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101.
《Tetrahedron letters》2004,45(10):2085-2088
Various trans-β-alkylstyrenes (55-90% yield) were isolated from the free radical addition/elimination process of α-iodocarboxylic acid derivatives with β-nitrostyrenes using dilauroyl peroxide as initiator. The corresponding xanthates give low yields of the alkene under similar conditions. 相似文献
102.
Nicolas Puljic Matthias Albert Anne‐Lise Dhimane Louis Fensterbank Emmanuel Lacte Max Malacria 《Helvetica chimica acta》2006,89(10):2297-2305
The titanocene(III) chloride mediated opening of silyloxiranes has been examined. Electron transfer from the metal leads to α‐silyl radicals with total regiocontrol. The radicals could be trapped by various olefins, and the corresponding adducts were obtained in good yields (Table). Further substitution of the oxirane by alkyl groups proved detrimental to the reactions, but ring opening remained essentially regioselective. 相似文献
103.
Rui Xiaotian Wataru Ota Prof. Tohru Sato Minori Furukori Prof. Yasuo Nakayama Prof. Takuya Hosokai Eri Hisamura Kazuhiro Nakamura Kenshiro Matsuda Dr. Kohei Nakao Prof. Andrew P. Monkman Prof. Ken Albrecht 《Angewandte Chemie (International ed. in English)》2023,62(28):e202302550
A series of carbazole-dendronized tris(2,4,6-trichlorophenyl)methyl (TTM) radicals have been synthesized. The photophysical properties of dendronized radicals up to the fourth generation were compared systematically to understand how structure–property relationships evolve with generation. The photoluminescence quantum yield (PLQY) was found to increase with the increasing generation, and the fourth generation (G4TTM) in cyclohexane solution showed a PLQY as high as 63 % at a wavelength of 627 nm (in the deep-red region) from the doublet state. The dendron modification strategy also showed a blue-shift of the emission on increasing the generation number, and the photostability was also increased compared to the bare TTM radical. 相似文献
104.
Marta Lovisari Oscar Reid Kelly Aidan R. McDonald 《Angewandte Chemie (International ed. in English)》2023,62(31):e202303083
Heme and chlorin π-cation radical oxidants are widely implicated in biological and synthetic oxidation catalysis. Little insight into the role of π-cation radicals in proton coupled electron transfer (PCET) oxidation is available. We prepared a NiII-porphyrin-π-cation complex ([NiII(P⋅+)]) and found it to be capable of the oxidation of a variety of simple hydrocarbon substrates. Interestingly, some of the products were hydroxylated, with ([NiII(P⋅+)]) working in concert with atmospheric O2 to yield hydroxylated hydrocarbons. Kinetic data suggested that the porphyrin-π-cation radical species oxidised substrates through a concerted PCET mechanism, where the porphyrin-π-cation radical accepted the electron, and the proton was transferred to a free anion. Our findings highlight the potential role of π-cation radicals as hydrocarbon activators, demonstrating that porphyrin ligand non-innocence could be a readily manipulated resource for oxidation catalyst development. 相似文献
105.
Dr. Qinhua Zhang Dr. Bo An Dr. Yu Lei Zhixiao Gao Dr. Haonan Zhang Prof. Sheng Xue Prof. Xin Jin Prof. Wengang Xu Zihan Wu Prof. Mingbo Wu Prof. Xin Yang Prof. Wenting Wu 《Angewandte Chemie (International ed. in English)》2023,62(36):e202304699
Developing new reactive pathway to activate inert C(sp3)−H bonds for valuable oxygenated products remains a challenge. We prepared a series of triazine conjugated organic polymers to photoactivate C−H into aldehyde/ketone via O2→H2O2→⋅OH→Cl⋅→Cl2⋅−. Experiment results showed Cl2⋅− could successively activate C(sp3)−H more effectively than Cl⋅ to generate unstable dichlorinated intermediates, increasing the kinetic rate ratio of dichlorination to monochlorination by a factor of 2,000 and thus breaking traditional dichlorination kinetic constraints. These active intermediates were hydrolyzed into aldehydes or ketones easily, when compared with typical stable dichlorinated complexes, avoiding chlorinated by-product generation. Moreover, an integrated two-phase system in an acid solution strengthened the Cl2⋅− mediated process and inhibited product overoxidation, where the conversion rate of toluene reached 16.94 mmol/g/h and the selectivity of benzaldehyde was 99.5 %. This work presents a facile and efficient approach for selective conversion of inert C(sp3)−H bonds using Cl2⋅−. 相似文献
106.
Shiyang Xu Wei Zhang Caiyi Li Yanjing Li Hongxin Zeng Prof. Yingwei Wang Yang Zhang Prof. Dawen Niu 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218303
We herein report a method that enables the generation of glycosyl radicals under highly acidic conditions. Key to the success is the design and use of glycosyl sulfinates as radical precursors, which are bench-stable solids and can be readily prepared from commercial starting materials. This development allows the installation of glycosyl units onto pyridine rings directly by the Minisci reaction. We further demonstrate the utility of this method in the late-stage modification of complex drug molecules, including the anticancer agent camptothecin. Experimental studies provide insight into the reaction mechanism. 相似文献
107.
Huaipu Yan Qian Liao Yuqing Chen Gagik G. Gurzadyan Binghui Lu Chao Wu Lei Shi 《Angewandte Chemie (International ed. in English)》2023,62(24):e202302483
Catalytic metal hydride hydrogen atom transfer (MHAT) reactions have proven to be a powerful method for alkene functionalization. This work reports the discovery of Co-porphines as highly efficient MHAT catalysts with a loading of only 0.01 mol % for unprecedented chemoselective allene functionalization under photoirradiation. Moreover, the newly developed bimetallic strategy by the combination of photo Co-MHAT and Ti catalysis enabled the successful carbonyl allylation with a wide range of amino, oxy, thio, aryl, and alkyl-allenes providing expedient access to valuable β-functionalized homoallylic alcohols in over 100 examples with exceptional regio- and diastereoselectivity. Mechanism studies and DFT calculations supported that selectively transferring hydrogen atoms from cobalt hydride to allenes and generating allyl radicals is the key step in the catalytic cycle. 相似文献
108.
Alexander S. Harmata B. J. Roldan Corey R. J. Stephenson 《Angewandte Chemie (International ed. in English)》2023,62(4):e202213003
The field of strain-driven, radical formal cycloadditions is experiencing a surge in activity motivated by a renaissance in free radical chemistry and growing demand for sp3-rich ring systems. The former has been driven in large part by the rise of photoredox catalysis, and the latter by adoption of the “Escape from Flatland” concept in medicinal chemistry. In the years since these broader trends emerged, dozens of formal cycloadditions, including catalytic, asymmetric variants, have been developed that operate via radical mechanisms. While cyclopropanes have been studied most extensively, a variety of strained ring systems are amenable to the design of analogous reactions. Many of these processes generate lucrative, functionally decorated sp3-rich ring systems that are difficult to access by other means. Herein, we summarize recent efforts in this area and analyze the state of the field. 相似文献
109.
110.
Dr. Xiaoye Yu Anirban Maity Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2023,62(48):e202310288
α-Trifluoromethylated ketones have attracted significant attention as valuable building blocks in organic synthesis. Such compounds are generally accessed through trifluoromethylation of ketones. Here we report an alternative disconnection approach for the construction of α-CF3 carbonyl compounds by using aroyl fluorides as bifunctional reagents for fluoroaroylation of gem-difluoroalkenes through cooperative photoredox and N-heterocyclic carbene (NHC) catalysis. This strategy bypasses the use of expensive or sensitive trifluoromethylation reagents and/or the requirement for ketone pre-functionalization, thus enabling an efficient and general synthetic method to access α-CF3-substituted ketones. A wide variety of gem-difluoroalkenes and aroyl fluorides bearing a diverse set of functional groups are eligible substrates. Notably, the developed methodology also provides rapid access to mono- or difluoroalkyl ketones. Mechanistic studies reveal that merging photoredox catalysis with NHC catalysis is essential for the reaction. 相似文献