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891.
[Structure: see text] A new probe based on an anthryl derivative bearing an azadiene side chain selectively senses Cu2+ in acetonitrile through two different channels: the yellow-to-orange color change and a remarkable enhancement of the fluorescence, whereas the pyrenyl analogous behaves as a fluorescent sensor for Cu2+ and Hg2+ in aqueous environment. 相似文献
892.
Two unsymmetrical ditopic hexadentate ligands designed for the simultaneous recognition of two different trivalent lanthanide ions have been synthesized, L(AB2) and L(AB3), where A represents a tridentate benzimidazole-pyridine-benzimidazole coordination unit, B2 a diethylamine-substituted benzimidazole-pyridine-carboxamide one, and B3 a chlorine-substituted benzimidazole-pyridine-carboxamide moiety. Under stoichiometric 2:3 (Ln/L) conditions, these ligands self-assemble with lanthanide ions to yield triple-stranded bimetallic helicates. The crystal structures of four helicates with L(AB3) of composition [LnLn'(L(AB3))3](ClO4)6.solv (CeCe, PrPr, PrLu, NdLu) show the metal ions embedded into a helical structure with a pitch of about 13.2-13.4 A. The metal ions lie at a distance of 9.1-9.2 A and are nine-coordinated by the three ligand strands, which are oriented in a HHH (head-head-head) fashion, where all ligand strands are oriented in the same direction. In the presence of a pair of different lanthanide ions in acetonitrile solution, the ligand L(AB3) shows selectivity and gives high yields of heterobimetallic complexes. L(AB2) displays less selectivity, and this is shown to be directly related to the tendency of this ligand to form high yields of HHT (head-head-tail) isomer. A fine-tuning of the HHH left arrow over right arrow HHT equilibrium and of the selectivity for heteropairs of Ln(III) ions is therefore at hand. 相似文献
893.
The reaction of enantiopure 4-oxoazetidine-2-carbaldehydes with unmodified ketones was catalyzed by L-proline as well as by D-proline, to give the corresponding gamma-amino-beta-hydroxy ketones with good yields and diastereoselectivities. The obtained results implied that (2R,3R)-4-oxoazetidine-2-carbaldehydes and L-proline are a matched pair for diastereoselective induction. 相似文献
894.
Elena Añez Santiago Herrero Reyes Jiménez-Aparicio José L. Priego M. Rosario Torres Francisco A. Urbanos 《Polyhedron》2010
The substitution of the acetate ligand in [Ru2Cl(DPhF)3(O2CMe)] (DPhF− = N,N′-diphenylformamidinate) by the pentafluorobenzoate group gives the complex [Ru2Cl(DPhF)3(O2CC6F5)(OH2)] (1), and the reaction of 1 with AgSO3CF3 leads to the compound [Ru2(DPhF)3(O2CC6F5)(OH2)2]SO3CF3 (2). The low donor character of the pentafluorobenzoate ligand compared to the acetate group decreases the electron density of the Ru25+ unit which permits ligands to bond at both axial positions of the diruthenium moiety. The use of the [Au(CN)2]− group yields the new complex {[Ru2(DPhF)3(O2CC6F5)][Au(CN)2]} (3). Complexes 1–3 are characterized by elemental analysis, 19F{1H} NMR, IR and electronic spectroscopy, mass spectrometry and variable-temperature magnetic measurements. The crystal structure of 2·H2O is also reported. The magnetic properties of complex 1 is in accordance with the ground-state configuration σ2π4δ2(π*δ*)3. In contrast, the slope of representation of the magnetic moment towards temperature in complex 2 indicates a gradual transition from essentially high spin (S = 3/2) to low spin (S = 1/2) configuration. 相似文献
895.
896.
Mosto Bousmina Mokhtar Aouina Bushra Chaudhry Robert Guénette Rosario E. S. Bretas 《Rheologica Acta》2001,40(6):538-551
Non-linear rheology of a mixture of two viscoelastic immiscible liquids undergoing high deformation flow was considered. Using Grmela's formalism (Grmela 1986, 1989, 1993a, b) and the coarse grained picture given by Onuki (1987) and Doi and Ohta (1991), we have derived a set of highly non-linear time-dependent transport equations that take into account a direct coupling between the rheology and morphology. Breakup, coalescence, and the high deformation of the interface were considered. Models of Doi and Ohta (1991), Lee and Park (1994), and Grmela et al. (1998) are recovered as special cases. The parameters of?the model were given a physical meaning in both shear and elongational flows and the predictions of the model were ¶compared to the predictions of the previous models on the basis of experimental results obtained on two model?blends PDM/PB polydimethylsiloxane/poly(1-butene) and PP/PS polypropylene/polystyrene blends. 相似文献
897.
Natale Badalamenti Maurizio Bruno Rosario Schicchi Anna Geraci Mariarosaria Leporini Rosa Tundis Monica Rosa Loizzo 《Molecules (Basel, Switzerland)》2022,27(10)
The aim of the present study is to investigate the chemical profile, antioxidant activity, carbohydrate-hydrolysing enzyme inhibition, and hypolipidemic effect of essential oils (EOs) extracted from Sicilian Citrus maxima (pomelo) flavedo. Using gas-chromatography-mass spectrometry analysis (GC-MS) we analysed the Eos of five cultivars of C. maxima, namely, ‘Chadock’, ‘Maxima’, ‘Pyriformis’, ‘Terracciani’, and ‘Todarii’, and their blends. The antioxidant activity was performed by using a multi-target approach using 2,2′-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic acid (ABTS), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability power (FRAP), and β-carotene bleaching tests. The α-amylase, α-glucosidase, and lipase-inhibitory activities were also assessed. GC-MS analyses revealed D-limonene as the main monoterpene hydrocarbon in all cultivars, albeit with different percentages in the range of 21.72–71.13%. A good content of oxygenated monoterpenes was detected for all cultivars, especially for ‘Todarii’. The analysis of the principal components (PCA), and related clusters (HCA), was performed to find chemo-diversity among the analysed samples. EOs from ‘Chadock’ and ‘Maxima’ were statistically similar to each other, and they differed from P3 in the smaller amount of sesquiterpene hydrocarbons, while the oils from ‘Terracciani’ and ‘Todarii’ were found to be chemically and statistically different. ‘Chadock’ EO was the most active to scavenge radicals (IC50 values of 22.24 and 27.23 µg/mL in ABTS and DPPH tests, respectively). ‘Terracciani’ EO was the most active against both lipase and α-amylase, whereas the blends obtained by the combination (1:1 v/v) of C. maxima ‘Maxima’ + ‘Todarii’ were the most active against α-glucosidase. Generally, the blends did not exert a unique behaviour in potentiating or reducing the bioactivity of the pomelo EOs. 相似文献
898.
Paul Varava Tak Hin Wong Zhaowen Dong Anastasia Yu. Gitlina Andrzej Sienkiewicz Wolfram Feuerstein Rosario Scopelliti Farzaneh Fadaei-Tirani Kay Severin 《Angewandte Chemie (International ed. in English)》2023,62(25):e202303375
The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to isolate a stable radical cation and diamagnetic dications. The latter are also accessible by oxidative dimerization of diazoolefins. 相似文献
899.
900.
Fang-Che Hsueh Thayalan Rajeshkumar Bastiaan Kooij Rosario Scopelliti Kay Severin Laurent Maron Ivica Zivkovic Marinella Mazzanti 《Angewandte Chemie (International ed. in English)》2023,62(9):e202215846
Thorium redox chemistry is extremely scarce due to the high stability of ThIV. Here we report two unique examples of thorium arenide complexes prepared by reduction of a ThIV-siloxide complex in presence of naphthalene, the mononuclear arenide complex [K(OSi(OtBu)3)3Th(η6-C10H8)] ( 1 ) and the inverse-sandwich complex [K(OSi(OtBu)3)3Th]2(μ-η6,η6-C10H8)] ( 2 ). The electrons stored in these complexes allow the reduction of a broad range of substrates (N2O, AdN3, CO2, HBBN). Higher reactivity was found for the complex 1 which reacts with the diazoolefin IDipp=CN2 to yield the unexpected ThIV amidoalkynyl complex 5 via a terminal N-heterocyclic vinylidene intermediate. This work showed that arenides can act as convenient redox-active ligands for implementing thorium-ligand cooperative multielectron transfer and that the reactivity can be tuned by the arenide binding mode. 相似文献