oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 68 )

2018 ( 1703 )

2017 ( 1767 )

2016 ( 1931 )

Custom range...

Search Results: 1 - 10 of 81782 matches for " 韩春蕊 "
All listed articles are free for downloading (OA Articles)
Page 1 /81782
Display every page Item
松香改性高分子材料的研究和应用进展
孙大卫,徐永霞,
化工进展 , 2013,
Abstract: 综述了国内外松香改性制备高分子材料的研究现状,分别介绍了松香改性酚醛树脂、聚氨酯、聚丙烯酸、醇酸树脂等高分子材料的制备和应用现状,比较了一步法和两步法制备松香改性酚醛树脂的优缺点,详述了半连续种子乳液聚合法/细乳液聚合法制备松香改性聚丙烯酸酯类高分子材料;对松香综合改性高分子材料的发展趋势进行展望,指出了基于松香双键和羧基综合改性制备色泽浅、软化点高的高分子材料及松香改性其它生物质基类高分子材料的发展潜力,以期促进松香改性高分子材料的制备和应用研究。
枞酸和去氢枞酸生物活性衍生物研究进展
,宋湛谦,商士斌
化工进展 , 2010,
Abstract: 分析对比了提纯枞酸的几种方法,综述了去氢枞酸的提纯方法,概括总结了枞酸和去氢枞酸的生物活性衍生物的合成和生物活性研究现状,并展望了其发展趋势。
丹参c4h基因pet32a原核表达载体的构建
张婷婷?,丽?,莲?
西北农林科技大学学报(自然科学版) , 2011,
Abstract: 【目的】克隆丹参中肉桂酸-4-羟化酶基因(smc4h)的核心区,并构建smc4h基因的原核表达载体。【方法】设计合成smc4h基因全长引物,应用pcr克隆smc4h基因的编码区并添加酶切位点,应用ecorⅴ、notⅰ双酶切smc4h-pgm-t后与原核表达载体pet32a连接,转化到大肠杆菌bl21(de3)中进行双酶切鉴定,诱导表达重组蛋白并进行sds-page电泳以及westernblot分析。【结果】克隆得到了1200bp大小的基因片段,经测序鉴定其为smc4h基因片段;连接表达载体测序结果表明,smc4h-pet32a构建成功,其诱导表达蛋白经sds-page检测及westernblot分析发现,重组蛋白表达效果较好,且主要以包涵体形式存在。【结论】成功构建了smc4h-pet32a原核表达载体,并成功诱导了smc4h-pet32a重组蛋白的表达。
干旱-复水处理对杠柳幼苗光合作用及活性氧代谢的影响
安玉艳,郝文芳,,,梁宗锁,**
应用生态学报 , 2010,
Abstract: 采用人工控制土壤水分试验,以80%田间持水量处理为对照,研究了3次干旱-复水处理对2年生杠柳幼苗叶片光合作用,根、茎、叶膜脂过氧化和抗氧化系统的影响.结果表明:在干旱条件下,杠柳叶片相对含水量和光合速率(pn)显著降低,光合色素含量升高.干旱复水后,叶片相对含水量完全恢复,反映了杠柳较强的旱后修复能力;叶绿素含量和pn均明显高于对照,表现出补偿效应,适度干旱诱导了杠柳的抗旱适应性.干旱胁迫使pn下降,以气孔限制为主,但在中午发生了非气孔限制;幼叶、新茎和细根中的超氧阴离子产生速率升高,丙二醛含量则降低,说明这些幼嫩组织未受到氧化伤害.不同器官中sod、cat和pod活性及变化趋势不同,以细根的3种保护酶的反应最为灵敏,说明细根是杠柳适应干旱环境的重要器官.器官间的相互合作与协调使杠柳能有效地适应干湿交替的干旱环境.
无患子皂素的表面活性及复配增效性能
杨鹤群,,赵丹青,孙达峰,张卫明,蒋建新
化工进展 , 2015, DOI: 10.16085/j.issn.1000-6613.2015.12.035
Abstract: 无患子皂素是一种天然非离子型表面活性剂,30℃时其临界胶束浓度(cmc)值为0.1g/L,最低表面张力(gcmc)为48.48mN/m,具有较好的表面活性。30~60℃之间,无患子皂素的gcmc与cmc值基本保持不变;溶液偏酸性时,无患子皂素的最低表面张力下降幅度较大,cmc值不变;盐度对无患子皂素表面性能有一定的影响。此外,无患子皂素具有较好的抗硬水能力,且与其他合成表面活性剂复配有一定的增效作用,尤其是与十六烷基三甲基溴化铵形成的复配体系,其临界胶束浓度增效50.0%,并且降低表面张力的能力增效4.08%。无患子皂素起泡性强,泡沫稳定,国标GB/T7162—1994条件下(溶液浓度C=2.5g/L)泡沫高度H0为135.6mm,且复配体系的初始泡沫高度均有一定的增加。
干旱胁迫对黄土高原4种蒿属植物叶形态解剖学特征的影响
王勇?,梁宗锁?,梅?,莲?,于靖?
生态学报 , 2014,
Abstract: 以黄土高原演替初期阶段的猪毛蒿(artemisiascopariawaldst.etkit.)、茭蒿(artemisiagiraldiipamp.)、铁杆蒿(artemisiagmeliniiweb.exstechm.)3种优势种和1种常见种黄花蒿(artemisiaannualinn.)为供试材料,采用盆栽试验与称重控水法,将土壤含水量分别控制在田间最大持水量的75%(适宜水分对照)、55%(中度干旱)和35%(重度干旱),研究干旱胁迫对菊科蒿属植物叶片形态解剖学的影响,揭示植物叶片生态适应机制,为生态恢复过程中植被演替的规律提供理论依据。于植物营养生长末期选取代表性的叶片,分别采用电子扫描显微镜、电子透射显微镜和光学显微镜对叶表皮特征、亚细胞显微特征和组织结构进行观察。结果表明:干旱胁迫下,这4种植物表现为不同程度的叶片增厚、栅栏组织厚度、叶片紧实度和角质层厚度增加;3种旱生型植物猪毛蒿、茭蒿和铁杆蒿的叶片下表皮具有浓密的表皮毛,有利于防止水分过度蒸腾,而中生型黄花蒿叶片无此功能;铁杆蒿和黄花蒿上表皮毛稀少,不利于保水和防止强光照,干旱胁迫下依靠降低上表皮气孔密度和叶细胞叶绿体数目来适应环境;茭蒿和猪毛蒿叶绿体形态相似,具有较厚的基粒和浓密的基粒片层,强光下容易引起氧化损伤,猪毛蒿通过浓密的上表皮毛而茭蒿通过较强的抗氧化机制防止光能过剩,两者在重度干旱下均产生大量脂质体。4种蒿属植物中黄花蒿的叶片解剖学特征受到干旱的影响变化最大,铁杆蒿和猪毛蒿次之,茭蒿最弱,3种优势种的干旱适应性显著强于黄花蒿,干旱下叶片解剖学的结论与干旱耐受性指标结果一致。
一类双稳系统的动力学性质及其在林业工程上的应用
Dynamic Properties of Bistable System and Its Application in Forestry Engineering
 [PDF]

林啸,
Dynamical Systems and Control (DSC) , 2016, DOI: 10.12677/DSC.2016.54016
Abstract:
双稳系统中的不稳定点对图像增强起到了决定性的作用,使其充当了一个阈值的角色,在一定条件下,使得不稳定的点(也就是阈值)趋于稳定的点,以实现图像增强。本文研究了一类双稳系统,分析了该系统的线性稳定性,利用该性质,在特殊的时间点下,通过初值遍历每一个像素值,实现了图像直方图均衡化,达到了图像增强较好的效果。
The unstable point in the bistable system plays a decisive role and acts as a threshold in image enhancement. Under certain conditions, let the unstable point (that is, the threshold) tend to a stable point in order to achieve the image enhancement. In this paper, a class of bistable systems is studied and the linear stability of the system is analyzed. By using this property, the image histogram equalization is realized by traversing each pixel value at the special time point. Better results.
罗望子多糖分级提取及其与黄原胶凝胶骨架材料缓释性能研究
刘彦涛,明会,段久芳,,张卫明,蒋建新
- , 2018, DOI: 10.13360/j.issn.2096-1359.2018.02.009
Abstract: 将罗望子多糖胶粉分别在50和100℃(TSP50和TSP100)条件下分级提取与纯化,其提取得率分别为28.71%和36.24%。X射线衍射图谱结果表明,在100℃下提取的罗望子多糖分级组分的结晶度明显高于50℃条件下提取的组分的结晶度。采用湿法造粒制备罗望子分级多糖与黄原胶不同质量配比的控释茶碱的缓释材料,并比较分析了其缓释性能。体外释药结果表明,在药物释放12 h时,仅含罗望子多糖骨架片的药物累积释放率最大,TSP50和TSP100分别达到载药量的93.4%和81.6%。当罗望子多糖和黄原胶的质量比例为40:60时,TSP50和TSP100的药物累积释放量最小,分别为67.2%和67.4%,表现出最为持续的药物释放性能。溶胀性能结果表明,罗望子多糖和黄原胶质量比例为40:60时,制备的骨架片均在溶胀6 h时表现出最高溶胀率,TSP50和TSP100溶胀率分别为285%和312%。
Tamarind seed polysaccharide(TSP)was fractional extracted from tamarind seed powder at 50℃ and 100℃, and the TSP yields were 28.71% and 36.24%, respectively. The main monosaccharide components in both two fraction TSPs(TSP50 and TSP100)were xylose, galactose and glucose with a ratio of 1.00:1.48:2.85 and 1.00:1.65:3.20, respectively. The FT-IR spectra of the TSP displayed peaks at 1 376 cm-1, 1 039 cm-1, 943 cm-1 and 899 cm-1, which were the characteristic absorption peaks of tamarind seed polysaccharide. Results from X-ray diffractograms(XRD)showed that the TSP samples extracted at 50℃ and 100℃ both presented a broad band centered at 2θ=19.4°. The crystallinity of the TSP100 was much higher than that of TSP50. The matrix tablets of theophylline were prepared by a wet granulation technique by using TSP and xanthan as raw materials. The ratios of tamarind seed polysaccharide(TSP50 and TSP100):xanthan in the matrix tablets were 20:80, 40:60, 60:40, 80:20, 100:0(TX20:80 to TX100:0). The in vitro drug release test showed that the cumulative drug release rate from the matrix tablets containing only TSP50 or TSP100 reached 93.4% and 81.6% of original drug within 12 h, respectively. While the most sustained drug release was found in the formulation of TX40:60 with both TSP50 and TSP100 matrices, which released 67.2% and 67.4% of original drug within 12 h, respectively. These results could be attributed to the viscosity and swelling properties of two polysaccharides. The results of swelling properties showed that the maximum swelling rate were 285% and 312% of the matrix tablets of TX40:60 and xanthan gum. We also found that the swelling index of the TSP100 was obviously higher than that of the TSP50, which might be due to a more difficult dissolution of the TSP100 with a higher molecular weight
Batch Preparation of TiO2 Hollow Spheres by Templating Against PSA-A Latex
以PSA-A乳胶粒为模板批量制备TiO2空心球

HAN Chun-Rui,
,吕伟丽,吴秀勇,傅洵,胡正水

无机材料学报 , 2005,
Abstract: With Ti(SO4)2 as raw material, and water as dispersion medium, the PSA-A latex/titanium hydrolysis compounds core-shell microspheres were prepared by templating against PSA-A latex with carboxyl. The TiO2 hollow spheres of 450nm were obtained by calcining the as-prepared core-shell microspheres. TG-DSC, SEM, TEM, IR and XRD measurements were used to characterize the samples. The investigations of the core-shell formatting process and the effect of experimental conditions on pH value changes indicated that the varing rate of pH value was the determining factor for a successful coating. The optimum varing rate of pH value for core-shell microspheres formation was obtained and TiO2 hollow spheres were prepared in batches under the conditions of 230g/L PSA-A latex and 1mol/L Ti(SO4)2.
松香基含氮杂环衍生物的研究进展
李娟,李保同,徐永霞,刘泽学,段久芳,,查显俊
化工进展 , 2015, DOI: 10.16085/j.issn.1000-6613.2015.10.034
Abstract: 在松香中引入杂环,可赋予松香特殊的生物和光学等活性,而松香基含氮杂环衍生物则是在松香中引入含氮的杂环,是松香基衍生物的重要组成部分。本文以羧基改性、菲环改性和综合改性为主线,根据羧基上的还原、胺化、酰基化、缩合、闭环等反应和菲环上的氧化、亲电取代反应(溴代、选择性硝化)、重氮化、缩合和闭环等反应类型,由18位羰基酰化改性、18位烷基碳原子成环改性、18位烷基相连氮原子成环改性、11,12位碳成环改性、12,13位碳成环改性、13,14位碳成环改性和综合成环改性分类,系统综述松香基咪唑啉、噻唑、唑、呋咱、喹啉、吲哚、吖啶等含氮杂环衍生物的研究现状,详细归纳了该类衍生物的生物活性、缓蚀活性、荧光活性和表面活性的性能应用,并对松香基含氮杂环衍生物的合成和应用研究趋势进行了展望。指出该类化合物在有机金属催化材料和染料敏化太阳能电池等功能性化合物开发中具有重要发展潜力。
Page 1 /81782
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.