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101.
102.
One hundred and forty-seven species of spores and pollen referred to 77 genera found in the crudeoil samples taken from four petroliferous provinces of the Tarim Basin of Xinjiang Provincehave been studied in this paper. By means of these spore and pollen fossils, the geological ages anddistribution of the petroleum source rocks of the basin are judged. Also, the principles and methodsto judge the petroleum source of a petroleum province by spore/pollen and other microfossils in crudeoils are explained. 相似文献
103.
本文在两次标准加入法[1]的基础上,提出了三组份同时测定的三次标准加入法,并应用于钼、钨和钛的流动注射同时测定。测定条件:[水杨基荧光酮(SAF)]=1.25 ×10-4mol/L,[溴化+六烷基三甲基铵(CTMAB)」=2.5×10-3mol/L,pH1.35,25℃,采样、进样时间分别为10s和18s,进样频率128次/h。为消除组份间协同作用引起的吸光度加合性的偏离,定义了三组份协同系数。将其引入三组份同时测定方法,补偿了吸光度对线性的偏离。补偿后钼、钨和钛的测定范围分别为0.05~0.35,0.25~1.00,0.025~0.30mg/L。测定了钢样及模拟样品中钼、钨和钛含量,结果较好。 相似文献
104.
在仔细研辉光放电光源工作过程的基础上,在国内首先设计、制成了HGZ-Ⅱ型自动辉光放电光源。该光源除换样品外,实现了抽空、进气、对光、预燃、曝光、充气、复位等摄谱全过程的自动控制。有水压、真空度、短路保护措施和醒铃线路。设计合理,性能良好,操作简便,工作安全,可靠。程控部分的编排包括顺序控制。时序控制和条件控制。由于使用了通用执行元、器件,降低了成本,提高了耐用性。为满足表层,逐层分析的需要,还专门设计了计数电路。供电源实现了高压直流供电和脉冲供电。该光源可应用于合金中主成分和少量杂质分析及金属、合金表层,逐层成分分析。 相似文献
105.
The current status of plasma source-mass spectrometry (PS-MS) is reviewed. An overview of interference effects that exist, alternative plasma sources available, and mass spectrometer interface studies is provided. A discussion of current and future development areas in plasma source mass spectrometry is also included. 相似文献
106.
Organophosphorus compounds have been applied in two ways in chemical synthesis. They can either be used as a reagent in a step of the synthesis (for example, in the Wittig reaction) or they can be incorporated directly into the target molecule. This second application, in particular, has expanded greatly in the last few years with the preparation of low-coordination phosphorus compounds. These include the phosphaalkynes, which are of great interest to organic and inorganic chemists. Phosphaalkynes have been employed in the synthesis of heterocyclic compounds, phosphaarenes and their valence isomers, and polycyclic compounds. Further applications have been the use of phosphaalkynes as new ligand systems in complex chemistry and their cyclooligomerization with organometallic reagents. While the chemical properties of phosphaalkynes have little in common with those of nitriles, they are in many ways very similar to those of the isoelectronic acetylenes. 相似文献
107.
108.
Hong Shen James E. Mark Carl J. Seliskar Harry B. Mark Jr. William R. Heineman 《Journal of Solid State Electrochemistry》1997,1(3):241-247
One problem associated with using bare solid metal electrodes, such as gold and platinum, in stripping analysis to determine
heavy metal ions such as lead and copper ions in dilute solutions is that underpotential deposition (UPD) gives multiple stripping
peaks in the analysis of mixtures. These peaks are often overlapped and cannot be conveniently used for analytical purposes.
Bifunctional alkylthiols, such as 3-mercaptopropionic acid, with an ionizable group on the other terminal end of the thiol
can form self-assembled monolayers (SAMs) on the surface of the gold electrode. It is shown that such an SAM-modified gold
electrode minimizes the UPD effects for the stripping analysis of lead and copper. The anodic peak potential shifts and the
peak shape changes, indicating that the SAM changes the deposition and stripping steps of these heavy metal ions. Thus, the
sensitivity levels for both single species and mixtures can be significantly improved for the conventional solid electrodes.
The mechanism of the deposition reaction at the SAM-modified gold electrodes is discussed.
Received: 29 May 1997 / Accepted: 24 June 1997 相似文献
109.
110.
The molecular characterization of unknown naturally presented major histocompatibility complex (MHC) class II glycopeptides carrying complex glycans has so far not been achieved, reflecting the different fragmentation characteristics of sugars and peptides in mass spectrometric analysis. Human leukocyte antigen (HLA)-DR-bound peptides were isolated by affinity purification, separated via high performance liquid chromatography and analyzed by matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry. We were able to identify two naturally processed MHC class II ligands, CD53(122-136) and CD53(121-136), carrying complex N-linked glycan side chains by a combination of in-source and collision-induced fragmentation on a quadrupole time-of-flight tandem mass spectrometer. 相似文献