共查询到20条相似文献,搜索用时 31 毫秒
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E-112型EPR(Electronic Paramagnetic Resonance)波谱仪是Varian公司生产的。运行及操作中出现几次故障,其中以自动频率控制(AFC)失控较为典型。 相似文献
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德国Darmstadt重离子研究中心P.Armbruster和S.Hofmann等在用锌铅同位素轰击铅同位素的实验中,于1996年2月9日获得一个第112号元素的原子。 相似文献
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The triply bonded heavier main-group compounds have a textbook trans-bent geometry, in contrast to a familiar linear form found for the lightest analogues. Strikingly, the unexpected linear group 13 E≡E triple bonds were herein found in the D4h-symmetry E2Li62+ clusters, and they possess a large barrier (>18.0 kcal/mol) towards the dissociation of Li+. The perfectly surrounded Li4 motifs and two linear coordinated Li atoms strongly suppress the increasing nonbonded electron density of heavier E atoms, making two degenerate π bonds and one multi-center σ bond in linear heavier main-group triple bonds. The surrounding Li6 motifs not only creates an effective electronic structure to form a linear E≡E triple bond, but the resulting electrostatic interactions account for the highly stable global E2Li62+ clusters. 相似文献
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胶束电动毛细管色谱法测定硫酸多粘菌素E药物中的多粘菌素E1和E2 总被引:1,自引:0,他引:1
采用胶束电动毛细管色谱法(MECC)对硫酸多粘菌素E药物中的主要成分多粘菌素E1和E2进行了分离,并测定了多粘菌素E1、E2的含量。分别考察了电泳电压、表面活性剂种类、Brij-35(月桂醇聚氧乙烯醚)浓度、乙腈含量、磷酸盐缓冲液的pH值、氯化钠浓度等实验参数对实验结果的影响,从而确定了最佳的分离条件: 电泳电压为10 kV,运行缓冲液为含有30 mmol/L Brij-35、5%(体积分数)乙腈、0.167 mol/L氯化钠的磷酸二氢钠缓冲液(0.01 mol/L,pH 4.1)。在优化的实验条件下,E1和E2得到了较好的分离,分离度达到1.94。以多粘菌素E1为例,柱效和峰面积的日间及日内测定的相对标准偏差(RSD)均小于5%。E1和E2在硫酸多粘菌素E药物中的含量分别为67%和32%。该方法简便、快速、准确、重现性好。 相似文献
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《广东微量元素科学》2003,(5)
维生素E参与血红素或血红素蛋白质的合成 ,并能同时影响ALS和ALAD活性。在实验中观察到 ,维生素E缺乏的大鼠发生铅中毒时 ,可出现贫血、脾大和红细胞脆性增加 ,通过饲料补充维生素E则可预防由铅引起的红细胞变形 (LevanderOA ,1 975 ,1 979)。Dhawan也发出 ,在接触铅的同时 ,补充维生素E可预防血ALAD活性下降、尿中ALA升高及铅在血和肝中的蓄积。维生素E对铅的这种预防作用可能与其抗氧化特性和影响药物代谢酶系有关。Trivedi ( 1 998)最近观察到 ,用维生素E预处理可降低肝、心LPO含量 ,增加肝、肾过氧化氢酶(CAT)活性。维生素… 相似文献
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Dr. Karre Nagaraju Dr. Dongshun Ni Prof. Dr. Dawei Ma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22223-22226
Kopsinitarines A–E are complex octacyclic caged Kopsia alkaloids with strained cage skeletons and a unique cyclic hemiaminal bridge that makes total synthesis challenging. Herein, we disclose the first total synthesis of kopsinitarine E. The key synthetic features include a SmI2-mediated radical cascade cyclization and a subsequent semi-pinacol rearrangement to install the key carbocyclic skeleton, a chemoselective hydrosilyl amide reduction to construct the hemiaminal ether bridge, and an intramolecular Mannich reaction to establish the highly strained cage system. 相似文献
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长春应化所研制成功氢氧化制硝酸用稀土复合氧化物非铂催化剂RC-112,取代了我国短缺、依赖进口、价格昂贵的金属铂催化剂,催化活性与铂铜接近,生产强度提高30%,价格则低很多。RC-112催化剂的结构属于稀土钙钛矿型,用于氨氧化制硝酸为国内外首创。 相似文献
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收集了遗尿症患儿112名,测定了其发中钙,锰,铁,铜,锌,铜六种元素,并与正常同年龄同性别组对照,结果男性患儿发钙下降(P〈0.01),发锰下降(P〈0.05),发铜升高(P〈0.01),综合男女患儿发样,其中男性与女性患儿的发锰,钙均下降,相一致,遗尿症中医辨证属于虚证,所属脏腑为肾。微量元素锰的缺乏与肾虚有密切关系,本结果提示缺锰可作为遗尿症的参数指标之一。 相似文献
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The diacetylenic adducts, Fe2(CO)6{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe2(CO)6(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (1H, 13C, 77Se, and l25Te) spectroscopy. Trends in the chemical shifts of 77Se and 125Te NMR spectra of Fe2(CO)6{-EC(H) = C(C CMe)E} with a variation of EE are discussed. 相似文献
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Amination of geranyllinalyl acetate 1 with diethylamine and Pd(OAc)2 · 2PPh3 as catalyst gave N,N‐diethylgeranylgeranylamine 3 (E/Z=91/9) in 85% yield. Amine 3 was treated by ethyl chloroformate followed by KOAc to give geranylgeranyl acetate 2 in 82% yield. Then 2 was hydrolyzed to afford geranylgeraniol 4 in 94% yield. 相似文献
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Olga A. Gapurenko Vladimir Ya. Lee Ruslan M. Minyaev Vladimir I. Minkin Akira Sekiguchi 《Tetrahedron letters》2017,58(21):2054-2057
Hybrid cationic pyramidanes {E15[E144R4]}+ (E15 = P–Bi; E14 = C–Ge, R = H, SiMe3) have been studied by the DFT calculations, and their structures, electronic properties and bonding nature are discussed. Square-pyramidal geometry in the real neutral compounds {E15[E144(SiMe3)4]}+[AlCl4]? is preserved. 相似文献
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分子蒸馏分离天然维生素E 总被引:8,自引:0,他引:8
天然维生素E(d1.2,5,7,8.[四甲基-2-(4,8,12.三甲基)十三烷基]色满醇-6-醋酸酯)工业上是从油脂真空脱臭的馏出物中提取。溶剂萃取法工艺简单,但难以找到特效的溶剂且纯度及产品收率均较低;化学处理法产品中有机物残留,限制了产品的应用;超临界萃取技术操作条件比较温和,分离容易,但一次性投资大。本文尝试对由酯化法制成的脂肪酸甲酯维生素E混合物,采用分子蒸馏技术进行分级分子蒸馏,以期获得高纯度的脂肪酸甲酯和纯度达50%以上的天然维生素E,为工业化生产提供参考。 相似文献