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排序方式: 共有64条查询结果,搜索用时 15 毫秒
1.
Christelle de Bellefontaine Flore Josse Martine Domurado Dominique Domurado 《Applied biochemistry and biotechnology》1994,48(2):117-123
In order to detect low levels of enzyme activity, specifically glucose oxidase, in biological samples, an immunoenzymatic assay was developed since currently available methods could not be used because of either their lack of sensitivity or the conditions prevailing in our samples: turbidity of the medium, presence of redox systems other than glucose oxidase, and high concentration of proteins. The principle of the method is to coat a polystyrene surface with a fragment Fc-specific anti-IgG, then with an antibody directed against the looked-for enzyme, which is simultaneously the antigen and the enzyme activity required for immunoenzymatic detection. We applied this concept to biological samples after glucose oxidase administration to mice. This method achieves specificity and sensitivity (20 ng/mL or 1 ng) with samples of biological origin. No marker is needed since the antigen itself possesses an enzyme activity. This method, which requires a small sample volume (50 ΜL, 20 ΜL, if necessary), can be extended easily to the many enzymes currently used as markers. It could also be applied to the native enzymes of medical interest for which antibodies and a colorimetric reaction are available. 相似文献
2.
Michel Josse Xavier Gerbaux Armand Hadni 《International Journal of Infrared and Millimeter Waves》1993,14(7):1381-1387
Conclusion We have presented the possibility to make optical coatings on quartz in the FIR and we have got a transmission coefficient as high as 97% at room temperature. It will rise probably close to 100% at liquid helium temperature where the quartz two-phonon difference processes are frozen. The use of polyethylene or TPX is also possible to make plates and lenses. The reflectivity losses are smaller because the refractive index is much smaller, but they cannot be further reduced by any coating because there is no transparent material with n1.2 in the FIR. These lenses are very useful in the FIR (except around 60 cm–1 if they are made of polyethylene). TPX is quite transparent over the whole FIR range, and also in the visible with nearly the same refractive index as in the FIR. Alignments can be made with visible light, and still work in the FIR. 相似文献
3.
Le Grand F George G Akoka S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,174(1):171-176
Deuterium site-specific natural isotope abundance (Ai) is routinely measured by NMR spectroscopy and quantified using an internal reference peak. This study demonstrates that the substitution of the chemical compound used as internal reference by an electronically generated signal (the ERETIC method) allows a dramatic reduction of the experimental time. Measurements of Ai on eight samples of methylsalicylate have been performed using either an internal reference (TMU) or ERETIC. No significant difference in accuracy or precision had been found between the two methods. However, because the method is applicable in partially saturated conditions, the experiment time was divided by a factor of 4 and the drawbacks associated with an internal chemical reference were avoided when ERETIC was used. 相似文献
4.
Functional electro-optic polymer thin films embedded in microcavity structures have been poled by an all-optical procedure based on the interference of multiphoton absorption processes. The photoinduced X((2)) tensor was then further addressed at modal resonance for the fundamental wavelength, leading to significant enhancement of the second-harmonic-generation efficiency. An order-of-magnitude enhancement, which is due to electric field resonant conditions inside the microcavity, has been probed by an optical parametric oscillator, in comparison with a single-path thin-film configuration. This configuration opens new perspectives in the realm of nonlinear photonic device processing. 相似文献
5.
Two 2,6‐Dioxabicyclo[3.3.1]nonan‐3‐ones from Phragmanthera capitata (Spreng.) Balle (Loranthaceae) 下载免费PDF全文
Bruno N. Lenta Joél T. Ateba Jean R. Chouna Makoah N. Aminake Flore Nardella Gabriele Pradel Beate Neumann Hans Georg Stammler Catherine Vonthron‐Sénécheau Silvère Ngouela Norbert Sewald 《Helvetica chimica acta》2015,98(7):945-952
Phytochemical investigation of the leaves of Phragmanthera capitata collected on Cassia spectabilis tree led to the isolation of two natural lactones, rel‐(1R,5S,7S)‐7‐[2‐(4‐hydroxyphenyl)ethyl]‐2,6‐dioxabicyclo[3.3.1]nonan‐3‐one ( 1 ) and 4‐{2‐[rel‐(1R,3R,5S)‐7‐oxo‐2,6‐dioxabicyclo[3.3.1]non‐3‐yl]ethyl}phenyl 3,4,5‐trihydroxybenzoate ( 2 ) together with the known compounds betulinic acid ( 3 ), dodoneine ( 4 ), quercetin 3‐O‐α‐L ‐rhamnopyranoside ( 5 ), quercetin 3‐O‐α‐L ‐arabinofuranoside ( 6 ), quercetin ( 7 ), betulin ( 8 ), lupeol ( 9 ), and sitosterol ( 10 ). Their structures were established by means of modern spectroscopic techniques, and the relative configuration of compound 1 was confirmed by X‐ray analysis. Compounds 1 and 2 were tested in vitro for their antiplasmodial activity against the Plasmodium falciparum chloroquine sensitive‐strains NF54 and 3D7. Compound 2 exhibited good antiplasmodial activity against both strains with IC50 of 2.4 and 4.9 μM , respectively, while compound 1 was inactive. 相似文献
6.
L. Vernac M. Pinard V. Josse E. Giacobino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):129-135
Using a quantum theory for an ensemble of two- or three-level atoms driven by electromagnetic fields in an optical cavity,
we show that the various spins associated with the atomic ensemble can be squeezed. Two kinds of squeezing are obtained: on
the one hand self-spin squeezing when the input fields are coherent ones and the atomic ensemble exhibits a large non-linearity;
on the other hand squeezing transfer when one of the incoming fields is squeezed.
Received 14 August 2001 and Received in final form 7 November 2001 相似文献
7.
An efficient, enantioselective synthesis of a disubstituted bis-THF scaffold 5 is described, as well as an efficient differentiation of the 1,3-diol unit. [reaction: see text] 相似文献
8.
Lok-Hang Yan Flore Dagorn Edmond Gravel Blandine Séon-Méniel Erwan Poupon 《Tetrahedron》2012,68(31):6276-6283
Lycopodium alkaloids are unique (and often impressive in terms of structures) polycyclic alkaloids that attract great interest from a biological point of view and that also provide ideal targets for total synthesis. Propylpiperidine units closely related to pelletierine are involved in the biosynthesis of these alkaloids. Therefore, stable pelletierine-like compounds, especially a (R)-phenylglycinol-based oxazolopiperidine analog, were prepared and their reactivity investigated. The compounds described in this work expand the tool-box of small building blocks in the piperidine series and pelletierine analogs and could be suitable for the synthesis of Lycopodium alkaloids following biosynthetically inspired strategies. 相似文献
9.
Delphine Declerck Albert Nguyen Van Nhien Solen Josse Jan Szymoniak Philippe Bertus Claudia Bello Pierre Vogel Denis Postel 《Tetrahedron》2012,68(6):1802-1809
The titanium-mediated cyclopropanation reaction using Ti(OiPr)3Me/EtMgBr/BF3·OEt2 has been applied to various 2-cyanopyrrolidines for the synthesis of functionalized 2-(1-aminocyclopropyl)pyrrolidine-3,4-diol derivatives (dideoxyiminoalditols). Under the same experimental conditions the trans-5-azidomethyl-2-cyanopyrrolidine derivative was not cyclopropanated but reduced into the corresponding 5-amino-2-cyano derivative. After polyol deprotection 2-(1-aminocyclopropyl)pyrrolidine-3,4-diols were obtained and their inhibitory activity towards 13 glycosidases has been evaluated. (2S,3S,4R,5S)-2-(1-Aminocyclopropyl)-5-methylpyrrolidine-3,4-diol (38), which has the same absolute configuration as l-fucose, is a moderate (IC50=44 μM), but selective, inhibitor of α-l-fucosidase from human placenta. 相似文献
10.
Sana Tfaili Cyril Gobinet Gwendal Josse Jean-François Angiboust Arlette Baillet Michel Manfait Olivier Piot 《Analytical and bioanalytical chemistry》2013,405(4):1325-1332
Caffeine is utilised as a reference for permeation studies in dermatology and cosmetology. The present work aimed to monitor the permeation of a caffeine solution through the skin. For this purpose, Raman and infrared studies were performed. Raman microspectroscopy permitted a dynamic follow-up of the caffeine diffusion. In complementary, infrared microimaging provided information of the caffeine localization in the skin by applying multivariate statistical processing on skin tissue sections. Herein, we prove the possibility of tracking low concentrations of caffeine through the skin and we highlight some experimental limitations of vibrational spectroscopies. 相似文献