نتایج جستجو برای: polyethers
تعداد نتایج: 219 فیلتر نتایج به سال:
beside ziegler-natta and phillips catalysts the development of methylaluminoxane (mao) as cocatalyst incombination with metallocenes or other transition metal complexes for the polymerization of olefins haswidely increased the possibilities in controlling the polymer composition, polymer structure, tacticity and special properties with high precision. these catalysts allow the synthesis of isot...
The mechanism governing the redox-stimulated switching behavior of a tristable [2]rotaxane consisting of a cyclobis(paraquat-p-phenylene) (CBPQT(4+)) ring encircling a dumbbell, containing tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units which are separated from each other along a polyether chain carrying 2,6-diisopropylphenyl stoppers by a 4,4'-bipyridinium (BIPY(2+)) ...
Silicone softeners have a firm place in final finishing for a very important reason. A piece of fabric which has been subjected to pretreatment ,dyeing and fixing processes is almost impossible to be appealing to any one without taking a corrective measures of handle. The Application of silicone softeners turns hard and a brittle fabric into a soft pleasant textile with which the buyer can expe...
STATEMENT OF PROBLEM Providing the dental laboratory with an accurate replication of the hard and soft tissue of a patient is important. Therefore, it is essential to examine whether clinicians critically evaluate impressions routinely before sending them to the laboratory. PURPOSE This study evaluated the quality of impressions sent to commercial laboratories for the fabrication of fixed par...
The macrotetrolides are a family of cyclic polyethers derived from tetramerization, in a stereospecific fashion, of the enantiomeric nonactic acid (NA) and its homologs. Isotope labeling experiments established that NA is of polyketide origin, and biochemical investigations demonstrated that 2-methyl-6,8-dihydroxynon-2E-enoic acid can be converted into NA by a cell-free preparation from Strepto...
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