共查询到19条相似文献，搜索用时 203 毫秒
1.
报道了一种新型胆固醇分子印迹的聚合有机凝胶.以3-胆固醇酰氧基丙酸(COPA)为模板分子,通过可聚合凝胶剂N-十八烷基马来酰胺酸(ODMA)在甲基丙烯酸β-羟乙酯、甲基丙烯酸和聚乙二醇二甲基丙烯酸酯混合溶液的自组装,首先形成稳定的超分子有机凝胶,经UV光引发原位聚合,再经乙醇提取模板分子后制得胆固醇非共价印迹的聚合有机凝胶.偏光显微镜(POM)和场发射扫描电镜(FE-SEM)表明ODMA在单体混合物中自组装形成带状聚集体,这为其后形成的印迹聚合有机凝胶的孔穴稳定性提供了保证.印迹聚合有机凝胶对胆固醇的吸附效率可达到64%,并与ODMA和COPA的含量有关.实验表明,当ODMA的含量由1wt%增加到3 wt%时,吸附量由15.7 mg/g增加到22.9 mg/g.当COPA的含量由4 wt%增加到7 wt%时,吸附量由16.8 mg/g增加到22.2 mg/g.然而,当ODMA含量过多时,吸附量反而下降,这主要归因于体系网络密度的增加导致扩散阻力增加.而COPA含量过多时,可能干扰ODMA的自组装,影响印迹孔穴的稳定性,同样使得吸附量下降. 相似文献
2.
rPA(K)是经过缺失/定点突变技术所获得的t-PA突变体.本实验以IPTG诱导,实现了rPA(K)在原核系统中的表达.实验证明目的 产物的表达形式为包涵体,且当以IPTG诱导3h时,表达量最高,为41%.此后对该表达产物进行了初步纯化,即通过对不同超声破碎次数,包涵体洗涤液(脲,Trition Ⅹ-100,乙醇)的不同浓度对纯化的影响因素进行了摸索.结果表明,超声2次,2M脲,0.5%Triton Ⅹ-100,20%乙醇对目的蛋白纯化的效果最好,从而为进一步的纯化和复性奠定基础. 相似文献
3.
以羟丙基甲基纤维素（HPMC）为纳米氢氧化钙的稳定剂和纸质档案的加固剂,制备HPMC稳定的纳米Ca(OH)2醇水分散液（H-C分散液）,用于纸张脱酸加固处理。利用X射线衍射仪、激光粒度仪、紫外—可见分光光度计对H-C分散液进行表征,考察HPMC对纳米Ca(OH)2醇水分散液稳定性的影响;采用扫描电镜、pH计、万能材料试验机、耐折度仪等表征H-C分散液对纸张的脱酸加固作用。结果表明,HPMC可长时间稳定纳米Ca(OH)2醇水分散液;对纳米Ca(OH)2具有裹覆作用,提高其在纸张上的均匀分散并减少纳米Ca(OH)2与纸张直接接触,减轻纳米Ca(OH)2对纸张的影响。H-C分散液在提高纸张pH的同时增强纸张的机械性能,并为纸张提供了一定的碱储量。 相似文献
4.
目的 构建稳定表达人α-HNP-1的转基因细胞系,为稳定生产α-HNP-1并将其应用于医药开发提供生产细胞源.方法 真核表达载体pcDNA3.1(-)/HNP-1经酶切和测序鉴定后,用脂质体转染法转染昆明白小鼠胚胎干细胞来源的上皮细胞,通过不同浓度的G418加压筛选,建立稳定转染的胚胎干细胞来源的上皮细胞系,用RT-PCR及抑菌试验检测α-HNP-1的表达.结果 建立了稳定转染的ES来源的上皮细胞系,成功地表达目的 基因,其培养上清液及细胞冻融液具有抑菌作用,结论 真核表达载体稳定转染胚胎干细胞来源的上皮细胞系,为进一步研究α-HNP-1的功能奠定了基础. 相似文献
5.
以大豆基因组DNA为模板,利用聚合酶链式反应(PCR)技术克隆了大豆胰蛋白酶抑制剂基因KSTI3的全长DNA片段,并将其构建到pMD18-T vector上.核苷酸序列测定结果表明:该基因片段全长654bp,与已发表的KSTI3基因序列同源性达99%.将反义+正义基因片段插入到pBI121 35S启动子下,构建重组质粒pBIKSTI3.通过冻融法将该重组质粒转入农杆菌EHA105中,获得了siRNA表达体系.利用农杆菌介导法将带有pBIKSTI3的菌株转化大豆,从2棵再生植株中得到2100bp的特异性扩增条带,而未转化的植株中无该片段的产生. 相似文献
6.
在分析采用ADO.NET技术与LINQ技术检索数字档案的优缺点基础上,通过实验测试证明采用LINQ技术检索的性能更加稳定、优势更加明显. 相似文献
7.
相关反馈是一种根据用户或系统的相关性判断重构初始检索提问的方法,已被证明可以有效地改进检索效果.具体到学术文献,其引用关系表征了文献内容上的相关性,因而可以为相关反馈提供有价值的辅助信息.本文提出了一种基于引用上下文、文献同被引和文献耦合的相关反馈改进算法.该算法的基本思想包括:利用学术文献的引用上下文信息扩充词包模型(bags of words)进行文本表示;在相关文献判断阶段利用相关文献在引文网络中与其他文献的同被引强度和耦合强度扩充相关文献集合;结合基于聚类的相关反馈思想抽取查询扩展项.实验证明该算法提高了相关反馈效果.此外,相关分析的结果表明文献同被引以及文献耦合强度与文献内容相似度具有显著的相关性. 相似文献
8.
文章结合试验梁,运用有限元分析软件Ansys对二次受力下CFRP加固钢筋混凝土梁受弯承载力进行了分析,并与实验值进行了对比分析。结果表明Ansys值与实验值吻合较好,有限元分析可以很好的用于二次受力下CFRP加固钢筋混凝土梁受弯承载力研究。 相似文献
9.
基于知识的协同过滤推荐系统研究 总被引：2，自引：2，他引：0
传统的基于项目的协同过滤算法,不能很好地解决数据稀疏和新项目问题(冷启动)带来的推荐质量下降的问题.笔者从智能检索的思想出发,提出一种新的基于知识的协同过滤推荐算法.该算法借助于领域本体,表达语义知识,增加了项目之间的关联信息;考虑到领域本体中结点、边、深度和密度对相似性计算的不同影响,算法结合信息论中的互信息相关概念,对相似性计算公式进行改进,提高了运算精度.实验结果表明,该算法相对于传统的基于项目的协同过滤推荐算法而言,可有效缓解由数据集稀疏和冷启动带来的问题,显著提高推荐系统的推荐质量. 相似文献
10.
要实现网络信息或数字图书馆信息的有效多语言获取,需充分考虑用户交互.通过用户实验,检验用户相关反馈机制在多语言信息获取中的作用,并分析用户行为特点.实验结果证明,查询扩展、翻译优化以及两者的结合均是有效的用户相关反馈方法. 相似文献
11.
《文物保护研究》2013,58(4):275-277
AbstractThe safety and physical properties of commercially available glycol ethers are discussed. While propylene and ethylene glycol ethers have approximately the same physical properties, the former have safer metabolic activities. A table is included to illustrate the range of glycol ethers available. 相似文献
12.
《文物保护研究》2013,58(3):154-158
AbstractPolyethylene glycol 1540 was tested in the preservation of a waterlogged, carved, and painted wooden bowl from a prehistoric site on Patarata Island, Veracruz, Mexico. The procedure successfully employed water and Carbowax 1540 in a partial substitution process. 相似文献
13.
Natural polymers as alternative consolidants for the preservation of waterlogged archaeological wood
In recent years, there has been increased interest in examining alternative polymers for the conservation of archaeological artefacts, particularly waterlogged timbers, providing better, renewable, greener alternatives to poly(ethylene glycol) (PEG). The degradation of PEG consolidants in the timbers of the sixteenth century warship Mary Rose has been examined and the rheological and thermal properties of PEG have been compared with its monomethyl and dimethyl ethers and several polysaccharide consolidants (chitosan, guar, and 2-hydroxyethyl cellulose) in order to evaluate their potential as alternative consolidants for the conservation of waterlogged wooden artefacts. Additionally, the effect of the polymers on the archaeological wood was characterised by thermogravimetric analysis and solid-state nuclear magnetic resonance spectroscopy. The results suggest that the future of conservation technologies lies with polysaccharide consolidant materials, which show enhanced compatibility with wooden artefacts with no detectable side effects while also being cheap, with extremely low toxicity, renewable, and sustainably resourced. 相似文献
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15.
利用原子转移自由基聚合(ATRP)和前体聚合物重氮偶合反应相结合的方法,制备了一种新型含强推拉电子型偶氮苯的嵌段共聚物PEG-b-P6CNAzo.首先使用大分子引发剂PEGBr引发单体甲基丙烯酸6(N-甲基苯胺基)己酯进行ATRP聚合,得到作为前体聚合物的两嵌段共聚物PEG-b-P6MA,然后再与4-氰基苯胺的重氮盐进行重氮偶合反应得到目标产物PEG-b-P6CNAzo.利用GPC1、H-NMR、UV-Vis等手段对制得的聚合物进行了详细的表征.1H-NMR分析结果表明PEG-b-P6MA的聚合度为122-b-13,重氮偶合反应转化率接近100%.GPC结果表明PEG-b-P6MA与PEG-b-P6CNAzo均具有较窄的分子量分布.向浓度为0.2 g/L的PEG-b-P6CNAzo四氢呋喃溶液中以0.5 mL/h速率加水,该嵌段共聚物可以形成直径约11 nm的棒状胶束. 相似文献
16.
《文物保护研究》2012,57(1):28-36
ABSTRACTA pre-restoration diagnosis revealed a high amount of pyrite in the wood of the Lyon Saint-Georges 4 shipwreck (end of the second century). The occurrence of this phase is supposed to result from the microbiologically influenced corrosion of the iron fasteners. So, all the nails and metallic elements were removed from the remains before treatment and the wreck was consolidated by polyethylene glycol impregnation coupled to a specific desalination process. Treated and non-treated samples extracted from the wreck were studied in order to identify the iron/sulfur-containing compounds present in the wood before and after treatment and figure out its effect. Sample analyses relied on an original approach combining magnetic characterization methods and more common elemental and structural analysis methods. The results showed that the treatment was effective in removing soluble salts. However, a large amount of unstable iron sulfides remained inside the wood. 相似文献
17.
《文物保护研究》2013,58(3):111-125
AbstractThe problem of conservation of sound waterlogged oak and in particular the limitations of polyethylene glycol impregnation are briefly considered. Development of a new process involving dehydration with acetone and impregnation with rosin is described. Results pertaining to the experimental evaluation of the procedure are presented and suggest good success in its use. Applications of the process in the conservation of soft- and heavily waterlogged woods are described. 相似文献
18.
Samar Binkheder Raniah Aldekhyyel Jwaher Almulhem 《Journal of the Medical Library Association》2021,109(2):219
Objective:Understanding health informatics (HI) publication trends in Saudi Arabia may serve as a framework for future research efforts and contribute toward meeting national “e-Health” goals. The authors’ intention was to understand the state of the HI field in Saudi Arabia by exploring publication trends and their alignment with national goals.Methods:A scoping review was performed to identify HI publications from Saudi Arabia in PubMed, Embase, and Web of Science. We analyzed publication trends based on topics, keywords, and how they align with the Ministry of Health''s (MOH''s) “digital health journey” framework.Results:The total number of publications included was 242. We found 1 (0.4%) publication in 1995–1999, 11 (4.5%) publications in 2000–2009, and 230 (95.0%) publications in 2010–2019. We categorized publications into 3 main HI fields and 4 subfields: 73.1% (n=177) of publications were in clinical informatics (85.1%, n=151 medical informatics; 5.6%, n=10 pharmacy informatics; 6.8%, n=12 nursing informatics; 2.3%, n=4 dental informatics); 22.3% (n=54) were in consumer health informatics; and 4.5% (n=11) were in public health informatics. The most common keyword was “medical informatics” (21.5%, n=52). MOH framework–based analysis showed that most publications were categorized as “digitally enabled care” and “digital health foundations.”Conclusions:The years of 2000–2009 may be seen as an infancy stage of the HI field in Saudi Arabia. Exploring how the Saudi Arabian MOH''s e-Health initiatives may influence research is valuable for advancing the field. Data exchange and interoperability, artificial intelligence, and intelligent health enterprises might be future research directions in Saudi Arabia. 相似文献
19.
Jordan A. Comins Stephanie A. Carmack Loet Leydesdorff 《Journal of Informetrics》2018,12(4):1223-1231
One essential component in the construction of patent landscapes in biomedical research and development (R&D) is identifying the most seminal patents. Hitherto, the identification of seminal patents required subject matter experts within biomedical areas. In this article, we report an analytical method and tool, Patent Citation Spectroscopy (PCS), for the online identification of landmark patents in user-specified areas of biomedical innovation. Using USPTO data, PCS mines the cited references within large sets of patents at the internet and provides an estimate of the historically most impactful prior work. We show the efficacy of PCS in three case studies of biomedical innovation with clinical relevance: (1) RNA interference (RNAi), (2) cholesterol and (3) cloning. PCS mined and analyzed cited references related to patents on RNA interference and correctly identified the foundational patent of this technology, as independently reported by subject matter experts on RNAi intellectual property. Secondly, we apply PCS to a broad set of patents dealing with cholesterol – a case study chosen to reflect a more general, as opposed to expert, patent search query. PCS mined through cited references and identified the seminal patent as that for Lipitor, the groundbreaking medication for treating high cholesterol as well as the pair of patents underlying Repatha. The final case study, cloning, highlights some of the advantages conferred by the PCS methodology in identifying seminal patents. These cases suggest that PCS provides a useful method for identifying seminal patents in areas of biomedical innovation and therapeutics. The interactive tool is free-to-use at: http://www.leydesdorff.net/comins/pcs/index.html. 相似文献