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Bulo RE Ehlers AW de Kanter FJ Schakel M Lutz M Spek AL Lammertsma K Wang B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(11):2732-2738
Reaction of an in situ generated phosphinidene complex [PhPW(CO)(5)] with the aromatic azulene and guaiazulene leads to unexpected 1,4-adducts of the seven-membered ring and to C--H bond insertion of the five-membered ring. A DFT analysis suggests that the reaction is initiated by formation of a eta(1)-complex between the phosphinidene and the five-membered ring of the aromatic substrate. Four conformations of this complex were identified. Two convert without barrier to the slightly more stable syn- and anti-1,2-adducts. These undergo pericyclic 1,7-sigmatropic rearrangements with remarkably low barriers to give 1,4-adducts, with an inverted configuration at the phosphorus center. An X-ray crystal structure is presented for one of the 1,4-adducts of guaiazulene. The other two eta(1)-complexes insert with modest barriers into a C--H bond of the five-membered ring. 相似文献
64.
Bon RS Sprenkels NE Koningstein MM Schmitz RF de Kanter FJ Dömling A Groen MB Orru RV 《Organic & biomolecular chemistry》2008,6(1):130-137
Alkylation and oxidation of 2H-2-imidazolines, followed by regioselective deprotection, thionation and microwave-assisted Liebeskind-Srogl reaction, efficiently led to 2-aryl-2-imidazolines as new analogues of p53-hdm2 interaction inhibitors (Nutlins). 相似文献
65.
Groenendaal B Vugts DJ Schmitz RF de Kanter FJ Ruijter E Groen MB Orru RV 《The Journal of organic chemistry》2008,73(2):719-722
An efficient, one-pot synthetic protocol toward triazinane diones, a rather unexplored class of heterocyclic scaffolds combining phosphonates, nitriles, aldehydes, and isocyanates is described. The optimization of the reaction, synthesis of a small library of different triazinane diones, as well as alternative routes toward the triazinane dione scaffold are discussed. 相似文献
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Bulo RE Allaart F Ehlers AW de Kanter FJ Schakel M Lutz M Spek AL Lammertsma K 《Journal of the American Chemical Society》2006,128(37):12169-12173
anti-W(CO)(5)-complexed 9-methyl-9-phosphabicyclo[6.1.0]nonatriene represents a covalently interlocked molecular bevel gear. Correlated movement of the phosphorus atom and the eight-membered ring by way of a "walk" rearrangement makes gear slippage impossible. The gearing motion is transferred to the four-toothed W(CO)(5) propeller connected to the rotating phosphorus atom, enabling a gearing ratio of 2:1 according to B3LYP and Car-Parrinello Molecular Dynamics calculations. Methyl substitution of the eight-membered ring tempers the gearing process, with the PMeW(CO)(5) entity passing the substituted carbon atom only at temperatures above 50 degrees C. 相似文献
68.
Gelens E De Kanter FJ Schmitz RF Sliedregt LA Van Steen BJ Kruse CG Leurs R Groen MB Orru RV 《Molecular diversity》2006,10(1):17-22
Optimization of Radziszewski's four-component reaction employing a microwave-assisted protocol, led to a small library of
48 imidazoles with a success rate of 65% (conversion > 45%). All three diversity points of the four-component reaction were
varied. Aromatic and aliphatic inputs were successfully implemented and mono-, di-, tri- and tetrasubstituted imidazoles with
various substitution patterns were synthesized. Furthermore, unsymmetrical diketones could successfully be used which improved
the intrinsic diversity of the method significantly. If the unsymmetrical diketone 1,2-phenylpropanedione (R1 and R2) was used two regioisomers were formed. Depending on the type of amine (R4) and aldehyde (R3) applied, regioselectivity was modest to good. Based on these results, a reaction mechanism is proposed. 相似文献
69.
Paravidino M Bon RS Scheffelaar R Vugts DJ Znabet A Schmitz RF de Kanter FJ Lutz M Spek AL Groen MB Orru RV 《Organic letters》2006,8(23):5369-5372
[Structure: see text] In a search for new multicomponent strategies leading to valuable small heterocycles, a new highly diastereoselective four-component reaction (4CR) was found in which a phosphonate, nitriles, aldehydes, and isocyanoacetates combine to afford functionalized 3-isocyano-3,4-dihydro-2-pyridones. In this strategy, initially a 1-azadiene is generated, which is trapped in the same pot by an isocyanoacetate as the fourth component. Multicomponent reactions (MCRs) that lead to heterocycles containing isocyano substituents are unprecedented and offer many possibilities for further differentiation. 相似文献
70.
Magnetic field dependent biradical CIDNP has been observed in the natural abundance 13C and 1H NMR spectra taken immediately after irradiation of cyclic ketones in an auxiliary magnet. The 13C field dependence curves differ from the corresponding 1H curves: The maxima of the curves for the C11 and C12 biradicals appear at a higher magnetic field strength, and the 13C curves are broader than the 1H curves. These differences are due to the different magnitudes of the hyperfine coupling constants for 13C and 1H and can be accounted for by a model based on a stochastic Liouville method which incorporates the dynamics of the biradicals. 相似文献