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排序方式: 共有137条查询结果,搜索用时 15 毫秒
81.
Francieli M. Libero Maurício C.D. Xavier Francine N. Victoria Patrícia S. Nascente Lucielli Savegnago Gelson Perin Diego Alves 《Tetrahedron letters》2012,53(24):3091-3094
We describe herein the synthesis and antifungal activity of new 5-arylchalcogenoalkyl-1H-tetrazoles 4. Arylchalcogenoalkyl-1H-tetrazoles 4 have been synthesized in high yields by reaction of arylchalcogenolate anions with chloronitriles 2, and subsequent [2+3] cycloaddition of resulting arylchalcogenoalkylnitriles 3 with sodium azide by zinc catalysis in aqueous solution. The obtained compound 4a was screened for antifungal activity and presented inhibitory property against seven fungal strains. This protocol is an efficient method to produce new selenium–nitrogen compounds with antifungal activity. 相似文献
82.
Juliana Cordeiro Cardoso Ricardo Luiz C. AlbuquerqueJr. Francine Ferreira Padilha Felipe Oliveira Bittencourt Osvaldo de Freitas Paula Santos Nunes Newton L. Pereira Maria José Vieira Fonseca Adriano Antunes S. Araújo 《Journal of Thermal Analysis and Calorimetry》2011,104(1):249-254
The use of biodegradable natural polymers has increased due to the over-solid packaging waste. In this study, a chemical modification
of the casein molecule was performed by Maillard reaction, and the modified polymer was evaluated by polyacrylamide gel electrophoresis
(PAGE), thermogravimetry/derivative thermogravimetry (TG/DTG), FT-IR, and 1H-NMR spectroscopy. Subsequently, films based on the modified casein were obtained and characterized by mechanical analysis,
water vapor transmission, and erosion behavior. The PAGE results suggested an increase of molecular mass of the modified polymer,
and FT-IR spectroscopy data indicated inclusion of C–OH groups into this molecule. The TG/DTG curves of modified casein presented
a different thermal decomposition profile compared to the individual compounds. Mechanical tests showed that the chemical
modification of the casein molecules provided higher elongation rates (45.5%) to the films, suggesting higher plasticity,
than the original molecules (13.4%). The modified casein films presented higher permeability (0.505 ± 0.006 μg/h mm3) than the original polymer (0.387 ± 0.006 μg/h mm3) films at 90% relative humidity (RH). In pH 1.2, modified casein films presented higher erosion rates (32.690 ± 0.692%) than
casein films (19.910 ± 2.083%) after 8 h, suggesting an increased sensibility for erosion of the modified casein films in
acid environment. In water (pH 7.0), the films erosion profiles were similar. Those findings indicate that the modification
of molecule by Maillard reaction provided films more plastic, hydrophilic, and sensitive to erosion in acid environment, suggesting
that a new polymer with changed properties was founded. 相似文献
83.
Direct monoacetalization of glyoxal by methanol or ethanol is described. Yields of 50 to 70% are obtained. 相似文献
84.
Chiral Ligands Derived from Monoterpenes: Application in the Synthesis of Optically Pure Secondary Alcohols via Asymmetric Catalysis
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Dr. Mohammed Samir Ibn El Alami Prof. Dr. Mohamed Amin El Amrani Dr. Francine Agbossou‐Niedercorn Dr. Isabelle Suisse Prof. Dr. André Mortreux 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1398-1413
The preparation of optically pure secondary alcohols in the presence of catalysts based on chiral ligands derived from monoterpenes, such as pinenes, limonenes and carenes, is reviewed. A wide variety of these ligands has been synthesized and used in several catalytic reactions, including hydrogen transfer, C?C bond formation via addition of organozinc compounds to aldehydes, hydrosilylation, and oxazaborolidine reduction, leading to high activities and enantioselectivities. 相似文献
85.
Selective Hydrosilylation of Esters to Aldehydes Catalysed by Iridium(III) Metallacycles through Trapping of Transient Silyl Cations
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Dr. Yann Corre Vincent Rysak Dr. Frédéric Capet Dr. Jean‐Pierre Djukic Dr. Francine Agbossou‐Niedercorn Dr. Christophe Michon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):14036-14041
The combination of an iridium(III) metallacycle and 1,3,5‐trimethoxybenzene catalyses rapidly and selectively the reduction of esters to aldehydes at room temperature with high yields through hydrosilylation followed by hydrolysis. The ester reduction involves the trapping of transient silyl cations by the 1,3,5‐trimethoxybenzene co‐catalyst, supposedly by formation of an arenium intermediate whose role was addressed by DFT calculations. 相似文献
86.
Till Bousquet Mouhamad Jida Mohamad Soueidan Rebecca Deprez-Poulain Francine Agbossou-Niedercorn Lydie Pelinski 《Tetrahedron letters》2012,53(3):306-308
A Passerini three component condensation between a carboxylic acid, an aldehyde, and an isocyanide at high temperature under solvent-free conditions was developed. This methodology allows the formation of a broad range of α-acyloxyamides in excellent yields in short reaction times. 相似文献
87.
Mouhamad Jida Mohamad Soueidan Nicolas Willand Francine Agbossou-Niedercorn Lydie Pelinski Guillaume Laconde Rebecca Deprez-Poulain Benoit Deprez 《Tetrahedron letters》2011,52(14):1705-1708
A facile and rapid synthetic approach of N-benzyl-2-substituted piperazine building-blocks via an Ugi strategy is described. This strategy is high yielding (80-92% overall yield), step-efficient and fast using microwave heating and tert-butylisocyanide as a convertible isocyanide. This method is useful for the obtention of key intermediates in medicinal chemistry. 相似文献
88.
Mills NS Cheng FE Baylan JM Tirla C Hartmann JL Patel KC Dahl BJ McClintock SP 《The Journal of organic chemistry》2011,76(2):645-653
Dications of 9-(3-phenyl-1H-inden-1-ylidene)-5H-dibenzo[a,d]cycloheptene, 5(2+), were prepared by oxidation with SbF(5) in SO(2)ClF, and their magnetic behavior was compared to dications of 9-(3-phenyl-1H-inden-1-ylidene)-9H-fluorene, 2(2+). The good correlation between the experimental (1)H NMR shifts for the dications that were oxidized cleanly and the chemical shifts calculated by the GAIO method supported the use of the nucleus independent chemical shifts, NICS, to evaluate the antiaromaticity of the indenyl systems of 2(2+)/5(2+) and their unsubstituted parent compounds, 6(2+) and 7(2+), as well as the antiaromaticity of the fluorenyl system of 2(2+)/7(2+) and the aromaticity of the dibenzotropylium system of 5(2+)/6(2+). Antiaromaticity was shown to be directly related to the amount of charge in the antiaromatic systems, with the antiaromatic systems more responsive to changes in the calculated NBO charge than the aromatic systems. The antiaromaticity was also shown to be directly related to the amount of delocalization in the ring system. The aromaticity of the dibenzotropylium system was much less responsive to changes in the amount of charge in the tropylium system, because the aromatic system was much more completely delocalized. Thus, antiaromatic species are more sensitive probes of delocalization than aromatic ones. 相似文献
89.
2,6-Diisopropylphenol (propofol) is a potent anesthetic drug with fast onset of the anesthetic effect and short recovery time for the patients. Outside of the United States, propofol is widely used in performing target controlled infusion anesthesia. With the long term vision of an electrochemical sensor for in vivo monitoring and feedback controlled dosing of propofol in blood, different alternatives for the electrochemical quantification of propofol using diverse working electrodes and experimental conditions are presented in this contribution. When the electrochemical oxidation of propofol takes place on a glassy carbon working electrode, an electrochemically active film grows on the electrode surface. The reduction current of the film is proportional to the propofol concentration and the accumulation time. Based on these findings a stripping analytical method was developed for the detection of propofol in acidic solutions between 0 and 30 μM, with a detection limit of 5.5±0.4 μM. By restricting the scanned potential window between 0.5 V and 1.0 V in cyclic voltammetric experiments, the formation of the electrochemically active polymer can be prevented. This allowed the development of a direct voltammetric method for assessing propofol in acidic solutions between 0 and 30 μM, with a 3.2±0.1 μM (n=3) detection limit. The stripping method has a better sensitivity but somewhat worse reproducibility because the electrode surface has to be renewed between each experiment. The direct method does not require the renewal of the electrode surface between measurements but has no adequate selectivity towards the common interfering compounds. 相似文献
90.
Florian Medina Nathalie Duhal Christophe Michon Francine Agbossou-Niedercorn 《Comptes Rendus Chimie》2013,16(4):311-317
The catalyst-free reactions of activated alkenes with primary and secondary amines were investigated leading to various mono- and di-hydroamination products, the latter being rare and original. These reactions were shown to depend first on the strength of the nucleophile. Temperature and steric hindrance of the reagents were the other key factors controlling the selectivity of these aza-Michael reactions. In spite of their poor nucleophilicities, some N-heterocyclic amines could react with different activated alkenes affording valuable intermediates. Such results tended to demonstrate the hydrogen-bonding interactions between activated alkenes and poly-nitrogen aromatic cycles may control these concerted or fully conjugate aza-Michael additions. 相似文献