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91.
Abstract The ability of macrocyclic polyethers to activate enolates has been studied in the alkylation of de-oxybenzoin (1) with butyl derivatives nBuY (Y = Br, I, OMes) catalyzed by crown ether PHDB18C6 (7) or cryptand [2.2.2,C10] (8) under phase-transfer catalysis (PTC) and homogeneous (chlorobenzene) conditions. The enolate reactivity is mainly determined by the ligand (cryptand > crown ether) and solvent (increasing with the polarity, in the order: toluene < chlorobenzene < 1,2dichlorobenzene). Regioselectivity of the reaction is also remarkably affected by ligand and alkylating agent. 相似文献
92.
Piotr Majewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):151-154
Abstract The dialkylphosphinic acids, 5a-5e, can be obtained by reacting bis(trimethylsiloxy)phosphine with the highly reactive alkyl halides, 2a-2e, in the presence of chlorotrimethylsilane and triethylamine, followed by ethanolysis of the resulting trimethylsilyl dialkylphosphinates, 4a-4e. 相似文献
93.
《合成通讯》2013,43(10):1615-1624
ABSTRACT Sitaxsentan sodium (1, TBC11251Na) is an ETA selective endothelin antagonist under clinical development for pulmonary arterial hypertension and congestive heart failure. Second generation compounds, as exemplified by TBC2576 (2) are currently under development in our laboratories. To rapidly access analogs of 1 and 2, a route was developed for the selective alkylation or acylation of the corresponding di- or trianions derived from these two highly functionalized compounds. We report here on this straightforward, yet effective, procedure consisting of treating the di- or trianions with an excess amount of electrophiles, followed by a rapid quench. In this manner, selective alkylation or acylation of 1 and 2 was achieved with satisfactory yields. 相似文献
94.
A concise approach for the total synthesis of attenols A and B is described involving MacMillan’s α-aminooxylation, Evan’s asymmetric alkylation, Brown’s allylation, and spiro-ketalization as key steps. This approach has successfully demonstrated the α-aminooxylation protocol for the construction of the anti-1,3-diol unit. 相似文献
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98.
QI GuoPeng JIANG Feng SUN XueWen & ZHAO SuoQi School of Chemical Engineering Tianjin University Tianjin China State key Laboratory of Heavy Oil Processing Petroleum University of China Beijing China 《中国科学:化学》2010,(5)
The isotope exchange method was employed to investigate the catalytic mechanism of ionic liquid in alkylation of benzenes with olefins.It is proposed that alkylation was induced by the Lewis acid AlCl3 which attracted π electrons of 1-dodecene to shift toward 1-carbon,thus forming a carbonium ion.The carbonium ion further reacted with benzenes to form a complex.Due to unstabilit of the complex,a deuterated ring proton was transferred into an electronegative 1-carbon of the side chain to substitute for the A... 相似文献
99.
Liangru Yang Yunfei Li Pu Mao Jinwei Yuan Yongmei Xiao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):780-788
AbstractThe catalytic activity of a series of chiral heteroaryl coordinated chelating N-heterocyclic carbene (NHC) palladium complexes towards asymmetric allylic alkylation (AAA) were presented here. The effects of different N-substituents, NHC backbones and chelate rings on the catalytic activity and the enantioselectivity of the alkylation of (E)-1,3-diarylallyl acetates with dialkyl malonate were investigated. The results showed that, under the optimized conditions, complexes 3a, 3b, and 3i carrying the pyridinyl-coordinated five-membered chelate ring showed high catalytic activity and chiral induction efficiency. The corresponding alkylated products were obtained in high yields with moderate ee. Furthermore, it was found that the substituents of (E)-1,3-diarylallyl acetates and the type of the nucleophile affect the results as well. 相似文献
100.
Oguejiofo T. Ujam Kyle Devey William Henderson Brian K. Nicholson Michael R. Mucalo Corry Decker 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1508-1525
Abstract The immobilization of the dinuclear platinum(II) sulfido complex [Pt2(μ-S)2 (PPh3)4] on solid supports has been investigated. Reaction with haloalkyl functionalized polymers [Merrifield's resin (chloromethylated polystyrene), chloropropyl silica, chloropropyl controlled pore glass, and bromopropyl polysiloxane] gives complexes immobilized through alkylation of one of the sulfide ligands, forming a μ-thiolate ligand acting as an anchor to the polymer support, akin to well-established reactions of [Pt2(μ-S)2(PPh3)4] with molecular alkylating agents. The model complex [Pt2(μ-S)(μ-SCH2SiMe3)(PPh3)4]PF6 was prepared as the first molecular silicon-containing derivative of [Pt2(μ-S)2(PPh3)4] and was fully characterized by NMR spectroscopy, electrospray ionization-mass spectrometry, and single-crystal X-ray diffraction. Immobilization of [Pt2(μ-S)2(PPh3)4] by phosphine exchange reactions was also achieved using commercial polystyrene-grafted triphenylphosphine or a new immobilized phosphine [derived by sequential functionalization of Merrifield's resin with a polyether amine and then Ph2PCH2OH]. 相似文献