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991.
992.
二阶非线性光学聚合物材料 总被引:3,自引:0,他引:3
非线性光学材料是一类具有很高实用价值的功能材料。综述了聚合物二阶非线性光学材料的研究、极化聚合物在实用化研究方面取得的新进展,介绍了提高极化聚合物生色团高温取向稳定性、设计合成光损失较小的生色团以及优化聚合物主体的新方法。 相似文献
993.
通过动态力学参数温度谱,研究了尼龙1010/6、尼龙1010/66两个共聚物系列的动态力学参数与组成的关系。研究表明尼龙1010/6、尼龙1010/66在测试温度范围内出现三个明显的松驰转变:α、β、γ,其中各共聚物的β、γ松驰温度相差不大,而α松驰温度随组成改变有明显改变。一般均聚物的α松驰温度较高,共聚物的α松驰温度均低于均聚物,二个系列以尼龙1010/6(29.8/70.2)、尼龙1010/ 相似文献
994.
The results of studies of IR and Raman spectra of volatile inorganic hydrides of Group IV–VI and Periods 3 and 4 elements
in the liquid state are surveyed and analyzed. The mechanisms of intermolecular interactions in these liquids are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 629–644, April, 1999. 相似文献
995.
The thermoelastic behaviour of an unfractionated polystyrene was studied in the temperature interval 353–453 K in the regimes
of isobaric cooling and of isothermal quasi-adiabatic loading, respectively. The main experimental results can be summarized
as follows.
1. In the temperature interval far above the glass transition temperature Tg, both the temperature and volume relaxations of the polystyrene melt after sudden pressure jumps were completely reversible
and proved to be simple exponential functions of the time. Therefore, by a straightforward application of Eqs (1) and (2)
to the relevant thermoelastic data obtained in a single experimental run one can arrive at the reasonable values of the specific
volume, specific heat capacity, thermal diffusivity and heat conductivity of the polymer in the equilibrium melt state.
2. In the temperature interval close to Tg, both the temperature and volume relations of the supercooled polystyrene melt in compression/expansion cycles became markedly
asymmetric and non-exponential. The low values of the exponent β in the fractional-exponent Eq. (5) for the volume relaxation
suggest a broad spectrum of relaxation times indicating the high degree of coupling between different mechanisms of the molecular
motions involved.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
996.
用MonteCarlo方法对两嵌段共聚高分子在固液界面的吸附进行模拟,获得了固液界面区总链节密度和吸附链节浓度分布、链附着率、表面覆盖率和吸附量等信息,考察了吸附性链节的对比吸附能 ε>An 和两嵌段共聚高分子中吸附性链节比例f对它们的影响.结果表明,较大时,吸附量先随f的增加而上升,在f=0.4左右达到最大值后逐渐下降. 相似文献
997.
A. Chalabi. 《Mathematics of Computation》1999,68(227):955-970
We focus in this study on the convergence of a class of relaxation numerical schemes for hyperbolic scalar conservation laws including stiff source terms. Following Jin and Xin, we use as approximation of the scalar conservation law, a semi-linear hyperbolic system with a second stiff source term. This allows us to avoid the use of a Riemann solver in the construction of the numerical schemes. The convergence of the approximate solution toward a weak solution is established in the cases of first and second order accurate MUSCL relaxed methods.
998.
999.
ALPHA Collaboration Marco Guagnelli Jochen Heitger Rainer Sommer Hartmut Wittig 《Nuclear Physics B》1999,560(1-3):465-481
We explain how masses and matrix elements can be computed in lattice QCD using Schrödinger functional boundary conditions. Numerical results in the quenched approximation demonstrate that good precision can be achieved. For a statistical sample of the same size, our hadron masses have a precision similar to what is achieved with standard methods, but for the computation of matrix elements such as the pseudoscalar decay constant the Schrödinger functional technique turns out to be much more efficient than the known alternatives. 相似文献
1000.
V. K. Jain 《Crystal Research and Technology》2004,39(9):784-787
Electron paramagnetic resonance of Gd3+ in Eu2Zn3(NO3)12·24H2O single crystals is studied at ≈9.45 GHz and at 298 and 77 K. Gd3+ substitutes for the Eu3+ site. In addition to the allowed fine structure lines, forbidden transitions (ΔM = ±2,±3,±4,±5) are observed. The superposition model is applied to the zero‐field splitting parameter b20. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献