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521.
Ahmad Waseem E. Birgitte Lane Dolores Harrison Naushin Waseem 《Experimental cell research》1996,223(2):203
Keratin filaments in simple epithelial cells are heteropolymers of keratin 8 (K8) and keratin 18 (K18), which can be stained by the monoclonal antibody (MAb) LE61. This antibody has been widely used to study keratin expression in normal and neoplastic tissues. In this study we have found that MAb LE61 does not react with individual keratin polypeptides either derived from natural sources or expressed as recombinant proteins inEscherichia coli.However, when K8 or K18 bound to nitrocellulose were incubated with complementary keratin they became reactive with this antibody. A mixture of K8 and K18 in solution also reacted strongly with the MAb LE61 in ELISA. These observations suggest that the antibody recognizes a discontinuous epitope on the keratin complex. The antibody also reacted with complexes of K8 and K18 with other keratins. To locate the epitope of this antibody we have expressed K8 and K18 fragments, deleted from the amino- and carboxyl-termini, as fusion proteins with glutathioneS-transferase. These fragments were able to form a heterotypic complex with the complementary keratin. Binding of the MAb LE61 to these complexes mapped the two halves of the epitope on K8, between residues 353 and 367, and on K18, between residues 357 and 385. The two halves of the epitope appear to be in close association in the heterotypic complex since deletions from the amino-terminus did not influence the antibody binding. The highly conserved nature of this epitope in both type I and type II keratins could explain the MAb LE61 reactivity with complexes of K8 or K18 with other keratins. 相似文献
522.
Borys Kierdaszuk Krzysztof Krawiec Zygmunt Kazimierczuk Ulla Jacobsson Nils G. Johansson Birgitte Munch-petersen 《Nucleosides, nucleotides & nucleic acids》2013,32(8):1883-1903
Abstract Nucleoside analogues with modified sugar moieties have been examined for their substrate/inhibitor specificities towards highly purified deoxycytidine kinase (dCK) and thymidine kinases (tetrameric high-affinity form of TK1, and TK2) from human leukemic spleen. In particular, the analogues included the mono-and di-O′-methyl derivatives of dC, dU and dA, syntheses of which are described. In general, purine nucleosides with modified sugar rings were feebler substrates than the corresponding cytosine analogues. Sugar-modified analogues of dU were also relatively poor substrates of TK1 and TK2, but were reasonably good inhibitors, with generally lower Ki values vs TK2 than TK1. An excellent discriminator between TK1 and TK2 was 3′-hexanoylamino-2′,3′-dideoxythymidine, with a Ki of ~600 μM for TK1 and ~0.1 μM for TK2. 3′-OMe-dC was a superior inhibitor of dCK to its 5′-O-methyl congener, consistent with possible participation of the oxygen of the (3′)-OH or (3′)-OMe as proton acceptor in hydrogen bonding with the enzyme. Surprisingly α-dT was a good substrate of both TK1 and TK2, with Ki values of 120 and 30 μM for TK1 and TK2, respectively; and a 3′-branched α-L-deoxycytidine analogue proved to be as good a substrate as its α-D-counterpart. Several 5 ′-substituted analogues of dC were 相似文献
523.
Consistent production of phenolic compounds byPenicillium brevicompactum for chemotaxonomic characterization 总被引:1,自引:0,他引:1
Birgitte Andersen 《Antonie van Leeuwenhoek》1991,59(2):115-123
A consistently produced group of fungal secondary metabolites fromPenicillium brevicompactum has been purified and identified as the Raistrick phenols. These compounds are shown to exist separately as an equilibrium mixture in aqueous solutions. The Raistrick phenols have all been included in the metabolite profile ofP. brevicompactum. By means of thin layer chromatography-scanning and high performance liquid chromatography-UV diode array detection, the chromatographic and spectroscopic data can be used in the chemotaxonomic characterization of the fungus. 相似文献