| http://www.w3.org/ns/prov#value | - TECHNICAL FIELDThe present invention relates to novel chromene compounds and to the use of the chromene compounds.BACKGROUND ARTPhotochromism is a reversible action of a compound which quickly changes the color when it is irradiated with light containing ultraviolet rays, such as the sunlight or the light of a mercury lamp, and resumes its initial color when it is nolonger irradiated with light an
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