An intelligent suitcase is designed, which can move automatically or can be artificially dragged. With the device of differential mechanism, the suitcase can decelerate, obtain different velocity of ...the two wheels and sheer off according to the signal of the motor driver. Meanwhile, the transform of automatic control and artificial drag is achieved through the clutch. Electron magnetic brake is equipped to control braking. The AT89S51 single-chip is used to auto control the suitcase. In order to ensure the distance between the suitcase and the user, the ultrasonic sensors and the method of the time difference location measured are used. It's very convenient for people to travel and worth while to practice.
Aphis gossypii were collected from cotton fields with low insecticide use and propagated on cotton seedlings grown under hydroponics. The offsprings of the aphids were selected with fenvalerate, ...omethoate, and mixture of fenvalerate-omethoate (1:8 AI) by immersion method. Up to 16 generations, resistance of fenvalerate selected population was as high as 4324.4 and the other two populations were 22.3 and 16.5 fold respectively. The above mentioned 3 selected populations showed significant or high level of cross-resistance to deltamethrin, fenvalerate and cyhalothrin. But to some organophosphate, carbamate and organic chlorates, their cross were not significant. Using enzyme inhibitor for bioassay and in vitro enzyme activity measurements the data showed that there is a relationship between resistance and increased activities of carboxesterase and oxidase.
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