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941.
Schön P Bonod N Devaux E Wenger J Rigneault H Ebbesen TW Brasselet S 《Optics letters》2010,35(23):4063-4065
We demonstrate the ability of single-subwavelength-size nanoapertures fabricated in a gold metal thin film to enhance second-harmonic generation (SHG) as compared to a bare metal film. Nonlinear microscopy imaging with polarization resolution is used to quantify the SHG enhancement in circular and triangular nanoaperture shapes. The dependence of the measured SHG enhancement on circular aperture diameters is seen to originate from both phase retardation effects and field enhancements at the nanoaperture edge. Triangular nanoapertures exhibit superior SHG enhancement compared with circular ones, as expected from their noncentrosymmetric shape. 相似文献
942.
Sophie Grivaux 《Comptes Rendus Mathematique》2010,348(3-4):155-159
943.
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947.
Highly Stereocontrolled Ring‐Opening Polymerization of Racemic Alkyl β‐Malolactonates Mediated by Yttrium [Amino‐alkoxy‐bis(phenolate)] Complexes 下载免费PDF全文
Dr. Cédric G. Jaffredo Dr. Yulia Chapurina Dr. Evgueni Kirillov Prof. Dr. Jean‐François Carpentier Dr. Sophie M. Guillaume 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7629-7641
Yttrium [amino‐alkoxy‐bis(phenolate)]amido complexes have been used for the ring‐opening polymerization (ROP) of racemic alkyl β‐malolactonates (4‐alkoxycarbonyl‐2‐oxetanones, rac‐MLARs) bearing an allyl (All), benzyl (Bz) or methyl (Me) lateral ester function. The nature of the ortho‐substituent on the phenolate rings in the metal ancillary dictated the stereocontrol of the ROP, and consequently the syndiotactic enrichment of the resulting polyesters. ROP promoted by catalysts with halogen (Cl, Br)‐disubstituted ligands allowed the first reported synthesis of highly syndiotactic PMLARs (Pr ≥ 0.95); conversely, catalysts bearing bulky alkyl and aryl ortho‐substituted ligands proved largely ineffective. All polymers have been characterized by 1H and 13C{1H} NMR spectroscopy, MALDI‐ToF mass spectrometry and DSC analyses. Statistical and thermal analyses enabled the rationalization of the chain‐end control mechanism. Whereas the stereocontrol of the polymerization obeyed a Markov first‐order (Mk1) model for the ROP of rac‐MLABz and rac‐MLAAll, the ROP of rac‐MLAMe led to a chain end‐control of Markov second‐order type (Mk2). DFT computations suggest that the high stereocontrol ability featured by catalysts bearing Cl‐ and Br‐substituted ligands does not likely originate from halogen bonding between the halogen substituent and the growing polyester chain. 相似文献
948.
949.
The 6,6‐Dicyanopentafulvene Core: A Template for the Design of Electron‐Acceptor Compounds 下载免费PDF全文
Dr. Aaron D. Finke Dr. Burkhard O. Jahn Dr. Anas Saithalavi Dr. Christian Dahlstrand Dr. Djawed Nauroozi Sophie Haberland Dr. Jean‐Paul Gisselbrecht Prof. Dr. Corinne Boudon Dr. Edgar Mijangos Dr. W. Bernd Schweizer Dr. Sascha Ott Dr. Henrik Ottosson Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8168-8176
The electron‐accepting ability of 6,6‐dicyanopentafulvenes (DCFs) can be varied extensively through substitution on the five‐membered ring. The reduction potentials for a set of 2,3,4,5‐tetraphenyl‐substituted DCFs, with varying substituents at the para‐position of the phenyl rings, strongly correlate with their Hammett σp‐parameters. By combining cyclic voltammetry with DFT calculations ((U)B3LYP/6‐311+G(d)), using the conductor‐like polarizable continuum model (CPCM) for implicit solvation, the absolute reduction potentials of a set of twenty DCFs were reproduced with a mean absolute deviation of 0.10 eV and a maximum deviation of 0.19 eV. Our experimentally investigated DCFs have reduction potentials within 3.67–4.41 eV, however, the computations reveal that DCFs with experimental reduction potentials as high as 5.3 eV could be achieved, higher than that of F4‐TCNQ (5.02 eV). Thus, the DCF core is a template that allows variation in the reduction potentials by about 1.6 eV. 相似文献
950.
Sarah Coffinet Ahmad Rifai Christophe Genty Yasmine Souissi Sophie Bourcier Michel Sablier Stéphane Bouchonnet 《Journal of mass spectrometry : JMS》2012,47(12):1582-1593
Aqueous solutions of metolachlor and metolachlor‐d6 were photolyzed with UV‐visible radiations. The structures of 15 by‐products of metolachlor were determined through gas chromatography‐mass spectrometry analyses using electron and chemical ionization combined with multistage mass spectrometry. The photolysis by‐products of metolachlor resulted mainly from dehalogenation and hydroxylation, in some cases accompanied by cyclization. In silico tests for toxicity prediction showed that the toxicity of some photolysis products is expected to be greater than that of metolachlor. Persistence studies showed that the by‐product relative abundances vary in large amounts with the irradiation time. The post‐photolysis evolution of the solution was also studied, in order to determine the persistence of the main by‐products. It allowed to establish that most of the by‐products can be found more than 12 h after the end of the photolysis, which is of a great concern as treated water is generally available for consumption only a few hours after treatment in most of industrial processes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献