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E. L. Esmans M. Belmans I. Vrijens Y. Luyten F. C. Alderweireldt L. L. Wotring 《Nucleosides, nucleotides & nucleic acids》2013,32(5):865-876
Abstract A method was elaborated for the analysis of a few original pyridine-C-nucleosides via microbore DLI/LC-MS. The compounds were analyzed on a 10RP8 column (25 cm × 1 mm) using a number of 0.01 M HCOONH4/CH3OH mixtures as eluant. Under appropriate LC-MS conditions, both α- and β-anomers were separated and identified. All nucleosides were characterized by the protonated molecular ion [MH]+, [B+30]+ and [B+44]+-fragment ions. Assignment of the α, β-configuration at C1′ was done with the aid of 13C-NMR. From the DLI/LC-MS data, a semi-preparative HPLC-method was developed to purify the pyridine-C-nucleosides prior to biological evaluation. 相似文献
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Background
Transmembrane (TM) proteins are proteins that span a biological membrane one or more times. As their 3-D structures are hard to determine, experiments focus on identifying their topology (i. e. which parts of the amino acid sequence are buried in the membrane and which are located on either side of the membrane), but only a few topologies are known. Consequently, various computational TM topology predictors have been developed, but their accuracies are far from perfect. The prediction quality can be improved by applying a consensus approach, which combines results of several predictors to yield a more reliable result. 相似文献65.
MARY BETH REW M. ZACHARIAH PEERY STEVEN R. BEISSINGER MARTINE BRUB JEFFREY D. LOZIER EMILY M. RUBIDGE PER J. PALSB
LL 《Molecular ecology resources》2006,6(1):241-244
We developed 31 novel, polymorphic microsatellite loci in the marbled murrelet (Brachyramphus marmoratus), a critically endangered seabird. Variability was tested on 15 individuals from the Santa Cruz, California population, with each locus characterized by two to 12 alleles. Observed levels of heterozygosity ranged from 0.13 to 0.93. These loci provide a valuable means of assessing the population structure and demographic parameters of this species, which may be critical to its conservation across a fragmented habitat. 相似文献
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David A. Berry Linda L. Wotring John C. Drach Leroy B. Townsend 《Nucleosides, nucleotides & nucleic acids》2013,32(9):2001-2011
Abstract The Lewis acid catalyzed ribosylation of 5(4)-cyano-4(5)-(5-methyl-1,2,4-oxadiazol-3-yl)-1H-imidazole (2) with 1-O-acetyl-2,3,5-tri-O-benzoyl-B-D-ribose gave only 4-(5-methyl-1,2,4-oxadiazol-3-yl)-1-(2,3,5-tri-O-benzoy 1-B-D-ribofuranosyl)imidazole-5-carbonitrile (3). Treatment of 3 with methanolic ammonia gave 4-(5-methyl-1,2,4-oxadiazol-3-yl)-1-(6-D-ribofuranosyl)imidazole-5-carbonitrile (4). Treatment of 4 with hydrogen peroxide in ammonia gave -(5-methyl-1,2,4-oxadiazol-3-yl)-1-(B-D-ribofuranosyl)imidazole-5-carboxamide (5). When 5 was treated with sodium hydride in dimthyl-sulfoxide a rearrangement (mononuclear heterocyclic rearrangement, m.h.r.) occurred to give a modest 17% yield of 4-acetamido-1-(B-D ribofuranosyl)imidazo[4,5-d]pyridazin-7-one (6). Treatment of 6 with aqueous ammonia gave4-amino-l-(B-D-ribofuranosyl)imidazo[4,5-d]pyridazin-7-one (1). The synthesis of compound 1 using the m.h.r. for the preparation of a single regioisomer of the imidazo[4,5-d]pyridazin-7-one ring system, has demonstrated the potential of this methodology. Neither compound 5 nor 6 affected the growth or replication of human foreskin fibroblasts (HFF cells) or human cytomegalovirus (HCMV). In contrast, compound 1 inhibited the replication of HCMV (IC50=29 μM) but produced visual cytotoxicity in uninfected HFF cells (IC50=70μM). Compound 1 also inhibited the proliferation of L1210 murine leukemic cells (IC50=25μM), whereas the precursors 4 and 6 did not. 相似文献
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Leroy B. Townsend Vladimir G. Beylin Linda L. Wotring 《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):29-66
Abstract The synthesis of several 3,5,7-trisubstituted pyrazolo-[3,4-e][1,3]oxazines by ring annulation of the appropriately substituted pyrazoles is described. These specific compounds can be viewed as analogs of the C-nucleoside antibiotics formycin, formycin B and oxoformycin B. The biochemical and chemotherapeutic activity of these pyrazolo[3,4-e][1,3]oxazines is also disscussed. 相似文献
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