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排序方式: 共有204条查询结果,搜索用时 31 毫秒
1.
Omar El Tall Nicole Jaffrezic‐Renault Monique Sigaud Olivier Vittori 《Electroanalysis》2007,19(11):1152-1159
Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD. 相似文献
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3.
Hétérocycles à fonction quinone. 7. Benzo[f]quinazolinediones-7,10 à action antitumorale potentielle
Hlne Parrot-Lopez Jean-Michel Delacotte Jean Renault Suzanne Cros 《Journal of heterocyclic chemistry》1986,23(4):1039-1043
Few benzo[f]quinazoline-7,10-diones 4a-c are prepared by oxidation, with potassium nitrosodisulfonate, of the corresponding benzo[f]quinazolinamines, made by reduction of the nitro analogues which were obtained from 8-methoxybenzo[f]quinazolin-1(2H)-one. The compound 4a shows an interesting cytotoxicity. 相似文献
4.
The adsorption at the air-water interface of native and various glycated forms of beta-Lactoglobulin B (beta-LG), prepared under two different experimental conditions, was investigated by ellipsometry, surface tension and shear elastic constant measurements. The measurements were performed in 0.1 M phosphate buffer, 0.1 M NaCl, pH 6.8. It was found that the interfacial properties of beta-LG were more affected when the glycation was performed in solution than in the dry-way system. Dry-way glycated beta-LG, despite a higher glycation extent, affected slightly its interfacial behaviour. Solution glycated beta-LG exhibited a higher adsorption and more rigid interface as expressed by shear elastic constant measurement at saturation (16.5 mN/m against 8.7 and 11.5 mN/m for native and control treated beta-LG, respectively). These results were attributed to the specific molecular species induced during glycation in solution, which includes monomers and unfolded covalent homodimers of beta-LG molecules with a high tendency to self-association via non-covalent interactions. 相似文献
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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
7.
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
8.
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
9.
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
10.
Mouna Hnaien Sergei Dzyadevych Florence Lagarde Nicole Jaffrezic‐Renault 《Electroanalysis》2012,24(6):1441-1445
In this work, a fast, sensitive and miniaturised conductometric sensor based on interdigitated electrodes, working in differential mode, was developed for the determination of cationic surfactants. The membrane was composed of a polymer (PVC), a plasticizer (dinonylphtalate (DNP)) and a carrier (sodium tetraphenylborate (NaBΦ4)). The sensor response was linear from at least 10?9 M to 10?2 M for dodecyltrimethylammonium (DTA+). No significant loss of sensor response was observed after 8 weeks. The sensor exhibited a lower sensitivity and a narrower dynamic range for tetrabutylammonium, decyltrimethylammonium and cetyltrimethylammonium cationic surfactants. A ten times lower sensitivity was observed for laurylsulfate anionic surfactant, (LS?). 相似文献