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21.
高密度燃料HDF-1与橡胶的相容性研究 总被引:3,自引:0,他引:3
报道了在室温和70 ℃下橡胶材料G402氟硅胶、丁腈胶5171、丁腈胶4170、贮囊橡胶用合成的高密度燃料HDF-1浸泡后性能如伸长率、邵尔硬度、重量、面积体积的变化,并与采用3号喷气燃料(RP-3)实验结果进行对照。用红外光谱测定了燃料浸泡前后橡胶组成的变化。实验结果表明,G402氟硅胶和贮囊对于HDF-1和RP-3有相近的相容性,丁腈胶5171对HDF-1的相容性比对RP-3的相容性稍差,丁腈胶4170对HDF-1的相容性比对RP-3的相容性更差的结果。因此,丁腈胶5171和丁腈胶4170不能用于HDF-1储存和输送,原使用RP-3系统的橡胶密封件不能直接使用HDF-1。 相似文献
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A one-pot procedure for the efficient synthesis of a small library of t-RNA inhibitor analogues was developed. Thus,Rh2(OAc)4 catalyzed three-component 1,3-dipolar cycloaddition reactions of carbonyl ylides derived from diazoindan-1,3-dione and aldehydes with other dipolarophiles in 1,1,2,2-tetrachloroethane at 80 ℃ gave ring fused tetrahydrofurans having three stereocenters in good yield. 相似文献
24.
Semyon Rabinovich 《Accreditation and quality assurance》2007,12(11):603-608
The “Guide to the expression of uncertainty in measurement” (GUM) is an extremely important document. It unifies methods for
calculating measurement uncertainty and enables the consistent interpretation and comparison of measurement results, regardless
of who obtained these measurements and where they were obtained. Since the document was published in 1995, it has been realised
that its recommendations do not properly address an important class of measurements, namely, non-linear indirect measurements.
This drawback prompted the initiation of the revision of the GUM in the Working Group 1 of the Joint Committee for Guides
in Metrology, which commenced in October 2006. The upcoming revision of the GUM provides the metrological community with an
opportunity to improve this important document, in particular, to reflect developments in metrology that have occurred since
the first GUM publication in 1995. Thus, a discussion of the directions for this revision is important and timely. By identifying
several shortcomings of the GUM and proposing directions for its improvement, we hope this article will contribute to this
discussion.
Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher. 相似文献
25.
B. V. Derjaguin Ya. I. Rabinovich A. I. Storozhilova G. I. Shcherbina 《Progress in Surface Science》1993,43(1-4):321-331
Four different experimental methods were applied to finding the values of the thermal slip coefficient of gases. The values obtained, kt = 1.05 ÷ 1.13, tally well with the value kt = 1.17, calculated by Ivchenko and Yalamov (4) for the case of full accomodation, and with the value kt′ = 1.17, derived from irreversible thermodynamics by Bakanov, Derjaguin and Roldugin (23) for the same case. 相似文献
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EI Rodriguez Martinez CI Barriga-Paulino MI Zapata CC Chinchilla AM López-Jiménez CM Gómez 《BMC neuroscience》2012,13(1):104-23
ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages. 相似文献
28.
利用高温固相法成功制备了Er~(3+)单掺、Er~(3+)/Yb~(3+)共掺杂Ca_(12)Al_(14)O_(32)F_2上转换发光样品。在980 nm激光激发下,Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺杂样品均呈现出较强的绿光(528,549 nm)和较弱的红光(655 nm)发射,分别归因于Er~(3+)离子的~2H_(11/2),~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→~4I_(15/2)能级跃迁。随着Er离子浓度的增加,单掺杂样品上转换发光强度先增大后减小,最佳掺杂浓度为0.8%。共掺杂Yb~(3+)后,Er~(3+)的发光强度明显增大。还原气氛下合成的样品上转换发光强度增大约两倍,可能和笼中阴离子基团变化有关。发光强度和激发光功率的关系表明所得上转换发射为双光子吸收过程,借助Er~(3+)-Yb~(3+)体系能级结构详细讨论了上转换发射的跃迁机制。 相似文献
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Yu. K. Tovbin A. B. Rabinovich 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(2):329-331
The characteristics of a vapor-liquid interface are calculated using the lattice gas model applied to the analysis of the states of metastable supersaturated vapor, depending on the size of a liquid drop and the system temperature. The interaction of molecules is considered in a quasi-chemical approximation describing the effects of direct correlations of nearby molecules. It is found that considering the density fluctuation increases the drop radius, corresponding to the condition of the generation of a new phase. 相似文献