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101.
Anikó Nemes Tamás Csóka Szabolcs Béni Zsófia Garádi Dénes Szabó József Rábai 《Helvetica chimica acta》2020,103(8):e2000081
Four new chiral α-(nonafluoro-tert-butoxy)carboxylic acids were synthesized from naturally occurring α-amino acids (alanine, valine, leucine and isoleucine, respectively), and tested in 1H- and 19F-NMR experiments as chiral NMR shift reagents. The NMR studies were carried out at room temperature, using CDCl3 and C6D6 as solvents, and (RS)-α-phenylethylamine and (RS)-α-(1-naphthyl)ethylamine as racemic model compounds. To demonstrate the applicability of the reagents, the racemic drugs ketamine and prasugrel were also tested. 相似文献
102.
Mt Mikls Major Gerg Rvid Szabolcs Balogh Attila Bnyei Gyrgy Lendvay Dvid Frigyes Jzsef Bakos Gergely Farkas 《应用有机金属化学》2019,33(2)
A series of chiral pentane‐2,4‐diyl‐based thioether‐amine ligands [ 4 and 5 ; (R,S)‐ and (S,S)‐R1SCH(CH3)CH2CH(CH3)NHR2, respectively, where 4a R1 = iPr, R2 = Ph; 4b R1 = tBu, R2 = Ph; 4c R1 = 1‐Ad, R2 = Ph; 5a R1 = iPr, R2 = Ph; 5b R1 = tBu, R2 = Ph; 5c R1 = 1‐Ad, R2 = Ph; 5d R1 = iPr, R2 = 4‐MeOC6H4; 5e R1 = iPr, R2 = 4‐MeC6H4; 5f R1 = iPr, R2 = 3,5‐Me2C6H3] with stereogenic S‐ and N‐donor atoms has been prepared starting from cyclic sulfates via optically pure γ‐aminoalcohol or 2,4‐dimethylazetidine intermediates. The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished starting from the same source of chirality. The modular ligand structure and the novel synthetic strategies developed for their synthesis allowed the easy modification of the ligands’ (i) S‐ and (ii) N‐substituents, as well as (iii) the relative stereochemistry within the ligand backbone. Six‐membered [Pd(N,S)Cl2]‐type chelate complexes of the diastereomerically related ligands 4a and 5a were synthesized and characterized by X‐ray crystallography in the solid phase, by density functional theory calculations and in solution by NMR spectroscopy. The coordination of 5a resulted in the formation of a single chair conformation by the stereospecific locking of both stereolabile (N and S) donor atoms. In contrast, compound 4a forms rapidly equilibrating palladium species due to the fast inversion of the sulfur donor. Ligands with stereochemically fixed donor atoms provided robust and efficient catalytic systems that can be effectively applied in alkylene carbonates as green reaction media. Remarkably, the phosphine‐free catalysts are air‐stable, and at room temperature in the presence of moisture gave excellent ee’s (up to 93%) in asymmetric allylation processes thanks to the double stereoselective coordination. 相似文献
103.
Bérczes Attila Dujella Andrej Hajdu Lajos Tengely Szabolcs 《Monatshefte für Mathematik》2016,180(3):469-484
Monatshefte für Mathematik - Diophantine sets, i.e. sets of positive integers A with the property that the product of any two distinct elements of A increased by 1 is a perfect square, have a... 相似文献
104.
Szabolcs Borsányi Ydalia Delgado Stephan Dürr Zoltán Fodor Sándor D. Katz Stefan Krieg Thomas Lippert Dániel Nógrádi Kálmán K. Szabó 《Physics letters. [Part B]》2012
We study QCD thermodynamics using two flavors of dynamical overlap fermions with quark masses corresponding to a pion mass of 350 MeV. We determine several observables on Nt=6 and 8 lattices. All our runs are performed with fixed global topology. Our results are compared with staggered ones and a nice agreement is found. 相似文献
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Characterization of antioxidant phenolics in Syringa vulgaris L. flowers and fruits by HPLC‐DAD‐ESI‐MS
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Gergő Tóth Csenge Barabás Anita Tóth Ágnes Kéry Szabolcs Béni Imre Boldizsár Erzsébet Varga Béla Noszál 《Biomedical chromatography : BMC》2016,30(6):923-932
In this study the polyphenolic composition of lilac flowers and fruits was determined for the first time. For the identification of compounds, accurate molecular masses and formulas, acquired by LC and ESI‐TOF‐MS and fragmentation pattern given by LC‐ESI/MS/MS analyses, were used. Our chromatographic system in conjunction with tandem MS was found to be valuable in the rapid separation and determination of the multiple constituents in methanolic extracts of lilac flowers and fruits. Altogether 34 phenolics, comprising 18 secoiridoids, seven phenylpropanoids, four flavonoids and five low‐molecular‐weight phenols, were identified. As marker compounds two secoiridoids (oleuropein and nuzhenide), two phenylpropanoids (acteoside and echinacoside) and rutin were quantified by validated methods. As a result of quantitative analysis, it was confirmed that flowers contain significant amounts of phenylpropanoids (acteoside, 2.48%; echinacoside, 0.75%) and oleuropein (0.95%), while in fruits secoiridoid oleuropein (1.09%) and nuzhenide (0.42%) are the major secondary metabolites. The radical scavenging activities of the extracts and the constituents were investigated by DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) and ABTS [2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid)] assays. Both extracts show remarkable antioxidant activities. Our results clearly show that lilac flowers and fruits are inexpensive, readily available natural sources of phenolic compounds with pharmacological and cosmetic applications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
110.
The performance of 5 cm long narrow-bore columns packed with 2.6-2.7 μm core-shell particles and a column packed with 1.7 μm totally porous particles was compared in very fast gradient separations of polar neutral active pharmaceutical compounds. Peak capacities as a function of flow-rate and gradient time were measured. Peak capacities around 160-170 could be achieved within 25 min with these 5 cm long columns. The highest peak capacity was obtained with the Kinetex column however it was found that as the flow-rate increases, the peak capacity of the new Poroshell-120 column is getting closer to that obtained with the Kinetex column. Considering the column permeability, peak capacity per unit time and per unit pressure was also calculated. In this comparison the advantage of sub-3 μm core-shell particles is more significant compared to sub-2 μm totally porous particles. Moreover it was found that the very similar sized (dp = 2.7 μm) and structured (ρ = 0.63) new Poroshell-120 and the earlier introduced Ascentis Express particles showed different efficiency. Results obtained showed that the 5 cm long narrow bore columns packed with sub-3 μm core-shell particles offer the chance of very fast and efficient gradient separations, thus these columns can be applied for fast screening measurements of routine pharmaceutical analysis such as cleaning validation. 相似文献