نتایج جستجو برای: polybiphenyl alkylene
تعداد نتایج: 169 فیلتر نتایج به سال:
The crystalline structure of two biodegradable odd-odd polyesters (i.e., poly(nonamethylene pimelate) (PES 9,7) and poly(nonamethylene azelate) (PES 9,9)) was investigated by means of electron and X-ray diffraction of single crystals and oriented fibers, respectively. Truncated rhombic crystals were obtained with an aspect ratio that was strongly depended on the supercooling degree. The crystal...
At T≥ 140 °C, different primary aromatic amines (pX-C(6)H(4)NH(2); X = H, OCH(3), CH(3), Cl) react with both ethylene- and propylene-carbonates to yield a chemoselective N-alkylation process: bis-N-(2-hydroxyalkyl)anilines [pX-C(6)H(4)N(CH(2)CH(R)OH)(2); R = H, CH(3)] are the major products and the competitive formation of carbamates is substantially ruled out. At 140 °C, under solventless cond...
The X-ray crystal structures were solved for complexes with Torpedo californica acetylcholinesterase of two bivalent tacrine derivative compounds in which the two tacrine rings were separated by 5- and 7-carbon spacers. The derivative with the 7-carbon spacer spans the length of the active-site gorge, making sandwich interactions with aromatic residues both in the catalytic anionic site (Trp84 ...
The 4'-n-alkyl-4-cyanobiphenyls and 4'-n-alkoxy-4-cyanobiphenyls provide colourless liquid crystal phases which are chemically and photochemically stable. In many cases, the mesophases are produced at quite low temperatures, and indeed two members of the n-alkyl series are nematic at room temperature. Eutectic mixtures prepared from members of the two series give wide nematic ranges, e. g., fro...
Measurement of total base of blood serum supplies information indispensable for the complete description of the electrolyte balance in many physiological and pathological states. Older methods involving separate analyses of the principal cations or their conversion to sulfates, with subsequent determination of sulfate, were time-consuming, while the latter was of doubtful accuracy. More recentl...
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