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71.
James A. Cochran 《Arkiv f?r Matematik》1977,15(1-2):215-222
72.
Abachi S Abbott B Abolins M Acharya S Adam I Adams DL Adams M Ahn S Aihara H Alvarez G Alves GA Amos N Anderson EW Antipov Y Aronson SH Astur R Avery RE Baden A Balamurali V Balderston J Baldin B Bantly J Bartlett JF Bazizi K Behnke T Bendich J Beri SB Bezzubov V Bhat PC Bhatnagar V Biswas N Blazey G Blessing S Boehnlein A Borcherding F Borders J Bozko N Brandt A Brock R Bross A Buchholz D Burtovoi V Butler JM Callot OH Castilla-Valdez H Chakraborty D Chekulaev S Chen J Chen L Chen W Chopra S 《Physical review letters》1994,72(7):965-969
73.
L. G. Hansen D. Green J. Cochran S. Vermette B. Bush 《Fresenius' Journal of Analytical Chemistry》1997,357(4):442-448
Samples of 3 matrices (air, superficial dust and subsurface soil) from an aged PCB-containing landfill were extracted and
the extracts refined for bioassay. Acetone: hexane extraction was modestly selected for non-planar compounds. Coplanar PCBs
and PCDFs were enriched about 2-fold in the subsequent benzene:methylene chloride extracts of the soil. Extract refinement
with Florisil slurry and alumina column chromatography did not appreciably change the composition of the extracts. CB 28 (2,4,4′-triCB)
dominated in all extracts. The congener composition of soil and air were surprisingly similar, being enriched in tri- and
tetraCBs while dust retained higher proportions of congeners with 4 and 5 chlorines. It is postulated that anaerobic dechlorination
in the moist subsurface soil depleted the higher chlorinated congeners; more volatile congeners escaped into the atmosphere
while moderately chlorinated congeners were trapped in the superficial dust and debris. The refined extracts represent distinct
compositions of environmental PCB mixtures suitable for bioassay. 相似文献
74.
A technique is described for measuring nanogram amounts of testosterone using high-performance liquid chromatography with detection by a flow-through spectrophotometer. The addition of a non-radioisotopic internal standard (4-androsten-11 beta-ol-3,17-dione) to the biological specimen automatically corrects for testosterone losses due to extraction and non-quantitative sample injection into the high-performance liquid chromatograph. This new method, which can be performed by inexperienced personnel, is shown to be rapid, precise, accurate and specific for testosterone. 相似文献
75.
A metal-free oxidative cyclization of ureas onto unactivated alkenes using iodosylbenzene and an acid promoter is described. The products isolated are predominantly bicyclic isoureas resulting from an intramolecular oxyamination reaction. The acid type and urea substitution have a strong effect on the product formed. A variety of substrates form the isourea with high diastereoselectivity via syn addition including di- and trisubstituted alkenes. Hydrolysis of the isourea gives access to new diastereomerically pure prolinol derivatives. 相似文献
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