135 research outputs found
一步法合成烷基糖苷的工艺研究
烷基糖苷是一种新型世界级非离子型表面活性剂,具有优良特性,特别是它对环境绿色友好无污染,符合当前人们对环境保护越来越重视的趋势。烷基糖苷用途广泛,可以应用于洗涤剂、化装品、食品、医药、农药等诸多产品领域。 本文进行了烷基糖苷合成制备的研究工作,采用一步法合成的工艺,即以月桂醇和葡萄糖为原料,在催化剂和一定的条件(不同的醇糖比,剂糖比,温度)下进行合成反应。随后对反应混和物进行脱醇、脱色漂白、抽真空干燥及最后的产品分析。由于采用一步法直接用高碳醇进行反应,避免了在反应中引入低碳醇,从而避免了最终产品中含有低级糖苷而限制产品的用途。过量的高碳醇经处理后可以重新使用,降低了生产成本。 首先筛选出...Alkyl Polyglycoside (APG) is a non-ionic surfactant which possess excellent peculiarity, especially no pollution to surroundings. APG is applied in many fields, such as detergent, cosmetics, food, medicine, pesticides and plastic. In this thesis dodecyl polyglucoside is synthesized by the direct reaction of lauryl alcohol with glucose in the presence of catalyst. A whole route contains residual l...学位:工学硕士院系专业:化学化工学院化学工程系_化学工程学号:19993300
Study on Corrosion Resistance of Zr-0.8Sn-1Nb-0.3Fe Alloy after Kr~+ Ion Irradiation
采用高压釜腐蚀实验研究了2种不同制备工艺下的Zr-0.8Sn-1Nb-0.3Fe合金(1#,2#)经360℃、5~25; dpa的Kr~+辐照后、在400℃/10.3 MPa过热蒸汽中的耐腐蚀性能,用透射电子显微镜(TEM)、扫描电镜(SEM)、; X射线衍射仪(XRD)分析合金腐蚀后氧化膜显微组织结构。结果表明,100; d腐蚀后,合金的腐蚀增重随着辐照剂量的增加而增加,由于1#合金中的第二相比2#合金更为细小、弥散,相同辐照剂量下,前者的腐蚀增重较低。腐蚀转折前; ,从蒸汽腐蚀侧到锆合金基体,氧化膜中的氧含量逐渐降低,靠近蒸汽侧的氧化膜主要由等轴晶形态的单斜ZrO_2组成,而基体界面处的氧化膜主要为柱状晶形; 态的四方ZrO_2和六方Zr_3O;腐蚀转折后,基体界面处的氧化膜呈"花菜"状生长,"花菜"尺寸大小与氧化膜生长速率的高低及不均匀生长趋势的大小; 呈对应关系。The corrosion resistance of Zr-0.8Sn-1Nb-0.3Fe alloys prepared by two; different processes was investigated in 400℃/18.6MPa superheated steam; by static autoclave after irradiated by 360℃ with Kr~+-irradiation of; 5~25 dpa. The microstructures of oxidation film after corrosion were; analyzed by TEM, SEM, and XRD. The results showed that the corrosion; weight-gain increased with the irradiation dose, while the weight-gain; of 1# alloy with smaller and more dispersive SPPs than 2# alloy was; lower under the same irradiation dose. Before corrosion turning, the; oxygen content in the oxidation film decreased from the steam-side to; the zirconium matrix. The oxidation film beside the steam-side was; mainly composed by equiaxied monoclinic ZrO_2 crystal, while near the; film/matrix interface by columnar quartet ZrO_2 crystal and hexagonal; Zr_3O crystal. After transition of corrosion weight, the film near the; interface grew like cauliflowers, and the size of cauliflowers were; corresponded to the growth rate and uneven growth trend of oxidation; film
Synthesis and Characterization of Lanthanide Complexes Involving Cyclopentadienyl and N-phenylzohydroxamic Acid
合成了以茂基和 N-苯基苯甲异羟肟酸为配体的一系列新型稀土金属有机配合物 Cp2 Ln L( Cp=η5-C5H5;Ln=Sm,Nd,Gd,Dy,Ho,Er,Yb Pr;L=C6H5CONOC6H5)。产物经元素分析、IR和 MS表征A series of new mixed-ligand organolanthanide complexes involving cyclopentadienyl and N-phenylbenzohydroxamic acid ligands Cp 2LnL(Cp=η 5-C 5H 5; Ln=Nd,Sm,Gd,Dy,Ho,Er,Yb Pr; L=C 6H 5CONOC 6H 5) have been synthesized. All the complexes were characterized by elemental analysis, IR and MS spectra.安徽省自然科学基金 ( 0 0 0 46 5 0 9);; 安徽省教育厅项目基金 ( 2 0 0 0 j10 90
Food source and feeding habit of Helice tientsinensis from the common reed vegetation in high marsh of Yellow River Delta,China
Investigating the composition of food sources with stable isotope method can provide direct evidence for the top-down control in the coastal wetland.In this study,we examined food source and feeding habit of Helice tientsinensis of common reed (Phragmites australis) vegetation in high marsh of Yellow River Delta.The results showed that the density of crab was (5.5 1.5) ind·m~(-2),with the behavior of climbing P.australis to feed on the leaves at night.Under the same indoor experimental condition,H.tientsinensis showed feeding preference on fresh leaves of P.australis.The stable isotope food source analysis showed that the leaves of P.australis were one of the important food sources of H.tientsinensis in the field.There were temporal variations in the proportion of fresh leaves [May:(6.44.9) %,July:(5.84.9) %,September:(12.58.8) %] and dead leaves [May:(12.47.8) %,July:(15.59.9) %,September:(15.19.4) %].Therefore,H.tientsinensis could inhibit P.australis's growth and affect litter decomposition through feeding disturbance behavior.</p
黄体生成素β亚基Trp8Arg和Ile15Thr突变与多囊卵巢综合征
【目的】探讨黄体生成素(luteinizing hormone,LH)β亚基Trp8Arg和Ile15Thr突变与中国人多囊卵巢综合征(polycystic ovary syndrome,PCOS)的关系。【方法】采用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)技术检测113例PCOS患者和68例正常妇女,分析LHβ亚基基因突变与PCOS之间的关系。【结果】PCOS组血清LH、睾酮、游离睾酮及胰岛素抵抗指数(HOMA-IR)均显著高于对照组(P<0.05)。在两组中均有β亚基突变发现,Trp8Arg突变率在PCOS组16例(14.16%),对照组4例(5.88%);Ile15Thr突变率在PCOS组15例(13.27%),对照组4例(5.88%),突变频率在两组间没有统计学差异。两组中突变杂合子与非突变者性激素水平没有统计学差异。【结论】PCOS患者促性腺激素和性激素水平发生紊乱。PCOS组LHβ亚基Trp8Arg和Ile15Thr突变发生率高于正常对照组,但差异未有统计学意义。本研究未发现突变杂合子改变了LH的生物学功能
Effect of salinity on microbial densities of soil in the dilution plate technique applied in mangrove areas
作者简介:张瑜斌(1970~) ,男,湖南郴州人,博士,副教授,主要从事海洋微生物学与海洋生态学研究. E2mail: zhangyb@gdou. edu. cn
通讯作者Corresponding author. E2mail: linpeng@jingxian. xmu. edu. cn[中文文摘]在使用稀释平板法分离潮间带红树林及其对照光滩土壤微生物以及计数时,多数情况下使用陈海水制作培养基和稀释水,很少考虑培养基和稀释水的盐度对最终计数结果的影响。使用稀释平板法研究了盐度对福建九龙江口红树林区与深圳福田红树林保护区土壤微生物平板计数的影响,结果表明培养基与稀释水盐度对微生物数量有明显的影响。统计分析显示细菌的海水稀释效果优于淡水,而放线菌与真菌则刚好相反(P<0.05,一个例外)。海水不适合配制红树林区土壤微生物平板计数的培养基,从0~35,高盐度的平板培养基会降低微生物的数量,尤其是放线菌的数量,尽管培养基的盐度对真菌影响无规律,但细菌数量在低盐度时比在高盐度和不加氯化钠时要多。根据盐度效应,提出了稀释平板技术应用于潮间带的红树林及其相应光滩时的优化方法,认为细菌应该用海水作无菌稀释水,而放线菌和真菌则应用淡水作稀释水;包括光滩在内的红树林区土壤微生物分离与计数的培养基宜控制较低盐度范围。[英文文摘]When the soilmicrobial densities are determined in mangroves and correspondingmudflat at the same tidal level by the dilution p late method, the agarmedia and dilution water are generallymade up of aged seawater in most cases, and effects of salinity in agar media and dilution water on the enumeration of microbes is seldom taken into consideration. The effects of salinity on soil microbial counting from the samples in mangrove areas in Jiulongjiang Estuary of Fujian, and Futian Mangrove Nature Reserve of Shenzhen, China, were tested by dilution p late technique. The results showed that the soil microbial densities in mangroves and mudflat were significantly influenced by the salinity of dilution water and agarmedia. For the bacteria, the seawater served as sterilized dilution water was significantly ( P < 0. 05) more benefic to the enumeration on the p lates than the freshwater, but in reverse for the actinomycetes and fungi. The increasing salinity of media within 35 significantly decreased microbial colonies on the p lates, especially for the actinomycetes, in sp ite of the fact that the effect of salinity ofmedia on fungal numberswas not indefinite. The bacterial colonieswere more abundant on the agar p lates with low salinity than with high salinity or without any NaCl. It was p roposed that some methodological
imp rovements were needed when the dilution p late technique was app lied to microbial counting in the samp les of mangrove forest and mudflat at the same tidal level in inter2tidal zone. The sterilized dilution water should be p repared with seawater
for the bacteria, but with freshwater or low saline water for the actinomycetes and fungi. The salinity of agarmedia should be low for the microbial isolation and enumeration of soil samples from the mangrove areas including mudflats.国家自然科学基金资助项目(30270272
第十八届美国理论与应用力学大会总结
1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学
Damage to mangroves from extreme cold in early 2008 in southern China
通讯作者Author for correspondence (E-mail: [email protected])2008年初,我国南方19个省经历了50年一遇的持续低温雨雪冰冻天气。极端气候对华南沿海各省的红树林区造成不同程度的危害。2008年3月,在我国南方各省红树林区的10个代表性地点,对这次寒害造成的红树植物伤害程度进行了系统的调查。结果表明:冬季低温对红树林的影响极为显著,特别是在低纬度的海南、广西和广东湛江,由于极端低温正值夜间退潮,对红树林的影响更为显著;在纬度较高的福建,本地红树种类秋茄(Kandelia obovata)、桐花树(Aegiceras corniculatum)和白骨壤(Avicennia marina)及引种的木榄(Bruguiera gymnorrhiza)等,由于长期适应于冬季较低的气温或在种植前经过抗寒锻炼,具有较强的抗寒能力。各地主要红树植物中,广布种秋茄、桐花树和白骨壤最为耐寒,其耐寒性均大于红树科的木榄、海莲(Bruguiera sexangula)和红海榄(Rhizophora stylosa)。海桑(Sonneratia caseolaris)对温度的敏感性最强,抗寒能力最低,因此,即使在其原产地海南也受到较为严重的寒害,在纬度更高的引种地出现大面积受害甚至全部死亡,而从孟加拉国引种的无瓣海桑(Sonneratia apetala)却显示出一定的抗寒能力。同一地点的红树植物幼苗的抗寒能力低于大树。此次寒害也造成了苗圃场的种苗大量死亡,成熟的植株提前落花落果,这势必会影响后继一两年内红树林的自然更新和人工造林。因此,在未来红树林造林或人工引种中,一定要考虑到红树植物的抗寒能力。国家自然科学基金(30671646和30700092);厦门大学“闽江学者”启动基
Martin Amis's Money: A Suicide Note: Returning to the Real from Hyperreality
近年来,美国少数族裔文学异军突起,发展迅猛,成为当代美国文坛独特而亮丽的一道风景。族裔作家频频获奖,有时甚至连续包揽国家图书奖和普利策奖等重要文学奖项。美国当代族裔文学的欣欣向荣也促进了我国美国族裔文学研究的繁荣发展。从早期的粗浅译介,到后来兴起的政治批评,再到如今的美学回归,国内族裔文学批评的趣味与范式经历了重要转变。"9·11"之后,特别是2016年特朗普(Donald Trump)当选"美利坚分裂总统"后,美国社会和文化语境发生了重大转折,族裔关系危机再次突出,种族问题重新成为人们不得不面对和思考的一项紧迫议题
反刍动物雪尿分析:3个指数在评价营养样状态中的比较及应用(英文)
基于以往的综述和研究性文章,本文对通过尿液分析评价反刍动物营养状态的3个指数进行了讨论和比较:相对于A:C比值而言,U:C比值不能够反映不同年份动物的营养限制情况,A:C比值和U:C比值均会因随机抽样的原因导致对动物营养状态的过高或过低估计,在一些物种中A:C比值不如PD:C灵敏。并对这些指数在今后研究中的应用进行了初步探讨
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