全文获取类型
收费全文 | 263篇 |
免费 | 8篇 |
国内免费 | 9篇 |
专业分类
化学 | 95篇 |
晶体学 | 4篇 |
力学 | 39篇 |
物理学 | 142篇 |
出版年
2022年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 1篇 |
2013年 | 14篇 |
2012年 | 12篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 16篇 |
1999年 | 22篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 46 毫秒
191.
192.
Koutalas G Pispas S Hadjichristidis N 《The European physical journal. E, Soft matter》2004,15(4):457-464
Well-defined poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) (PI-P2VP-PEO) triblock terpolymers were synthesized by anionic polymerization high-vacuum techniques. The terpolymers formed spherical three-layer (onion-type) micelles in neutral and acidic pH aqueous media as evidenced by static and dynamic light scattering. In pure water, kinetically frozen micelles with a core composed of a soft PI inner part and a hard P2VP outer shell and protected by a neutral PEO corona were formed. In acidic media the core was formed by the soft PI hydrophobic segment, whereas the corona consisted of an inner cationic polyelectrolyte P2VPH+ part and an outer PEO shell. The aggregation numbers were found to be high in all cases, due to the high hydrophobicity of the core-forming blocks. In the latter case an increase in size was observed due to the electrostatic repulsions between the P2VPH+ chains in the inner part of the corona, which is also responsible for the lower aggregation numbers observed in the acidic solutions. The interaction of these onion-type micelles with cationic (DTMAB) and anionic (SDS) surfactants led to the formation of mixed polymer/surfactant aggregates. Their structural characteristics could be varied by combining changes in surfactant type and concentration, solution pH and type of electrostatic interaction, leading to interesting, block-copolymer-based, environmentally responsive colloidal systems. 相似文献
193.
Ghaouar N Benhamou M Derouiche A Gharbi A 《The European physical journal. E, Soft matter》2005,16(4):409-413
We present here a theoretical study of kinetics of phase separation within a mixture made of two chemically incompatible ramified polymers. For simplicity, we assume that they have the same topology. We are interested in the variation of the relaxation rate, q, versus the wave number q, in the vicinity of the spinodal temperature. The kinetics is governed by local (Rouse) and reptation motions (faster and slower modes). For qRG 1 (RG being the gyration radius), kinetics is entirely controlled by local motions where each chain moves inside its own tube, and we show that the corresponding characteristic frequency, {-1}q, scales as {-1}q
Gq6, where G is a known topological factor. For qRG 1, however, kinetics is rather dominated by long-wavelength (reptation) motions where unlike ramified polymers creep inside a long tube. For this case, we find that {-1}q
( 0 )q2 (c - ), where ( 0 ) is another known topological factor that represents the total mobility of free monomers belonging to connected chains and reticulation points, and c accounts for the critical value of the segregation parameter. Finally, the derived relaxation rate must be compared to that relative to a linear polymer mixture. 相似文献
194.
Khokhlov AR Semenov AN Subbotin AV 《The European physical journal. E, Soft matter》2005,17(3):283-306
Shapes of globules formed by amphiphilic multi-block-copolymers in a selective solvent are considered theoretically. We focus on copolymers consisting mostly of insoluble H-units forming large core surrounded by a shell of soluble P-blocks. It is shown that the globule becomes non-spherical when the effective shell tension is low enough. The resultant shape depends on the shell bending energy: it is prolate if this energy is larger than the elastic energy of the core, and oblate in the opposite case. The central result is the prediction of the formation of a surface pattern of fingers accompanying or even preempting the shape transition mentioned above. We elucidate and discuss the following finger morphologies: 1) nearly spherical knob; 2) a necklace of spherical beads extending away from the surface; 3) mostly cylindrical fingers; 4) large thorn-like fingers. The first 3 morphologies develop at equilibrium as the shell area increases (or, equivalently, the shell tension decreases). Considering the relevant kinetical aspects we show that formation of fingers is a nucleation and growth process, and that the energy of their equilibrium nucleation is likely to be high. Therefore, the finger formation may be delayed, and may actually occur in the regime where the plain spherical surface is metastable. It is the last morphology (thorn-like fingers) that characterizes the metastable regimes when the finger formation is controlled by a high activation energy. The universal features of the above predictions inviting experimental tests are discussed. 相似文献
195.
In a SANS experiment, we have directly determined for the first time the conformation of hyaluronan, a model semirigid polyelectrolyte. At high ionic strength, this is completely possible, where the scattered intensity crosses over (when decreasing q) from a q(-1) rod variation to a q(-2) and, where fitting to the "wormlike" chain model gives the backbone, intrinsic, persistence length: L0 = 86.5 A. At low ionic strength, we can safely check that the measured persistence length appears increased by at least the amount predicted by Odijk for the electrostatic contribution, L(e) (approximately kappa(-2), square of the Debye screening length). However, the intensity at the lowest q is not only due to the single chain, since it crosses over from a q(-1) to a q(-4) variation, characteristic of polymer associations. 相似文献
196.
The European Physical Journal E - The structure of aqueous dispersion of charged anisotropic nano-composites (synthetic Laponite clays) have been studied by NMR and numerical simulations based on a... 相似文献
197.
G. Migliorini V.G. Rostiashvili T.A. Vilgis 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):61-73
The Langevin dynamics of a self-interacting chain embedded in a quenched random medium is investigated by making use of the
generating functional method and one-loop (Hartree) approximation. We have shown how this intrinsic disorder causes different
dynamical regimes. Namely, within the Rouse characteristic time interval the anomalous diffusion shows up. The corresponding
subdiffusional dynamical exponents have been explicitly calculated and thoroughly discussed. For the larger time interval
the disorder drives the center of mass of the chain to a trap or frozen state provided that the Harris parameter, (Δ/b
d)N
2 - νd≥1, where Δ is a disorder strength, b is a Kuhnian segment length, N is a chain length and ν is the Flory exponent. We have derived the general equation for the non-ergodicity function f (p) which characterizes the amplitude of frozen Rouse modes with an index p = 2πj/N. The numerical solution of this equation has been implemented and shown that the different Rouse modes freeze up at the same
critical disorder strength Δ
c ∼ N
- γ where the exponent γ ≈ 0.25 and does not depend from the solvent quality.
Received 17 December 2002 Published online 23 May 2003
RID="a"
ID="a"e-mail: vilgis@mpip-mainz.mpg.de 相似文献
198.
Summary We consider the configurations and the various regimes when an alternating, symmetric, multiblock copolymer made of successive
sequences of A and B monomers with equal lengthZ is at the interface between two immiscible solvents that are respectively good for one of the sequences and poor for the
other one. We find two semi-dilute regimes, when the copolymers overlap. For monomer concentrations belowГ
**, we find a first range where the thickness of the copolymers is constant and equal to the radius of a sequence. For concentrations
larger thanГ
**, a second regime appears, where the seqeunces stretch our and adopt a conformation similar to what was reported for grafted
polymers. Finally at a concentrationГ
sat, the interface is completely saturated, and the copolymers form micelles in the bulk: it becomes energetically more favourable
to have copolymers in the bulk than at interface.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4‘8, 1994. 相似文献
199.
S.-j. Chen Y. C. Chiew J. A. Gardecki S. Nilsen M. Radosz 《Journal of Polymer Science.Polymer Physics》1994,32(10):1791-1798
The pressure-volume-temperature (P-V-T) properties of monodisperse alternating poly(ethylene-propylene) (hydrogenated polyisoprene) melts of varying molecular weights are measured at 0.1 MPa < P < 200.1 MPa, and 290 K < T < 510 K in a dilatometer-type apparatus. The Flory-Orwoll-Vrij (FOV), Modified Cell Model (MCM), Sanchez-Lacombe (SL), and the Statistical Associating Fluid Theory (SAFT) equations of state are found to correlate the experimental data with excellent accuracy, except either at low pressures and high temperatures, or at high pressures and low temperatures. On average, MCM and SAFT fit the data slightly better than FOV and SL. The equation-of-state parameters are found to be independent of molecular weight, especially for SAFT, as required by the theory. © 1994 John Wiley & Sons, Inc. 相似文献
200.
Maurice Abraham Ioannis Ziogas Marie-Christine Abraham 《Journal of solution chemistry》1990,19(7):693-709
Fused salt-water systems extending from pure fused salt to pure water have been less studied than dilute aqueous solutions, despite their practical and theoretical importance. Even fewer studies have been made regarding the influence of the temperature upon transport properties. The present publication brings new interesting information on the viscous flow properties of the following two fused nitrate-water systems containing monovalent and divalent cations: AgNO3–TINO3–M(NO3)2–H2O where M=Ca or Cd, with the TINO3 and M(NO3)2 mole fractions in the anhydrous salt fixed at 0.436 and 0.100, respectively. The parameters in the Arrhenius, Eyring, Batschinski and the Abraham and Abraham equations are found to be well correlated with the properties of the components of the melts. The temperature effect allows a discussion to be made in terms of structural features such as holes and free volumes. 相似文献