Why is the use of pesticides less effective?

A medicinal agent often has a good insecticidal effect when it is first used, but as the dosage continues to increase and the range of use continues to expand, cases of increased resistance have emerged. The most prominent is esfenvalerate, which is often called

Introduction to the history of grinding machines

In the 1830s, in order to adapt to the hardening of parts such as watches, bicycles, sewing machines and firearms, the United Kingdom, Germany and the United States developed grinding machines using natural abrasive wheels. These grinders were modified from the existing machine tools such as

Five things to do in the spring and ready to act again

Before the renovation, set the layout of the house. If the suite wants to be divided into two bookshelves and cabinets, then the sofa, including lights, etc., should be positioned before the "hard".

Case study: Why did the German tool company win?

Case study: Why did the German tool company win?

Qiqihar No. 1 Machine Factory uses a large number of tools every month and orders from a German tool factory for a long time. Once, under the order of 5 million yuan tool to the Germans, the results o