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951.
Thirteen novel NO-releasing derivatives of betulinic acid (BA) bearing two types of NO-donors (nitrates and furoxans) were synthesized and evaluated for their antitumor activity. The results showed that furoxan-based derivatives exhibited higher antitumor activity than nitrate-based derivatives, with compounds 11a and 11b displaying promising potency against B16 cell lines and HepG2 cell lines (IC50 < 1 μmol/L). Wesupposed that NO-releasing amount of these derivatives which can be detected by Griess method may contribute more to their antitumor activity. As a result, furoxan-based derivatives released larger amount of NO than that of nitrate-based derivatives, which partially explained the higher anti-tumor activity of the former. 相似文献
952.
Stereochemical determination of tetrahydropyran-substituted xanthones from fungus Chaetomium murorum
Meng-Hua Wang Li Li Tao Jiang Xue-Wei Wang Bin-Da Sun Bo Song Qiu-Bo Zhang Hong-Mei Jia Gang Ding Zhong-Mei Zou 《中国化学快报》2015,26(12):1507-1510
Chaetoxanthone D (1), a new tetrahydropyran-substituted xanthone originated from polyketide pathway, together with the four known natural products chaetoxanthone C (2), alternariol methyl ether (3), alternariol (4) and 2,5-dimethyl-7-hydroxychromone (5) was isolated from a strain of Chaetomium murorum. The structures of these compounds were elucidated based on extensive spectroscopic analyses. The absolute configurations of 1 and 2 were determined by using quantum chemical electronic circular dichroism (ECD) calculations. 相似文献
953.
Using cheap n‐butylamine as template, ZSM‐5 zeolites have been successfully synthesized and coated on monolithic interconnected macroporous Al2O3 by the secondary growth method. The use of cheap n‐butylamine could significantly reduce the synthesis cost. Hierarchical monolithic ZSM‐5 zeolites were prepared from synthetic mixtures with different H2O/Na2O or SiO2/Al2O3 ratio. The synthesized samples were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR) and N2 adsorption‐desorption. The results show that the hierarchical monolithic zeolites were obtained with cheap n‐butylamine template as template. During the hydrothermal reaction process, the morphology of the micrometer‐sized support was well maintained. The irregular crystals were formed in a wide range of the H2O/Na2O or SiO2/Al2O3 ratio of synthetic mixtures and coated on monolithic Al2O3. The relative crystallinity of the zeolites was highest at H2O/Na2O=250 or SiO2/Al2O3=160. This type of composites exhibited hierarchical porous structures and relatively high specific surface areas. 相似文献
954.
955.
利用高效液相色谱(HPLC)对喹啉黄各组分进行分离并定量,通过液相色谱–串联质谱(LC–MS/MS)对各组分进行定性。以0.01 mol/L乙酸铵溶液和甲醇为流动相进行梯度洗脱,利用Agilent XDB–C18色谱柱对喹啉黄各组分进行分离,峰面积归一化法定量。质谱采用电喷雾负离子(ESI–)模式电离,多反应监测(MRM)模式检测,对喹啉黄各组分进行定性。结果表明,喹啉黄主要成分为喹啉黄一钠盐和喹啉黄二钠盐,分别各有两种同分异构体,各组分质量浓度在5.0~100.0μg/m L范围内与峰面积呈良好的线性关系。加标回收率为98.2%~99.1%,测定结果的相对标准偏差为0.90%~1.58%(n=6)。该方法具有良好的精密度和准确度,可用于喹啉黄中各组分的测定。 相似文献
956.
The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peonylike CuO micro/nanostructures about 3-5 μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as the building block, were self-assembled into multilayer structures under the action of ethidene diamine, and then grew into uniform peony-like CuO architecture. The novel peony-like CuO micro/nanostructures exhibit a high cycling stability and improved rate capability. The peony-like CuO micro/nanostructures electrodes show a high reversible capacity of 456 mAh/g after 200 cycles, much higher than that of the commercial CuO nanocrystals at a current 0.1 C. The excellent electrochemical performance of peony-like CuO micro/nanostructures might be ascribed to the unique assembly structure, which not only provide large electrode/electrolyte contact area to accelerate the lithiation reaction, but also the interval between the multilayer structures of CuO nanoplates electrode could provide enough interior space to accommodate the volume change during Li~+ insertion and de-insertion process. 相似文献
957.
Upon anthracene-sensitizing, triplet excitation dynamics of β-carotene(β-Car) were studied in nhexane, in methanol, and in acetonitrile, respectively, by ns flash photolysis spectroscopy. In n-hexane,only the bleaching of the ground state absorption(GSB) and the excitation triplet(~3Car*) absorption were observed, and there were no cationic species detected. In both methanol and acetonitrile, similar excitation dynamics were observed, i.e.,~3Car* having a similar lifetime to that in n-hexane, and the immediate generation of the cation dehydrodimer(~#[Car]2~+) upon excitation following transformation into the radical cation Car*~+, since Car*~+ has much longer lifetime in acetonitrile than in methanol. The results prove that both solvent and carotenoid structure determine the triplet excitation mechanism. 相似文献
958.
Jia Wen Pengyi Xiaa Ziming Zhenga Yongqian Xua Hongjuan Lia Fengyu Liub Shiguo Suna 《中国化学快报》2017,28(10):2005-2008
The pH values of lysosomes in cancer cells is slightly lower than that in normal cells, which can be used to distinguish cancer cells from normal cells. According to this, a naphthalimide-rhodamine based fluorescent probe(hereafter referred to as RBN) with a pK_a of 4.20 was designed and synthesized for ratiometric sensing of cellular pH via fluorescence resonance energy transfer(FRET), which can respond to different pH precisely through ratiometric fluorescence intensity(Ⅰ_(577)/Ⅰ_(540)). RBN can be employed to distinguish cancer cells from normal cells on the basis of different fluorescent response, in particular, RBN showed excellent water solubility and low cell toxicity, all these are quite significant for potential application in cancer diagnose and therapy. 相似文献
959.
In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries(LIBs)—SnS_2 nanoparticle/graphene(SnS_2 NP/GNs) nanocomposite.The nanocomposite consists of SnS_2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS_2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS_2contribute to the electrochemical performance of SnS_2 NP/GNs. 相似文献
960.
以双酚F(4,4′-BPF)为模板分子,α-甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用沉淀聚合法合成4,4′-BPF分子印迹聚合物(MIPs)。运用傅里叶红外(FT-IR)光谱对产物的结构进行表征,并对其吸附等温线、吸附动力学、吸附热力学及选择性识别性能进行研究。结果表明:MIPs对水相中4,4′-BPF具有特异性吸附,最大吸附容量为82.8 mg/g;Freundlich模型拟合吸附等温线的相关系数R2=0.995;热力学参数ΔG、ΔS、ΔH均小于0,表明此吸附过程是自发进行的、熵减的、放热的。 相似文献