Author S.R. Zhou
,
S.R. Qiao
,
S.H. Bai and C.S. Tian Faculty 401
,
Northwestern Polytechnical University
,
Xian 710072
,
ChinaManuscript received 18 October 1998
金属学报(英文版)
The tensile properties of three different carbonfiberreinforced carbon composites (C/C), mat C/C, 2D laminate and 4D C/C, were investigated under the combined influence of temperature and loading rate. From the experiments the following could be concluded: loading rate between 10-1-10 mm/min was valid; the fracture stress of the three kinds of C/C composites increased with increasing temperature in the range from room temperature to 1900, and the initial modulus of 2D laminate C/C composites increased with the increase of temperature up to 2000.
关键词:
tensile testing
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null
,
null
,
null
ZHOU Weixian Northwestern Polytechnical University
,
Xi′an
,
China
金属学报(英文版)
Based on the experimental data,it was clarified that the plastic strain ratio R-value is not equal to Hill's r-value for Ti sheet.From the non-quadratic orthotropic yield function pro- posed recently by the author,an optimal expression between yield stress and r-value for Ti sheet was developed on overall investigation.The suitable value of exponent in the function seems to be 6—8.Thus,an equation was suggested to estimate strength for the pressure vessel made of Ti sheet.
关键词:
Ti sheet
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null
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null
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null
朱良
,
王晶
,
李晓慧
,
锁红波
,
张亦良
材料研究学报
针对应力比对疲劳寿命影响的问题,以TC18钛合金堆焊成形(利用多层堆焊的方法制备)试样为研究对象,进行了3种应力比(R=0.5、R=0.06、R=-1)的疲劳实验,得出相应的疲劳极限,应用"应力幅值寿命模型"和"三参数寿命模型"得到6条S-N曲线.根据裂纹扩展速率与疲劳寿命的积分关系,以两种疲劳寿命数学模型为基础,系统地研究了应力比(R)与疲劳寿命曲线(S-N)的关系,提出了考虑应力比的疲劳寿命(R-S-N)数学模型.根据本文提出的修正公式,建立了适用TC18钛合金堆焊成形材料的两种R-S-N数学模型,结果表明:用应力幅值寿命模型可对中等疲劳寿命区进行准确的预测,而三参数寿命模型更适合中长寿命区域的预测.提出的两种R-S-N数学模型与实验值吻合良好,并可在工程上预测任意应力比下的疲劳寿命曲线.
关键词:
材料科学基础学科
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应力比
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疲劳寿命
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疲劳极限
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R-S-N数学模型
陈衍强
,
邱孝苹
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徐修容
色谱
doi:10.3321/j.issn:1000-8713.2005.03.017
以1-氟-2,4-二硝基-5-L-缬氨酰胺(Marfey试剂)为衍生试剂,采用反相高效液相色谱法分离了3-取代-(R,S)-β-丙氨酸对映异构体.采用梯度洗脱(流动相 A:体积分数为0.1%的三氟乙酸乙腈溶液;流动相B:体积分数为0.1%的三氟乙酸水溶液)成功分离了 32种3-取代-(R,S)-β-丙氨酸衍生物,所有化合物都是R型异构体衍生物(R-L)较S型异构体衍生物(S-L)先洗脱.除3-羟基苯和4-羟基苯的疏水参数较小,但其取代的β-丙氨酸衍生物的保留时间较长、分离因子较小外,其他疏水参数大的取代基的β-丙氨酸衍生物保留时间都长于疏水参数小的取代基的β-丙氨酸衍生物.该文同时测定了R-和S-β-丙氨酸的对映体过剩值.
关键词:
高效液相色谱法
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3-取代-(R,S)-β-丙氨酸衍生物
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对映异构体
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对映体过剩值
秦丽娜
,
喻晓蔚
,
徐岩
催化学报
doi:10.3724/SP.J.1088.2011.10601
研究了非水有机溶剂体系中脂肪酶不对称转酯化拆分(R,S)-α-苯乙醇反应,比较了15种不同微生物来源的脂肪酶,从中优选出催化活性及对映选择性较高的脂肪酶Lipase PS,系统考察了影响该酶催化不对称转酯化反应的关键因素,获得了优化的催化拆分工艺条件.结果表明,脂肪酶Lipase PS在非水反应体系中,以正己烷为反应介质,初始水活度为0.75,底物苯乙醇和乙酸乙烯酯浓度分别为0.3和0.6 mol/L,加酶量5 mg/ml,35℃,200 r/min,反应14h后,底物(R,S)-α-苯乙醇的转化率达44.7％,产物(R)-乙酸苯乙酯的光学纯度达98.6％.水活度可影响酶对底物的转化率和对映选择性.
关键词:
脂肪酶
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转酯化
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(R,S)-α-苯乙醇
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对映选择性
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水活度
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(R)-乙酸苯乙酯
王德发
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宋雅茹
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胡玉萍
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杨亦平
,
侯冬岩
色谱
doi:10.3321/j.issn:1000-8713.2003.04.027
利用卵类粘蛋白手性固定相高效液相色谱法直接拆分了S,S-和R,R-N-对甲基苯磺酰基-1,2-二苯基乙二胺(TsDPEN).研究了流动相中有机调节剂的种类和含量、缓冲溶液的酸度、盐浓度和流速等色谱条件对拆分结果的影响.结果表明,在25 ℃时,采用0.02 mol/L的磷酸二氢钾缓冲溶液(pH 4.56)(含20%(体积分数)乙腈)作流动相,流速0.4 mL/min,能得到最佳的基线分离.分离度和选择因子分别为2.67和2.23,流出时间在10 min之内.方法简单、快速.
关键词:
高效液相色谱
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卵类粘蛋白柱
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N-对甲基苯磺酰基-1,2-二苯基乙二胺
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对映体分离
侯长军
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黄清菁
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霍丹群
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张宿义
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沈才洪
,
张良
功能材料
Receptor-Spacer-Fluorophore(R-S-F)结构型荧光分子传感器是由可选择性结合客体的主体基团与传递信号的荧光团通过桥联基团连接而成的一类分子传感器,结合了超分子在分子识别中良好的选择性和荧光信号的高灵敏度两个优点,成为一类可用于检测金属离子并具巨大发展潜力的新型光学敏感材料.以超分子主体化合物冠醚、杯芳烃结构为分类依据,从主体基团选择性能角度综述了近5年已成功合成并用于金属离子检测的R-S-F型荧光分子传感器及其研究的最新进展.
关键词:
荧光分子传感器
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分子识别
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冠醚
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杯芳烃
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卟啉
Journal of Physics and Chemistry of Solids
The changes of Mn-Y (Y = S, Se, Te) bond lengths R with the Mn composition x in the diluted magnetic semiconductors Zn1-xMnxY are calculated from the optical spectra and their pressure shifts. The calculated results suggest that the Mn-Y bond lengths change little with the Mn composition x-much less than expected from lattice parameters as determined by X-ray diffraction. These results are also in good agreement with the observed values obtained from the EXAFS measurements. It appears that for ternary A(1-x)M(x)Y (M denotes the divalent transition-metal ion) alloys the changes of M-Y bond lengths R with the M composition x can be studied from their optical spectrum data. (C) 2000 Elsevier Science Ltd. All rights reserved.
关键词:
semiconductors;high pressure;crystal fields;luminescence;light;properties;absorption fine-structure;local-structure;dependence;pressure;exafs
马丽
,
何亚兵
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金日哲
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卞证
,
高连勋
应用化学
doi:10.3969/j.issn.1000-0518.2009.05.005
化合物3-{6-[(1R,2R,4S)-2-羟基-1,3,3-三甲基二环[2.2.1]庚烷-2-基]-吡啶-2-基}-1,1'-(R)-联萘-2,2'-酚(1)与特戊酰氯反应,得到单个羟基封端的化合物3-{6-[(1R,2R,4S)-2-羟基-1,3,3-三甲基二环[2.2.1]庚烷-2-基]-吡啶-2-基}-2'-特戊酰基-1,1'-(R)-联萘-2,2'-酚(2).化合物2与MoO2(acac)2进行配位得到金属配合物3-{6-[(1R,2R,4S)-2-羟基-1,3,3-三甲基二环[2.2.1]庚烷-2-基]-吡啶-2-基}-2'-特戊酰基-1,1'-(R)-联萘-2,2'-酚合钼(酰)[Mo(Ⅵ)-2],通过核磁共振氢谱、红外光谱和质谱测试技术对其结构进行了表征,用X射线单晶衍射测定了化合物的晶体结构.结果表明,化合物晶体属单斜晶系,空间群为P21,晶胞参数α=1.179 34(10)nm,b=2.304 5(2)nm,c=1.518 88(13)nm,α=90°,β=112.84°,γ=90°,V=3.804 2(6)nm3,Z=4,μ=0.392 mm-1,D=1.298 Mg/m3,F(000)=1 544,R1=0.077 5,wR2=0.193 4,GOF=1.122.在配合物中,钥原子处于六配位的八面体配位环境,配位原子分别来自1个分子水中的O原子、配体分子中1个酚羟基的O,吡啶环中的O,醇羟基中的O形成ONO三齿配合物.配合物Mo(Ⅵ)-2在萘乙烯的不对称环氧化反应中,得到中等活性和较低的对映选择性.
关键词:
吡啶醇基联萘酚
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钼(Ⅵ)配合物
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晶体结构
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不对称催化
Li ZHOU(Department of Civil Engineering
,
Wuyi University
,
Jiangmen 529020
,
China)
材料科学技术（英文）
The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.
关键词:
