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排序方式: 共有368条查询结果,搜索用时 274 毫秒
91.
92.
A new electrochemiluminescence (ECL) DNA assay is developed using quantum dots (QDs) as DNA labels. When nanoporous gold leaf (NPGL) electrodes are used, sensitivity of the ECL assay is remarkably increased due to ultra-thin nanopores. In this assay, target DNA (t-DNA) is hybridized with capture DNA (c-DNA) bound on the NPGL electrode, which is fabricated by conjugating amino-modified c-DNA to thioglycolic acid (TGA) modified at the activated NPGL electrode. Following that, amino-modified probe DNA is hybridized with the t-DNA, yielding sandwich hybrids on the NPGL electrode. Then, mercaptopropionic acid-capped CdTe QDs are labeled to the amino group end of the sandwich hybrids. Finally, in the presence of S2O82− as coreactant, ECL emission of the QD-labeled DNA hybrids on the NPGL electrode is measured by scanning the potential from 0 to −2 V to record the curve of ECL intensity versus potential. The maximum ECL intensity (Im,ECL) on the curve is proportional to t-DNA concentration with a linear range of 5 × 10−15 to 1 × 10−11 mol/L. The ECL DNA assay can be used to determine DNA corresponding to mRNA in cell extracts in this study. 相似文献
93.
Bin Zhu Qingbiao Wang Esben F. Roge Peng Nan Zhijun Liu Yang Zhong 《Chemistry of Natural Compounds》2006,42(4):422-425
Hydrodistilled leaf oils of Pistacia chinensis Bunge from five locations in China were analyzed using GC/MS. A total of 58
compounds was identified in the oils, and a relatively high variation in their contents was found. The major compounds include
β-phellandrene (0.54–53.86%), α-pinene (4.74–54.44%), β-pinene (0.49–42.90%), caryophyllene (5.64–20.01%), cis-ocimene (tr−43.93%), eudesmadiene (0–15.06%), and camphene (tr−20.57%). Cluster analysis classified the leaf oils into two
chemotypes: one rich in α-pinene and β-pinene, and the other rich in β-phellandrene.
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 341–343, July–August, 2006. 相似文献
94.
Joaquim C. S. Lima Ruberlei Godinho de Oliveira Virgínia C. Silva Paulo Teixeira de Sousa Jr Ivana M. P. Violante Antonio Macho 《Natural product research》2020,34(5):726-730
AbstractFridericia chica, Bignoniaceae, is a tropical tree-creeper used as a traditional remedy for a number of diseases, highlighting inflammation. Our objective was to corroborate the popular anti-inflammatory use of the hydroethanolic extract from the leaves (HEFc) and of its isolated 4′,6,7-trihydroxy-5-methoxyflavone (5-O-methylscutellarein) [1], described here for the first time. Quantitative analysis indicated 8.77?±?0.23?mg/g of this compound in the extract. Neither HEFc nor [1] was cytotoxic in vitro. In LPS-induced peritonitis in mice, oral pre-treatment with HEFc or [1] led to decreased leukocyte migration to the peritoneal cavity and a reduction in the concentrations of pro-inflammatory cytokines (TNFα and IL-1β). Also, the anti-inflammatory cytokine IL-10 was enhanced following treatment with [1]. Overall, these results validate the traditional use of Fridericia chica as anti-inflammatory, and indicate that the compound 5-O-methylscutellarein may participate in this effect. 相似文献
95.
Qian Gao Zongmin Wei Yun Liu Fang Wang Shuting Zhang Carmo Serrano Lingxi Li Baoshan Sun 《Molecules (Basel, Switzerland)》2022,27(3)
Moringa oleifera leaves have been widely used for the treatment of inflammation, diabetes, high blood pressure, and other diseases, due to being rich in polyphenols. The main objective of this work was to largely separate the main polyphenols from Moringa oleifera leaves using the technique of high-speed counter-current chromatography (HSCCC). The phenolic composition in Moringa oleifera leaves was first analyzed qualitatively and quantitatively by UPLC-Q-Exactive Orbitrap/MS and UPLC-QqQ/MS, respectively, indicating that quercetin and kaempferol derivatives, phenolic acid and apigenin are the main polyphenols in Moringa oleifera leaves, with quercetin and kaempferol derivatives predominating. Furthermore, the conditions of HSCCC for large-scale separation of polyphenols from Moringa oleifera leaves were optimized, which included the selection of the solvent system, flow rate and the sample load. Only by one-step HSCCC separation (within 120 min) under the optimized conditions, six quercetin and kaempferol derivatives, a phenolic acid and an apigenin could be individually isolated at a large scale (yield from 10% to 98%), each of which possessed high purity. Finally, the isolated polyphenols and phenolic extract from Moringa oleifera leaves (MLPE) were verified to have strong neuroprotective activities against H2O2-induced oxidative stress in PC-12 cells, suggesting that these compounds would contribute to the main beneficial effects of Moringa oleifera leaves. 相似文献
96.
反相高效液相色谱法测定毛竹叶中总黄酮 总被引:16,自引:0,他引:16
用反相高效液相色谱法,RP-C8柱为固定相,甲醇-水-冰乙酸(40+60+2)为流动相,以芦丁为参照物外标法定量,辅以二极管阵列检测技术,测定了毛竹叶中总黄酮的含量,并与光度法作了比较。 相似文献
97.
关于Poisson群胚的结构 总被引:3,自引:0,他引:3
令(ΓP,α,β)是Poisson群胚.如果它的每个α-纤维与β-纤维至多交于一点,则Γ在任一点x的特征分布有直和分解△(x)=△α(x)+△β(x),其中△α(x)Txα-1(u),△β(x)Txβ-1(u)且它们都是△(x)的辛子空间.由此得到辛叶Sx的辛子流形S和S,使在映射α之下,S辛微分同胚于P中辛叶Su,在映射β之下,S反辛微分同胚于P中辛叶Sv(定理4和5).对于一般的Poisson群胚,也可得到类似的S和S,它们差一局部辛微分同胚是唯一确定的(定理6).把以上结果用于辛群胚,还可得到一些更具体的性质(定理7及其推论). 相似文献
98.
99.
随着人类生活质量的提高,农产品重金属污染问题备受关注。农作物中的重金属元素会通过食物链侵害人体健康,而不同重金属元素对人体毒害差别较大,因此农作物中含有重金属元素的类别识别至关重要。传统重金属元素检测方法存在环节多、耗时长、成本高等缺点,但高光谱遥感技术具有信息使用量大,理化反演能力强,分析速度快,无损监测等优势,逐渐成为农作物重金属污染分析的重要手段之一。以不同CuSO4·5H2O和Pb(NO3)2浓度梯度土壤胁迫下典型农作物玉米生长的叶片光谱为研究对象,引入光谱包络线去除(CR)、光谱比值(SR)、分数阶微分(FOD)同时结合改进红边比值指数(MSR)构建铜铅元素识别指数(CLI);通过挑选与铜铅元素种类相关性最强的三个分数阶微分阶数的CLI值建立铜铅元素判别特征点(CLDFP);再利用欧式聚类(EC)将训练集样本分为铜污染与铅污染两类并结合圆心连线的垂直平分线(PB),建立基于EC-PB识别铜铅元素种类的二维坐标系下判别规则线(CLDRL)和三维坐标系下判别规则面(CLDRP),从而实现玉米叶... 相似文献
100.