of Carr-Purcell-Meiboom-Gill (CPMG) acquisition would produce numerous artifacts. Generally, adding ETA to any N-dimensional experiment creates an N + 1 dimensional experiment, with an additional dimension associated with the echo count, n, or an evolution time that is an integer multiple of the spacing between echo maxima. Here we present a modified approach, called phase incremented echo train acquisition (PIETA), where the phase of the mixing pulse and every other refocusing pulse, φ(P), is incremented as a single variable, creating an additional phase dimension in what becomes an N + 2 dimensional experiment. A Fourier transform with respect to the PIETA phase, φ(P), converts the φ(P) dimension into a Δp dimension where desired signals can be easily separated from undesired coherence transfer pathway signals, thereby avoiding cumbersome or intractable phase cycling schemes where the receiver phase must follow a master equation. This simple modification eliminates numerous artifacts present in NMR experiments employing CPMG acquisition and allows "single-scan" measurements of transverse relaxation and J-couplings. Additionally, unlike CPMG, we show how PIETA can be appended to experiments with phase modulated signals after the mixing pulse. 相似文献