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排序方式: 共有539条查询结果,搜索用时 15 毫秒
1.
P.S Erdman M Fajardo K.M Sando W.C Stwalley 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,88(4):447-481
Experimental results are reported for a unique spectroscopic device called the Plasma Spectroscopy Cell. Optical absorption of lithium metal vapor was observed at high density and temperature. Absorption spectra are analyzed using theoretical calculations of absorption cross sections for lithium-helium interactions, and singlet and triplet state transitions of diatomic lithium in the visible spectral range. This is believed to be the most complex example yet calculated in which absolute bound-bound, bound-free, free-bound, and free-free contributions for all possible optically allowed transitions are all included, in quite respectable agreement with experiment. 相似文献
2.
K. D. Duch M. Heel H. Kalinowsky F. Kayser E. Klempt B. May O. Schreiber P. Weidenauer M. Ziegler D. Bailey S. Barlag J. M. Butler U. Gastaldi R. Landua C. Sabev W. Dahme F. Feld-Dahme U. Schaefer W. R. Wodrich J. C. Bizot B. Delcourt J. Jeanjean H. Nguyen E. G. Auld D. A. Axen K. L. Erdman B. Howard R. Howard B. L. White S. Ahmad M. Comyn G. M. Marshall G. Beer L. P. Robertson M. Botlo C. Laa H. Vonach C. Amsler M. Doser J. Riedlberger U. Straumann P. Truöl ASTERIX Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,45(2):223-234
Antiproton-proton annihilation at rest in a gaseous H2 target at NTP into the final state π+ π? K ± π? (K 0) with an undetectedK 0 or \(\bar K^0 \) has been investigated. We observe theE(1420) resonance in the invariant mass spectrum (K 0)miss K ± π? with massM E =1413±8 MeV/c2 and widthГ E =62 ± 16MeV/c2 and find evidence for the production of thef 1(1285). The absolute branching ratio of \(\bar p\) p → π+ π? E 0,E 0 →K 0 L K ± π ? at (61±6)%P wave annihilation is (3.0±0.9)·10?4 of all annihilations. The observed suppression of theE production fromP wave with respect to theS wave together with some simple selection rules suggest that the quantum numbers of theE(1420) areJ pc=0?+ and not I++. 相似文献
3.
M. Jonathan Fray Paul Allen Paul R. Bradley Clare E. Challenger Michael Closier Tim J. Evans Mark L. Lewis John P. Mathias Carly L. Nichols Yvonne M. Po-Ba Hayley Snow Mark H. Stefaniak Hannah V. Vuong 《Tetrahedron》2006,62(29):6869-6875
The synthesis of ten substituted aminomethylene tetrahydro-isoquinolines is described, proceeding in eight steps from 5-hydroxyisoquinoline via reductive amination of N-Boc tetrahydro-isoquinoline 5-carboxaldehyde. Likewise, reductive amination was used to prepare four substituted dihydro-isoindoles from the corresponding aldehyde. The dihydro-isoindole ring system was conveniently accessed via a 2+2+2 cycloaddition reaction. 相似文献
4.
Michael I. Bruce Andrew Catlow Mark G. Humphrey George A. Koutsantonis Michael R. Snow Edward R.T. Tiekink 《Journal of organometallic chemistry》1980,338(1):59-80
A reinvestigation of the reaction between C2(CO2Me)2 and RuH(PPh3)2(η-C5H5) and some related complexes is reported. Initial cis addition is followed by conversion into the trans isomer. In the case of the bis-(PPh3) complex, isomerisation is followed by chelation of the ester CO group with concomitant displacement of one PPh3ligand. The resulting chelate complex reacts with CO or CNBut to give the (Z)-RuC(CO2Me)CH(CO2Me) complexes; the (E)-isomer of the carbonyl complex is obtained by addition of C2(CO2Me)2to RuH(CO)(PPh3)(η-C5H5). The 1Hand 13C NMR spectra are not a reliable guide to assignment of the stereochemistry of the vinyl group. Other products isolated from the initial reaction are the bis-insertion product CH(CO2Me)} -(PPh3)(η-C5H5) and the 1/2 PPh3/C2(CO2Me)2 adduct. The molecular structures of Ru{(Z)-C(CO2Me)CH(CO2Me)}(CO)(PPh3(η-C5H5) · 0.5EtOH, Ru{(E)-C(C2Me)CH(CO2Me)}(dppe)(η-C5H5) and CH(CO2Me)}(PPh3)(η-C5H5) have been determined. The cis isomer is monoclinic, space group P21,with a 9.328(8), b 17.385(10), c 10.356(7) Å, β 101.78(3)° and Z = 2; 2107 data with I ≥ 2.5σ(I) were refined to R = 0.076 Rw = 0.085. The trans isomer is triclinic, space group P, with a 10.404(7) b 11.221(6), c 13.230(9) Å, α 92.67(5), β 110.56(5), γ 106.21(5)° and Z = 2; 2520 data with I ≥ 2.5σ(I) were refined to R = 0.055 Rw = 0.068. The butadienyl complex is monoclinic, space group P21/a, with a 19.655(8), b 8.674(4), c 21.060(5) Å, β 116.22(3)° and Z = 4; 2724 data with I ≥ 2.5σ(I) were refined to R = 0.042, Rw = 0.047. 相似文献
5.
The title intermediate () is produced on photolysis of hexakis(2,6-diethyl-phenyl)cyclotrigermane () or bis(2,6-diethylphenyl)bis(trimethylsilyl)germane () as evidenced by trapping experiments, and thermally dimerizes to tetrakis(2,6-diethyl-phenyl)digermene (). Diarylgermylenes such as do not form stable triethylamine adducts (e.g. ) as has been previously reported. 相似文献
6.
V. L. Shirokii V. A. Knizhnikov T. P. Konovalov Z. P. Zubreichuk A. A. Erdman S. E. Nefedov I. L. Eremenko A. I. Yanovskii Yu. T. Struchkov N. A. Mayer 《Russian Chemical Bulletin》1993,42(4):732-733
Co-electrolysis of potassium 1,2-dicarbadodecahydroundecaborate and indene in 0.1N sodium bromide solution in dimethylsulfoxide using iron electrodes afforded -indenyl--(3)-1,2-dicarbollyliron(III).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 764–765, April, 1993. 相似文献
7.
Characterization of inclusion complexes of betamethasone-related steroids with cyclodextrins using high-performance liquid chromatography 总被引:1,自引:0,他引:1
HPLC was used to study the inclusion complexes formed between various beta- and gamma-cyclodextrins and a series of corticosteroids related to betamethasone. Apparent association constants were measured in acetonitrile-water for a set of 13 steroids. An increase in the stability of the steroid-cyclodextrin complex is observed at lower concentrations of acetonitrile. The effects of the nature of the halide at the 9-position, the location of a double bond within the C-ring, substitution at the 9- and 11-positions, and modification of the D-ring of the steroid backbone were studied. The 11- and 17-positions were found to be critically involved in the inclusion process. Larger apparent association constants were obtained with gamma-cyclodextrin (gamma-CD) than with beta-cyclodextrin (beta-CD) due to the increased diameter of the gamma-CD cavity. Van't Hoff plots were constructed to examine the thermodynamic properties of the inclusion process. Plots constructed using retention factors were found to be nonlinear when gamma-CD was present in the mobile phase. This is due to an increase in the strength of the inclusion complex as temperature decreases. Plots constructed using apparent association constants were linear, indicating that the mechanism of inclusion does not change over the range of temperatures studied (10 to 80 degrees C). Enthalpy-entropy compensation was observed for 11 of the 13 steroids studied. The usefulness of cyclodextrins to achieve the separation of steroids in HPLC is discussed and a practical application for the analysis of a steroid and three potential impurities is described. 相似文献
8.
Abstract— The ability of the two-spotted spider mite, Tetranychus urticae Koch, to detect and avoid various wavelengths was examined. The mites were given a choice between two regions: an area on a leaf exposed to light of defined spectral composition or an area protected from certain selected wavelength components. The mites showed little avoidance of visible, UV-A or UV-C wavelengths. In contrast, the animals strongly avoided the UV-B spectral region, indicating that this arthropod can discriminate and respond to the presence of UV-B wavelengths. The adult mites did not appear to be killed by the amount of UV-B they could receive on a sunny summer day in Kentucky (i.e. 20 SU). However, the egg laying capacity of the females was reduced in a linear fashion as dose increased. Thus, avoidance of high UV-B regions on a leaf may contribute to the survival of the species in nature. 相似文献
9.
Heidari AH Braun RJ Hirsa AH Snow SA Naire S 《Journal of colloid and interface science》2002,253(2):295-307
The drainage of a thin liquid film with an insoluble monolayer down a vertical wall is studied. Lubrication theory is used to develop a model where the film is pinned at the top with a given thickness and the film drains into a bath at the bottom. A nonlinear equation of state is used for the surface tension and the surface viscosity is a nonlinear function of the surfactant concentration; these are appropriate for some aqueous systems. The three partial differential equations are solved via discretization in space and then the resulting differential algebraic system is solved. Results are described for a wide range of parameters, and the conditions under which the free surface is immobilized are discussed. 相似文献
10.
Cinabro D Henderson S Liu T Saulnier M Wilson R Yamamoto H Bergfeld T Eisenstein BI Gollin G Ong B Palmer M Selen M Thaler JJ Sadoff AJ Ammar R Ball S Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y 《Physical review letters》1994,72(10):1406-1410