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以金相、X射线衍射和拉伸试验研究Si 对Fe-Mn-C合金显微结构和拉伸性能的影响。实验结果表明,Si有助于Fe-Mn-C合金在固溶状态形成退火孪晶,在形变中促使发生形变感生γ→ε马氏体转变和孪生切变。拉伸形变中形成的形变ε-马氏体相变强化和形变孪晶平和退火孪晶的应变强化,他Fe-Mn-C合金强度提高和塑性降低。 相似文献
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主要研究了添加Ni对Sn-0.7Cu焊料的物理性能及其润湿性能的影响,分别测试了焊料的熔化温度、电阻率、热膨胀系数、抗腐蚀性能及其润湿性。结果表明:添加微量的Ni元素使得Sn-0.7Cu合金焊料的熔点有小幅度的升高,当添加Ni含量为0.2wt%时,Sn Cu基焊料熔点为228.83℃;焊料电阻率随着Ni含量的增加而增加;焊料的热膨胀系数随Ni含量的增加而降低。当Ni含量为0.12wt%时,焊料在室温到100℃区间其热膨胀系数为12×10-6/℃。同时,增加焊料中Ni元素的含量提高了焊料的抗腐蚀能力及其在Cu基板上铺展面积。 相似文献
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金属氧化物及其复合纳米纤维具有独特性能和潜在的应用价值,一直为人们所关注。本文提出了一种简便制备CuO/SiO2纳米复合纤维的新方法。即将静电纺丝技术与溶胶凝胶法结合,得到前驱体纤维;随后在适当的温度下热处理去除有机成分,最终得到直径150～200 nm的质量比为10%CuO/90%SiO2复合纳米纤维。使用SEM、TG-DTG、XRD、FT-IR、BET、UV-Vis技术手段对样品进行表征。SEM、TG-DTG、XRD、FT-IR结果表明该纤维的成分、形貌和晶相很大程度上受到煅烧温度的影响。BET结果表明该纤维的比表面积为141.95 m2/g,是纳米结构。光吸收测量结果发现该纤维的紫外光吸收性能随纤维晶相改变而改变。 相似文献
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电解沉积纳米晶体Cu的热稳定性及机械性能研究 总被引：1，自引：0，他引：1
采用电解沉积技术制备出无孔隙、无污染、微观应变很小的 理想 "纳米晶体单质Cu样品.对电解沉积纳米晶体Cu进行冷轧处理,首次发现纳米晶体材料具有室温下的超塑延展性,在冷轧过程初始阶段样品有少量的加工硬化,当变形量达到一定程度时(ε >80 0 % ),加工硬化效应消失。恒定的晶粒尺寸,恒定的位错密度,以及恒定的硬度值,说明纳米晶体Cu的塑性变形机制由晶界行为所控制,并非位错运动机制。系统的研究了纳米晶体中微观应变对其热稳定性的影响,发现随纳米晶Cu样品中微观应变的增加,晶粒长大的起始温度升高,而微观应变释放的起始温度下降 相似文献
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《内江科技》2021,(2)
本文采用真空电弧熔炼炉制备Ti-15Mo-Cux (x=0,8,1 6,20,25质量比)系钛合金,通过X射线衍射(XRD)、扫描电镜(SEM)、洛氏硬度仪、电化学腐蚀等方法,实验研究了Cu含量对Ti-15Mo-Cux合金微观组织结构、力学性能、耐腐蚀性的影响。结果表明:Ti-1 5Mo-8Cu主要由β相组成;Ti-15Mo-6Cu主要由原始的β相,伴有针晶间针状α相及短棒状初生相且树枝晶出现分布均匀的第二相颗粒状和黑色带状物Ti_2Cu;Ti-15Mo-20Cu主要由残留的β相组织和组织粗大的CuTi_2和CuTi化合物相组成;当Cu的质量比在0.25%变化时,硬度变化趋势是升高-降低-平稳的变化规律;合金电化学腐蚀实验表明Ti-15Mo-8Cu合金在3.5%NaCl溶液中耐腐蚀性最优。综上所述,通过对Ti-15Mo-Cux(x=0、8、16、20、25质量比)系列显微组织、硬度测试以及耐腐蚀性能测试综合分析,Ti-15Mo-8Cu合金的力学性能和耐腐蚀性能优于其它四种合金。 相似文献
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利用电解沉积技术制备出高纯度、高致密度的块状纳米Cu样品。在室温下冷轧Cu样品可得到延伸率超过 51 0 0 %的超塑延展性 ,切冷轧过程中无加工硬化效应产生。从微观结构方面研究讨论了纳米晶Cu样品的变形机制。 相似文献
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以恶唑啉为导向基团 ,通过邻位锂化方便地高非对映选择性地合成了一系列平面手性二茂铁硫恶唑啉、硒恶唑啉和膦恶唑啉配体 .应用于 1 ,3 二苯基烯丙基醋酸酯的烯丙基烷基化反应 ,ee值最高可达 99%,膦氮配体在烯丙基胺化反应中 ,ee值最高也可达 97%.此外 ,发现中心手性起到了决定产物ee值和绝对构型的作用 ,平面手性和中心手性的匹配在取得高对映选择性上是重要的 .设计合成的一类平面手性二茂铁修饰的手性口袋型双膦配体 ,由于有平面手性的辅助而具有更有效的诱导效应 .这类配体在前手性亲核试剂的不对称烯丙基化生成季碳氨基酸衍生物构及alpha 位双取代季碳酮反应中 ,ee值最高分别可达到 75 %和 95 %.设计合成的 1 ,1’ 二茂铁膦氮配体 ,在单取代的烯丙基醋酸酯的钯催化区域选择性及对映选择性的烯丙基烷基化及胺化反应中 ,显示了非常高的反应活性、区域选择性和对映选择性 .配体中BINOL羟基由于和苄胺存在分子间氢键而对反应的选择性起到了关键作用 ,并从实验上给予了证明 相似文献
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《Journal of The Franklin Institute》2022,359(18):10907-10930
Zhang neural network (ZNN) is widely applied to solving time-dependent problems. For the sake of the implementation on the digital hardware platform, ZNN models need to be discretized. In this paper, as a further study of Zhang et al. discretization (ZeaD) formulas, a novel general 9-instant ZeaD formula is presented, and clear constraints are firstly given with proof. To evaluate the presented 9-instant ZeaD formula, three continuous-time models for time-dependent matrix inversion and pseudoinversion are presented with the help of Getz-Marsden dynamic system (GMDS) and ZNN. Then the corresponding discrete-time models are obtained by using the 9-instant ZeaD formula. According to the comparison experiments, the 9-instant ZeaD formula is substantiated to be effective and consistent with the theory. Furthermore, the problem of mobile angle-of-arrival (AoA) localization is investigated as a more specific and practical problem. In order to overcome the singularity problem of the tangent function in the representation of the AoA localization system, a new representation with sine and cosine functions is presented. Similarly, the continuous-time model is derived and discretized. Through comparison experiments, the discrete-time model obtained by the 9-instant ZeaD formula achieves desirable results, which further show the efficacy of the 9-instant ZeaD formula. 相似文献
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In this paper, the results on the stability of a weighted diamond of polynomials which was studied by Kharitonov and Tempo (Systems Control Lett. 22 (1994)) are simplified for low-order polynomials. Specifically, for n=3 and 4, the number of polynomials required to check the stability is four and six, respectively, instead of eight. Further, diamond of polynomials which were studied by Barmish et al. (IEEE Trans. Automat. Control AC-37 (9) (1992)) are also investigated. 相似文献
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Venkateshwari A Sri Manjari K Krishnaveni D Nallari P Vidyasagar A Jyothy A 《Indian journal of clinical biochemistry : IJCB》2011,26(2):136-139
Pancreatic fibrosis is a key pathological feature in the etiology of chronic pancreatitis that leads to obliteration of exocrine
and endocrine pancreatic tissues and its replacement by fibrous tissue resulting in clinical manifestations. Matrix metalloproteinase
9 is a member of the MMP family that is also known as gelatinase B, degrades type IV collagen of extracellular matrix and
basal membrane. The present study is aimed at evaluating the clinical significance of plasma concentration of MMP-9 in chronic
pancreatitis. The samples were obtained from 112 chronic pancreatitis patients and an equal number of age and sex matched
healthy controls. MMP-9 levels were quantitatively measured by ELISA assay. Statistical analysis was applied to test the significance
of results. The present study revealed a significant increase of plasma MMP 9 levels in chronic pancreatitis patients compared
to control subjects. Elevated levels were also observed in all the patient groups compared to control subjects with regard
to sex, age, addictions etc. MMP-9 degrades the type IV collagens in normal basement membrane, which in turn activates the
pancreatic stellate cells which promote the development of pancreatitic fibrosis. Thus, elevated plasma levels of MMP-9 may
act as a susceptibility factor for the development of chronic pancreatitis. 相似文献
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BackgroundThere is a large amount of industrial wastewater produced by the mushroom industry during the canning processing each year, which could provide abundant carbon, nitrogen and inorganic salts for microbial growth. The aim of this study was to optimize the culture conditions for Bacillus licheniformis cultured in the Agaricus bisporus industrial wastewater to produce the agricultural microbial fertilizer.ResultsIn this work, the maximal biomass of B. licheniformis could be obtained under the following culture conditions: 33.7°C, pH 7.0, 221 rpm shaking speed, 0.5% wastewater, 2 (v:v, %) inoculum dose, loading liquid of 60 mL/250 mL and a culture time of 24 h, and the average experimental value obtained was 1.35 ± 0.04 × 109 Obj/mL, which was within the 95% confidence interval of the predicted model (1.29–1.38 × 109 Obj/mL), and met the national microbial fertilizers' standard in China. Furthermore, the field experiment results showed that the fermentation broth of B. licheniformis could significantly improve the yield of Anoectochilus roxburghii.ConclusionsAgaricus bisporus industrial wastewater can be used to produce agricultural microbial fertilizer.How to cite: Huang J, Huang A, Lu L, et al. Improving the yield of Anoectochilus roxburghii by Bacillus licheniformis cultured in Agaricus bisporus industrial wastewater. Electron J Biotechnol 2020;48. https://doi.org/10.1016/j.ejbt.2020.08.002. 相似文献
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Leonurus japonicus Houtt. [L. heterophyllus Sweet, L. artemisia (Lour.) S. Y.
Hu] is one of the most important traditional Chinese medicines used as a remedy for gynaeco-
logical disease since ancient times. A cytological investigation on the species was carried out
and the materials for chromosomal examination were collected from 26 localities in 20 provi-
noes and autonomous regions of this country. The number of chromosomes in root tip cell of
the species was found to be 20 on the whole (Tab. 1:1), agreeing with those reported by Ma and
al.[2] and probably by Chuang and al.[3] as well.
The genus Leonurus L. is variable in its chromosomes with an aneuploidy of x=9, 10 and
12. The present authors would propose that the primitive basic number of chromosome in the
genus is 9, and thus both 10 and 12 are derived, for: (1) among the 9 species (including 1 sub-
species) heretofore cytologically examined, x=9 occurring in 66.7%, x=10 occurring in 22.2%,
while x=12 occurring only in 11.1%; (2) in generaclosely related to the genus under considera-
tion, such as Panzeria, Galeobdolon and Lamium x=9 being the sole basic number.
But L. japonicus exhibits a mixoploidy of 2n=20 (occurring at the rate of 53.30% of the
total amount of cells examined), 2n=18 (30.70%), and 2n=16 (15.99%) in our work. (Table
1). Since the original basic number of chromosome of the genus is 9 as proposed above, 2n=
20 would be considered as a derived one and the occurrence of 2n=18 probably suggests an
early evolutionary trend of 2n=18→20 of the pecies in question. 相似文献
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南极假丝酵母(Candida antarctica)脂肪酶A在毕赤酵母中的表达、纯化及性质 总被引：1，自引：0，他引：1
将编码南极假丝酵母脂肪酶A的基因进行克隆,与pPIC9K连接构建成重组载体,并将其电转化入毕赤酵母GS115中。通过MD和MM平板及PCR扩增,筛选和鉴定重组子。重组细胞经过120 h培养后,发酵液上清酶活达到13 U/mL。聚丙烯酰胺凝胶电泳显示,重组脂肪酶分子量约为50 kD,比原始脂肪酶略大。粗酶液经中空纤维素膜超滤浓缩、硫酸铵分级沉淀和离子柱交换层析后,得到在SDS-PAGE上显示为单一条带的重组脂肪酶。该酶最适反应温度为75℃,在70℃保持30 min后,仍具90%以上的活性,最适反应pH值为7.0,在pH6.0～8.0的范围内,具有一定的稳定性。 相似文献
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关系的概念是社会网络分析的核心,关系强度的测量建立在强弱关系理论基础之上,随着在线社交网络的发展,关系的细分更加必要,三维关系模型旨在改进静态、二元的强弱关系模式,从三个维度对关系强度进行重新构造,即心理维度、结构维度及工具维度。应用文献分析和实证分析的方法,建立了在线网络中的关系测量模型,结果表明,通过量化在线网络中用户的互动行为,可以将每个维度的关系强度归一化为 [0,1] 的连续变量,同现有方法相比,三维关系可以细分关系图谱,在设计SNS功能、隐私控制、朋友推荐及信息扩散等方面,三维关系模型无疑具有重要的理论指导作用。 相似文献
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利用脂肪酸组成分析鉴定海洋细菌的初步研究 总被引：3，自引：0，他引：3
报道了利用脂肪酸组成分析鉴定海洋细菌的初步研究结果。以16S rRNA鉴定的9株具生物活性的海洋细菌为研究对象,标准条件培养后测定其脂肪酸组成和含量,同时参照Ivanova和Venkateswaran等研究的5株Pseudoalteromonas属海洋细菌的脂肪酸测定结果(培养条件与本实验一致),通过SPSS软件对这些细菌进行脂肪酸聚类分析,并与它们的16S rRNA序列聚类分析(运用ClustalX软件)进行比较。结果表明脂肪酸组成可以作为海洋细菌鉴定到属的依据之一,但仅依靠脂肪酸将海洋细菌不能鉴定到种。 相似文献
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Effective manipulation and understanding of the structural and dynamic behaviors of a single polyelectrolyte (PE) under alternating current (AC) electric fields are of great scientific and technological importance because of its intimate relevance to emerging bionanotechnology. In this work, we employ fluorescence correlation spectroscopy (FCS) to study the conformational and AC-electrokinetic behaviors of a model annealed PE, poly(2-vinyl pyridine) (P2VP) under both spatially uniform and non-uniform AC fields at a single molecule level. Under spatially uniform AC-fields, we observe a gradual and continuous coil-to-globule conformational transition (CGT) of single P2VP at varied AC-frequency when a critical AC-field strength is exceeded, in contrast to the pH-induced abrupt CGT in the absence of AC-fields. On the contrary, under spatially non-uniform AC-fields, we observe field-driven net flow and accumulation of P2VP near high AC-field regions due to combined AC electro-osmosis and dielectrophoresis but surprisingly no conformational change. Thus, distinct AC-electric polarization effect on single annealed PE subject to AC-field homogeneity is suggested. 相似文献