全文获取类型
收费全文 | 113篇 |
免费 | 1篇 |
专业分类
化学 | 68篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 13篇 |
物理学 | 24篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有114条查询结果,搜索用时 26 毫秒
51.
Grady R. Blacken Michael Volný Matthew Diener Karl E. Jackson Pratistha Ranjitkar Dustin J. Maly František Tureček 《Journal of the American Society for Mass Spectrometry》2009,20(6):915-926
Zirconium, titanium, and hafnium oxide-coated stainless steel surfaces are fabricated by reactive landing of gas-phase ions
produced by electrospray ionization of group IVB metal alkoxides. The surfaces are used for in situ enrichment of phosphopeptides
before analysis by matrix-assisted laser desorption ionization (MALDI) mass spectrometry. To evaluate this method we characterized
ZrO2 (zirconia) surfaces by (1) comparison with the other group IVB metal oxides of TiO2 (titania) and HfO2 (hafnia), (2) morphological characterization by SEM image analysis, and (3) dependence of phosphopeptide enrichment on the
metal oxide layer thickness. Furthermore, we evaluated the necessity of the reactive landing process for the construction
of useful metal oxide surfaces by preparing surfaces by electrospray deposition of Zr, Ti, and Hf alkoxides directly onto
polished metal surfaces at atmospheric pressure. Although all three metal oxide surfaces evaluated were capable of phosphopeptide
enrichment from complex peptide mixtures, zirconia performed better than hafnia or titania as a result of morphological characteristics
illustrated by the SEM analysis. Metal oxide coatings that were fabricated by atmospheric pressure deposition were still capable
of in situ phosphopeptide enrichment, although with inferior efficiency and surface durability. We show that zirconia surfaces
prepared by reactive landing of gas-phase ions can be a useful tool for high throughput screening of novel phosphorylation
sites and quantitation of phosphorylation kinetics. 相似文献
52.
Résumé On généralise un résultat de Dobbs-Lancaster sur les espaces vectorielles au cadre des modules sur un anneau principal finiR. SoitV une module libre de type fini. On trouve une formule explicite et des valeurs dans la limite du nombre anticipé de générateurs
d'un sousmodule arbitraire deV. De plus, on calcule ces valeurs anticipés quand tout sousmodule a un poids naturel (par exemple, quant a sa cardinalité).
Enfin, on trouve une formule explicite et des valeurs dans la limite du rang anticipé du sousmodule libre le plus grand contenu
dan un sousmodule arbitraire deV.
相似文献
53.
Magnetic nanoparticles dispersed as a ferrofluid with volumetric concentrations in the range 0.4 to 10% and sizes ranging from 59–77 Å have been studied via magnetic measurements at room and low temperatures. Remanence measurements have been used to determine switching and coupling effects. Particle size and concentration effects have been investigated and we find that the samples with higher concentrations have larger coercivities than expected due to coupling effects. Interactions have been found to be demagnetising overall as expected for dipolar interacting systems. Surface effects become evident below 10 K when thermal effects are weak. 相似文献
54.
Grady Venville John Wallace Lonie J. Rennie John Malone 《School science and mathematics》1998,98(6):294-302
The culture of the middle years of schooling in Western Australia, as in many parts of the world, is predominantly discipline based. This paper focuses on exceptions to this norm by describing examples of integrated teaching of science, mathematics, and technology in seventh- to ninth-grade classrooms. Several different forms of integration were found in the 16 Western Australian schools examined in this study, including thematic approaches, cross-curricular approaches, technology-based projects, and local community projects. Interviews with teachers in these schools raised several implementation issues, including the process of getting started, implications for teachers and students, implications for schedule structure, and implications for departmental structure. All the forms of integration observed in this study were through secondary means, in which the discrete subject discipline boundaries were being maintained. The deep culture of subject disciplines, underwritten by curriculum documents organized in terms of subjects, means that there may be few incentives for teachers to teach and students to learn in an integrated manner. 相似文献
55.
Maneedaeng A Haller KJ Grady BP Flood AE 《Journal of colloid and interface science》2011,356(2):598-604
Competitive counterion binding of sodium and calcium to micelles, and mixed micellization have been investigated in the systems sodium dodecylsulfate (NaDS)/sodium decylsulfate (NaDeS) and NaDS/sodium 4-octylbenzenesulfonate (NaOBS) in order to accurately model the activity of the relevant species in solution. The critical micelle concentration (CMC) and equilibrium micelle compositions of mixtures of these anionic surfactants, which is necessary for determining fractional counterion binding measurements, is thermodynamically modeled by regular solution theory. The mixed micelle is ideal (the regular solution parameter β(M)=0) for the NaDS/NaOBS system, while the mixed micelle for NaDS/NaDeS has β(M)=-1.05 indicating a slight synergistic interaction. Counterion binding of sodium to the micelle is influenced by the calcium ion concentration, and vice versa. However, the total degree of counterion binding is essentially constant at approximately 0.65 charge negation at the micelle's surface. The counterion binding coefficients can be quantitatively modeled using a simple equilibrium model relating concentrations of bound and unbound counterions. 相似文献
56.
Let X be a projective complex K 3 surface. Beauville and Voisin singled out a 0-cycle cX on X of degree 1 and Huybrechts proved that the second Chern class of a rigid simple vector-bundle on X is a multiple of cX if certain hypotheses hold. We believe that the following generalization of Huybrechts? result holds. Let M be a moduli space of stable pure sheaves on X with fixed cohomological Chern character: the set whose elements are second Chern classes of sheaves parametrized by the closure of M (in the corresponding moduli spaces of semistable sheaves) depends only on the dimension of M. We will prove that the above statement holds under some additional assumptions on the Chern character. 相似文献
57.
Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)–Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near β=3.2. The theory with both Z2 vortices and monopoles and SO(3)–Z2 monopoles eliminated is simulated in the strong-coupling (β=0) limit on lattices up to 604. Here, as in the high-β phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any β . Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of α∼1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data. 相似文献
58.
Experimental Mechanics - Eradication of established implant-associated and bacterial biofilm-forming infections remains difficult in part because these biofilms remain well-adhered to the implant... 相似文献
59.
60.