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141.
A direct quantitative method is presented that is based upon the use of multiple headspace solid phase microextraction (HS-SPME) to monitor biogenic volatile organic compounds (BVOCs) released from a living leaf of Pelargonium hortorum in situ. Seventeen BVOCs were detected by GC-MS after a single SPME extraction using a CAR/DVB/PDMS fibre. An internal standard was employed to determine the absolute amounts of seven terpenoid compounds released from a P. hortorum leaf. The quantitative analysis was performed over two days, with extraction preformed for 20 min every 3 h. The amount of volatiles extracted varied with the time of day, with two maxima recorded at 14:00 (day 1) and 17:00 (day 2), corresponding to 236 and 277 ng of the seven terpenoids recorded, respectively. These results indicate that multiple HS-SPME in combination with an internal standard is a simple, quick, and quantitative technique for analysising BVOC emissions from a live plant sample. 相似文献
142.
143.
固相氯化法合成氯化聚乙烯的红外光谱研究 总被引:2,自引:0,他引:2
本文研究在不同条件固相氯化聚乙烯(CPE)的红外光谱,探讨了一步和两步氯化合成的CPE的结构差别,着重讨论了两步氯化的CPE结构特点。从观察表征结晶结构和—(CH_2)_n—链段氯分布的特征频率变化表明,低温固相氯化主要发生在无定形区,并且在CPE中形成高氯化和低氯化链段(或未氯化)的嵌段结构。在两步固相氯化时,晶区受到较大程度的破坏,氯化作用已不局限在无定形区,其结晶结构的破坏主要同第二步氯化程度有关,即使CPE氯含量相同,若前后两步氯化程度不同,结构有很大差异。 相似文献
144.
利用N,N-二(2-氯乙基)氨基磷酰二异氰酸酯和胺的加成反应,合成了2,4,6三氧-1,3,5,2三氮磷杂环己烷衍生物,它们的结构经^1HNMR,IR和元素分析所证实。初步生物活性测试结果表明,部分化合物具有一定的抗肿瘤活性。 相似文献
145.
Jo‐Nan Chen Fang‐Ming Hsu Hui‐Chun Wang Chung‐Wen Wu Pao‐Swu Cheng Wen‐Liang Tsai 《中国化学会会志》2006,53(4):931-938
Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 . 相似文献
146.
Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis. 相似文献
147.
从唇形科植物铁轴草中分离得去甲克罗烷二萜化合物Teucvidin,通过催化氢化、酯交换、水解等反应合成了8个衍生物,用^1HNMR、MS和IR确定了其结构,初步生物活性测定结果表明,化合物Ⅱ和Ⅳa的拒食作用显著。 相似文献
148.
Timothy B. Hutson Ming J. W. Chang Joseph T. Keller David J. Long 《Mikrochimica acta》1988,94(1-6):339-341
Fourier transform infrared techniques were used to monitor mammalian cell growth plated on attenuated total reflection (ATR) crystals. Consistently, the growth kinetics plots generated from the obtained spectra demonstrated a sigmoidal curve representing a sequence of slow, rapid, then tapering cell growth which correlated well with non-spectral cell growth determinations. Significant advantages over traditional methods of measuring cell growth kinetics are demonstrated. The technique has promising potential to be used to study events in areas such as toxicology and cell biology. 相似文献
149.
Ming Guo Jue Wang Man Xiong Ronghui Wu Xuejuan Yang Jianzhong Zhou Minghui Li Jiajun Li 《大学化学》1986,35(12):237-246
In order to improve university laboratory teaching and practical education under the background of information technology, as well as overcome the difficulty for practical training, develop a virtual simulation experiment platform for rapid pyrolysis of natal materials and high-performance liquid chromatographic (HPLC) detection of its components. The experiment integrates the actual operation process of the plant to produce cleaved products by rapid pyrolysis of biomass with HPLC detection. The virtual experiment is divided into biomass sample pretreatment, rapid biomass pyrolysis, bio-oil extraction, and HPLC determination of complex components, making the biomass cleavage workshop "real" through simulation. This virtual simulation experiment fully integrates the utilization of biomass resources and basic chemistry courses (such as organic chemistry, instrumental analysis, chemical engineering principles, etc.), which are widely involved in agricultural and forestry majors with advantageous characteristics value. 相似文献
150.
Discharge performance of K2FeO4 electrode under different conditions was studied by the constant electric current discharge method. The electrochemical characteristics of K2FeO4 electrode were investigated for the first time by means of cyclic voltammetry. The results show that the K2FeO4 electrode made at moderate pressure (20MPa) and discharged at lower current has better discharge performance. It is also found that K2FeO4 electrode is significantly rechargeable. 相似文献