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排序方式: 共有131条查询结果,搜索用时 15 毫秒
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1 Results This paper presents the development of platinum nanocomposites structures based on organically modified c.a.2 nm core platinum nanoparticles.The chemical modification of the 4-mercaptoaniline functionalized particles by various in coming molecules is evidenced and precisely quantified.The particles can be dissolved like molecules in various solvents depending on the features of the new crown and X-rays shows that the interparticle distance is affected by the crown modification.These platinum n... 相似文献
3.
Ana Cuesta Laia Pedrola Teresa Sevilla Javier García-Planells María José Chumillas Fernando Mayordomo Eric LeGuern Ignacio Marín Juan J Vílchez Francesc Palau 《Nature genetics》2002,30(1):22-25
We identified three distinct mutations and six mutant alleles in GDAP1 in three families with axonal Charcot-Marie-Tooth (CMT) neuropathy and vocal cord paresis, which were previously linked to the CMT4A locus on chromosome 8q21.1. These results establish the molecular etiology of CMT4A (MIM 214400) and suggest that it may be associated with both axonal and demyelinating phenotypes. 相似文献
4.
G. Zamboni E. Perez P. L. Parmeggiani 《Cellular and molecular life sciences : CMLS》1982,38(10):1188-1189
Summary In rats adapted to a 1212 h light-dark (LD) schedule, cyclic AMP concentration in the preoptic region showed a L minimum and D maximum. No significant fluctuations were observed in the parietal cortex.Supported by grant No. 79.01946.04 awarded by the National Research Council (CNR), Rome, Italy. 相似文献
5.
Dealing with Distances and Transformations for Fuzzy C-Means Clustering of Compositional Data 总被引:1,自引:0,他引:1
Javier Palarea-Albaladejo Josep Antoni Martín-Fernández Jesús A. Soto 《Journal of Classification》2012,29(2):144-169
Clustering techniques are based upon a dissimilarity or distance measure between objects and clusters. This paper focuses on the simplex space, whose elements??compositions??are subject to non-negativity and constant-sum constraints. Any data analysis involving compositions should fulfill two main principles: scale invariance and subcompositional coherence. Among fuzzy clustering methods, the FCM algorithm is broadly applied in a variety of fields, but it is not well-behaved when dealing with compositions. Here, the adequacy of different dissimilarities in the simplex, together with the behavior of the common log-ratio transformations, is discussed in the basis of compositional principles. As a result, a well-founded strategy for FCM clustering of compositions is suggested. Theoretical findings are accompanied by numerical evidence, and a detailed account of our proposal is provided. Finally, a case study is illustrated using a nutritional data set known in the clustering literature. 相似文献
6.
Cdk1 is sufficient to drive the mammalian cell cycle 总被引:1,自引:0,他引:1
Santamaría D Barrière C Cerqueira A Hunt S Tardy C Newton K Cáceres JF Dubus P Malumbres M Barbacid M 《Nature》2007,448(7155):811-815
7.
Aeschlimann M Bauer M Bayer D Brixner T García de Abajo FJ Pfeiffer W Rohmer M Spindler C Steeb F 《Nature》2007,446(7133):301-304
Adaptive shaping of the phase and amplitude of femtosecond laser pulses has been developed into an efficient tool for the directed manipulation of interference phenomena, thus providing coherent control over various quantum-mechanical systems. Temporal resolution in the femtosecond or even attosecond range has been demonstrated, but spatial resolution is limited by diffraction to approximately half the wavelength of the light field (that is, several hundred nanometres). Theory has indicated that the spatial limitation to coherent control can be overcome with the illumination of nanostructures: the spatial near-field distribution was shown to depend on the linear chirp of an irradiating laser pulse. An extension of this idea to adaptive control, combining multiparameter pulse shaping with a learning algorithm, demonstrated the generation of user-specified optical near-field distributions in an optimal and flexible fashion. Shaping of the polarization of the laser pulse provides a particularly efficient and versatile nano-optical manipulation method. Here we demonstrate the feasibility of this concept experimentally, by tailoring the optical near field in the vicinity of silver nanostructures through adaptive polarization shaping of femtosecond laser pulses and then probing the lateral field distribution by two-photon photoemission electron microscopy. In this combination of adaptive control and nano-optics, we achieve subwavelength dynamic localization of electromagnetic intensity on the nanometre scale and thus overcome the spatial restrictions of conventional optics. This experimental realization of theoretical suggestions opens a number of perspectives in coherent control, nano-optics, nonlinear spectroscopy, and other research fields in which optical investigations are carried out with spatial or temporal resolution. 相似文献
8.
Epigenetic asymmetry of imprinted genes in plant gametes 总被引:12,自引:0,他引:12
Gutiérrez-Marcos JF Costa LM Dal Prà M Scholten S Kranz E Perez P Dickinson HG 《Nature genetics》2006,38(8):876-878
Plant imprinted genes show parent-of-origin expression in seed endosperm, but little is known about the nature of parental imprints in gametes before fertilization. We show here that single differentially methylated regions (DMRs) correlate with allele-specific expression of two maternally expressed genes in the seed and that one DMR is differentially methylated between gametes. Thus, plants seem to have developed similar strategies as mammals to epigenetically mark imprinted genes. 相似文献
9.
Kozyrev SV Abelson AK Wojcik J Zaghlool A Linga Reddy MV Sanchez E Gunnarsson I Svenungsson E Sturfelt G Jönsen A Truedsson L Pons-Estel BA Witte T D'Alfonso S Barizzone N Barrizzone N Danieli MG Gutierrez C Suarez A Junker P Laustrup H González-Escribano MF Martin J Abderrahim H Alarcón-Riquelme ME 《Nature genetics》2008,40(2):211-216
10.
Antoni Camins Javier G. Pizarro Daniel Alvira Javier Gutierrez-Cuesta Aurelio Vazquez de la Torre Jaume Folch Francesc X. Sureda Ester Verdaguer Felix Junyent Joaquín Jordán Isidre Ferrer Mercè Pallàs 《Cellular and molecular life sciences : CMLS》2010,67(22):3865-3882
In the present study we demonstrated that neurotoxin MPP+-induced DNA damage is followed by ataxia telangiectasia muted (ATM) activation either in cerebellar granule cells (CGC) or in B65 cell line. In CGC, the selective ATM inhibitor KU-55933 showed neuroprotective effects against MPP+-induced neuronal cell loss and apoptosis, lending support to the key role of ATM in experimental models of Parkinson’s disease. Likewise, we showed that knockdown of ATM levels in neuroblastoma B65 cells using an ATM-specific siRNA attenuates the phosphorylation of retinoblastoma protein without affecting other cell-cycle proteins involved in the G0/G1 cell-cycle phase. Moreover, we demonstrated DNA damage, in human brain samples of PD patients. These findings support a model in which MPP+ leads to ATM activation with a subsequent DNA damage response and activation of pRb. Therefore, this study demonstrates a new link between DNA damage by MPP+ and cell-cycle re-entry through retinoblastoma protein phosphorylation. 相似文献