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991.
Vijay Mahadevan Iyer Helen Stoeckli‐Evans Anthony D'Alo Luisa De Cola Peter Belser 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):o259-o261
Structure analyses of 4,4′‐bis(4‐hydroxybutyl)‐2,2′‐bipyridine, C18H24N2O2, (I), and 4,4′‐bis(4‐bromobutyl)‐2,2′‐bipyridine, C18H22Br2N2, (II), reveal intermolecular hydrogen bonding in both compounds. For (I), O—H·N intermolecular hydrogen bonding leads to the formation of an infinite two‐dimensional polymer, and π stacking interactions are also observed. For (II), C—H·N intermolecular hydrogen bonding leads to the formation of a zigzag polymer. The two compounds crystallize in different crystal systems, but both molecules possess Ci symmetry, with one half molecule in the asymmetric unit. 相似文献
992.
Maria Luisa Di Vona Riccardo Polini Paolo Sebastianelli Silvia Licoccia 《Journal of Sol-Gel Science and Technology》2004,31(1-3):95-98
The study of non-hydrolytic reactions for the synthesis of Mg x Al2(1?x)Ti(1+x)O5 solid solution with x = 0.6 is reported. The reagents chosen were Al(OsBu)3, Ti(OiPr)4, TiCl4 and Mg(NO3)2·6H2O in toluene. The reactions were followed using 13C Nuclear Magnetic Resonance (NMR) spectroscopy. Sol-gel synthesized powders were calcined in air at 300, 500, 1000, and 1200°C for 1 h. The powders were analysed by X-Ray Diffraction (XRD) demonstrating the formation of a Mg0.6Al0.8Ti1.6O5 phase in samples treated at the higher calcination temperature. 相似文献
993.
Consolación P. Menaut Jose M. Pico Carlos Franjo Eulogio Jimenez Luisa Segade María I. Paz Andrade 《Journal of solution chemistry》1998,27(12):1139-1148
Excess molar volumes at 25°C of the ternary systems 2-butanone + 1 -chlorooctane + octane and 2-pentanone + 1-chlorooctane + octane and of binary mixtures 2-butanone + octane, 2-pentanone + octane, and 1-chlorooctane + octane, were determined using an Anton Paar DMA 60/602 densimeter. All the experimental values were compared with the results obtained by empirical expressions for estimating ternary properties from binary data. Variable degree polynomials were fitted to the results. 相似文献
994.
Cotrone S Cafagna D Cometa S De Giglio E Magliulo M Torsi L Sabbatini L 《Analytical and bioanalytical chemistry》2012,402(5):1799-1811
Most of the success of electronic devices fabricated to actively interact with a biological environment relies on the proper choice of materials and efficient engineering of surfaces and interfaces. Organic materials have proved to be among the best candidates for this aim owing to many properties, such as the synthesis tunability, processing, softness and self-assembling ability, which allow them to form surfaces that are compatible with biological tissues. This review reports some research results obtained in the development of devices which exploit organic materials' properties in order to detect biologically significant molecules as well as to trigger/capture signals from the biological environment. Among the many investigated sensing devices, organic field-effect transistors (OFETs), organic electrochemical transistors (OECTs) and microcantilevers (MCLs) have been chosen. The main factors motivating this choice are their label-free detection approach, which is particularly important when addressing complex biological processes, as well as the possibility to integrate them in an electronic circuit. Particular attention is paid to the design and realization of biocompatible surfaces which can be employed in the recognition of pertinent molecules as well as to the research of new materials, both natural and inspired by nature, as a first approach to environmentally friendly electronics. 相似文献
995.
Dr. Sara Pellegrino Dr. Alessandro Contini Prof. Francesca Clerici Dr. Alessandro Gori Donatella Nava Prof. Maria Luisa Gelmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(28):8705-8715
A very efficient synthesis of orthogonally protected 1H‐azepine‐4‐amino‐4‐carboxylic acid, abbreviated as Azn, a conformationally restricted analogue of ornithine, was realized. It was obtained on a gram scale in good overall yield in five steps, three of which did not require isolation of the intermediates, starting from the readily available 1‐amino‐4‐oxo‐cyclohexane‐4‐carboxylic acid. Both enantiomers were used for the preparation of pentapeptide models containing Ala, Aib, and Azn. Conformational studies using both spectroscopic techniques (NMR, CD) and molecular dynamics on model 5‐mer peptides showed that the (R)‐Azn isomer possesses a marked helicogenic effect. 相似文献
996.
997.
Enantioselective Synthesis of Tertiary Propargylic Alcohols under N‐Heterocyclic Carbene Catalysis 下载免费PDF全文
Eduardo Sánchez‐Díez Dr. Maitane Fernández Dr. Uxue Uria Prof. Efraim Reyes Prof. Luisa Carrillo Prof. Jose L. Vicario 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8384-8388
A straightforward procedure to carry out the enantioselective benzoin reaction between aldehydes and ynones by employing a chiral N‐heterocyclic carbene (NHC) as catalyst was developed. Under the optimized reaction conditions, these ynones undergo a clean and selective 1,2‐addition with the catalytically generated Breslow intermediate, not observing any byproduct arising from competitive Stetter‐type reactivity. This procedure allows the preparation of tertiary alkynyl carbinols as highly enantioenriched materials, which have the remarkable potential to be used as chiral building blocks in organic synthesis. 相似文献
998.
Harnessing the ortho‐Directing Ability of the Azetidine Ring for the Regioselective and Exhaustive Functionalization of Arenes 下载免费PDF全文
Marina Zenzola Dr. Leonardo Degennaro Dr. Piera Trinchera Laura Carroccia Dr. Arianna Giovine Dr. Giuseppe Romanazzi Prof. Dr. Piero Mastrorilli Rosanna Rizzi Dr. Luisa Pisano Prof. Dr. Renzo Luisi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12190-12200
This work demonstrates how the directing ability of the azetidine ring could be useful for regioselective ortho‐C?H functionalization of aryl compounds. Robust polar organometallic (lithiated) intermediates are involved in this synthetic strategy. The reagent n‐hexyllithium emerged as a safer, yet still effective, basic reagent for the hydrogen/lithium permutation relative to the widely used reagent nBuLi. Two different reaction protocols were discovered for regioselective lithiation at the ortho positions adjacent to the azetidine ring, which served as a toolbox when other competing directing groups were installed on the aromatic ring. The coordinating ability of the azetidine nitrogen atom, as well as the involvement of dynamic phenomena related to the preferential conformations of 2‐arylazetidine derivatives, were recognized to be responsible for the observed reactivity and regioselectivity. A site‐selective functionalization of the aromatic ring was achieved for aryl azetidines with either coordinatively competent groups (e.g. methoxy) or inductively electron‐withdrawing substituents (e.g. chlorine and fluorine). By fine‐tuning the reaction conditions, regioselective introduction of several substituents on the aromatic ring could be realized. Several substitution patterns were accomplished, which included 1,2,3‐trisubstitution, 1,2,3,4‐tetrasubstitution, and 1,2,3,4,5‐pentasubstitution, up to the exhaustive substitution of the aromatic ring. 相似文献
999.
Gagliardo M Rodríguez G Dam HH Lutz M Spek AL Havenith RW Coppo P De Cola L Hartl F van Klink GP van Koten G 《Inorganic chemistry》2006,45(5):2143-2155
A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthesis of a novel terpyridine-pincer (3, TPBr) bridging ligand, 4'-{4-BrC6H2(CH2NMe2)2-3,5}-2,2':6',2' '-terpyridine. Mononuclear species [PdX(TP)] (X = Br, Cl), [Ru(TPBr)(tpy)](PF6)2, and [Ru(TPBr)2](PF6)2, synthesized by selective metalation of the NCNBr-pincer moiety or complexation of the terpyridine of the bifunctional ligand TPBr, were used as building blocks for the preparation of heterodi- and trimetallic complexes [Ru(TPPdCl)(tpy)](PF6)2 (7) and [Ru(TPPdCl)2](PF6)2 (8). The molecular structures in the solid state of [PdBr(TP)] (4a) and [Ru(TPBr)2](PF6)2 (6) have been determined by single-crystal X-ray analysis. Electrochemical behavior and photophysical properties of the mono- and heterometallic complexes are described. All the above di- and trimetallic Ru complexes exhibit absorption bands attributable to (1)MLCT (Ru --> tpy) transitions. For the heteroleptic complexes, the transitions involving the unsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bands observed in the electronic spectra for TPBr and [PdCl(TP)] have been assigned with the aid of TD-DFT calculations. All complexes display weak emission both at room temperature and in a butyronitrile glass at 77 K. The considerable red shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)2]2+ indicates stabilization of the luminescent 3MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopic studies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and 77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetallic complex [Ru(TPPdSCN)(tpy)](PF6)2, are indicative of charge redistribution through the bridging ligand TPBr. The results are in line with a weak coupling between the {Ru(tpy)2} chromophoric unit and the (non)metalated NCN-pincer moiety. 相似文献
1000.
Benati L Bencivenni G Leardini R Minozzi M Nanni D Scialpi R Spagnolo P Zanardi G 《The Journal of organic chemistry》2006,71(1):434-437
[reaction: see text] Aromatic azides are inert toward tributylgermanium hydride under thermal conditions in the absence and in the presence of a radical initiator but in the presence of catalytic amounts of benzenethiol undergo fast reaction, yielding reduced anilines and 2-germylated derivatives in high overall yields. 相似文献