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101.
Stephen J. Spells 《Polymer》1985,26(13):1921-1928
The chain conformation of solution-crystallized polyethylene has previously been confirmed by infra-red spectroscopy, using the CD2 bending bandshape for samples with a minority of the deuterated species1–3. The method of calculating the i.r. band profile from molecular conformational models is now developed to give a more accurate representation of doublet splittings and to include the singlet component. The CH2 bending profile is calculated for samples with a deuterated matrix, and the good agreement with experimental data indicates that the same molecular model is applicable for samples with the deuterated polymer as either guest or matrix, for identical crystallization conditions. This result implies that isotopic fractionation is unimportant under these conditions. 相似文献
102.
J G De Nobel F M Klis A Ram H Van Unen J Priem T Munnik H Van Den Ende 《Yeast (Chichester, England)》1991,7(6):589-598
To study cell-cycle-related variations in wall permeability of Saccharomyces cerevisiae, two approaches were used. First, an asynchronous culture was fractionated by centrifugal elutriation into subpopulations containing cells of increasing size. The subpopulations represented different stages of the cell cycle as judged by light microscopy. Cell wall porosity increased when these subpopulations became enriched with budded cells. Secondly, synchronous cultures were obtained by releasing MATa cells from alpha-factor induced G1-arrest. These cultures grew synchronously for at least two generations. The cell wall porosity increased sharply in these cultures, shortly before buds became visible and was maximal during the initial stages of bud growth. It decreased in cells which had completed nuclear migration and before abscission of the bud had occurred. The porosity reached its lowest value during abscission and in unbudded cells. We examined the incorporation of mannoproteins into the wall during the cell cycle. SDS-extractable mannoproteins were incorporated continuously. However, the incorporation of glucanase-extractable mannoproteins, which are known to affect cell wall porosity, showed cyclic oscillations and reached its maximum after nuclear migration. This coincided with a rapid decrease in cell wall porosity, indicating that glucanase-extractable mannoproteins might contribute to this decrease. 相似文献
103.
Arjunan Arulchakkaravarthi Rakesh Kumar Parthasarathy Santhanaraghavan Sivaramakrishnan Muralithar Rengasamy Gopalakrishanan Perumalsamy Ramasamy 《Materials Research Innovations》2002,6(5-6):273-276
Organic molecular scintillating crystals are noted for their good timing and particle discrimination process. Trans-stilbene
is one such candidate noted for its good particle detection characteristics for the past five decades. Progressive strengthening
of detection characteristics of trans-stilbene has been attempted by improving crystal perfection. A series of timing resolution
studies have been carried out for the Bridgman grown trans-stilbene crystals under different experimental conditions. The
results were compared with the previously reported values. Pulse shape discrimination process has been carried out for 241Am and 252Cf sources and good discrimination has been obtained for gamma-alpha and gamma-neutron sources from the grown organic phosphor
crystal.
Electronic Publication 相似文献
104.
二十世纪末,全球网络经济过热和电信业陷入之际,正是中国电信业深化体制改革、破除垄断、全面引入竞争之时。面对复杂的国际国内形势,中国电信业在一系列关系发展全局的重大问题上,坚持理性与务实,保持了行业积极稳健的发展。我国电信业目前正处于新的发展时期,面对新的机遇和挑战,在总结国内外实践的基础上,要进一步加深对电信发展基本问题的认识,要正确处理好一系列带有全球性、战略性、方向性的重大关系问题。 相似文献
105.
Crack propagation tests were carried out on 2024-T3 sheet specimens to study the effects of omitting low-amplitude cycles from the gust-dominated TWIST load sequence (MiniTWIST) and the removal of small load ranges from the manoeuvre-dominated FALSTAFF load sequence (short FALSTAFF). In other tests high-amplitude loads of TWIST and MiniTWIST were truncated at different levels. The results are compared with data from similar test programmes, including crack initiation. Attention is paid to unstationary crack growth retardation and a transient retardation during initial crack growth started by an artificial crack. 相似文献
106.
Johan M. Thevelein 《Yeast (Chichester, England)》1994,10(13):1753-1790
107.
本文论述了局部施肥对植株地上部与地下部的影响。局部施肥促进了施肥区根系的发达 ,第一侧根与第二侧根较多 ,根的吸收表面积增多 ,根鲜重增加 ,对养分的吸收能力增强 ,但整个根系与地上部的干鲜重下降。 相似文献
108.
平面Z-型软磁铁氧体频率特性的研究 总被引:2,自引:0,他引:2
研究分析了Co2Z材料显微结构与磁性能的关系,在普通铁氧体工艺中引入预磁化处理方法,并适当控制二次再结晶现象,成功地研制出高性能的Co2Z型宽频材料,Z-型铁氧体材料的共振频率可达1.8GHz以上,截止频率在1GHz附近,起始磁导率在8-13之间,介电常数相对较低(ε'<30)。 相似文献
109.
110.
We modeled nisin's anticlostridial activity and assessed the antagonistic or potentiating influences of food ingredients. The model systems contained yeast extract, proteose peptone, and glucose; were supplemented with protein (0.075, 0.75, 7.5% w/v), phospholipid (0.075, 0.75, 7.5% w/v), or soluble starch (5, 17.5, 30% w/v); and were adjusted to pH 5.5, 6.0, or 6.5. Samples inoculated with 104/mL spores were incubated at 15, 25, or 35°C. Statistical analysis developed an equation (r2= 0.76) that modeled the response and identified temperature as the most significant (α 0.001) variable. Nisin lost effectiveness with increasing temperature. Nisin concentration had significant positive and phospholipid negative, linear effects. Many interactive effects were significant (α 0.20). Nisin inhibited C. botulinum until its residual level dropped below a threshold, which decreased from 154 IU/mL at 35°C to 12 IU/mL at 15°C. 相似文献