全文获取类型
收费全文 | 103篇 |
免费 | 1篇 |
国内免费 | 4篇 |
专业分类
化学 | 67篇 |
晶体学 | 2篇 |
力学 | 6篇 |
物理学 | 33篇 |
出版年
2023年 | 4篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 1篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1984年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有108条查询结果,搜索用时 15 毫秒
1.
F. Aliotta M. E. Fontanella M. Pieruccini G. Salvato S. Trusso C. Vasi R. E. Lechner 《Colloid and polymer science》2002,280(2):193-202
The role played by the solvation water molecules on the macroscopically observed sol–gel transition in lecithin/cyclohexane/water
reverse micelles is investigated by quasielastic neutron scattering, dielectric relaxation and conductivity measurements.
The experimental results are juxtaposed to those from spherical Aerosol OT reverse micelles. It is shown how the results from
lecithin-based system can be interpreted only assuming that, in contrast to Aerosol OT systems, the water molecules are entrapped
at the interfaces without coalescing into an inner water pool. It is suggested that, in the case of lecithin, the solvation
water can induce a change in the surface curvature, in such a way promoting the formation of branch points. Such a hypothesis
is supported by the temperature dependence of the conductivity which agrees with the hypothesis of an intermicellar bond percolation.
The investigation of the structures imposed by an external electric field is also studied. The observed electrorheological
behaviour seems to confirm the existence of a percolated transient network in the gel phase.
Received: 21 March 2001 Accepted: 24 August 2001 相似文献
2.
In this paper, we present a rheological study of a compact layer of highly swollen gel beads. The flow regimes of these systems are modelled by an elastic sinusoid moving in a Newtonian fluid. This model predicts a yield stress varying with the square root of the elastic modulus of the gel bead. The slope at the origin (at zero velocity) of the flow curve is expected to depend only on geometrical parameters and on the solvent viscosity. The experimental data are in qualitative agreement with the theoretical predictions. 相似文献
3.
Many polysaccharide chains can adopt ordered helical and ribbon-like secondary structures. It seems however that these chains are often so stiff and extended that the cooperative interactions necessary for stability in the solvent environment can only be achieved when inter-chain as well as intra-chain interactions are favorable. Hence we commonly find two-or more-stranded associations of helices, of ribbons, or of helices with ribbons. These can be regarded as tertiary and higher levels of structure. The ordered secondary structure characteristically requires a regular repeating sequence of sugar residues, and the termination of this sequence by insertion of a residue of different type may also terminate the secondary structure and hence the association in which it is involved. This is the mechanism by which native polysaccharides may link up to form three dimensional networks, or gels, in which state they perform their natural roles in maintaining the hydration and integrity of biological tissues. For several polysaccharides there is evidence that the mechanism of biological control over the fine topology and properties of the gel network is mediated by enzymes which modify sugar residues at the polymer level to change the pattern of “interrupting” sugar residues. 相似文献
4.
The drying and sintering processes of SiO2–ZrO2 alkoxide-derived gels have been studied by means of DSC technique. In the drying process, most part of water and alcohols are removed from the gels. For the SiO2 gel such elimination occurs at the end of the drying process, however for the ZrO2 gel this elimination occurs during the whole drying time. An intermediate behavior is observed for the binary system SiO2–ZrO2 gels. In the sintering process, the DSC technique allows to determine the elimination of water and alcohols retained within the structure (open or close pores) and the well-known hydroxyl condensation of silica gel between 700° and 800°C is also observed. The ZrO2 gel shows the final hydroxyl condensation at the heating temperature of 600°C. For the binary SiO2–ZrO2 gels, the hydroxyl condensation has been associated to the activation energy needed for the dissociation of silica hydroxyls. This energy decreases with the ZrO2 concentration in the gel resulting in a sintering treatment of 500°C leading to the entire hydroxyl condensation for the gel with 75% ZrO2–25% SiO2.
By studying the temperature of the DSC peaks, it is possible to know the temperature at which most part of water and alcohols are leaving the gel, and these results can be used in order to select the corresponding drying or sintering schedules for obtaining a well-fabricated material. 相似文献
5.
Rayleigh-Brillouin light scattering experiments were performed on gelatin gels in order to obtain the (hypersonic) sound velocity and sound attenuation as a function of gelatin concentration. The results show that in the high frequency regime there is a strong coupling in the gel between the dynamics of the network and that of the fluid. The network sound velocity varies with
1/2. Sound attenuation increases with increasing gelatin concentration. 相似文献
6.
Jun-Wei Chen Yu-Yi Kuo Kuan-Ting Chen Chao-Ran Wang Chih-Yu Chao 《Molecular Crystals and Liquid Crystals》2015,611(1):139-145
We demonstrate that the supramolecular structure can be formed through the fibrous self-assembly of the polyfluorene-based polymer F8BT in liquid crystal (LC) 5CB. With the utility of alignment layer, the F8BT molecules can be aligned and formed oriented polymer network. We found that the presence of oriented polymer network makes twisted nematic LC exhibit excellent electro-optical properties (EO) of driving voltage reduction and EO bump peak elimination. The polyfluorene-based supramolecular structure provides the function of stabilizing LC molecules. We consider this functional self-assembled network has potential to apply in various devices for the ability of improving performance in operating property. 相似文献
7.
ZHANG Jixiang LI Hexian** WANG Guochang WANG Lin WANG Ying HE Binglin State Key Laboratory of Functional Polymer Materials For Adsorption Separation Institute of Polymer Chemistry Nankai University Tianjin China 《Chinese Journal of Reactive Polymers》2002,(2)
1. INTRODUCTION Crosslinked polymer gels have solid-liquid dual performance, which play an important role in modern high technology [1]. A wide variety of functional and intelligent materials can be prepared via chemical modification of crosslinked polym… 相似文献
8.
Basu A Joanny JF Jülicher F Prost J 《The European physical journal. E, Soft matter》2008,27(2):149-160
We discuss general features of noise and fluctuations in active polar gels close to and away from equilibrium. We use the
single-component hydrodynamic theory of active polar gels built by Kruse and coworkers to describe the cytoskeleton in cells.
Close to equilibrium, we calculate the response function of the gel to external fields and introduce Langevin forces in the
constitutive equations with correlation functions respecting the fluctuation-dissipation theorem. We then discuss the breakage
of the fluctuation-dissipation theorem due to an external field such as the activity of the motors. Active gels away from
equilibrium are considered at the scaling level. As an example of application of the theory, we calculate the density correlation
function (the dynamic structure factor) of a compressible active polar gel and discuss possible instabilities. 相似文献
9.
Rottereau M Gimel JC Nicolai T Durand D 《The European physical journal. E, Soft matter》2005,18(1):15-19
The influence of the Brownian step size in off-lattice Monte Carlo simulations of the aggregation and gelation of spheres
is studied. It is found that the kinetics are strongly influenced if the step size is larger than the mean smallest distance
between the sphere surfaces. The structure of the clusters and the gels is influenced, but only over length scales smaller
than the step size. Using large step sizes leads to a narrower size distribution of the clusters. Implications of the present
results are discussed for simulations reported in the literature in which the Brownian step size was chosen equal to the sphere
diameter. 相似文献
10.
Diffusion-limited cluster aggregation and gelation of hard spheres is simulated using off-lattice Monte Carlo simulations.
A comparison is made of the wall-particle correlation function with the particle-particle correlation function over a range
of volume fractions, both for the initial system of randomly distributed spheres and for the final gel state. For randomly
distributed spheres the correlation functions are compared with theoretical results using the Ornstein-Zernike equation and
the Percus-Yevick closure. At high volume fractions (φ > 40%) gelation has little influence on the correlation function, but
for φ < 10% it is a universal function of the distance normalized by correlation length (ξ) of the bulk. The width of the
depletion layer is about 0.5ξ. The concentration increases as a power law from the wall up to r ≈ ξ, where it reaches a weak maximum before decreasing to the bulk value. 相似文献