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排序方式: 共有448条查询结果,搜索用时 31 毫秒
291.
292.
A. Świtaj-Zawadka P. Konieczka J. F. Biernat Y. Takao K. Mita S. Komar M. Wesołowski A. Przyjazny J. Namieśnik 《Journal of Thermal Analysis and Calorimetry》2006,86(2):531-536
Reference materials are used in every laboratory
in order to assure the appropriate quality of analytical results. The production
of reference materials is not an easy task especially in the case of gaseous,
toxic and malodorous compounds. Thermal decomposition of immobilized compounds
is a convenient way for the generation of those kinds of mixtures. Temperature
is an important variable in this process. In this case, thermoanalytical techniques
(thermogravimetry and differential scanning calorimetry (TG-DSC)) and scanning
electron microscopy (SEM) were used for checking the temperature range which
had been previously determined using thermal desorber-gas chromatograph-flame
ionization detector (TD-GC-FID) system. 相似文献
293.
294.
Itaru Natori Shizue Natori Hiroyuki Sekikawa Hisaya Sato 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5223-5231
Soluble poly(para‐phenylene) having a long polymer chain (more than six repeat units) was synthesized with a tert‐butyl end‐group (t‐PPP) and was found to have improved solubility and excellent optical properties. Poly(1,3‐cyclohexadiene) (PCHD) consisting of only 1,4‐cyclohexadiene (1,4‐CHD) units was synthesized with a tert‐butyl end‐group (t‐PCHD), and completely dehydrogenated to obtain t‐PPP. This end‐group effectively prevented the crystallization of t‐PPP, and polymers containing up to 16 repeat units were soluble in tetrahydrofuran. Soluble t‐PPP obtained had an ability to form a tough thin film prepared by spin‐coating method. Optical analyses of t‐PPP provided strong evidence for a linear polymer chain structure. A block copolymer of t‐PPP and a soluble polyphenylene (PPH) was then synthesized, and the excellent optical properties were retained by this block copolymer along with its solubility. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5223–5231, 2008 相似文献
295.
The transmission and the reflection spectra of a thin CuCl single crystal of 0.15μ thickness have been measured in the Z3-exciton resonance region at 1.6K by using a weak dye-laser light as a light source. Well resolved interference fringes have been obtained over the exciton resonance. In the higher energy region than the longitudinal exciton's energy, the separation of adjacent fringes cannot be explained by interference of the lower branch polariton waves (LBP) or the upper branch polariton waves (UBP). These structures have been explained by the mutual interference effect between the UBP and LBP waves, anomalous waves. This has been confirmed by the measurements of two-photon absorption due to the excitonic molecule via respective polariton states. 相似文献
296.
Three-wave mixing of light has been observed in connection with a giant two-photon absorption generating excitonic molecules. The efficiency of mixing of light for energies 2Ω1 - Ω2 and 2Ω2 - Ω1 is enhanced remarkably when Ω1 and/or Ω2 is varied across the giant two-photon absorption band-region. Moreover, the mixed lights with energies 3Ω1 - 2Ω2 and 4Ω1 - 3Ω2 have also been detected. 相似文献
297.
298.
An enhanced binding of an N-particle system linearly coupled to a scalar bose field is investigated, where N ≥ 2. It is not assumed that this system has a ground state for a zero coupling. It is shown, however, that there exists
a ground state for sufficiently large values of a coupling constant. Basic ingredients of the proof are a weak coupling limit
and a modified HVZ theorem. 相似文献
299.
Itaru Natori Shizue Natori Hiroyuki Sekikawa Kenji Ogino 《Journal of polymer science. Part A, Polymer chemistry》2010,48(2):342-350
The effect of solvent on the dehydrogenation of poly(1,3‐cyclohexadiene) (PCHD) with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) [or 2,3,5,6‐tetrachloro‐1,4‐(p‐)‐benzoquinone (TCQ)] was examined to improve the reactivity of benzoquinones for this dehydrogenation reaction. The dehydrogenation of PCHD with DDQ (or TCQ) was strongly affected by the type of solvent, and aromatic hydrocarbon based solvents were appropriate for this dehydrogenation reaction. A charge‐transfer complex between DDQ (or TCQ) and aromatic hydrocarbons was formed in the reaction mixture, and the reactivity of the complex was much higher than that of free DDQ (or TCQ). The formation of a DDQ–aromatic hydrocarbon complex, which has a large diamagnetic shift of the 13C NMR signals with respect to DDQ, was the primary factor for improvement of the reactivity of DDQ. For the TCQ–aromatic hydrocarbon complex, the existence of an electron‐withdrawing group on the aromatic hydrocarbon was the major factor for improvement of the reactivity of TCQ. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 342–350, 2010 相似文献
300.