The revised national mandatory standard on polyethylene blown mulch film for agricultural uses was officially issued in October 2017.The new standard defines the increase of the minimum thickness of mulch film,which c...The revised national mandatory standard on polyethylene blown mulch film for agricultural uses was officially issued in October 2017.The new standard defines the increase of the minimum thickness of mulch film,which can prevent the overuse of ultra-thin mulch film and promote the recycling and aging-resistance of mulch film,according to Sha Nansheng,Deputy-Director of Science and Technology Division,MIIT.展开更多
简要介绍了国家标准GB/T 19348.1、欧洲标准EN 584-1和美国标准ASTM E 1815对胶片系统的分类,胶片系统分类常用指标及其含义。指出各个国家射线标准胶片分类的体系略有不同,但其胶片系统的分类依据都是按梯度、颗粒度和梯度-噪声比的数...简要介绍了国家标准GB/T 19348.1、欧洲标准EN 584-1和美国标准ASTM E 1815对胶片系统的分类,胶片系统分类常用指标及其含义。指出各个国家射线标准胶片分类的体系略有不同,但其胶片系统的分类依据都是按梯度、颗粒度和梯度-噪声比的数值大小来划分的。通过对不同标准所规定的常用指标限值大小的对比,找出了不同胶片分类系统之间的关系和等价性。展开更多
文摘The revised national mandatory standard on polyethylene blown mulch film for agricultural uses was officially issued in October 2017.The new standard defines the increase of the minimum thickness of mulch film,which can prevent the overuse of ultra-thin mulch film and promote the recycling and aging-resistance of mulch film,according to Sha Nansheng,Deputy-Director of Science and Technology Division,MIIT.
文摘简要介绍了国家标准GB/T 19348.1、欧洲标准EN 584-1和美国标准ASTM E 1815对胶片系统的分类,胶片系统分类常用指标及其含义。指出各个国家射线标准胶片分类的体系略有不同,但其胶片系统的分类依据都是按梯度、颗粒度和梯度-噪声比的数值大小来划分的。通过对不同标准所规定的常用指标限值大小的对比,找出了不同胶片分类系统之间的关系和等价性。
