排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A
two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum
distillation of the total oil. Step two was a medium pressure LC separation with an AgNO3 impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related
sesquiterpene alcohols (75% of the oil). 相似文献
2.
3.
4.
5.
Brown GV Beiersdorfer P Chen H Scofield JH Boyce KR Kelley RL Kilbourne CA Porter FS Gu MF Kahn SM Szymkowiak AE 《Physical review letters》2006,96(25):253201
By implementing a large-area, gain-stabilized microcalorimeter array on an electron beam ion trap, the electron-impact excitation cross sections for the dominant x-ray lines in the Fe XVII spectrum have been measured as a function of electron energy establishing a benchmark for atomic calculations. The results show that the calculations consistently predict the cross section of the resonance line to be significantly larger than measured. The lower cross section accounts for several problems found when modeling solar and astrophysical Fe XVII spectra. 相似文献
6.
Physicochemical and surface properties of alumina modified with rare earth oxides, III. Dispersion of supported platinum 总被引:1,自引:0,他引:1
Piotr Kirszensztejn Leszek Wachowski Agnieszka Szymkowiak Magdalena Hofman Robert Przekop 《Reaction Kinetics and Catalysis Letters》2004,81(1):189-195
The effect of various amounts of lanthanides on the dispersion of Pt on Al2O3 — Ln2O3 (where Ln = La, Ce) has been studied by hydrogen chemisorption in a pulse chromatographic system.This revised version was published online in December 2005 with corrections to the Cover Date. 相似文献
7.
A. Sosa E. Bravin J. Harasimowicz A. Jeff C. P. Welsch The AEḡIS collaboration 《Hyperfine Interactions》2014,229(1-3):169-174
Detailed diagnostic of antiproton beams at low energies is required for essentially all experiments at the Antiproton Decelerator (AD), but will be particularly important for the future Extra Low ENergy Antiproton ring (ELENA) and its keV beam lines to the different experiments. Many monitors have been successfully developed and operated at the AD, but in particular beam profile monitoring remains a challenge. A dedicated beam instrumentation and detector test stand has recently been setup at the AE \(\bar {g}\) IS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Located behind the actual experiment, it allows for parasitic use of the antiproton beam at different energies for testing and calibration. With the aim to explore and validate different candidate technologies for future low energy beam lines, as well as the downstream antihydrogen detector in AE \(\bar {g}\) IS, measurements have been carried out using Silicon strip and pixel detectors, a purpose-built secondary emission monitor and emulsions. Here, results from measurements and characterization of the different detector types with regard to their future use at the AD complex are presented. 相似文献
8.
9.
Summary A series of Al2O3-SnO2 catalysts with Al2O3 to SnO2 molar ratio of 1:1, 1:0.5, 1:0.2 and 1:0.1 were synthesized by sol-gel technique and characterized by thermal analysis and FTIR. In the case of binary gels - addition of tin component leads to better crosslinking than in pure alumina gel and as a result to a much uniform texture structure. 相似文献
10.