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排序方式: 共有116条查询结果,搜索用时 15 毫秒
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Richard A. Bunce James E. Schammerhorn Legrande M. Slaughter 《Journal of heterocyclic chemistry》2006,43(6):1505-1511
A diastereoselective synthesis of 1,2,3,3a,4,5‐hexahydropyrrolo[1,2‐a]quinoline‐5‐carboxylic esters has been developed using a tandem reduction‐double reductive amination reaction. The nitro dicarbonyl cyclization substrates were synthesized by alkylation of methyl (2‐nitrophenyl)acetate with 2‐bromomethyl‐1,5‐hexadiene derivatives, followed by ozonolysis. Catalytic hydrogenation of each substrate gave the target heterocycle, along with a deacylated product and an adduct resulting from capture of the intermediate hydroxylamine by the side chain carbonyls. The product ratio varied dramatically with the catalyst and the hydrogen pressure. Cyclization to the title compounds was highly diastereoselective, producing each hexahydropyrrolo[1,2‐a]‐quinoline as a single stereoisomer with the all‐cis geometry. The competing processes have not been observed in previous heterocyclization studies but can be attributed to greater strain in the system, which slows the final ring closure. 相似文献
76.
Nikky Kortbeek Aleida Braaksma Ferry HF Smeenk Piet JM Bakker Richard J Boucherie 《The Journal of the Operational Research Society》2015,66(7):1061-1076
The design and operations of inpatient care facilities are typically largely historically shaped. A better match with the changing environment is often possible, and even inevitable due to the pressure on hospital budgets. Effectively organizing inpatient care requires simultaneous consideration of several interrelated planning issues. Also, coordination with upstream departments like the operating theatre and the emergency department is much-needed. We present a generic analytical approach to predict bed census on nursing wards by hour, as a function of the Master Surgical Schedule and arrival patterns of emergency patients. Along these predictions, insight is gained on the impact of strategic (ie, case mix, care unit size, care unit partitioning), tactical (ie, allocation of operating room time, misplacement rules), and operational decisions (ie, time of admission/discharge). The method is used in the Academic Medical Center Amsterdam as a decision-support tool in a complete redesign of the inpatient care operations. 相似文献
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Barrette J Bellwied R Braun-Munzinger P Cleland WE Cormier T Dadusc G David G Dee J Diebold GE Dietzsch O Duek E Fatyga M Fox D Greene SV Germani JV Hall JR Hemmick TK Herrmann N Hogue RW Hong B Jayananda K Kraus D Kumar BS Lacasse R Lissauer D Llope WJ Ludlam TW Majka R Makowiecki D Mark SK Mitchell JT Muthuswamy M O'Brien E Pruneau C Rotondo FS Sandweiss J da Silva NC Simon-Gillo J Slaughter J Sonnadara U Stachel J Takai H Takagui EM Throwe TG Waters L Winter C Wolf K Wolfe D Woody CL Xu N 《Physical review letters》1993,70(12):1763-1766
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JM Pakarinen H Moisio S Holopainen P Vainiotalo 《Rapid communications in mass spectrometry : RCM》1999,13(14):1485-1490
2-Methoxyethanol chemical ionization of amines, carboxylic acids and amino acids has been found to produce numerous adduct ions. The most intense adduct ions for amines are [M + H](+) and [M + 77](+), for carboxylic acids [M + 27](+), [M + 59](+) and [M + 77](+), and for amino acids [M + H](+), [M + 13](+), [M + 27](+) and [M + 77](+). Either the adduct ion [M + H](+) or [M + 77](+) was the most abundant ion found for amino acids. The proton affinities of amino acids are noticed to control the formation of the [M + H](+) and [M + 77](+) ions. The relative abundance of [M + 13](+) and [M + 27](+) ions varied for different amino acids being most intense for phenylalanine and aspartic acid. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
79.
A high-performance liquid chromatographic procedure was developed for the determination of di-(2-ethylhexyl)phthalate (DEHP) concentrations in human whole blood samples. The solvent extraction of DEHP was found to be highly variable between samples obtained from different subjects (coefficient of variation of 30.4%). The recovery of DEHP following extraction with ethyl acetate was negatively correlated with serum lipid content, as expressed by the sum of serum cholesterol and triglyceride concentrations (r = -0.864). The technique of standard addition of DEHP allowed a single-point calibration of DEHP extractability in individual blood samples, and provided an accurate estimation of DEHP concentration (coefficient of variation of approximately 6% in replicate samples). The potential for intersample variability in the solvent extraction of other highly lipid-soluble compounds should be considered. 相似文献
80.
Para-nitroaniline (PNA) and nitrosobenzene have been studied in the gas phase by X-ray photoelectron spectroscopy using Al Kα X-ray (1486.6 eV) radia 相似文献