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Although the efficient preparation of cyclooctanoids has remained a long-standing objective, a real breakthrough was possible only relatively recently with the development of more specific reagents and by the development of new reactions. The direct construction of carbocyclic eight-membered rings from acyclic precursors is still a challenge, mainly because of unfavorable entropic and enthalpic factors that preclude ring formation. This Minireview describes the utilization of ring-closing metathesis (RCM) as a new approach to synthesize cyclooctanoids. 相似文献
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Jing Tan Xianxiu Xu Dr. Lingjuan Zhang Yifei Li Qun Liu Prof. 《Angewandte Chemie (International ed. in English)》2009,48(16):2868-2872
Up to four adjacent stereocenters can be formed stereoselectively in the construction of a pyrrolizidine unit through a novel organocatalytic reaction that involves treatment of various dienones with ethyl isocyanoacetate (see scheme; DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene). Mechanisms for this atom‐economic, one‐pot synthesis have been proposed.
656.
Subaramaniam Thangamalar Prof. Dr. Kannupal Srinivasan 《European journal of organic chemistry》2023,26(7):e202201084
The ring-opening reaction of nitro-substituted donor-acceptor cyclopropanes with pyrazoles in DMSO was investigated. Unexpectedly, the cyclopropanes underwent Kornblum-type ring-opening oxidation with DMSO to form aroylmethylidene malonates as intermediates in the reactions. The intermediates further underwent aza-Michael addition with pyrazoles in tandem manner to give the corresponding aza-Michael adducts. The highlights of the methodology include the occurrence of ring-opening/oxidation under neutral conditions with DMSO and formation of aza-Michael adducts with pyrazoles under catalyst-free conditions. 相似文献
657.
Vijay Babu Pathi Arindam Manna Ravuri Srinath Supriyo Adhikary Prof. Dr. Biswadip Banerji 《European journal of organic chemistry》2023,26(28):e202300256
Regioselective synthesis of N-fused benzimidazo-indolo-isoquinoline heterocycles via Pd-catalyzed domino coupling reaction of 1-(1-methyl-1H-indol-2-yl)-1H-benzimidazoles and aryl halides was developed. This one pot methodology proceeded via a five-member carbopalladacycle intermediate and provided direct and facile route to access structurally complex polyheterocycles in moderate to good yields. These unique hybrid molecules resembled structural similarity with naturally isolated alkaloids. Notably, the present domino process occurred through activation of three C−H bonds and the simultaneous formation of two new C−C bonds in one-shot. These molecules exhibited strong solid and solution phase fluorescence and their emission spectra in both the medium are reported here. 相似文献
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Elisa Brambilla Alessandra Gritti Valentina Pirovano Antonio Arcadi Raimondo Germani Matteo Tiecco Giorgio Abbiati 《European journal of organic chemistry》2023,26(16):e202300204
We describe an alternative and more sustainable method for the synthesis of 2,2’-disubstituted 3,3’-biindoles starting from 2,2’-diaminotolanes and (hetero)arylaldehydes. The key feature of the approach is the use of an acidic Deep Eutectic Solvent (DES) able to exploit a double activity, i. e., solvent and Brønsted Acid (BA) catalyst, avoiding the use of Volatile Organic Compounds (VOCs) as solvents and additional acid catalysts. By this way, we synthesized twenty-five biindoles, including eighteen new compounds. The reactions run quickly under mild conditions by microwave heating at 70 °C, with yields ranging from good to very good. The reaction scope is rather broad. The medium demonstrated to be reusable at least five times with only a slight reduction in yields. Based on experimental evidence and previous literature findings, a plausible mechanism is proposed. 相似文献
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Sebastian Beeck Prof. Dr. Hermann A. Wegner 《European journal of organic chemistry》2023,26(8):e202201289
Recently, we presented a novel enantioselective multicomponent reaction of phthalazines, aldehydes and thiols accessing thioether-substituted 1,2-dihydronaphthalenes. Herein, a comprehensive investigation on the mechanism of this domino inverse electron-demand (IEDDA)/thiol transfer reaction is disclosed. In particular, the origin of the stereochemical outcome has been rationalized, as well as structural requirement of the thiol component for an efficient transfer step. Detailed NMR spectroscopy studies uncover a competing reaction pathway resulting in N,S-acetals. In addition, DFT computations illuminate the mechanism of the group transfer process and enable an explanation for the formation of the most dominant by-product. The insights allow a direct prediction of suitable substrates for the reaction and provide the basis for further developments of novel stereoselective domino reactions. 相似文献