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991.
992.
A ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (Tg) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed. © 2003 Society of Chemical Industry 相似文献
993.
We have studied properties of quaternary alloy magnetic semiconductor (InGaMn)As grown on InP substrates by low-temperature molecular-beam epitaxy (LT-MBE). A large MCD peak whose intensity is larger than 500 mdeg for (InGaMn)As was observed. This peak intensity was about three times larger than that of typical (GaMn)As films. Relatively high Curie temperature of 83 K of [(In0.53Ga0.47)0.88Mn0.12]As was observed by Hall measurements. The carrier concentration of [(In0.53Ga0.47)0.88Mn0.12]As was estimated to be more than 1.0 × 1021 cm–3 by using the Curie–Weiss fitting of the Hall coefficient R
H, indicating that more than 40% of Mn atoms are activated. This means that (InGaMn)As has a higher activation ratio of Mn as acceptors than (GaMn)As. 相似文献
994.
详细介绍了采用两片浮点DSP ADSP21062实现某舰载雷达所需要完成的舰速补偿、反异步干扰和脉冲压缩的系统研制。通过采用分段匹配滤波的方法,极大地节约了时间和空间。与完成同样功能采用单片TMS320C6701的设计相比,本设计具有外围电路简单、系统调试容易等优点。 相似文献
995.
This paper reports how the study of formal logical reasoning provides insight into more everyday types of reasoning, such as that involved in language comprehension. Both of these types of cognition are thought to involve the use of mental models, and so it is reasonable to think that the cognitive operations needed for formal logical reasoning would be involved in everyday reasoning as well. We focused on three aspects of formal reasoning: (a) the integration of information into a common mental model, (b) the drawing of inferences, and (c) the coordination of alternative possibilities. We were able to show that the integration and inference components were related to narrative comprehension processes, but the coordination of alternative models was not. Thus, there is evidence for some overlap in the mental processes used in formal and everyday reasoning. This further justifies the study of formal logical reasoning as a window into certain types of everyday reasoning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
分数阶傅立叶变换是经典傅立叶变换的广义形式,它同时从时间域和频率域(或空间域)揭示信号特征。本文系统地分析了分数阶傅立叶变换三种定义形式及其所对应的光学实现系统的组成和原理,说明了光学信息处理系统实现分数阶傅立叶变换的有效性. 相似文献
997.
The equilibrium moisture content (EMC) characteristics of high oleic sunflower seeds and kernels between 10 and 55°C were determined by equilibrating the samples to known relative humidities (RH) above saturated salt solutions. EMC of the kernels was lower than that of seeds in the range of 11 to 96% ERH and at 25 and 40°C. Hysteresis effect was found for the EMC properties of seeds and kernels at 25°C. Four EMC-ERH models (modified Henderson, Chung-Pfost, Halsey, and Guggenheim-Anderson-de Boer) and their estimated parameters were evaluated for goodness of fit. GAB and Halsey equations showed the best fitting of experimental data although GAB equation adjusted for temperature described the EMC data the best. Components of the seed as oil content or hull/kernel ratio did not explain the slight differences in EMC found between the varieties. 相似文献
998.
999.
Kenji Nomura Hiromichi OhtaKazushige Ueda Toshio Kamiya Masahiro HiranoHideo Hosono 《Thin solid films》2003,445(2):322-326
We have investigated the characteristics of transparent metal-insulator-semiconductor field-effect transistors (MISFETs) fabricated using InGaO3(ZnO)m (m=integer) single-crystalline thin films as n-channel layers and amorphous alumina as gate insulator films. The MISFETs exhibit good characteristics such as insensitivity to visible light illumination, off-current as low as ∼1 nA with a positive threshold voltage of ∼3 V and on/off current ratio of 105. The field-effect mobility increased from ∼1 to ∼10 cm2 (V s)−1 as the m-value increased. Room temperature Hall mobility also increased. However, unexpectedly these values were lower than the field-effect mobility. It is explained by existence of shallow localized state in the homologous compounds. 相似文献
1000.
Rosa RicciardiChristine Gaillet Guylaine DucouretFrançoise Lafuma Françoise Lauprêtre 《Polymer》2003,44(11):3375-3380
The structure and rheological behavior of atactic poly(vinyl alcohol) (a-PVA) hydrogels prepared by freeze/thaw cycles were investigated as a function of polymer concentration and number of freeze/thaw cycles. The presence of phases with different mobilities was observed using 13C CP/MAS and DP/MAS NMR experiments. The degree of crystallinity of the a-PVA-rich phase was determined by 1H NMR free decay experiments. Measurements of the shear storage and loss modulus were performed at a fixed frequency of 1 Hz and a strain value of 0.1%, i.e. under conditions where the deformation imposed on the gel structure is entirely reversible. Results thus obtained showed that an increase in the number of freeze/thaw cycles induces an increase in the degree of crystallinity in the polymer-rich phase together with an increase in the storage modulus. The a-PVA hydrogels became more fragile as the number of freeze/thaw cycles was increased. Moreover, both the percentage of protons in a rigid environment measured by 1H NMR and the storage modulus values tended to a limiting value after six freeze/thaw cycles. These results show that the first five or six freeze/thaw cycles play a very important role in determining the hydrogel structure and rheological properties. A more detailed comparison of NMR and rheological data led to the conclusion that the storage modulus is mainly controlled by the a-PVA crystallinity while the hydrogen bond interactions have a much smaller contribution. 相似文献