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排序方式: 共有523条查询结果,搜索用时 46 毫秒
1.
Chong Saehwa Riley Brian J. Nienhuis Emily T. Lee Dongjin McCloy John S. 《Journal of chemical crystallography》2021,51(3):293-300
Journal of Chemical Crystallography - Four different rare-earth oxyapatites of Ca2RE8(SiO4)6O2 (RE?=?Pr, Tb, Ho, Tm) were synthesized using a solution-based method followed by drying,... 相似文献
2.
Riley L. Svec Paul J. Hergenrother 《Angewandte Chemie (International ed. in English)》2020,59(5):1857-1862
Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal‐catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non‐explosive and non‐toxic, and should find broad utility as a replacement for diazomethane. 相似文献
3.
Murray Riley Chandrasekaran Venkat Wierman Adam 《Foundations of Computational Mathematics》2021,21(6):1703-1737
Foundations of Computational Mathematics - Certifying function nonnegativity is a ubiquitous problem in computational mathematics, with especially notable applications in optimization. We study the... 相似文献
4.
Automated solvent system screening for the preparative countercurrent chromatography of pharmaceutical discovery compounds 下载免费PDF全文
James Bradow Frank Riley Laurence Philippe Qi Yan Brandon Schuff Guy H. Harris 《Journal of separation science》2015,38(23):3983-3991
A fully automated countercurrent chromatography system has been constructed to rapidly screen the commonly used heptane/ethyl acetate/methanol/water solvent system series and translate the results to preparative scale separations. The system utilizes “on‐demand” preparation of the heptane/ethyl acetate/methanol/water solvent system upper and lower phases. Elution‐extrusion countercurrent chromatography was combined with non‐dynamic equilibrium injection reducing the screening time for each heptane/ethyl acetate/methanol/water system to 17 min. The result enabled solvent system development to be reduced to under 2 h. The countercurrent chromatography system was interfaced with a mass spectrometer to allow selective detection of target components in crude medicinal chemistry reaction mixtures. Mass‐directed preparative countercurrent chromatography purification was demonstrated for the first time using a synthetic tetrazole epoxide derived from a routine medicinal chemistry support workflow. 相似文献
5.
We consider the canonical descending and ascending central series of ideals of an associative algebra. In particular, we prove that some ideal in the descending central series is finite-dimensional if and only if some ideal in the ascending central series is finite-codimensional. This result is the associative algebra analogue of results due to Reinhold Baer and Philip Hall in group theory and Ian Stewart in Lie algebra. We also prove various related results. 相似文献
6.
Dr. Tian Qin Dr. Lara R. Malins Jacob T. Edwards Rohan R. Merchant Alexander J. E. Novak Jacob Z. Zhong Riley B. Mills Ming Yan Dr. Changxia Yuan Dr. Martin D. Eastgate Prof. Phil S. Baran 《Angewandte Chemie (International ed. in English)》2017,56(1):260-265
Two named reactions of fundamental importance and paramount utility in organic synthesis have been reinvestigated, the Barton decarboxylation and Giese radical conjugate addition. N ‐hydroxyphthalimide (NHPI) based redox‐active esters were found to be convenient starting materials for simple, thermal, Ni‐catalyzed radical formation and subsequent trapping with either a hydrogen atom source (PhSiH3) or an electron‐deficient olefin. These reactions feature operational simplicity, inexpensive reagents, and enhanced scope as evidenced by examples in the realm of peptide chemistry. 相似文献
7.
Corrigendum: Crystallographic Snapshot of an Arrested Intermediate in the Biomimetic Activation of CO2 下载免费PDF全文
8.
The object of this investigation was to develop a technique or method for elastoplastic stress analysis using the optical effects of transparent materials. Of paramount importance was the selection and characterization of a suitable model material. In particular, it was desirable that the material be able to undergo large plastic strains while, at the same time, exhibiting a suitable level of optical response. A mixture of flexible and rigid polyester resins was found suitable, i.e., the mixture exhibited large strains and good optical response. It was found that unload birefringence (fringe order immediately upon removal of load) could be used to determine strain for a uniaxial-stress field. In particular, it provided a means for evaluating stress- and strain-concentration factors. Comparisons with other methods showed that the proposed method was reliable and gave results that are similar to those by other means. The usefulness of the material and method for two- and three-dimensional problems awaits further study. 相似文献
9.
This paper compares the results of tests which examined the effect of chisel plough wing geometry on tillage forces with those predicted by the Universal Earthmoving Equation as presented in E. McKyes' book Soil Cutting and Tillage, published by Elsevier (1985). The tests were conducted in the SAIT Tillage Test Track (an outside continous soil bin which contains a sandy loam soil) and in two field soild, one sandy loam and the other a red brown earth. The tests were conducted using a range of speeds from 5 to 15 km/h and at depths of 50 and 70 mm. The tests compared the effects of varying share wing width and rake angle. The comparison of the measured and predicted draft and vertical force responses showed a good correlation between the Universal Earthmoving Equation predictions and the measured width responses, but it did not always predict the correct rake angle responses. 相似文献