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991.
聚丙烯物理法微孔发泡操作条件与泡孔形态的关系研究 总被引:2,自引:0,他引:2
以超临界CO2流体和丁烷为发泡剂,用快速释压的方法,对PP的微孔发泡进行了研究,得到了泡孔密度达10^9泡孔/cm^2,泡孔直径为20-50μm的微孔泡沫塑料颗粒。研究表明,改变饱和压力和温度可以控制发泡的泡孔结构和密度。使用CO2为发泡剂,当温度低于90℃或压力低于6.0MPa时,PP很难出现发泡。提高温度使泡孔出现五边形的结构但泡孔尺寸增大;增加饱和压力,泡孔密度增加,泡孔直径减小。用超临界CO2流体和丁烷作发泡剂时所得到的泡孔密度分别为2.0×10^8-10^9和2.0×10^5—10^7泡孔/cm^3,泡孔平均尺寸分别为20—50μm和100—500μm。用超临界CO2流体和丁烷混合气体作为发泡剂时泡孔直径则出现了双峰分布的结构;加入成核剂炭黑后所得到的泡孔尺寸大于未加成核剂的情况,其泡孔密度和泡孔直径分别为7.0×10^6—1.6×10^9泡孔/cm^3和55—300μm。 相似文献
992.
采用水热加工技术研究(Mn,Zn)Fe2O4晶体粉末的合成条件,对水热体系的碱度、温度、时间进行了系统实验.结果表明在pH=7~12.5范围内可有效合成(Mn,Zn)Fe2O4.当温度在190~220℃时,完成合成所需的时间为1~2h,提高碱度有利于合成反应.本文还初步探讨了(Mn,Zn)Fe2O4的合成机理,为扩大实验提供依据. 相似文献
993.
Christer Löfstedt Bill S. Hansson Erik Petersson Peter Valeur Andrew Richards 《Journal of chemical ecology》1994,20(1):153-170
Extracts of different body parts of adult Trichoptera were tested for electrophysiological activity. Extracts of the IVth and Vth abdominal sternites of femaleHydropsyche angustipennis, Rhyacophila nubila, andR. fasciata, containing a paired exocrine gland, elicited significant electroan-tennographic responses when tested on conspecific male antennae. The paired gland occurs also in males of all the species, and inH. angustipennis, extracts from males were more active than female extracts when tested on male antennae. Female and male extracts from all species were analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). EAD-active peaks in female extracts, stimulating male antennae, were identified inH. angustipennis as nonan-2-one; and inR. nubila andR. fasciata as heptan-2-one, heptan-2-ol, nonan-2-one, and nonan-2-ol. EAD-active components from maleH. angustipennis stimulating male antennae were octan-2-one, nonan-2-one (major peak), (Z)-6-nonen-2-one, decan-2-one, and a methylbranched decan-2-one. Female extracts and synthetic mixtures of compounds identified from femaleH. angustipennis andR. fasciata were tested for attractivity in the field. High catches with control traps obscured the results, but a synthetic mixture of the four identified compounds was significantly attractive and not different from female extracts for attracting maleR. fasciata. InH. angustipennis, a synthetic six-component male blend, in which nonan-2-one was the major component, attracted significant numbers of male and femaleH. angustipennis. Extracts of maleR. nubila andR. fasciata contained acetophenone and hexanoic and octanoic acids but did not have any electrophysiological or behavioral activity on either male or female antennae of conspecifics. The occurrence of a female sex pheromone inRhyacophila and an aggregation pheromone inHydropsyche corresponds to earlier described differences in mating behaviors in the Rhyacophilidae and Hydropsychidae. 相似文献
994.
本文给出计算H2O-NH3-CO2三元体系在温度323.15K~473.15K、压力0.2MPa~8.0MPa、液相NH,摩尔分率≤0.3、富氨区条件下汽液平衡的UNIQUAC模型及其参数,模型的计算结果与试验数据吻合。该模型可用于尿素生产装置中蒸发冷凝、循环吸收以及水解精馏等过程的设备计算。 相似文献
995.
双波长分光光度法测定自来水中Fe2+和Fe3+的含量 总被引:5,自引:0,他引:5
采用双波长分光光度法测定 Fe2 和 Fe3 的方法 ,结果表明 ,在 λ1 =4 0 0 nm,λ2 =5 4 2 nm处 ,显色时间在 6 0 min~ 80 min,p H =4~ 5时能联合测定水中 Fe2 和 Fe3 ,其结果具有较高的精密度和准确度。 相似文献
996.
997.
Zvi Mendel Lev Zegelman Alfred Hassner Fabienne Assael Miriam Harel Shlomo Tam Ezra Dunkelblum 《Journal of chemical ecology》1995,21(3):331-341
The active component of the sex pheromone ofMatsucoccus josephi is (2E,6E,8E)-5,7-dimethyl-2,6,8-decatrien-4-one; the chemical is also a powerful kairomone of adult males and females of the bugElatophilus hebraicus the principal predator ofM. josephi. The presence of theZ isomer (2E,6Z,8E)-5,7-dimethyl-2,6,8-decatrien-4-one does not interfere with the attractancy of the activeE component forM. josephi males or the bug. Our results show a clear dose-response between trap catch ofM. josephi males andE. hebraicus. Conversely, increasing amounts of theZ isomer in the mixture did not affect the attraction of the scale insect males or the bug. The catch ofM. josephi males did not differ significantly among traps of different color, and was significantly higher with traps attached to the tree trunk than those suspended between trees. Comparison of the catch ofM. josephi among the three forests and between pine species suggests that the level of infestation ofPinus halepepsis andPinus brutia ssp.brutia is similar, despite the fact that the latter pine is resistant to the scale insect. Both sexes ofE. hebraicus were trapped in much lower numbers at the more infested sites. This may be related to interference with the activity ofE. hebraicus due to deterioration and drying of parts of the tree crowns and heavy colonization by generalist predators in injured trees. 相似文献
998.
The absorption of dilute CO2 into aqueous solutions of sterically hindered 2-methyl aminoethanol (MAE) and the desorption of CO2 from CO2-loaded MAE solutions into N2 stream were investigated separately for the various combinations of operational variables, using a hydrophobic microporous hollow fiber (polytetrafluoroethylene, PTFE) contained gas-liquid contactor with aqueous solutions of MAE as liquid media in the shell side at 30°C. The absorption of CO2 in this contactor is governed by resistance in the liquid and hollow fiber phases. The resistance to diffusion in the hollow fiber phase amounts to 76-80% of the total resistance. Nevertheless, the absorption rates of CO2 into aqueous MAE solutions in this contactor are higher than those into aqueous solutions of sterically hindered 2-amino-2-methyl-1-propanol (AMP) in the stirred tank with a plane unbroken gas-liquid interface. The process of desorption of CO2 from CO2-loaded MAE solutions can be regarded as being controlled by diffusion and chemical reaction in both the stagnant film of the liquid phase and the liquid-filled pore of the hollow fiber phase under the slow or intermediate reaction regime. Both absorption and desorption rates under the simultaneous absorption-desorption operation in a single unit tend to approach the respective constant values as process time elapses. The total absorption rate here seems to be almost balanced with the total desorpion rate at the constant mass transfer rate periods. 相似文献
999.
在离子液体[BMIM]BF_4-水中制备Cu_2O粒子 总被引:1,自引:0,他引:1
以CuCl2.2H2O和NaOH为原料,离子液体1-丁基-3-甲基咪唑四氟硼酸盐[BMIM]BF4-水混合溶剂为介质,利用化学还原法在112℃反应12 h合成了Cu2O粒子,考察了[BMIM]BF4对产物的影响。用XRD、ESEM/EDS和TEM/SAED对Cu2O粒子进行了结构和形貌表征;用FTIR和TG/DSC证实了离子液体修饰在Cu2O粒子的表面,从而有效地阻止了Cu2O粒子的氧化和团聚;用紫外-可见吸收光谱估测了Cu2O粒子的带隙能量为2.38 eV。离子液体在反应中发挥了还原剂、稳定剂、分散剂和模板剂的多重作用。 相似文献
1000.