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71.
The synthesis and binding abilities of peptides containing β-amino acids towards Cu(II) ions are presented. The peptides studied were: Ala-βAsp-Ser-Gly and Arg-Lys-βAsp-Val-Tyr. Potentiometric titrations were carried out to establish the stoichiometry of the resulting metal-ligand complexes. The copper(II) coordination mode of the complexes was investigated by performing detailed spectroscopic analyses (UV–Vis, CD) in strict correlation with potentiometric measurements. The results obtained on the β-peptides studied allowed the characterization of the influence of this structural modification on the coordination abilities of the peptides. Moreover, the role of the α-Asp position in the peptide chain was also described. 相似文献
72.
Marganiec-Gałązka Justyna Ziemek Tomasz Broda Ryszard Cacko Daniel Czudek Marek Jęczmieniowski Adam Kołakowska Ewa Lech Edyta Listkowska Anna Saganowski Paweł Tymiński Zbigniew 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(8):3283-3288
Journal of Radioanalytical and Nuclear Chemistry - The activity concentration of a 177Lu solution was measured by the Laboratory of Radioactivity Standards in the Radioisotope Centre POLATOM. The... 相似文献
73.
Justyna Werner Agnieszka Zgoła-Grześkowiak Tomasz Grześkowiak 《Journal of separation science》2022,45(7):1374-1384
A green and sensitive thin-film solid-phase microextraction method based on deep eutectic solvent was developed that enables simultaneous isolation, preconcentration, and determination of parabens in surface waters. Six new deep eutectic solvents were synthesized and used directly to prepare thin-film coatings on a stainless steel mesh support. Among the compounds obtained, the highest efficiency in the extraction of parabens was found for a material consisting of trihexyltetradecylphosphonium chloride and n-docosanol in a molar ratio of 1:2. For the proposed method, parameters affecting the extraction efficiency of parabens, such as the coating material, the desorption solvent, the volume of the sample, the pH of the sample, the extraction and desorption time, and the salting-out effect, were optimized. Under optimal conditions, the proposed method allowed us to achieve good precision between 3.6 and 6.5% and recovery ranging from 68.1 to 91.4%. The limits of detection range from 0.018 to 0.055 ng/mL. 相似文献
74.
Zofia Rzączyńska Anna Danczowska-Burdon Justyna Sienkiewicz-Gromiuk 《Journal of Thermal Analysis and Calorimetry》2010,101(2):671-677
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light
lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas
Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate
lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO− groups appear thus indicating that complexation process took place. 相似文献
75.
1-Hydroxyphosphonate 1 in the presence of triethylamine in acetonitrile solution undergoes irreversible rearrangement to phosphate 2 and reversible retro-phospho-aldol (retro-Abramov) reaction. The X-ray structures for 1 and 2 revealed that the phosphonate-phosphate rearrangement occurs with retention of configuration at the phosphorus atom. 相似文献
76.
Justyna Jarczyk 《Nonlinear Analysis: Theory, Methods & Applications》2010,72(5):2608-96
Let I⊂R be a non-trivial interval, s:I→(0,∞) be a function, and let φ,ψ be real continuous strictly monotonic functions defined on I. We consider the equation
77.
Justyna Kosakowska 《数学学报(英文版)》2008,24(10):1687-1702
In the present paper we describe a specialization of prinjective Ringel-Hall algebra to 1, for prinjective modules over incidence algebras of posets of finite prinjective type, by generators and relations. This gives us a generalisation of Serre relations for semisimple Lie algebras. Connections of prinjective Ringel-Hall algebras with classical Lie algebras are also discussed. 相似文献
78.
tert‐Butyl(tert‐butoxy)zinc Hydroxides: Hybrid Models for Single‐Source Precursors of ZnO Nanocrystals
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Kamil Sokołowski Dr. Iwona Justyniak Dr. Wojciech Bury Dr. Justyna Grzonka Prof. Zbigniew Kaszkur Łukasz Mąkolski Michał Dutkiewicz Agnieszka Lewalska Elżbieta Krajewska Dominik Kubicki Dr. Katarzyna Wójcik Prof. Krzysztof J. Kurzydłowski Prof. Janusz Lewiński 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5488-5495
Alkylzinc alkoxides, [RZnOR′]4, have received much attention as efficient precursors of ZnO nanocrystals (NCs), and their “Zn4O4” heterocubane core has been regarded as a “preorganized ZnO”. A comprehensive investigation of the synthesis and characterization of a new family of tert‐butyl(tert‐butoxy)zinc hydroxides, [(tBu)4Zn4(μ3‐OtBu)x(μ3‐OH)4?x], as model single‐source precursors of ZnO NCs is reported. The direct reaction between well‐defined [tBuZnOH]6 ( 16 ) and [tBuZnOtBu]4 ( 24 ) in various molar ratios allows the isolation of new mixed cubane aggregates as crystalline solids in a high yield: [(tBu)4Zn4(μ3‐OtBu)3(μ3‐OH)] ( 3 ), [(tBu)4Zn4(μ3‐OtBu)2(μ3‐OH)2] ( 4 ), [(tBu)4Zn4(μ3‐OtBu)(μ3‐OH)3] ( 5 ). The resulting products were characterized in solution by 1H NMR and IR spectroscopy, and in the solid state by single‐crystal X‐ray diffraction. The thermal transformations of 2 – 5 were monitored by in situ variable‐temperature powder X‐ray diffraction and thermogravimetric measurements. The investigation showed that the Zn?OH groups appeared to be a desirable feature for the solid‐state synthesis of ZnO NCs that significantly decreased the decomposition temperature of crystalline precursors 3 – 5 . 相似文献
79.
80.
Guzow K Rzeska A Mrozek J Karolczak J Majewski R Szabelski M Ossowski T Wiczk W 《Photochemistry and photobiology》2005,81(3):697-704
Photophysical properties of tyrosine and its derivatives with free and blocked functional groups were studied by steady state and time-resolved fluorescence spectroscopy and global analysis in organic solvents, such as methanol, 2-propanol, tetrahydrofuran (THF), and dimethylsulfoxide (DMSO). The mono-exponential fluorescence intensity decays were observed for all tyrosine derivatives in THF and DMSO solutions, whereas in alcohols some derivatives have bi-exponential decays. The rotamer population calculated from 1H nuclear magnetic resonance spectroscopy in DMSO does not correspond to the pre-exponential factors obtained from fluorescence spectroscopy. Moreover in the case of DMSO, the strong interaction of this solvent with the hydroxyl group of the fluorophore's phenol ring causes substantial changes in the fluorescence and nonradiative rate constants of tyrosine derivatives compared with those of tyrosine with a blocked hydroxyl group, Tyr(Me). The steady state and time-resolved fluorescence measurements in pure organic solvents and water-organic solvent mixtures indicate that the fluorescence quenching of the phenol chromophore of tyrosine by an acetyl or amide group or both depends on the polarity of the solvent used as well as the ability of the solvent to form hydrogen bonds with functional groups of tyrosine. 相似文献