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151.
A simple method for the rapid and simultaneous analysis of dichlorvos (DDVP), malathion, carbaryl, and 2,4-dichlorophenoxy acetic acid (2,4-D) in citrus fruit, which uses flow-injection ion spray ionization tandem mass spectrometry, has been developed for the first time. The method involves the combined use of stable isotopically labeled internal standards (DDVP-d6, malathion-d10, carbaryl-d7, and 2,4-D-d5) and a multiple reaction monitoring technique. The average recoveries for the pesticides at the same concentrations as their tolerance levels (DDVP: 0.1-0.2 μg g−1; malathion: 0.5-4.0 μg g−1; carbaryl: 1.0 μg g−1; 2,4-D: 1.0-2.0 μg g−1) ranged from 90 to 119% with the relative standard deviation (R.S.D.) ranging from 1.0 to 13.1% (n = 5). Analysis time, including sample preparation and determination, was only 15 min. The present method is effective for screening DDVP, malathion, carbaryl, and 2,4-D in citrus fruit.  相似文献   
152.
Novel pyridinium salts [N‐(α‐phenylbenzyl)‐, N‐(1‐naphthylmethyl)‐, or N‐cinnamyl p‐ or o‐cyanopyridinium hexafluoroantimonates] were synthesized by the reaction of p‐ or o‐cyanopyridine and the corresponding bromides followed by anion exchange with KSbF6. These pyridinium salts polymerized epoxy monomers at lower temperatures than previously reported for N‐benzyl‐2‐cyanopyridinium hexafluoroantimonate. The o‐substituted pyridinium salts showed higher activity than the p‐substituted ones, and the crosslinked epoxy polymers cured with these initiators showed higher glass‐transition temperatures. These pyridinium salts photoinitiated radical polymerization as well as cationic polymerization. The photopolymerization was accelerated by the addition of aromatic ketones as photosensitizers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1037–1046, 2002  相似文献   
153.
New conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100–200°C for 0–5 h. The number-average molecular weight M?n, the weight-average molecular weight M?w, and the oligomer yield increased with pressure, tem-perature, and time. The average molecular weight of the oligomer showed the maximum value (M?n: 830, M?w: 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV–VIS, field desorption mass (FDMS) spectra, and 13C NMR spec-trum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. 13C NMR spectrum of the oligomer showed the absence of sp-carbon (? C?). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. © 1995 John Wiley & Sons, Inc.  相似文献   
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57Fe Mössbauer measurements have been perforned at the first time on iron nitrides, FeNx(x>0.5), films prepared by rf sputtering and the measurements for γ-FeN0.09, γ'-Fe4N, ε-Fe2–3N and ζ-Fe2N have been also performed. Two new phases for x>0.5 have been identified: One has a ZnS-type structure denoted by γ" Another phase is denoted by γ''' in which iron atoms constitute a fcc lattice but the details of occupation sites of nitrogen atoms are not yet clear. The isomer shift of γ" relative to α-Fe at 300 K is rather small in comparison with that of other well known nitrides. The roam temperature Mössbauer spectra of γ''' consist of a sum of two doublets. Mössbauer spectra of γ" at 10 K do not indicate magnetically split pattern, but those of γ''' show magnetically split patterns at 10 K with the hyperfine fields of 30 T and 48 T, respectively. The component of 48 T is due to oxides, not due to nitrides.  相似文献   
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