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101.
本文介绍了用离子色谱法同时测定矿物包裹体中F~-、Cl~-、PO_4~(3-)、Br~-、NO_3~-、SO_4~(2-)6种阴离子的新方法。研究了流动相浓度对保留时间的影响以及消除负峰干扰的方法。 相似文献
102.
Samuel J. Oltmans Wolfgang E. Raatz Walter D. Komhyr 《Journal of Atmospheric Chemistry》1989,9(1-3):245-253
A series of nearly daily ozone vertical profiles obtained at station T-3 on Fletcher's Ice Island (85°N, 90°W) during the period January-March 1971 shows several significant ozone intrusions into the troposphere. These intrusions are not only associated with enhanced ozone amounts in the stratosphere but also require tropopause folding events to transport ozone into the troposphere. These folds in the Arctic tropopause appear to be capable of contributing significantly to the ozone budget of the Arctic troposphere during the late winter and spring seasons. The importance of tropopause folding for bringing ozone into the troposphere seen in the daily ozone profiles confirms the results found in the Arctic Gas and Aerosol Sampling Program aircraft flights. 相似文献
103.
David M. Livingstone Dieter M. Imboden 《Aquatic Sciences - Research Across Boundaries》1989,51(4):351-369
The mean heat budget of Lake Aegeri, Switzerland, is 950 MJ·m–2, comparable to that of neighbouring lakes. The annual variation in the net heat flux can be adequately described using a six-term heat balance equation based on 12 years of monthly mean meteorological and surface temperature data. Although the magnitude of the net heat flux is dominated by the radiative terms of the equation, the one-month backward shift of the net flux and total heat content extrema from the solstices and equinoxes respectively is due to the phase shift of the non-radiative with respect to the radiative terms. A linear approximation was used to express the net heat flux in terms of a heat exchange coefficient and an equilibrium temperature. The former varies from 17 to 28 W·m–2·K–1 in the course of a year; fluctuations in the latter are found to depend mainly on fluctuations in cloud cover and relative humidity, whilst the effect of fluctuations in air temperature and wind speed is slight. 相似文献
104.
铈硼硅石是一种罕见的稀土矿物,由于它含有某些化学性质近似的元素,故分析难度较大。本文研究了应用纸色层法和离子选择性电极法对铈硼硅石中某些主要成分和微成分的分离和测定条件,设计了较合理的铈硼硅石微量全分析流程。该流程也适合类似矿物的分析,与常法比较,本法具有快速、准确、成本低和用样少等优点。 相似文献
105.
空间运输联系的分布与交流规律研究 总被引:29,自引:6,他引:29
空间运输联系是指在自然、社会、经济诸要素综合作用下,区域间通过交通运输设施进行旅客和货物交流产生的相互联系与作用。采用定量与定性相结合的实证分析方法,本文研究了客货运输的地域分布特征、地域间交流联系生成的内在机制、基本类型和增长演变的趋势,划分出客运联系“单中心”、“多中心”,货运联系“互补性交流”、“竞争性交流”、“递接性交流等类型,并提出了非均衡系数、集中度、首位联系量等评价指标。 相似文献
106.
Donald C. Thornton Alan R. Bandy Robert G. Ridgeway Arthur R. Driedger III Marija Lalevic 《Journal of Atmospheric Chemistry》1990,11(4):299-308
Stable isotopic dilution was applied to the determination of dimethyl sulfide (DMS) in ambient air at the low part-per-trillion by volume (pptrv) levels. Perdeuterated DMS was used as an internal standard in the gas chromatography/mass spectrometry determination. The isotopically labelled internal standard provided insensitivity to possible losses of DMS in sampling and analysis. The lower limit of detection (LLD) was 1 pptrv with a sample acquisition time of 2 min. 相似文献
107.
The biogeochemical sulfur cycle in the marine boundary layer over the Northeast Pacific Ocean 总被引:1,自引:0,他引:1
T. S. Bates J. E. Johnson P. K. Quinn P. D. Goldan W. C. Kuster D. C. Covert C. J. Hahn 《Journal of Atmospheric Chemistry》1990,10(1):59-81
The major components of the marine boundary layer biogeochemical sulfur cycle were measured simultaneously onshore and off the coast of Washington State, U.S.A. during May 1987. Seawater dimethylsulfide (DMS) concentrations on the continental shelf were strongly influenced by coastal upwelling. Concentration further offshore were typical of summer values (2.2 nmol/L) at this latitude. Although seawater DMS concentrations were high on the biologically productive continental shelf (2–12 nmol/L), this region had no measurable effect on atmospheric DMS concentrations. Atmospheric DMS concentrations (0.1–12 nmol/m3), however, were extremely dependent upon wind speed and boundary layer height. Although there appeared to be an appreciable input of non-sea-salt sulfate to the marine boundary layer from the free troposphere, the local flux of DMS from the ocean to the atmosphere was sufficient to balance the remainder of the sulfur budget. 相似文献
108.
离子色谱—双电导法同时测定水样中多种阴离子的研究 总被引:2,自引:0,他引:2
本文在Dionex2020i离子色谱仪上,选用0.61×10~(-3)mol/L NaHCO_3-1.61×10~(-3)mol/LNa_2CO_3水溶液作淋洗液,在HPIC-AS4A阴离子分离柱上分离痕量F~-、NO_2~-、Br~-和较高浓度的Cl~-、NO_3~-、SO_4~(2-);选用2.0×10~(-3)mol/L TBAOH-6%CH_3CN水溶液作淋洗液,在MPIC-NS1分离柱上分离痕量F~-、Br~-和较高浓度的Cl~-,然后用串联双电导检测器的不同输出范围分别同时定量测定。本法特别适用于相邻两种离子浓度相差较大,前面高含量的离子对后面痕量离子测定有干扰的样品。用本文拟定的HPIC方法测定除铬后的地下水样中多种阴离子的结果与文献值吻合。 相似文献
109.
Stem wood of the Angiosperm Calluna vulgaris (Scotch heather), isolated at different depths from a selection of raised bog peat deposits, was chemically characterized using in-source pyrolysis mass spectrometry (Py-MS) and Curie-point pyrolysis gas chromatography mass spectrometry (Py-GC-MS). Light microscopy was performed to relate mass spectrometric characteristics with anatomical features. Peatified wood samples, isolated from increasing depth show a gradual decrease in carbohydrate content. This decrease in anatomically reflected in a selective removal of secondary cell wall material from the fibre-tracheids and wood parenchyma. During prolonged peatification a selective removal of hemicellulose sugars is observed, while a part of the cellulose fraction is preserved. This highly resistant cellulose is mainly located in the secondary cell walls of the vessels. The lignin macromolecule is preserved, but a gradual decrease in syringyl to guaiacyl ratio (S/G) is observed during peatification. Because no increase in catechol and phenolic compounds is observed, we conclude that S/G shifts are due to removal the of syringyl-rich secondary cell wall material and the retention of guaiacyl-rich compound middle lamella. Small chemical changes in the lignin macromolecule involve shifts in oxygen substitutions on the aliphatic side chains of the methoxyphenolics and the occurrence of aromatic acids. 相似文献
110.