| 摘要 |
<p>Compounds of the formula <CHEM> and salts thereof, W and W, being independently O and S, A being a nitrogen-containing heterocyclic ring system, E being O, S(O)m or NR3 where m is 0-2, R1, R2 and R3 is hydrogen, C1-C4 alkyl or C2-C4 alkenyl or alkynyl and E1 being hydrogen, halogen or one of a variety of organic substituents. The compounds are effective herbicides.</p> |
