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排序方式: 共有499条查询结果,搜索用时 31 毫秒
491.
492.
493.
A de Lange GD Dickenson EJ Salumbides W Ubachs N de Oliveira D Joyeux L Nahon 《The Journal of chemical physics》2012,136(23):234310
An extensive survey of the D(2) absorption spectrum has been performed with the high-resolution VUV Fourier-transform spectrometer employing synchrotron radiation. The frequency range of 90,000-119,000 cm(-1) covers the full depth of the potential wells of the B (1)Σ(u)(+), B' (1)Σ(u)(+), and C (1)Π(u) electronic states up to the D(1s) + D(2l) dissociation limit. Improved level energies of rovibrational levels have been determined up to respectively v = 51, v = 13, and v = 20. Highest resolution is achieved by probing absorption in a molecular gas jet with slit geometry, as well as in a liquid helium cooled static gas cell, resulting in line widths of ≈0.35 cm(-1). Extended calibration methods are employed to extract line positions of D(2) lines at absolute accuracies of 0.03 cm(-1). The D (1)Π(u) and B' (1)Σ(u)(+) electronic states correlate with the D(1s) + D(3l]) dissociation limit, but support a few vibrational levels below the second dissociation limit, respectively, v = 0-3 and v = 0-1, and are also included in the presented study. The complete set of resulting level energies is the most comprehensive and accurate data set for D(2). The observations are compared with previous studies, both experimental and theoretical. 相似文献
494.
Tominey A Andrew D Oliphant L Rosair GM Dupré J Kraft A 《Chemical communications (Cambridge, England)》2006,(23):2492-2494
Polyanionic microgels containing negatively charged tetrazole binding sites show supramolecular binding of various protonated amines (e.g. dibucaine and spermine) in a competitive aqueous medium at millimolar concentration. 相似文献
495.
Abdurrahman Coskun Ibrahim Unsal Mustafa Serteser Arno Fraterman 《Accreditation and quality assurance》2009,14(10):547-552
The precision and trueness of current instruments and methods in clinical laboratories is much better than in the past. However,
the z-score and other comparison variables that are currently used in external quality assessment programs are based on relative
data. Thus, they may change from program to program and also change over time within the same program and consequently may
not be useful or cost-effective. We therefore devised a test-specific decision limit for accepting or rejecting test results
based on a combination of the data of within- and between-subject biological variations. We then applied these limits to a
group of tests performed in our laboratory and compared our results with those of external quality assessment programs. In
addition, we combined external and internal quality control data on the same graph and prepared a two-dimensional graph for
different levels of control sera. Inspection of all results of control sera on this new graph was more useful for decision
making. We concluded that the z-score is not reliable for comparisons of test results in external quality assessment. As a substitute for this currently
accepted practice, we assert that control limits based on biological variation are more reliable, and can be useful in the
evaluation of both external and internal quality assessments and their combination on this new graph. 相似文献
496.
Arno W. Reitz 《Zeitschrift für Physik A Hadrons and Nuclei》1931,69(3-4):259-286
497.
Block copolymers and telechelic oligomers bearing methacrylate moities were obtained by means of a new highly selective end group reaction. Starting from polymethacrylates that were prepared by radical polymerization in the presence of mercaptanes as chain transfer agents, the resulting ester end group linked to the terminal tertiary carbon atom of the polymer backbone can be either transesterified or saponified selectively. The selectivity of the end group reactions was determined by MALDI-TOF-mass spectrometry. Polymethacrylate-b-poly(ethylene oxide)-, polymethacrylate-b-poly(methacrylic acid)- and polymethacrylate-b-polysiloxane-b-polymethacrylate-copolymers as well as α,ω-dihydroxy- and α,ω-dicarboxy-telechelic polymethacrylates were prepared by applying end group transesterification or end group saponification. 相似文献
498.
3-Chlorocyclopentene-(1) has been used as initiator in the quasiliving cationic polymerization of isobutene. Polyisobutenes in the molecular weight range Mw = 300 - 60000 Dalton with a molecular weight distribution MWD between 1.17 and 1.34 have been synthesized. The linear polymer was selectively hydrosilated on one or both ends. With a furan coupling agent, the PIB (polyisobutene) was dimerized, yielding polymers with a cyclopentene head- and tail group. 相似文献
499.
Frederik Bachhuber Joerg von Appen Richard Dronskowski Peer Schmidt Tom Nilges Arno Pfitzner Richard Weihrich 《ChemInform》2015,46(3):no-no
A complete stability range of known and new crystalline allotropes of phosphorus including recently discovered tubular modifications and not‐yet‐known crystal structures of [P12] nanorods, and not‐yet‐isolated [P14] nanorods is given using quantum chemical DFT calculations. 相似文献