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71.
Areces P Angeles Durán M Plumet J Hursthouse MB Light ME 《The Journal of organic chemistry》2002,67(10):3506-3509
Some N-substituted-3-azabicyclo[3.3.0]octen-7-one derivatives have been synthesized in an enantiomerically pure form starting from tri-O-acetyl-D-glucal via intramolecular Pauson-Khand (IPK) cycloaddition. 相似文献
72.
The paper obtains error estimates for approximation by radial basis functions on the sphere. The approximations are generated
by interpolation at scattered points on the sphere. The estimate is given in terms of the appropriate power of the fill distance
for the interpolation points, in a similar manner to the estimates for interpolation in Euclidean space. A fundamental ingredient
of our work is an estimate for the Lebesgue constant associated with certain interpolation processes by spherical harmonics.
These interpolation processes take place in ``spherical caps' whose size is controlled by the fill distance, and the important
aim is to keep the relevant Lebesgue constant bounded. This result seems to us to be of independent interest.
March 27, 1997. Dates revised: March 19, 1998; August 5, 1999. Date accepted: December 15, 1999. 相似文献
73.
Simon J. Coles Philip A. Gale Mark E. Light Colin N. Warriner 《Supramolecular chemistry》2013,25(7):469-486
A variety of furan and thiophene amide and thioamide cleft type anion receptors have been synthesised and crystallographically characterised. Unlike 2,5-diamidopyrrole anions, analogous 2,5-diamidofurans and thiophenes do not interlock in the solid state. The anion binding properties of these receptors have been investigated in DMSO/0.5% water solution using 1H NMR titration techniques. Solution studies and solid-state evidence suggests that the thiophene receptors may utilise a thiophene CH hydrogen atom for hydrogen bond formation to anions with a 2,4-diamidothiophene showing similar anion binding affinities to a 2,5-diamidopyrrole. 相似文献
74.
R. W. Light R. T. Paine 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):255-258
Abstract The reactions of SO2 with tris-dimethylaminophosphine, bis-dimethylaminofluorophosphine, bis-dimethylaminochlorophosphine, dimethylaminodifluorophosphine, dimethylaminodichlorophosphine, 1,3-dimethyl-2-fluoro-1,3,2-diazaphospholidine and 1,3-dimethyl-2-chloro-1,3,2-diazaphospholidine have been investigated. The complex reactions are dominated by facile oxidation of the respective phosphine to phosphoryl and thiophosphoryl derivatives. The new heterocyclic phosphines CH3 NCH2CH2N(CH3)P(O)F and CH3 NCH2CH2N(CH3)P(S)F have been isolated and characterized by NMR, infrared, and mass spectrometry. 相似文献
75.
76.
77.
Caltagirone C Gale PA Hiscock JR Brooks SJ Hursthouse MB Light ME 《Chemical communications (Cambridge, England)》2008,(26):3007-3009
Neutral 1,3-di(1H-indol-7-yl)ureas are selective dihydrogen phosphate receptors in polar solvent mixtures (DMSO-d(6)-25% water). 相似文献
78.
Cantillo D Avalos M Babiano R Cintas P Jiménez JL Light ME Palacios JC 《Organic letters》2008,10(6):1079-1082
An unusual thionation strategy of mesoionic compounds with aryl isothiocyanates enables a facile synthesis of 1,3-thiazolium-4-thiolate systems. The mechanistic pathway of such a transformation most likely involves a stepwise 1,3-dipolar cycloaddition, which is supported by theoretical calculations performed with a two-layer hybrid method (B3LYP/6-31G(d):PM3). 相似文献
79.
Terrasson V Planas JG Prim D Viñas C Teixidor F Light ME Hursthouse MB 《The Journal of organic chemistry》2008,73(22):9140-9143
Thionyl chloride (SOCl2) acts as halogenation reagent in its reaction with 1-[phenyl(hydroxy)methyl]-2-R-1,2-dicarba-closo-dodecaborane 1a, b but unexpectedly behaves as an oxidant for 1-[2'-pyridyl(hydroxy)methyl]-2-R-1,2-dicarba-closo-dodecaboranes 2a, b. The synthesis and characterization of all new compounds, including structure determinations of 1a, 2a, 1-[phenyl(chloro)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane 3a, and 1-[2'-pyridyl(oxo)methyl]-2-methyl-1,2-dicarba-closo-dodecaboranes 4a are reported and the possible pathways are discussed. 相似文献
80.
Avalos M Babiano R Cintas P Jiménez JL Light ME Palacios JC Pérez EM 《The Journal of organic chemistry》2008,73(2):661-672
A series of chiral imines derived from 1-amino-1-deoxyalditols such as d-glucamine, a rather unexplored raw material from the chiral pool, have been serendipitiously transformed into a novel family of N-acetyl-1,3-oxazolidines by means of an unexpected acetylation. The structure of these substances is supported by spectroscopic and crystallographic data. The acetylates also trigger a complex dynamic transformation, in which an initially configured trans oxazolidine converts into a more stable cis-configured derivative. Both isomers can also exist as rotational conformers (E,Z) as a consequence of the restricted rotation around the N-acetyl bond. The barriers to rotation have been determined by variable-temperature experiments. Overall, this transformation most likely involves the intermediacy of a chiral iminium ion, which has been documented in the synthesis of nitrogen heterocycles, thus explaining the experimental facts. 相似文献