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81.
It has been observed that the use of O6-protected deoxyguanosine phosphoramidites leads to a significant improvement in the automated synthesis of oligonucleotides on an insoluble support. 相似文献
82.
The phosphite-triester synthesis of four triribonucleotides containing novel vicinal 2′–5′ and 3′–5′ phosphodiester linkages is described. 相似文献
83.
Kelvin K. Ogilvie Mona J. Nemer Gholam H. Hakimelahi Zbigniew A. Proba Marc Lucas 《Tetrahedron letters》1982,23(26):2615-2618
Procedures have been developed for the synthesis of the N-levulinyl derivatives of cytidine, adenosine and guanosine. 相似文献
84.
Michael C Ogilvie 《Annals of Physics》1981,136(2):273-292
Field-theoretic methods are applied to a number of two-dimensional lattice models with Abelian symmetry groups. It is shown, using a vortex + spin-wave decomposition, that the Zp? Villain models are related to a class of continuum field theories with analogous duality properties. Fermion operators for these field theories are discussed. In the case of the Ising model, the vortices and spin-waves conspire to produce a free, massive Majorana field theory in the continuum limit. The continuum limit of the Baxter model is also studied, and the recent results of Kadanoff and Brown are rederived and extended. 相似文献
85.
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87.
Steven R. LaPlante Dale R. Cameron Norman Aubry Pierre R. Bonneau Robert Dziel Chantal Grand-Maître William W. Ogilvie Stephen H. Kawai 《Angewandte Chemie (International ed. in English)》1998,37(19):2729-2732
A weak inhibitor means faster exchange! Since the methyl ketone MK2 is a weak noncovalent peptidyl inhibitor of the human cytomegalovirus protease, exchange between the free and enzyme-bound forms is rapid. This allows for the use of transferred NOE NMR methods and molecular modeling, which show that the bound conformation of MK2 is an extended peptide. This is confirmed by the results of an X-ray crystallographic analysis of a related enzyme–inhibitor complex. 相似文献
88.
89.
AM Cardoso SM Alexandre CM Barros AJ Correia NM Nibbering 《Rapid communications in mass spectrometry : RCM》1999,13(19):1885-1888
The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
90.
AM Johnston CM Scrimgeour MO Henry LL Handley 《Rapid communications in mass spectrometry : RCM》1999,13(14):1531-1534
The conversion of nitrate (NO(3)(-)) to 1-phenylazo-2-naphthol (Sudan-1) has been examined as a method for natural abundance measurement of delta(15)N of NO(3)(-). The reaction results in dilution of NO(3)(-)-N with only one reagent-derived N and the product is readily concentrated from dilute samples by reverse phase chromatography. There is systematic isotopic fractionation during the reaction, but this can be allowed for by analysing known NO(3)(-) standards along with each sample set. Sudan-1 prepared from surface water samples containing approximately 50 &mgr;g NO(3)(-)-N can be analysed by automated continuous flow isotope ratio mass spectrometry with a precision of 0.2 per thousand (one standard deviation) and the accuracy is not affected by interference from other nitrogenous species in the sample or reagents. Copyright 1999 John Wiley & Sons, Ltd. 相似文献