全文获取类型
收费全文 | 67篇 |
免费 | 1篇 |
专业分类
化学 | 23篇 |
力学 | 2篇 |
数学 | 3篇 |
物理学 | 40篇 |
出版年
2023年 | 1篇 |
2019年 | 2篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2000年 | 8篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1980年 | 1篇 |
排序方式: 共有68条查询结果,搜索用时 125 毫秒
21.
J. Marfaing P. Rochette J. Pellerey P. Chaurand C. Suavet L. Folco 《Journal of magnetism and magnetic materials》2008
A collection of iron-rich micrometeorites from Antarctica have been investigated using electron spin resonance (ESR) and conventional magnetic methods to establish a complete magnetic codification of their specific characteristics. Due to the high selectivity of the ESR, the spectra show that the amount and nature of the magnetic impurities contained in these tiny-sized samples, mainly Ni and Cr ions, significantly modify their ESR responses. This result provides a criterion, the Ni/Cr content (identified by spectroscopy), useful for a faithful classification of this class of extraterrestrial particles with close magnetic properties. We attempt to separate the contribution of the different magnetic ions in the ESR response. This method can be easily extended to other magnetic impurities. 相似文献
22.
We investigate nonlinear oscillations in a fourth-order partialdifferential equation which models a suspension bridge. Previouswork establishes multiple periodic solutions when a parameterexceeds a certain eigenvalue. In this paper, we use Leray-Schauderdegree theory to prove that if the parameter is increased further,beyond a second eigenvalue, then additional solutions are created. 相似文献
23.
R. Boulay R. Gagnon D. Rochette J. R. Izatt 《International Journal of Infrared and Millimeter Waves》1984,5(9):1221-1234
Measurement of several parameters pertinent to process and quality control in the manufacture of paper products is a potentially important application of far-infrared lasers. Preliminary measurements of the transmittance and reflectance of moist paper sheets are presented, and their use to determine the percentage moisture content and the dry basis weight of the paper is discussed. 相似文献
24.
The interaction between multiwalled carbon nanotubes (MWCNTs) and aqueous poly(diallyl dimethylammonium) chloride (PDDA) was studied by X-ray photoelectron (XPS) and photoacoustic Fourier transform infrared (PA-FTIR) spectroscopies. We have found that the mild sonication of MWCNTs in aqueous PDDA results in a significant improvement of CNT dispersibility and greatly enhances their adhesion to Au and Si substrates. The MWCNT-PDDA interaction is due to the presence of an unsaturated contaminant in the PDDA chain, as confirmed by both XPS and PA-FTIR, which enters into a pi-pi interaction with the CNTs. Electrostatic group repulsions of the coated CNTs then provide the dispersibility and adhesion. 相似文献
25.
With the Gibbs free energy minimization method, the molar fraction of chemical species are determined in temperature range included between 1000 and 6000 K for several proportions of air, silver and silica and for pressures included between 1 and 50 bars. The enthalpy and the vaporization temperature of liquid silver and liquid silica are studied. The key role of pressure on composition, enthalpy and the vaporization temperature is shown. The electrical neutrality is study, and the importance of ionized gaseous silver at low temperature is shown even for low amount of silver. The increase of electronegative ions (Ag– and O–) with pressure is shown. The vapor pressures fitting coefficients of Ag and SiO2 are given. 相似文献
26.
Cara L Ryan David C Baranowski Babykumari P Chitramuthu Suneil Malik Zhi Li Mingju Cao Sandra Minotti Heather D Durham Denis G Kay Christopher A Shaw Hugh PJ Bennett Andrew Bateman 《BMC neuroscience》2009,10(1):1-22
Background
Progranulin is a secreted high molecular weight growth factor bearing seven and one half copies of the cysteine-rich granulin-epithelin motif. While inappropriate over-expression of the progranulin gene has been associated with many cancers, haploinsufficiency leads to atrophy of the frontotemporal lobes and development of a form of dementia (frontotemporal lobar degeneration with ubiquitin positive inclusions, FTLD-U) associated with the formation of ubiquitinated inclusions. Recent reports indicate that progranulin has neurotrophic effects, which, if confirmed would make progranulin the only neuroprotective growth factor that has been associated genetically with a neurological disease in humans. Preliminary studies indicated high progranulin gene expression in spinal cord motor neurons. However, it is uncertain what the role of Progranulin is in normal or diseased motor neuron function. We have investigated progranulin gene expression and subcellular localization in cultured mouse embryonic motor neurons and examined the effect of progranulin over-expression and knockdown in the NSC-34 immortalized motor neuron cell line upon proliferation and survival.Results
In situ hybridisation and immunohistochemical techniques revealed that the progranulin gene is highly expressed by motor neurons within the mouse spinal cord and in primary cultures of dissociated mouse embryonic spinal cord-dorsal root ganglia. Confocal microscopy coupled to immunocytochemistry together with the use of a progranulin-green fluorescent protein fusion construct revealed progranulin to be located within compartments of the secretory pathway including the Golgi apparatus. Stable transfection of the human progranulin gene into the NSC-34 motor neuron cell line stimulates the appearance of dendritic structures and provides sufficient trophic stimulus to survive serum deprivation for long periods (up to two months). This is mediated at least in part through an anti-apoptotic mechanism. Control cells, while expressing basal levels of progranulin do not survive in serum free conditions. Knockdown of progranulin expression using shRNA technology further reduced cell survival.Conclusion
Neurons are among the most long-lived cells in the body and are subject to low levels of toxic challenges throughout life. We have demonstrated that progranulin is abundantly expressed in motor neurons and is cytoprotective over prolonged periods when over-expressed in a neuronal cell line. This work highlights the importance of progranulin as neuroprotective growth factor and may represent a therapeutic target for neurodegenerative diseases including motor neuron disease. 相似文献27.
P. Munayco J. Munayco M. Valenzuela P. Rochette J. Gattacceca R. B. Scorzelli 《Hyperfine Interactions》2014,224(1-3):257-262
Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. 57Fe Mössbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert. 相似文献
28.
29.
Pascal André William Bussière David Rochette 《Plasma Chemistry and Plasma Processing》2007,27(4):381-403
Calculated values of viscosity, thermal and electrical conductivities of plasma formed in mixtures of silver (Ag) and silica
(SiO2) are presented. The calculations, which assume local thermodynamic equilibrium, are performed for three pressures (1, 10
and 30 atm) in the temperature range from 4,000 to 30,000 K. All the data for the potential interactions and the necessary
formulations to obtain values of transport coefficients are given in details. For atmospheric pressure, five mixtures (100%
Ag, 75% Ag and 25% SiO2, 50% Ag and 50% SiO2, 25% Ag and 75% SiO2, 100% SiO2) in weight percentage are studied. In order to analyse the pressure influence on the transport coefficients, three samples
of Ag–SiO2 mixtures (100% Ag, 50% Ag and 50% SiO2, 100% SiO2) in weight percentage are discussed for pressures of 1, 10 and 30 atm. In addition for the test case of oxygen plasma, we
compare the computation code results with values obtained by other authors: discrepancies are found and explained.
相似文献
30.