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131.
Florian Kühbeck Michael Müller Werner Back Tomas Kurz Martin Krottenthaler 《Enzyme and microbial technology》2007,41(6-7):711-720
In this investigation, the effect of hot trub (a precipitation product of the wort boiling process in beer manufacturing) addition on fermentation performance was observed under variation of yeast vitality, and origin and the amount of hot trub. Its addition improved suspended cell concentrations for all yeast vitalities tested, and the more trub was added, the greater the effect. Further, pilot-scale fermentations showed significantly lower pH values and an accelerated extract degradation, thus, advancing fermentation by roughly 1 day for hot trub addition versus the fermentation of extremely bright wort. Since the positive effect of trub has often been associated with its particulate characteristics, fermentations with fractionated model particles, such as poly(vinylpyrrolidones) and kieselguhr, of different particle sizes were carried out under variation of yeast vitality and particle amounts. The addition of both particle types also improved fermentation performance, however, the effect was not as great as that of hot trub. Particulate material may improve the development of CO2 from the fermenting medium, thus reducing its concentration and inhibitory effect on yeast metabolism. The most effective fraction of kieselguhr had a 40 μm peak which also occurred in particle size distributions of all hot trubs investigated. This could be of particular interest when discussing particle effects. 相似文献
132.
133.
Martin Dragosits Stefan Pflügl Simone Kurz Ebrahim Razzazi-Fazeli Iain B. H. Wilson Dubravko Rendic 《Applied microbiology and biotechnology》2014,98(8):3553-3567
Galactosidases are widespread enzymes that are used for manifold applications, including production of prebiotics, biosynthesis of different transgalactosylated products, improving lactose tolerance and in various analytical approaches. The nature of these applications often require galactosidases to be present in a purified form with clearly defined properties, including precisely determined substrate specificities, low sensitivity to inhibitors, and high efficiency and stability under distinct conditions. In this study, we present the recombinant expression and purification of two previously uncharacterized β-galactosidases from Aspergillus nidulans as well as one β-galactosidase from Aspergillus niger. All enzymes were active toward p-nitrophenyl-β-d-galactopyranoside as substrate and displayed similar temperature and pH optima. The purified recombinant galactosidases digested various complex substrates containing terminal galactose β-1,4 linked to either N-acetylglucosamine or fucose, such as N-glycans derived from bovine fibrin and Caenorhabditis elegans. In our comparative study of the recombinant galactosidases with the commercially available galactosidase from Aspergillus oryzae, all enzymes also displayed various degrees of activity toward complex oligosaccharides containing β-1,3-linked terminal galactose residues. All recombinant enzymes were found to be robust in the presence of various organic solvents, temperature variations, and freeze/thaw cycles and were also tested for their ability to synthesize galactooligosaccharides. Furthermore, the use of fermentors considerably increased the yield of recombinant galactosidases. Taken together, we demonstrate that purified recombinant galactosidases from A. niger and from A. nidulans are suitable for various glycobiological and biotechnological applications. 相似文献
134.
BACKGROUND: SCF (Skp1-Cullin-F-box) complexes are a major class of E3 ligases that are required to selectively target substrates for ubiquitin-dependent degradation by the 26S proteasome. Conjugation of the ubiquitin-like protein Nedd8 to the cullin subunit (neddylation) positively regulates activity of SCF complexes, most likely by increasing their affinity for the E2 conjugated to ubiquitin. The Nedd8 conjugation pathway is required in C. elegans embryos for the ubiquitin-mediated degradation of the microtubule-severing protein MEI-1/Katanin at the meiosis-to-mitosis transition. Genetic experiments suggest that this pathway controls the activity of a CUL-3-based E3 ligase. Counteracting the Nedd8 pathway, the COP9/signalosome has been shown to promote deneddylation of the cullin subunit. However, little is known about the role of neddylation and deneddylation for E3 ligase activity in vivo. RESULTS: Here, we identified and characterized the COP9/signalosome in C. elegans and showed that it promotes deneddylation of CUL-3, a critical target of the Nedd8 conjugation pathway. As in other species, the C. elegans signalosome is a macromolecular complex containing at least six subunits that localizes in the nucleus and the cytoplasm. Reducing COP9/signalosome function by RNAi results in a failure to degrade MEI-1, leading to severe defects in microtubule-dependent processes during the first mitotic division. Intriguingly, reducing COP9/signalosome function suppresses a partial defect in the neddylation pathway; this suppression suggests that deneddylation and neddylation antagonize each other. CONCLUSIONS: We conclude that both neddylation and deneddylation of CUL-3 is required for MEI-1 degradation and propose that cycles of CUL-3 neddylation and deneddylation are necessary for its ligase activity in vivo. 相似文献
135.
Mallo GV Kurz CL Couillault C Pujol N Granjeaud S Kohara Y Ewbank JJ 《Current biology : CB》2002,12(14):1209-1214
The term innate immunity refers to a number of evolutionary ancient mechanisms that serve to defend animals and plants against infection. Genetically tractable model organisms, especially Drosophila, have contributed greatly to advances in our understanding of mammalian innate immunity. Essentially, nothing is known about immune responses in the nematode Caenorhabditis elegans. Using high-density cDNA microarrays, we show here that infection of C. elegans by the Gram-negative bacterium Serratia marcescens provokes a marked upregulation of the expression of many genes. Among the most robustly induced are genes encoding lectins and lysozymes, known to be involved in immune responses in other organisms. Certain infection-inducible genes are under the control of the DBL-1/TGFbeta pathway. We found that dbl-1 mutants exhibit increased susceptibility to infection. Conversely, overexpression of the lysozyme gene lys-1 augments the resistance of C. elegans to S. marcescens. These results constitute the first demonstration of inducible antibacterial defenses in C. elegans and open new avenues for the investigation of evolutionary conserved mechanisms of innate immunity. 相似文献
136.
Gustavo Saluste Maria I. Albarran Rosa M. Alvarez Obdulia Rabal Miguel Angel Ortega Carmen Blanco Guido Kurz Antonio Salgado Paolo Pevarello James R. Bischoff Joaquin Pastor Julen Oyarzabal 《PloS one》2012,7(10)
A new chemical series, triazolo[4,5-b]pyridines, has been identified as an inhibitor of PIM-1 by a chemotype hopping strategy based on a chemically feasible fragment database. In this case, structure-based virtual screening and in silico chemogenomics provide added value to the previously reported strategy of prioritizing among proposed novel scaffolds. Pairwise comparison between compound 3, recently discontinued from Phase I clinical trials, and molecule 8, bearing the selected novel scaffold, shows that the primary activities are similar (IC50 in the 20 to 150 nM range). At the same time, some ADME properties (for example, an increase of more than 45% in metabolic stability in human liver microsomes) and the off-target selectivity (for example, an increase of more than 2 log units in IC50
vs. FLT3) are improved, and the intellectual property (IP) position is enhanced. The discovery of a reliable starting point that fulfills critical criteria for a plausible medicinal chemistry project is demonstrated in this prospective study. 相似文献
137.
138.
David P. Turner Graham Stinson A. David McGuire Yaxing Wei Tristram O. West Linda S. Heath Bernardus de Jong Brian G. McConkey Richard A. Birdsey Werner A. Kurz Andrew R. Jacobson Deborah N. Huntzinger Yude Pan W. Mac Post Robert B. Cook 《Global Change Biology》2012,18(4):1282-1299
We develop an approach for estimating net ecosystem exchange (NEE) using inventory‐based information over North America (NA) for a recent 7‐year period (ca. 2000–2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non‐fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a ?327 ± 252 TgC yr?1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (?248 TgC yr?1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (?297 TgC yr?1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr?1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr?1) due to land use change between 1993 and 2002. We compare these inventory‐based estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental‐scale NEE estimate for each ensemble is ?511 TgC yr?1 and ?931 TgC yr?1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional ?239 TgC yr?1 to the inventory‐based NA sink estimate, thus suggesting some convergence with the modeling approaches. 相似文献
139.
Detection of enzymatic activity on gel electrophoresis, namely zymography, is a technique that has received increasing attention in the last 10 years, according to the number of articles published. A growing amount of enzymes, mainly proteases, are now routinely detected by zymography. Detailed analytical studies are beginning to be published, as well as new patents have been developed. This new article updates the information covered in our last review, condensing the recent publications dealing with the identification of proteolytic enzymes in electrophoretic gel supports and its variations. The new advances of this method are basically focused towards two dimensional zymography and transfer zymography. Though comparatively fewer patents have been published, they basically coincide in the study of matrix metalloproteases. The tendency is foreseen to be very productive in the area of zymoproteomics, combining electrophoresis and mass spectrometry for the analysis of proteases. 相似文献
140.
Johannes Ott Stefan Wirth Kazem Nouri Christine Kurz Klaus Mayerhofer Johannes C Huber Clemens B Tempfer 《Reproductive biology and endocrinology : RB&E》2009,7(1):153-7