Avoid blind application It is only effective to apply zinc fertilizer to zinc-deficient plots and zinc-sensitive crops, so the application of zinc fertilizers should vary from place to place and from crop to crop and should not be applied blindly. Generally speaking, when the effective zinc co
Shanghai spot copper price chart March 10 According to the actual landform of underground coal mine and the demand of security monitoring, in this paper a coal mine wireless and integrated security monitoring system which combine wireless sensor network and wire monitoring network