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41.
42.
Lajos Horváth 《Journal of multivariate analysis》1983,13(1):202-209
The general asymptotic order of magnitude is determined for the maximal deviation of the multivariate product-limit estimate from the estimated survival function on Rk. This order depends on the joint behavior of the censoring and censored distributions in a well-defined way. Corresponding to specific joint behaviors, several lim sup results are deduced generalizing everything that is known in the univariate case. The results are also extended for the variable censoring model. 相似文献
43.
44.
Lajos Attila Papp Gabriel Hancu rpd Gyresi Hajnal Kelemen Zoltn‐Istvn Szab Bla Noszl Pavel Dubský Gerg Tth 《Electrophoresis》2019,40(21):2799-2805
Novel capillary electrophoresis methods using CDs as chiral selectors were developed and validated for the chiral separation of lansoprazole and rabeprazole, two proton pump inhibitors. Fourteen different neutral and anionic CDs were screened at pH 4 and 7 in the preliminary analysis. Sulfobutyl‐ether‐β‐CD with a degree of substitution of 6.5 and 10 at neutral pH proved to be the most suitable chiral selector for both compounds. Various dual CD systems were also compared, and the possible mechanisms of enantiomer separation were investigated. A dual selector system containing sulfobutyl‐ether‐β‐CD degree of substitution 6.5 and native γ‐CD proved to be the most adequate system for the separations. Method optimization was carried out using an experimental design approach, performing an initial fractional factorial screening design, followed by a central composite design to establish the optimal analytical conditions. The optimized methods (25 mM phosphate buffer, pH 7, 10 mM sulfobutyl‐ether‐β‐CD/20 mM γ‐CD, +20 kV voltage; 17°C temperature; 50 mbar/3 s injection, detection at 210 nm for lansoprazole; 25 mM phosphate buffer, pH 7, 15 mM sulfobutyl‐ether‐β‐CD/30 mM γ‐CD, +20 kV voltage; 18°C temperature; 50 mbar/3 s injection, detection at 210 nm for rabeprazole) provided baseline separation for lansoprazole (Rs = 2.91) and rabeprazole (Rs = 2.53) enantiomers with favorable migration order (in both cases the S‐enantiomers migrates first). The optimized methods were validated according to current guidelines and proved to be reliable, linear, precise, and accurate for the determination of 0.15% distomer as chiral impurity in dexlansoprazole and dexrabeprazole samples. 相似文献
45.
Gyrgy Kalaus Lajos Szab Jnos les Csaba Szntay Imre Juhsz Istvn Greiner Jnos Brlik Mria Kajtr‐Peredy 《Journal of heterocyclic chemistry》2000,37(2):245-251
The individual epimerization steps of vincadifformine ( 1 ), deethylvincadifformine isomers ( 2,3 ), their synthetic intermediates ( 4–13 ) as well as that of simpler compounds with D‐secoaspidospermane skeleton ( 15–17 ) were studied a ) in protic medium (boiling deuteroacetic acidic) and b ) under reductive (with sodium borodeuteride in boiling acetic acid, or with sodium borohydride in boiling deuteroacetic acid) conditions. 相似文献
46.
Lajos Kovács Pál Herczegh Gyula Batta István Farkas 《Journal of carbohydrate chemistry》2013,32(5):585-599
ABSTRACT The reactivity of the title compounds has been studied toward different nucleophiles and electrophiles. Unlike other ketene dithioacetals, compounds 3-5 did not add nucleophiles to the double bond. Instead, in the presence of Lewis acids they underwent substitution reaction at position 3. If the nucleophile was not strong enough, formation of 6 and 7 were observed. With 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranose (18), a 3:1 mixture of 11 and 12 was formed from 4. These observations may be interpreted in terms of easy formation of the allylic carbocation I which gives diastereomers with nucleophiles. However, this allylic ether-like behaviour was ruled out by the fact that compounds 9 and 10 did not undergo [2,3] sigmatropic rearrangement with lithium diisopropylamide. With N-bromosuccinimide compound 3 gave the 2-bromo derivative 8. Compounds 3 and 8 resisted common mercury salt assisted demercaptalization procedures. 相似文献
47.
JPC – Journal of Planar Chromatography – Modern TLC - Optimum conditions have been established for culture of the fungus Candida albicans (ATCC 90028) for microbial detection of zones... 相似文献
48.
Lajos Molnár 《Journal of Functional Analysis》2002,194(2):248-262
We present an analogue of Uhlhorn's version of Wigner's theorem on symmetry transformations for the case of indefinite inner product spaces. This significantly generalizes a result of Van den Broek. The proof is based on our main theorem, which describes the form of all bijective transformations on the set of all rank-one idempotents of a Banach space which preserve zero products in both directions. 相似文献
49.
Péter Csomós Lajos Fodor Antal Csámpai Pál Sohár 《Journal of heterocyclic chemistry》2011,48(5):1079-1084
We report a convenient approach for the synthesis of a new ring system: 4,5‐dihydro‐1,3‐thiazino[5,4‐b]indoles. The procedure involves the use of Lawesson's reagent in the presence of silica to achieve the one‐step ring‐closure reactions of 2‐benzoylamino‐3‐hydroxymethylindole intermediates to furnish 4,5‐dihydro‐2‐aryl‐1,3‐thiazino[5,4‐b]indoles. 2‐Phenylimino‐1,3‐thiazino[5,4‐b]indoles were obtained via the corresponding 3‐phenylthiourea‐2‐carboxylic acid ester derivatives by chemoselective reduction of the ester group, followed by ring closure under acidic conditions. The structures of the novel products were elucidated by IR, 1H‐NMR, and 13C‐NMR spectroscopy, including 2D‐HMQC, 2D‐HMBC, and DEPT measurements. J. Heterocyclic Chem., (2011). 相似文献
50.
Inhabitants of some Transylvanian farms in Romania have a valuable archaic knowledge of medicinal plants because of their isolation and the insufficiency of official medical treatment. In this work we present ethnobotanical data about the use of medicinal plant taxa for various respiratory diseases in the villages L?véte and Nagybacon. Altogether 34 plant taxa were documented in L?véte and 26 species in Nagybacon with 15 concordant data of the villages. This information plays an important role in the documentation of the disappearing indigenous medical information of the villages. 相似文献