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151.
A generalized equation was derived to calculate the melting temperatures of homopolymers and copolymers. The Gibbs‐Thomson equation for homopolymers and a modified application to copolymers were derived using the proposed equation. The melting temperature Tm0 in the Flory equation corresponds to the melting temperature TmC,∞ of copolymer crystals with stems of infinite length. Also, TmC,n*, the melting temperature for copolymer crystals with stems containing the maximum possible number of structural units, n*, should be used instead of Tm0 as the basis of supercooling in crystallization. The proposed equation shows good agreement with experimental data for α‐alkene‐ethylene homogeneous copolymers. 相似文献
152.
针对欢喜岭油田低微稠油的特点,采用常压蒸馏—氧化沥青联合装五的工艺流程,生产出AH-90重交通道路沥青。经测试表明,各项性能均达到我国现行重主通道路沥青技术指标。在高温稳定性、低温抗裂性等方面都优于新加坡壳牌沥青。是一种优质的道路沥青。 相似文献
153.
154.
聚酰胺的改性与加工应用 总被引:1,自引:0,他引:1
本文介绍了有关尼龙树脂材料改性,共聚和新品种尼龙等聚合物设计技术,聚合物合金等复合技术,以DSI等胶粘技术为中心的相关加工技术的动向和具体事例。 相似文献
155.
The effect of different amounts (5, 10 and 15%) of compressive deformation of austenite on the isothermal transformation of acicular ferrite in an alloy-steel weld metal has been investigated. It was found that prior deformation of austenite significantly enhanced acicular ferrite transformation. At the same isothermal transformation temperature, as a higher amount of prior deformation was applied, a greater quantity of acicular ferrite could be obtained and the size of acicular ferrite plates became much finer. These results implied that the effective nucleation sites of acicular ferrite increased with increasing amount of prior deformation. The other results also emphasized that the accumulated strain (due to prior deformation of austenite) could trigger acicular ferrite to nucleate on inclusions at high temperatures, where undeformed austenite remained stable. The acicular ferrite start temperature was found to be raised continuously by increasing the amount of prior deformation of austenite. Further evidence suggests that the application of deformation can boost the driving force for acicular ferrite formation. This phenomenon is similar to the case in which martensite forms under the influence of deformation. 相似文献
156.
Ruifeng Huang Daming Zhang 《IEEE transactions on magnetics》2007,43(3):974-981
After setting up a mathematical model for rectangular-shaped Mn-Zn ferrite capacitors, this paper investigates dimensional effects on the intrinsic complex permittivity and the measured apparent complex permittivity of Mn-Zn ferrite blocks. The simple block structure of the samples guarantees their easy and precise preparation. Above a few hundred kilohertz, dimensional effects make the measured apparent complex permittivity deviate from its intrinsic value. This paper uses a Newton-Raphson based method to trace the intrinsic complex permittivity and permeability from the measured impedances of two rectangular-shaped Mn-Zn ferrite capacitors in the frequency range from a few hundred kilohertz to 40 MHz. From the traced intrinsic complex permittivity and permeability, the apparent complex permittivity of a third sample with different dimensions is then calculated theoretically. The papers also presents results of experiments carried out to measure the apparent complex permittivity of the third sample; agreement between the measured and the calculated values is very good. This justifies the validity of the method presented in this paper, when used to determine the dimension-independent intrinsic complex permittivity and permeability of Mn-Zn ferrites 相似文献
157.
From the rhizomes of Polygonatum alte-lobatum, two new homologous series of 1,4-benzoquinones, polygonaquinones A and B, a novel homoisoflavanone, a new gentrogenin glycoside and 13 known compounds were isolated and characterized. The structures of the new compounds were determined as two homologous series of three 2,5-dihydroxy-3-methyl-6-alkyl-1,4-benzoquinones and three 2-hydroxy-3-methyl-6-alkyl-1,4-benzoquinones, with chain lengths C21 to C23, and 4',5,7-trihydroxy-6,8-dimethylhomoisoflavanone and gentrogenin 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)] -beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside. 相似文献
158.
1概况长湖水电厂装机2×36MW,70年代初投入运行。水轮发电机组制动器活塞直径为220,弹簧式复归,如图所示。长期以来,制动器复归不可靠,机组停机后,运行人员经常要把未复归的制动器闸板撬下。其原因是:(1)制动器在制动时,由于制动摩擦力的作用,制... 相似文献
159.
精选了一系列有机和无机化合物为成核剂,使用砂浴法和热台法制备了一系列不同β晶含量的等规聚丙烯,发现最有效的β成核剂是溶靛素灰 IBL 和溶蒽素金黄 IGK,首次表明β成核剂具有排列紧密的稠球结构特征,且含有硫原子。 相似文献
160.
M Eberstadt B Huang Z Chen RP Meadows SC Ng L Zheng MJ Lenardo SW Fesik 《Canadian Metallurgical Quarterly》1998,392(6679):941-945
When activated, membrane-bound receptors for Fas and tumour-necrosis factor initiate programmed cell death by recruiting the death domain of the adaptor protein FADD to the membrane. FADD then activates caspase 8 (also known as FLICE or MACH) through an interaction between the death-effector domains of FADD and caspase 8. This ultimately leads to the apoptotic response. Death-effector domains and homologous protein modules known as caspase-recruitment domains have been found in several proteins and are important regulators of caspase (FLICE) activity and of apoptosis. Here we describe the solution structure of a soluble, biologically active mutant of the FADD death-effector domain. The structure consists of six antiparallel, amphipathic alpha-helices and resembles the overall fold of the death domains of Fas and p75. Despite this structural similarity, mutations that inhibit protein-protein interactions involving the Fas death domain have no effect when introduced into the FADD death-effector domain. Instead, a hydrophobic region of the FADD death-effector domain that is not present in the death domains is vital for binding to FLICE and for apoptotic activity. 相似文献