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291.
介绍了四氧化锇催化不对称烯烃双羟基化的反应原理和以N-甲基吗啉-N-氧化物(N-methylmorpholine-N-oxide,NMO)、铁氰化钾K3[Fe(CN)6] 为氧化剂时烯烃双羟基化反应的催化循环;此外,还介绍了该催化反应立体选择性的机理和一些研究进展以及催化体系中手性配体的选择。 相似文献
292.
Pla-Quintana A Roglans A de Julián-Ortiz JV Moreno-Mañas M Parella T Benet-Buchholz J Solans X 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(9):2689-2697
The complete structural analysis of the palladium complexes of the triolefinic macrocycles (E,E,E)-1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-trienes, which featured from three identical to three different aryl groups, was achieved by performing X-ray diffraction studies, NMR spectroscopy, and other calculations. The stereochemical complexity is determined by the different isomers formed through complexation of the metal to one or other face of each of the three olefins involved. The palladacyclopropane formulation of the palladium-olefin interaction offers a clear picture of the stereogenicity of the olefin carbon atoms that are complexed to the metal. The energetically favorable isomers were identified in the solid-state and in solution by performing X-ray diffraction and NMR spectroscopic analysis, respectively. 相似文献
293.
294.
Ring opening reaction of oxabicylic alkenes 4 with in situ prepared organozinc halides 5 was catalyzed by palladacycle 3 with high efficiency. Good yields of the corresponding 1,2-dihydronaphth-1-ols (6) were provided when as low as 0.05 mol% of palladacycle 3 was used. 31P NMR study showed that the skeleton of 3 remained intact in the reaction, which implied that palladacycle 3 did not serve as a catalyst precursor but a catalyst in the reaction. 相似文献
295.
296.
A two-component condensation reaction between a 1,3-dicarbonyl-containing CH acid and an electron-poor acetylenic ester efficiently provides fully substituted electron-poor alkenes and pyranes in a one-pot reaction in the presence of silica gel in solvent-free conditions. 相似文献
297.
Olena VakuliukFrancesco G. Mutti Miguel LaraDaniel T. Gryko Wolfgang Kroutil 《Tetrahedron letters》2011,52(28):3555-3557
The allyl moiety of 4-allyl-anisol was oxidized in the presence of a Fe(III) porphyrin derivative to the corresponding α,β-unsaturated aldehyde in an initial oxidation step with perfect chemoselectivity. Molecular oxygen was employed as the sole environmental innocuous oxidant. The reaction was performed in an aqueous buffer/CH2Cl2 mixture using the detergent Tween 80 to homogenize the system. 相似文献
298.
Yue Jiang Yan Liang Dr. Mingxia Zhang Zhong Zhang Prof. Dr. Yiwei Liu 《欧洲无机化学杂志》2023,26(28):e202300301
Achieving highly selective oxidation of aryl alkenes to aldehydes is of great significance in chemical industry. Herein, the performance of catalytic aryl alkene oxidation is enhanced via constructing a hierarchical fractal polyoxometalate-based metal–organic framework (POM@MOF) containing hierarchical pores and layered surface structure, which improve the mass transfer efficiency of substrates and increase the accessibility to active POMs clusters. Accordingly, the activity of fractal POM@MOF is increased by 4.8 times compared with microporous counterpart in 4-tert-butylstyrene oxidation to aldehyde product. This work paves a way for designing efficient catalysts for selective oxidation of aryl alkenes via increasing the accessibility of active sites and broadening the diffusion channels by hierarchical construction. 相似文献
299.
Dr. Marco Ballarotto Dr. Bruno Cerra Prof. Andrea Temperini 《European journal of organic chemistry》2023,26(36):e202300552
Herein, we present a novel and metal-free approach to the stereospecific synthesis of E-stilbenes. Starting from substituted 6-arylhexa-3,5-dien-2-ones, a multicomponent enolacetylation/intermolecular Diels–Alder reaction was performed using ethyl acetate as a green solvent. The obtained cycloadducts were then oxidized without purification to produce the stilbenic products in good yields up to 67 % and with complete (E)-stereospecificity and regioselectivity. Moreover, heterostilbenes were synthetized using this approach, displaying the potential applications of this protocol in pharmaceutical and material sciences. The proposed methodology was further extended to the synthesis of diarylacetylenes, furnishing a new metal-free synthetic access to this important class of compounds. Furthermore, DFT calculations were performed confirming a concerted [4+2] reaction mechanism of the key ring-forming step. At last, the energetic analysis of the possible transition states helps to shed some light on the experimentally observed total regio- and chemoselectivity. 相似文献
300.