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All physical implementations of quantum bits (or qubits, the logical elements in a putative quantum computer) must overcome conflicting requirements: the qubits should be manipulable through external signals, while remaining isolated from their environment. Proposals based on quantum optics emphasize optimal isolation, while those following the solid-state route exploit the variability and scalability of nanoscale fabrication techniques. Recently, various designs using superconducting structures have been successfully tested for quantum coherent operation, however, the ultimate goal of reaching coherent evolution over thousands of elementary operations remains a formidable task. Protecting qubits from decoherence by exploiting topological stability is a qualitatively new proposal that holds promise for long decoherence times, but its physical implementation has remained unclear. Here we show how strongly correlated systems developing an isolated twofold degenerate quantum dimer liquid ground state can be used in the construction of topologically stable qubits; we discuss their implementation using Josephson junction arrays. Although the complexity of their architecture challenges the technology base available today, such topological qubits greatly benefit from their built-in fault-tolerance. 相似文献
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Organization of microtubules in dendrites and axons is determined by a short hydrophobic zipper in microtubule-associated proteins MAP2 and tau 总被引:35,自引:0,他引:35
Here we report that the microtubule-associated proteins MAP2 and tau share two separable functional domains. One is the microtubule-binding site which serves to nucleate microtubule assembly; the second is a short C-terminal alpha-helical sequence which can crosslink microtubules by means of a hydrophobic zipper interaction into dense stable parallel arrays characteristic of axons or dendrites. Thus, interactions between molecules of a single type are capable of drastically reorganizing microtubules and completely suppressing their dynamic properties. 相似文献
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M. M. Shemyakin Yu. A. Ovchinnikov V. T. Ivanov A. A. Kiryushkin G. L. Zhdanov I. D. Ryabova 《Cellular and molecular life sciences : CMLS》1963,19(11):566-568
Zusammenfassung Die Beziehungen zwischen Struktur und antimikrobieller Aktivität in der Reihe der Depsipeptide wurden untersucht. Cyclotetradepsipeptide sind praktisch inaktiv. Die grösste Aktivität besitzen die Cyclohexadepsipeptide mit regulärer Oxy- und Aminosäurensequenz. Eine weitere Vergrösserung des Depsipeptidringes führt zu einem Abfall der biologischen Aktivität. Cyclohexadepsipeptide mit irregulärer Oxy- und Aminosäurensequenz sind völlig inaktiv.
Communication XXVII in the SeriesStudies in Depsipeptide Chemistry. 相似文献
Communication XXVII in the SeriesStudies in Depsipeptide Chemistry. 相似文献
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Yu. A. Ovchinnikov V. T. Ivanov L. I. Barsukov E. I. Melnik N. A. Oreshnikova N. D. Bogolyubova I. D. Ryabova A. I. Miroshnikov V. A. Rimskaya 《Cellular and molecular life sciences : CMLS》1972,28(4):399-401
Zusammenfassung Untersuchungen mit Antamanid und Perhydroantamanid deuten darauf hin, dass für letzteres die Beeinflussung des Transportes von Na+- und K+-Ionen durch Membranen von Bedeutung sein kann. 相似文献
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Hauber E van Gasselt S Ivanov B Werner S Head JW Neukum G Jaumann R Greeley R Mitchell KL Muller P;HRSC Co-Investigator Team 《Nature》2005,434(7031):356-361
The majority of volcanic products on Mars are thought to be mafic and effusive. Explosive eruptions of basic to ultrabasic chemistry are expected to be common, but evidence for them is rare and mostly confined to very old surface features. Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously unknown traces of an explosive eruption at 30 degrees N and 149 degrees E on the northwestern flank of the shield volcano Hecates Tholus. The eruption created a large, 10-km-diameter caldera approximately 350 million years ago. We interpret these observations to mean that large-scale explosive volcanism on Mars was not confined to the planet's early evolution. We also show that glacial deposits partly fill the caldera and an adjacent depression. Their age, derived from crater counts, is about 5 to 24 million years. Climate models predict that near-surface ice is not stable at mid-latitudes today, assuming a thermo-dynamic steady state. Therefore, the discovery of very young glacial features at Hecates Tholus suggests recent climate changes. We show that the absolute ages of these very recent glacial deposits correspond very well to a period of increased obliquity of the planet's rotational axis. 相似文献
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M. M. Shemyakin Yu. A. Ovchinnikov V. T. Ivanov I. D. Ryabova 《Cellular and molecular life sciences : CMLS》1967,23(5):326-326
, . , -Gly5,10- , Gly5,10- . 相似文献
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Interaction of 1-anilino-8-naphthalene sulfonate with yeast glyceraldehyde-3-phosphate dehydrogenase
N. K. Nagradova R. A. Asryants M. V. Ivanov 《Cellular and molecular life sciences : CMLS》1971,27(10):1169-1170
1--8- () -3- () . []:[]<10:1 140 000 3±1 5×10–5
. , i 5×10–5
–6×10–5
M. , . 相似文献
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Fritz JH Rojas OL Simard N McCarthy DD Hapfelmeier S Rubino S Robertson SJ Larijani M Gosselin J Ivanov II Martin A Casellas R Philpott DJ Girardin SE McCoy KD Macpherson AJ Paige CJ Gommerman JL 《Nature》2012,481(7380):199-203
The largest mucosal surface in the body is in the gastrointestinal tract, a location that is heavily colonized by microbes that are normally harmless. A key mechanism required for maintaining a homeostatic balance between this microbial burden and the lymphocytes that densely populate the gastrointestinal tract is the production and transepithelial transport of poly-reactive IgA (ref. 1). Within the mucosal tissues, B cells respond to cytokines, sometimes in the absence of T-cell help, undergo class switch recombination of their immunoglobulin receptor to IgA, and differentiate to become plasma cells. However, IgA-secreting plasma cells probably have additional attributes that are needed for coping with the tremendous bacterial load in the gastrointestinal tract. Here we report that mouse IgA(+) plasma cells also produce the antimicrobial mediators tumour-necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS), and express many molecules that are commonly associated with monocyte/granulocytic cell types. The development of iNOS-producing IgA(+) plasma cells can be recapitulated in vitro in the presence of gut stroma, and the acquisition of this multifunctional phenotype in vivo and in vitro relies on microbial co-stimulation. Deletion of TNF-α and iNOS in B-lineage cells resulted in a reduction in IgA production, altered diversification of the gut microbiota and poor clearance of a gut-tropic pathogen. These findings reveal a novel adaptation to maintaining homeostasis in the gut, and extend the repertoire of protective responses exhibited by some B-lineage cells. 相似文献
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