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81.
Wen Li Xu Xu Zhuoshi Tang Yina Guo Dongqing Fei Na Yan Fangdi Hu 《Journal of separation science》2023,46(8):2200835
Recently, we confirmed that the 95% ethanol-extracted fraction of Codonopsis Radix, which contains several triterpenoids and sterols, possesses pharmacological activities. However, due to the low content and diverse types of triterpenoids and sterols, their similar structures, lack of ultraviolet absorption, and difficulty in obtaining controls, few studies have so far assessed their contents in Codonopsis Radix. We accordingly constructed an ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry technique for the simultaneous quantitative determination of 14 terpenoids and sterols. Separation was performed on the Waters Acquity UPLC HSS T3 C18 column (100 × 2.1 mm, 1.8 μm) with 0.1% formic acid (A) and 0.1% formic acid in methanol (B) as mobile phase under gradient elution. The determination coefficients for each of the matrix calibration curves were ≥0.9925. The average recovery ranged from 81.25% to 118.05%, with relative standard deviations of <4%. The contents of 14 components in 23 batches were quantified and further analyzed through chemometrics. Linear discriminant analysis can distinguish sample varieties. The quantitative analysis method can accurately determine the contents of 14 components and thereby provide the chemical basis for the quality control of Codonopsis Radix. It also could be a valuable approach for the classification of different Codonopsis Radix varieties. 相似文献
82.
针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成海胆状核壳结构复合粒子,正是这种结构将羰基铁粉颗粒与空气隔绝,使得复合粒子的抗氧化性能得到显著改善。与羰基铁粉复合吸波材料相比,氧化锌/羰基铁粉核壳粒子的复合材料吸收峰稍向低频移动,反射损耗小于-5 d B的带宽几乎保持不变,在不改变电磁吸波性能的前提下,提高了羰基铁粉粒子的使用温度。 相似文献
83.
采用1-苯基-3-甲基-5-吡唑啉酮(PMP)为柱前衍生化试剂,结合反相高效液相色谱法,建立了同时测定酵母细胞壁中甘露聚糖和β-葡聚糖的方法。样品中的多聚糖经盐酸高温水解得到甘露糖和葡萄糖,经PMP衍生后,以0.02 mol/L乙酸铵-乙腈(80.5∶19.5)为流动相等度洗脱,反相C18柱(4.6 mm×250 mm,5μm)分离,紫外检测器(波长250 nm)检测,所测2种单糖的含量通过换算后得到甘露聚糖和β-葡聚糖的含量。结果表明,甘露糖和葡萄糖在10.0~1 000 mg/L质量浓度范围内与对应峰面积呈良好的线性关系,相关系数(r2)大于0.999。样品在28.0~80.0 mg范围内加标水平的平均回收率为88.1%~91.0%,相对标准偏差(RSD)小于3%,甘露糖和葡萄糖的检出限(LOD)分别为0.10 mg/L和0.08 mg/L。该方法灵敏度高、准确性好、实用可靠,适用于酵母细胞壁样品中甘露聚糖和β-葡聚糖含量的分析测定。 相似文献
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86.
Ai‐Hua Zhou Fei Pan Dr. Chunyin Zhu Prof. Dr. Long‐Wu Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10278-10288
Fluorenes are a commonly encountered structural motif in materials science, pharmaceutical chemistry, and organic synthesis. Among various strategies towards the synthesis of this unique structure, transition metal‐catalyzed functionalization has emerged as one of the most efficient methods. This Minireview presents an overview of the recent advances in this emerging area by highlighting the reactions’ specificity and applicability and, where possible, provides a mechanistic rationale. 相似文献
87.
High capacity and cycling stability of poly(diaminoanthraquinone) as an organic cathode for rechargeable lithium batteries 下载免费PDF全文
Yi Fei Shen Ding Ding Yuan Xin Ping Ai Han Xi Yang Min Zhou 《Journal of Polymer Science.Polymer Physics》2015,53(4):235-238
Poly(1,5‐diaminoanthraquinone) is synthesized by oxidative polymerization of diaminoanthraquinone monomers and investigated as an organic host for Li‐storage reaction. Benefiting from its high density of redox‐active, Li+‐associable benzoquinone groups attached to conducting polyaniline backbones, this polymer undergoes its cathodic reaction predominately through Li+‐insertion/extraction processes, delivering a very high reversible capacity of 285 mAh g?1. In addition, the PDAQ polymer cathode exhibits an excellent rate capability (125 mAh g?1 at 800 mA g?1) and a considerable cyclability with a capacity retention of ~160 mAh g?1 over 200 cycles, possibly serving as a sustainable, high capacity Li+ host cathode for Li‐ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 235–238 相似文献
88.
Fei Wang Xueqian Wang Ping Ning Xuli Jing Yixing Ma Ping Wang Wei Chen 《Adsorption》2015,21(5):401-408
A series of adsorbents were studied for removal efficiency of carbon disulfide (CS2) under micro-oxygen conditions. It was found that activated carbon modified by Cu and cobalt sulfonated phthalocyanine (CoSPc) denoted as ACCu–CoSPc showed significantly enhanced adsorption ability. Reaction temperature was found to be a key factor for adsorption, and 20 °C seems to be optimal for CS2 removal. Samples were analyzed by N2-BET, XRD, XPS, SEM–EDS and CO2-TPD. The characterization results demonstrated that large quantities of SO4 2? anions were formed and adsorbed in the reaction process. SO2, CS2 and COS were detected in the effluent gas generated from the temperature programmed desorption of ACCu–CoSPc–CS2. Therefore, it can be concluded that ACCu–CoSPc most likely acted as a catalyst in the adsorption/oxidation process on the surface of the impregnated sample. The generated sulfide and sulfur oxide can cover the active sites of adsorbents, resulting in pronounced reduction of adsorbent activity. Finally, the exhausted ACCu–CoSPc can be regenerated by thermal desorption. 相似文献
89.
Remote Construction of Chiral Vicinal Tertiary and Quaternary Centers by Catalytic Asymmetric 1,6‐Conjugate Addition of Prochiral Carbon Nucleophiles to Cyclic Dienones 下载免费PDF全文
Yuan Wei Zunwu Liu Xinxin Wu Jie Fei Xiaodong Gu Xiaoqian Yuan Prof. Dr. Jinxing Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18921-18924
An unprecedented remote construction of chiral vicinal tertiary and quaternary centers by a catalytic asymmetric 1,6‐conjugate addition of prochiral carbon nucleophiles to cyclic dienones has been developed. Both 5H‐oxazol‐4‐ones and 2‐oxindoles were found to be very efficient carbon nucleophiles in this reaction at a remote position, giving products with excellent enantio‐ and diastereoselectivities (up to 99 % ee and >19:1 d.r. for 5H‐oxazol‐4‐ones and up to 97 % ee and >19:1 d.r. for 2‐oxindoles). 相似文献
90.