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991.
Trabolsi A Elhabiri M Urbani M Delgado de la Cruz JL Ajamaa F Solladié N Albrecht-Gary AM Nierengarten JF 《Chemical communications (Cambridge, England)》2005,(46):5736-5738
Owing to the complementarity between a bis-Zn(II)-porphyrin receptor and a fullerene ligand bearing two pyridine substituents, the substrate can be clicked onto the ditopic receptor, thus leading to a stable non-covalent macrocyclic 1 ratio 1 complex. 相似文献
992.
Florence Babonneau Laurence Yeung Nathalie Steunou Christel Gervais Ainhoa Ramila Maria Vallet-Regi 《Journal of Sol-Gel Science and Technology》2004,31(1-3):219-223
Ibuprofen molecules have been encapsulated in mesoporous MCM-41 type-silica functionalised or not by amino groups. They have been characterised by 13C and 1H solid state NMR spectroscopy. The 13C MAS single pulse or cross polarization NMR spectra, as well as the 1H MAS NMR spectra demonstrate an extremely high mobility of the ibuprofen molecules when the matrix is not functionalised. On the contrary, when the silica matrix is functionalized by amino groups, the 13C NMR response shows less mobility suggesting the existence of interactions between the amino groups and the carboxylic groups. Benzoic acid as well as benzamide have also been encapsulated and their NMR responses compared to that of ibuprofen. 相似文献
993.
994.
Mohamed Saadioui Nathalie Reynier Jean-François Dozol Zouhair Asfari Jacques Vicens 《Journal of inclusion phenomena and macrocyclic chemistry》1997,29(2):153-165
We report the synthesis and complexation properties towards alkalications of a photosensitive azo-modified calix[4]crown 5 in the1,3-alternate conformation. Selectivity of the cis-isomer towards Cs+ andRb+ was observed. 相似文献
995.
Van Hoof N De Wasch K Poelmans S Noppe H De Brabander H 《Rapid communications in mass spectrometry : RCM》2004,18(23):2823-2829
A multi-residue liquid chromatography/tandem mass spectrometry method (LC/MS2) was developed for the detection of the non-steroidal anti-inflammatory drugs acetylsalicylic acid (via the marker residue salicylic acid), flunixin, phenylbutazone, tolfenamic acid, meloxicam and ketoprofen, in bovine muscle. After extraction of the bovine muscle with acetonitrile, the cleanup was performed using a Oasis HLB column. The evaporated eluate was reconstituted and analysed by LC/MS2. To obtain optimal detection of salicylic acid and phenylbutazone, the ion trap mass spectrometric parameters activation q and maximum ion injection time, respectively, were optimised. The activation q for salicylic acid was increased to obtain reliable detection of both salicylic acid and its product ion. The maximum ion injection time for the time segment containing phenylbutazone was decreased since there were not enough scans across the chromatographic peak of this compound. The multi-residue method was able to detect the different analytes below or at the maximum residue limit (MRL) or minimum required performance limit (MRPL) or, in the case of phenylbutazone and ketoprofen, at 100 and 20 microg kg(-1), respectively. 相似文献
996.
997.
Olivier Robin Nathalie Remillard Paul Paquin 《Colloids and surfaces. A, Physicochemical and engineering aspects》1993,80(2-3):211-222
The influence of certain process variables (pressure and temperature), as well as composition variables (fat, protein and low molecular weight emulsifier concentrations) and the emulsification process used, on the size distribution of milk fat globules was studied in a dairy oil-in-water model emulsion and in homogenized milk. In the first case, the use of a central composite experimental design allowed us to obtain two nonlinear multiple regression equations relating the volume-weighted average diameter (
v) of the fat globules as well as the relative width of size distribution (CV) to the emulsification pressure (7.8–76.3 MPa) and temperature (35–100°C), and to sodium caseinate (0.5–3.9wt.%), butter oil (5.2–14.7 wt.%) and monoglyceride (0.08–0.88 wt.%) concentrations. These two functions, which account for 93.7 and 81.7%, respectively, of the variation in the average diameter and in the size distribution width of the microfluidized fat globules, were used to describe certain interactions between the different variables affecting the size of the microfluidized fat globules. They were also used to define the optimal conditions that correspond to the extremes of the average particle diameter and of the distribution width of the fat globules. These two functions also allowed us to predict fat globule parameters as a function of process and formulation conditions. In the second case, the microfluidization process lead to an overestimation (up to 0.3%) of the milk fat content as determined by a infrared analyser. 相似文献
998.
Justin S BryansNicola E.A Chessum Nathalie HutherAndrew F Parsons Franco Ghelfi 《Tetrahedron》2003,59(33):6221-6231
The copper(I) or ruthenium(II)-mediated radical cyclisation of halo-amides has been utilised to afford functionalised pyrrolidinones via 5-endo-trig or 5-exo-trig radical cyclisation pathways. This methodology has been applied to novel and concise syntheses of the anti-epileptic drug gabapentin and the biologically active natural product pulchellalactam. 相似文献
999.
Chiral bis(oxazoline)-based Rh(I)-, Ir(I)- and Ru(II)-complexes have been prepared and used for asymmetric transfer hydrogenation of prochiral ketones. The presence of a free hydroxyl group on the ligand is necessary for high enantioselectivity. With acetophenone, up to 50% conversion and 89% ee were achieved. 相似文献
1000.
Barboiu M Vaughan G Kyritsakas N Lehn JM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(3):763-769
The polyheterocyclic strands 1-H and 2-H adopt a helical shape enforced by the pyridine-pyrimidine helicity codon. The crystal structure of 2-H shows the formation of stacks of dimers of right- and left-handed individual helices. Treatment of 1-H and 2-H with silver triflate results in the generation of double-helical entities 1-DH and 2-DH, containing two strands and two silver ions. NMR studies and determination of the crystal structure of 2-DH indicate that the duplex is stabilized by coordination of each Ag(+) ion to two terminal bipyridine units, one from each strand, and by pronounced pi-pi stacking interactions between the internal heterocycles of the strands, yielding a very robust double helical structure. Reversible interconversion of the single and double helix may be achieved by addition of a cryptand capable of sequestering Ag(+) and releasing it by protonation. Thus, successive addition of acid and base leads to reversible interconversion between the shorter ( approximately 3.6 A) single helix and the longer ( approximately 10.3 A) double helix, resulting in the generation of pronounced extension/contraction motion. The system 1,2-H/1,2-DH represents a dynamic chemical device undergoing ionic modulation of reversible molecular mechanical motion fueled by acid/base neutralization. 相似文献