نتایج جستجو برای: crafts
تعداد نتایج: 2058 فیلتر نتایج به سال:
Coast Guard statistics indicate a national boating fatality rate of 9.6 deaths per 100,000 crafts. In 1977 in California, five fatalities and 70 serious injuries were directly attributable to waterskiing. The four cases reported here include three patients with propeller injuries, including one nearly fatal amputation. In each case basic measures for boating safety were overlooked.
An organocatalytic quadruple cascade initiated by a Friedel-Crafts-type reaction is described. The (S)-diphenylprolinol trimethylsilyl ether catalyzed reaction yields highly functionalized cyclohexenecarbaldehydes bearing a 1,1-bis[4-(dialkylamino)phenyl]ethene moiety and three contiguous stereogenic centers. The reaction tolerates various functional groups and all products are obtained with ve...
An asymmetric Friedel-Crafts alkylation reaction of 2-furfuryl ketones with β-trifluoromethyl enones has been developed via formal trienamine catalysis of a bifunctional primary amine-thiourea substance derived from L-tert-leucine, delivering the furan derivatives incorporating a stereogenic trifluoromethyl (CF3) group in good to high yields with excellent enantioselectivity.
An efficient and practical catalytic system for the anti-Markovnikov ruthenium-catalyzed hydroarylation of styrenes with acetophenone, allowing a straightforward access to bibenzyl backbones, is described for the first time: this process, involving regioselective C-H bond activation, is complementary to a Friedel-Crafts type reaction giving the branched adduct.
The treatment of 2-(2-vinylphenyl)acetaldehydes or 3-(2-vinylphenyl)propanals with BF 3 ·Et 2 O results in an intramolecular Prins reaction affording intermediary benzyl carbenium ions, which are then trapped by a variety electron-rich aromatics via Friedel–Crafts alkylation. This cascade Prins/Friedel–Crafts cyclization protocol paves expedient path to medicinally useful 4-aryltetralin-2-ol an...
Abstract In the modern world, management of companies has evolved from a model characterized by extraction, transformation, and generation waste towards more sustainable model. This transition affects even traditional sectors, such as crafts. A key aspect models is knowledge disposition consumers with respect to these new artisan products. To date, few works have addressed this research problem...
agunmukha river is an important water body having plentiful aquatic resources. the fisheries communities in the river are familiar with a diverse range of fishing gear and crafts to catch fish. therefore, the objectives of the present study were to explore fishing gear and fishing crafts, catch composition of the respective gearand identification of fish biodiversity of agunmukha river. a step ...
The purpose of this study is as a scientific responsibility well an effort to build literacy in the existence art and crafts city Bantul, which known creative field crafts. creativity Bantul people can be read explained from results artifact clear evidence innovation community creation meet needs life become part cultural life, especially Javanese culture. Art products that have identity are cr...
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