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H. Bürger H. Niepel G. Pawelke H.J. Frohn P. Sartori 《Journal of fluorine chemistry》1980,15(3):231-237
The electrofluorination of N(CH3)3 yields, along with fragmentation and recombination products and N(CF3)3 (I), minor quantities of the hitherto unknown compounds (CF3)2 NCF2H (II), CF3N(CF2H)2 (III) and N(CF2H)3 (IV). I –IV have been isolated and characterized by their 1H, 13C and 19F nmr and their E I and C I mass spectra. 相似文献
106.
Lorenz JC Frohn M Zhou X Zhang JR Tang Y Burke C Shi Y 《The Journal of organic chemistry》2005,70(8):2904-2911
This paper describes an efficient kinetic resolution process of trisubstituted cyclic olefins via a chiral dioxirane generated in situ from a fructose-derived ketone and Oxone. The substrates presented include a variety of 1,3-disubstituted and 1,6-disubstituted cyclohexenes with the stereogenic centers at allylic positions. A sequential desymmetrization and kinetic resolution of 1,4-cyclohexadienes by the chiral dioxirane was also found to be feasible. The initially formed monoepoxides can be kinetically resolved by continuing the reaction, leading to the increase or decrease of the ee values of monoepoxides depending on the diene systems. In some cases, a prochiral directing group is not required and the first formed epoxide stereoselectively directs the second epoxidation. When the coupled desymmetrization and kinetic resolution is used synergistically, high enantiopurity can be obtained for an epoxide from an intrinsically less enantioselective substrate. The observed absolute and relative stereochemistry as well as the changing optical purity can be effectively rationalized by transition state analysis. 相似文献
107.
BrF3 reacts with C6F5SiF3 to form C6F5BrF2, a volatile, colourless, and thermally stable solid, which melts at 35 – 36 °C without decomposition. Its chemical and spectroscopic properties are in contrast to the product described by Sams [1]. The reactivity of the BrF-bonds in C6F5BrF2 allows displacement of fluorine by groups stable against oxidation. With trifluoroacetic acid anhydride C6F5Br[O(O)CCF3]2 is formed as the first stable carboxylate of Br(III). 相似文献
108.
We report metathetical reactions of IF5 with series of α,β-trimethylsilylated ethanediolates with increasing numbers of CH3-groups in α- and β-positions. Short lived intermediates IF4[OC2H4?n(CH3)nO]X with X = Si(CH3)3 or IF4 and stable chelates IF3[OC2H4?n(CH3)nO] and IF[OC2H4?n(CH3)nO]2 (n = 0–4) are observed and characterized. Time and temperature dependence of 19F-NMR-spectra in relation to degree of methylation, arrangement and stereo-chemistry are discussed referring to previously published mono- and polynuclear I(V)-compounds containing a series of monodentate alcoholates CH3?n(CH3)nO? and (CH3)3CCH2O? (n = 0,2,3) [1,2] and of bidentate alcoholates ?O(CH2)nO? (n = 2,3,4,5,6,12) [1]. In contrast to aliphatic α,β-diolates the aromatic diolates 1,2-C6H4(O?)2, 1,2-C6Cl4(O?)2 rapidly undergo redox reactions even at low temperatures. 相似文献
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New examples of [C6F5Xe]+ salts of the weakly coordinating [BY4]- (Y = CN, CF3, or C6F5) anions were synthesized by metathesis of [C6F5Xe][BF4] with MI[BY4] (MI = K or Cs; Y = CN, CF3, or C6F5) in CH3CN at -40 degrees C, and were crystallized from CH2Cl2 or from a CH2Cl2/CH3CN solvent mixture. The low-temperature (-173 degrees C) X-ray crystal structures of the [C6F5Xe]+ cation and of the [C6F5XeNCCH3]+ adduct-cation are reported for [C6F5Xe][B(CF3)4], [C6F5XeNCCH3][B(CF3)4], [C6F5Xe][B(CN)4], and [C6F5XeNCCH3][B(C6F5)4]. The [C6F5Xe]+ cation, in each structure, interacts with either the anion or the solvent, with the weakest cation-anion interactions occurring for the [B(CF3)4]- anion. The solid-state Raman spectra of the [C6F5Xe]+ and [C6F5XeNCCH3]+ salts have been assigned with the aid of electronic structure calculations. Gas-phase thermodynamic calculations show that the donor-acceptor bond dissociation energy of [C6F5XeNCCH3]+ is approximately half that of [FXeNCCH3]+. Coordination of CH3CN to [C6F5Xe]+ is correlated with changes in the partial charges on mainly Xe, the ipso-C, and N, that is, the partial charge on Xe increases and those on the ipso-C and N decrease upon coordination, typifying a transition from a 2c-2e to a 3c-4e bond. 相似文献