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991.
Christiane Schotten Joseph L. Howard Robert L. Jenkins Anna Codina Duncan L. Browne 《Tetrahedron》2018,74(38):5503-5509
Inline, real time NMR and temperature measurements have been used to optimise the continuous flow synthesis of difluoromethyltrimethylsilane (TMSCF2H) by the reduction of the Ruppert-Prakash reagent (TMSCF3). These measurements were used to maximise the space-time-yield, while ensuring this exothermic process remains safe. In this way, a three-fold increase in space-time-yield was achieved compared to the reported batch procedure, isolating 25?g of pure TMSCF2H after 105?min. 相似文献
992.
993.
994.
995.
Richard Anderson Sampath Kannan Howard Karloff Richard E. Ladner 《Journal of Algorithms in Cognition, Informatics and Logic》2002,44(2):338
We present an O(n4)-time algorithm for the following problem: Given a set of items with known access frequencies, find the optimal binary search tree under the realistic assumption that each comparison can only result in a two-way decision: either an equality comparison or a less-than comparisons. This improves the best known result of O(n5) time, which is based on split tree algorithms. Our algorithm relies on establishing thresholds on the frequency of an item that can occur as an equality comparison at the root of an optimal tree. 相似文献
996.
In the Finsler-spacetime tangent bundle, a simple solution is determined to the torsion relations that were obtained previously to maintain (1) compatibility with Cartan's theory of Finsler space, (2) the almost complex structure, and (3) the vanishing of the covariant derivative of the almost complex structure. 相似文献
997.
998.
Howard Edan Katz 《Tetrahedron letters》1984,25(43):4905-4908
The synthesis of two macrocyclic bipyridines whose frameworksare suitable for alkyltin trichloride encapsulation is described. 相似文献
999.
1000.
Bruce M. Howard William Fenical Ken Hirotsu Barbara Solheim Jon Clardy 《Tetrahedron》1980,36(2):171-176
The structures of five new halogenated vinyl acetylenes are described which are natural products from various species of the red seaweed Laurencia. The structure of epoxyrhodophytin (1) was determined by spectral, chemical, and X-ray diffraction analyses. The structures of trans-rhodophytin (5) and trans-chondriol (8) are based on chemical and spectral comparisons with the previously reported compounds cis-rhodophytin (4) and cis-chondriol (7). The structures of cis-chondrin (14) and trans-chondrin (15) were secured by synthesis from cis- and trans-chondriol, respectively. The reactivity of these enol-ethers to various conditions of catalytic hydrogenation has been examined in detail. Hydrogenation yields an unexpected and facile incorporation of oxygen into the reaction products. Based upon these studies, and upon combustion analysis, the structure of rhodophytin has been revised as the vinyl ether rather than the vinyl peroxide originally proposed. 相似文献