Exchange Exchange is a marketplace in which shares, options and futures on stocks, bonds, commodities, and indexes are traded. Principal U.S. stock exchanges are: New York Stock Exchange (NYSE), American Stock Exchange (AMEX), and National Association of Securities Dealers Automatic Quotation System (Nasdaq).
From Wikipedia, the free encyclopedia. The DielsâAlder reaction is an organic chemical reaction (specifically, a [4+2] cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system.n a normal demand DielsâAlder reaction, the dienophile has an electron-withdrawing group in conjugation with the alkene; in an inverse-demand scenario, the dienophile is conjugated with an electron-donating group.
1 A fluorescence microscope, on the other hand, uses a much higher intensity light source which excites a fluorescent species in a sample of interest. 2  This fluorescent species in turn emits a lower energy light of a longer wavelength that produces the magnified image instead of the original light source.