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排序方式: 共有71条查询结果,搜索用时 15 毫秒
1.
Weir AJ Klein SR Abrams G Adolphsen CE Akerlof C Alexander JP Alvarez M Amidei D Baden AR Ballam J Barish BC Barklow T Barnett BA Bartelt J Blockus D Bonvicini G Boyarski A Boyer J Brabson B Breakstone A Brom JM Bulos F Burchat PR Burke DL Butler F Calvino F Cence RJ Chapman J Cords D Coupal DP DeStaebler HC Dorfan DE Dorfan JM Drell PS Feldman GJ Fernandez E Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gidal G Gladney L Glanzman T Gold MS Goldhaber G Green A Grosse-Wiesmann P Haggerty J 《Physical review D: Particles and fields》1990,41(5):1384-1388
2.
An online multidimensional liquid chromatographic system was developed for online clean-up, derivatisation and separation of biogenic amines in wines. The system consists of a cation-exchange precolumn, a derivatisation coil and an analytical column, and a column-switching valve. The entire system can be easily automated. The method proved to be quantitative and sensitive. Limits of detection were below 0.05 mg l(-1) for all amines and linearity was preserved over the tested range (0.05-15 mg l(-1)). The method was applied to the analysis of red wines of different origin. 相似文献
3.
On-line coupled liquid chromatography-gas chromatography 总被引:1,自引:0,他引:1
On-line coupled liquid chromatography–gas chromatography (LC–GC) is a powerful technique that combines the best features of LC and GC and is ideal for the analysis of complex samples. This review describes the unique features of on-line coupled LC–GC. The different interfaces and evaporation techniques are presented, along with their advantages and disadvantages. Guidelines are given for selecting a suitable LC–GC technique and representative applications are noted. 相似文献
4.
Pressurised hot water extraction-microporous membrane liquid-liquid extraction was coupled on-line with gas chromatography-mass spectrometry (PHWE-MMLLE-GC-MS) for the analysis of pesticides in grapes. MMLLE serves as a trapping step after PHWE. Water from PHWE is directed to the donor side of the membrane unit and the analytes are extracted to the acceptor solution on the other side. The role of MMLLE is to clean and concentrate the extract before on-line transfer to the GC via a sample loop and an on-column interface using partially concurrent solvent evaporation. The extraction conditions were investigated, and then the quantitative features such as linearity, limit of quantification (LOQ), extraction yield and enrichment factors. LOQs in the range 0.3-1.8 microg kg(-1) were achieved. Procymidone and tetradifon were found in the skins of the grapes. The results were in good agreement with those obtained by liquid-solid and ultrasonic extractions. 相似文献
5.
The structure of a large wing-span phosphine, in the oxide form, N,N-(5-n-butyl-5-oxodibenzo[b,d]phosphole-3,7-diyl)bis(benzamide), C30H27N2O3P, cocrystallized with dimethylformamide (DMF), C3H7NO, is reported. The title compound is crystallized in a triclinic system with cell dimensions of a = 10.295(8) b = 12.743(5) c = 13.239(6) Å, = 108.14(3), = 108.16(5), = 101.20(4)°, and V=1484.4(5) Å3, and forms a hydrogen-bonded dimer via two hydrogen bond linkages of the P—O ··· H—N type involving one of the two amide groups. 相似文献
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Totti Laitinen Sara Herrero Martín Jevgeni Parshintsev Tuulia Hyötyläinen Kari Hartonen Marja-Liisa Riekkola Markku Kulmala José Luis Pérez Pavón 《Journal of chromatography. A》2010,1217(1):151-159
Organic compounds in atmospheric nanoparticles have an effect on human health and the climate. The determination of these particles is challenged by the difficulty of sampling, the complexity of sample composition, and the trace-level concentrations of the compounds. Meeting the challenge requires the development of sophisticated sampling systems for size-resolved particles and the optimization of sensitive, accurate and simple analytical techniques and methods. A new sampling system is proposed where particles are charged with a bipolar charger and size-segregated with a differential mobility analyzer. This system was successfully used to sample particles from wood pyrolysis with particle sizes 30–100 nm. Particles were analyzed by four techniques: comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry, gas chromatography–time-of-flight mass spectrometry, gas chromatography–quadrupole mass spectrometry, and aerosol mass spectrometry (aerosol MS). In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source. Target compounds of the samples were polyaromatic hydrocarbons and n-alkanes. The analytical techniques were compared and their advantages and disadvantages were evaluated. The sampling system operated well and target compounds were identified in low concentrations. 相似文献
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The pyrolysis of Pubescens over Ni/C catalyst was studied at 350 °C in H2 flow. The presence of Ni/C catalyst efficiently improved the degradation of raw materials, and produced bio-oil with high content of phenols but low contents of acetic acid, furfural and water. In the reaction, Ni/C catalyst plays the role of catalytic decomposition and catalytic hydrogenation. The existence of the carbon carrier favors the formation of active Ni in small sizes with more defects, which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols. 相似文献
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