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T_(2)W-DRIVE-HR序列在钆造影核磁共振成像检测豚鼠实验性内耳内淋巴积水中的应用
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作者 马永勤 葛建刚 +4 位作者 季微 徐丽华 姜正林 王国华 周鑫 《中国CT和MRI杂志》 2023年第7期1-3,共3页
目的研究驱动平衡自旋回波序列(T_(2)W-DRIVE-HR)在钆造影核磁共振成像(MRI)时检测豚鼠内耳内淋巴积水的效果。方法8只雌性豚鼠分为两组,包括对照组和内淋巴积水模型组(腹腔注射醋酸去氨加压素),各组相应处理17天后进行内耳磁共振成像... 目的研究驱动平衡自旋回波序列(T_(2)W-DRIVE-HR)在钆造影核磁共振成像(MRI)时检测豚鼠内耳内淋巴积水的效果。方法8只雌性豚鼠分为两组,包括对照组和内淋巴积水模型组(腹腔注射醋酸去氨加压素),各组相应处理17天后进行内耳磁共振成像和组织形态学检查。结果T_(2)W-DRIVE-HR序列在矢状位扫描时内耳成像效果好。内耳磁共振成像结果表明,与对照组相比,积水模型组豚鼠耳蜗内淋巴体积明显增加(t=3.594,P<0.05);组织形态学结果表明,与对照组相比,积水模型组豚鼠耳蜗每一转中阶面积/(前庭阶面积+中阶面积)的比值明显升高(t=3.105,P<0.05)。结论腹腔注射醋酸去氨加压素诱导豚鼠内耳内淋巴积水,使用T_(2)W-DRIVE-HR序列在钆造影磁共振成像检测的内耳内淋巴积水与组织形态学检测结果一致,说明该序列可用于豚鼠内耳内淋巴积水的检测。 展开更多
关键词 内淋巴积水 磁共振成像 T_(2)wI-DRIVE-hr序列 内耳 豚鼠
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15W@80K全气体轴承室温活塞脉管制冷机研发
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作者 张银 倪竹青 +3 位作者 罗高乔 王波 刘婷 方露露 《低温工程》 CAS CSCD 北大核心 2024年第4期47-56,共10页
为了满足超大规格线列、面阵红外探测器及红外光学系统对大冷量、长寿命、低振动、紧凑化、高效率及轻型低温制冷机的需求,开展了15 W@80 K全气体轴承室温活塞脉管制冷机研发,采用Sage热力学软件进行了仿真分析,设计了首款基于全气体轴... 为了满足超大规格线列、面阵红外探测器及红外光学系统对大冷量、长寿命、低振动、紧凑化、高效率及轻型低温制冷机的需求,开展了15 W@80 K全气体轴承室温活塞脉管制冷机研发,采用Sage热力学软件进行了仿真分析,设计了首款基于全气体轴承支撑和室温活塞功回收技术的斯特林脉管制冷机,成功完成了工程样机研制并进行了性能测试。测试结果表明,散热流体温度20℃,制冷温度为80 K,制冷机在交流输入功率为320 W时,制冷量达到22 W,制冷效率达到6.875%;输入电功为397.9 W时,制冷量达到26.16 W,制冷效率为6.56%,冷量质量比(制冷量/质量)为3.1W/kg。散热流体温度20℃,制冷温度为60 K,制冷机在交流输入功率为360 W时,制冷量达到14 W,制冷效率为3.91%;制冷机在交流输入功率为400 W时,制冷量达到15.46 W,制冷效率为3.86%。验证了室温活塞调相技术的先进性,样机性能参数满足项目技术指标要求。 展开更多
关键词 15w@80K 全气体轴承支撑 室温活塞功回收 脉管制冷机 冷量质量比
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700℃超超临界锅炉用钢HR6W焊接接头性能的试验研究 被引量:3
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作者 卢征然 王炯祥 陈亮 《锅炉技术》 北大核心 2015年第3期53-56,共4页
介绍了HR6W材料的化学成分和力学性能及焊接填充材料,进行了环向对接焊接试验,焊接接头按JB/T 4730标准进行RT检测,接头做了拉伸、弯曲、冲击、硬度试验和金相分析。试验结果表明:材料焊接性能良好,接头性能能满足材料要求,焊接接头在70... 介绍了HR6W材料的化学成分和力学性能及焊接填充材料,进行了环向对接焊接试验,焊接接头按JB/T 4730标准进行RT检测,接头做了拉伸、弯曲、冲击、硬度试验和金相分析。试验结果表明:材料焊接性能良好,接头性能能满足材料要求,焊接接头在700℃高温持久试验外推1.0×105 h强度能满足材料在700℃工况条件下长期使用运行,为700℃超超临界机组锅炉高温受热面选用材料做好了技术储备。 展开更多
关键词 hr6w焊接接头 焊接工艺性能 力学性能
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高效超超临界机组用材HR3C和HR6W的热腐蚀行为及机理研究 被引量:2
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作者 鲍颖群 苟远波 梁志远 《材料保护》 CAS CSCD 北大核心 2020年第7期154-161,共8页
为对比熔盐环境下典型耐热钢HR3C和铁镍基合金HR6W的热腐蚀行为及机理,在高温腐蚀试验系统上开展了750℃和810℃条件下1 000 h的熔盐腐蚀试验,利用扫描电镜、X射线衍射仪及能谱分析仪等表征了腐蚀产物成分与分布。结果表明:HR6W的腐蚀... 为对比熔盐环境下典型耐热钢HR3C和铁镍基合金HR6W的热腐蚀行为及机理,在高温腐蚀试验系统上开展了750℃和810℃条件下1 000 h的熔盐腐蚀试验,利用扫描电镜、X射线衍射仪及能谱分析仪等表征了腐蚀产物成分与分布。结果表明:HR6W的腐蚀增重和腐蚀产物厚度均低于HR3C的;试验早期耐热材料的腐蚀主要受离子扩散控制,后期保护膜失效材料主要以失稳腐蚀为主。材料表面腐蚀产物主要为块状尖晶石结构和瘤状团聚物。产物主要为(Fe,Cr)2O3和Fe2O3,并有少量(Ni,Mn) Cr2O4。温度对于腐蚀过程的影响主要体现在提高反应离子活性与扩散速率,加速腐蚀的快速进行生成对应的腐蚀产物。模拟熔盐以熔融态盐膜形式沉积在耐热材料表面发生热腐蚀行为,且腐蚀层疏松多孔、层次分明,呈复合结构,即腐蚀外层为富Fe氧化物,腐蚀内层为富Cr氧化物,基体内侧出现明显内硫化区域。铁镍基合金HR6W的抗腐蚀性能优于耐热钢HR3C。 展开更多
关键词 超超临界机组 热腐蚀 机理 hr3C hr6w 腐蚀产物 熔盐
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3-D numerical modelling of Domino failure of hard rock pillars in Fetr6 Chromite Mine, Iran, and comparison with empirical methods 被引量:10
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作者 S.Dehghan K.Shahriar +1 位作者 P.Maarefvand K.Goshtasbi 《Journal of Central South University》 SCIE EI CAS 2013年第2期541-549,共9页
Fetr6 is an underground mine using the stope-and-pillar mining method. As there was some evidence regarding pillar failure in this mine, improving works such as roof support and replacing existing pillars with concret... Fetr6 is an underground mine using the stope-and-pillar mining method. As there was some evidence regarding pillar failure in this mine, improving works such as roof support and replacing existing pillars with concrete pillars (CP) were carried out. During the construction of the second CP, in the space between the remaining pillars, one of the pillars failed leading to the progressive failure of other pillars until 4 000 m 2 of mine had collapsed within a few minutes. In this work, this phenomenon is described by applying both numerical and empirical methods and the respective results are compared. The results of numerical modelling are found to be closer to the actual condition than those of the empirical method. Also, a width-to-height (W/H) ratio less than 1, an inadequate support system and the absence of a detailed program for pillar recovery are shown to be the most important causes of the Domino failure in this mine. 展开更多
关键词 hard rock Domino failure numerical modelling empirical method STOPE PILLAR extraction ratio w/H ratio
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Effect of Hydration Aging and Water Binder Ratio on Microstructure and Mechanical Properties of Sprayed Concrete 被引量:4
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作者 牛荻涛 王家滨 WANG Yan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第4期745-751,共7页
In order to study the durability of sprayed concrete (shotcrete), effects of different hydration aging and water-binder ratio (w/b) on the microstructure of cement paste and basic mechanical properties of test spe... In order to study the durability of sprayed concrete (shotcrete), effects of different hydration aging and water-binder ratio (w/b) on the microstructure of cement paste and basic mechanical properties of test specimens were investigated. The phase composition, mass percentage of ettringite and portland in hydration production and microstructure were characterized by X-ray diffraction (XRD), thermo gravimetry-differential scanning calorimetry (TG-DSC) and scanning electron microscopy (SEM), respectively. The experimental results showed that changes in phase composition was more significant than those of water-binder ratio. With hydration aging and water-binder ratio increased, the mass percentage of ettringite and portland was decreased from 4.42%, 1.49% to 3.31%, 1.35%, respectively and the microstructure of paste was significantly compacted. Likewise, the mechanical properties including cubic compressive strength and splitting tensile strength were rised obviously. 展开更多
关键词 hydration aging water binder ratio w/b) sprayed concrete(shortcrete) microstructuremechanical properties
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The Hydration of Blended Cement at Low W/B Ratio 被引量:1
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作者 胡曙光 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2003年第4期72-75,共4页
The hydration process,hydration product and hydration heat of blended cement paste mixed with mineral admixture and expansive agent at low W/B ratio are studied by XRD,thermo analysis,and calorimetry instrument,and th... The hydration process,hydration product and hydration heat of blended cement paste mixed with mineral admixture and expansive agent at low W/B ratio are studied by XRD,thermo analysis,and calorimetry instrument,and they were compared with those of pure cement paste.The results show that pure cement and blended cement at low W/B ratio have the same types of hydration products,but their respective amounts of hydration products of various blended cements at same ages and the variation law of the amount of same hydration products with ages are different;The joint effect of tumefaction of gel-ettringite due to water absorption and the expansive pressure on the pore and rift caused by the crystalloid ettringite is the impetus of the volume expansion of cement paste,and the former effect is much greater than the latter one. 展开更多
关键词 HYDratioN blended cement low w/B ratio expansion mechanism
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Change of the mode of failure by interface friction and width-to-height ratio of coal specimens 被引量:3
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作者 Gamal Rashed Syd S.Peng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2015年第3期256-265,共10页
Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings.Previous studies showe... Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings.Previous studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height(W/H) ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed. 展开更多
关键词 Bump Burst Coal strength Violent failure width-to-height(w/H) ratio Interface friction Stressestrain curve
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Ta/W比对一种粉末高温合金相组成和形貌的影响
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作者 李晓鲲 张义文 +3 位作者 贾建 白佳铭 张浩鹏 李新宇 《材料热处理学报》 CAS CSCD 北大核心 2023年第1期66-76,共11页
提高Ta、W元素的含量是新型镍基粉末高温合金设计和研究的趋势。为了研究Ta、W元素交互作用对粉末高温合金组织的影响,设计了一种高(W+Ta)的粉末高温合金,在保持(W+Ta)的总量(7.5%,质量分数)和其他元素含量相同的情况下,合金的Ta/W比从4... 提高Ta、W元素的含量是新型镍基粉末高温合金设计和研究的趋势。为了研究Ta、W元素交互作用对粉末高温合金组织的影响,设计了一种高(W+Ta)的粉末高温合金,在保持(W+Ta)的总量(7.5%,质量分数)和其他元素含量相同的情况下,合金的Ta/W比从4.0/3.5逐步下降到3.0/4.5。结果表明:Ta/W比的变化对合金的晶粒组织基本没有影响,对碳化物、γ′相的分布和含量影响不大,但强烈影响二次γ′相的形貌和尺寸。随Ta/W比的下降,二次γ′相的尺寸逐渐增大,形貌由近方形转变为不规则形状,甚至产生分裂趋势;γ′相和γ基体的晶格常数均减小,但γ基体晶格常数减小更多,导致合金γ′相/γ基体间错配度增大。W元素随着Ta/W比的降低从倾向分配在γ基体转变为分布在γ′相;除W外,Ta/W比对其他合金元素在γ′相/γ基体间的分配系数影响不大。 展开更多
关键词 镍基粉末高温合金 显微组织 相组成 元素分配 Ta/w
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A review of the effect of a/W ratio on fracture toughness (I) —experimental investigation in EPFM
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作者 LIQing-fen JINGuo WANGYan-bo 《Journal of Marine Science and Application》 2005年第1期1-7,共7页
Many experimental investigations have previously been performed and recentlydone on different shipbuilding structural steels where the specimens size and crack depth/specimenwidth (a/W) were varied. A series of intere... Many experimental investigations have previously been performed and recentlydone on different shipbuilding structural steels where the specimens size and crack depth/specimenwidth (a/W) were varied. A series of interesting results have been gained. It is worthwhile to havea review on the effect of a/W ratio on fracture toughness, and further theoretical analysis isnecessary. In this paper, experimental work in elastic-plastic fracture mechanics (EPFM) wasdiscussed. Tests had been carried out on 10 kinds of strength steels. Results showed that J_i andδ_i. values increased with decreasing a/W when a/W【0.3 for three-point bend specimens and thatshallow crack specimens which have less constrained flow field give markedly higher values oftoughness than deeply notched specimens. However, for a/W】0.3, the toughness was found to beindependent of a/W. Slip line field analysis shows that for shallow cracks, the hydrostatic stressis lower than that from standard deeply cracked bend specimen which develops a high level of cracktip constraint, provides a lower bound estimate of toughness, and will ensure an unduly conservativeapproach when applied to structure defects especially if initiation values of COD / J-integral areused. 展开更多
关键词 fracture toughness COD J-INTEGRAL a/w ratio shallow crack
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A review of the Effect of a/W ratio on fracture toughness (II)—experimental investigation in LEFM
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作者 LI Qing-fen FU Yu-dong XU Xiao-xue 《Journal of Marine Science and Application》 2005年第2期1-6,共6页
In part I of this series, experimental investigation in EPFM (elastic-plastic fracture mechanics) had been discussed. In this paper, experimental investigation in LEFM ( linear elastic fracture mechanics) is given... In part I of this series, experimental investigation in EPFM (elastic-plastic fracture mechanics) had been discussed. In this paper, experimental investigation in LEFM ( linear elastic fracture mechanics) is given. Fracture toughness tests had been carried out on three different strength steels, using both through-cracked specimens with different α/W ratio and semi-elliptical cracked specimens with variable crack size and shape. Results show that the fracture toughness KIC increases with decreasing α/W when α/W 〈 0.3 for three-point-bend specimens, and that for α/W 〉 0.3, it is independent of α/W. Shallow crack specimens, both through-cracked and surface-cracked, gave markedly higher values than deeply notched specimens. However, the effect of crack shape on fracture toughness is negligible. Results also show that the LEFM approach to fracture is not tenable for design stresses where αc is often very small, far less than 2.5 ( KIC/σy)^2. 展开更多
关键词 fracture toughness KIC α/w ratio through-cracked surface-cracked
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A review of the effect of a/W ratio on fracture toughness (Ⅲ)——theoretical analysis
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作者 LI Qing-fen ZHENG Wei SHU Hai-sheng 《Journal of Marine Science and Application》 2005年第3期1-4,共4页
In part I and II of this series, experimental investigation in both EPFM and LEFM had been discussed. In this part, further theoretical analysis is given. The theoretical development of Two Parameter Fracture Mechanic... In part I and II of this series, experimental investigation in both EPFM and LEFM had been discussed. In this part, further theoretical analysis is given. The theoretical development of Two Parameter Fracture Mechanics by Hancock etc, has rationalized our experimental results. This method can be applied to engineering practice, and will allow the advantage of enhanced toughness for specimens with low levels of constraint to be taken into account for defect assessment. 展开更多
关键词 two parameter fracture mechanics T-STRESS CONSTRAINT fracture toughness a/ w ratio
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超超临界HR6W钢平板钨极氩弧焊接焊缝的微观组织和性能
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作者 陈勇 《湖北理工学院学报》 2021年第5期40-43,共4页
为检验超超临界钢焊接工艺及焊缝接头的可靠性,通过万能拉伸实验研究了超超临界锅炉用钢HR6W平板钨极氩弧对接焊缝的焊接工艺及焊接接头性能,利用光学显微镜、扫描电子显微镜分析了其微观组织。结果表明:对于10 mm厚新型超超临界HR6W钢... 为检验超超临界钢焊接工艺及焊缝接头的可靠性,通过万能拉伸实验研究了超超临界锅炉用钢HR6W平板钨极氩弧对接焊缝的焊接工艺及焊接接头性能,利用光学显微镜、扫描电子显微镜分析了其微观组织。结果表明:对于10 mm厚新型超超临界HR6W钢,采用小电流I=50 A打底焊,焊接速度为10~12 mm/min,再将焊接电流增大至70 A,进行单面焊双面成型,焊接速度为15 mm/min,最后在焊缝背面采用小电流I=40 A,焊接速度为12 mm/min,增焊一道焊缝进行焊接变形矫正,可以得到焊缝成形美观,微观组织均匀,变形小,焊缝无裂纹,拉伸性能、冲击韧性和弯曲性能优良的焊接接头。 展开更多
关键词 hr6w 钨极氩弧焊 微观组织 力学性能
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Aging Behaviors of W-Ni-Fe Ternary Alloys with High Ni-to-Fe Ratios
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作者 Ronghua LI, Jihua HUANG, Sheng YIN and Jun ZHAOSchool of Materials Science & Engineering, University of Science & Technology Beijing, Beijing 100083, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2003年第6期631-633,共3页
The hardness variation of two kinds of alloys with 36 wt pct W content and 7/3, 9/1 Ni-to-Fe ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by X-ray diffraction a... The hardness variation of two kinds of alloys with 36 wt pct W content and 7/3, 9/1 Ni-to-Fe ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by X-ray diffraction and TEM. The results show that the strain aging hardness of W-Ni-Fe ternary alloy with 7/3 Ni-to-Fe ratio decreases monotonically with the increase of aging time. Under the same conditions, the hardness of 9/1 Ni-to-Fe ratio alloy decreases in the initial aging stage, but then increases as aging process goes on. X ray diffraction and TEM analysis show that there is not any precipitation depositing from the alloy with 7/3 Ni-to-Fe ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 Ni-to-Fe ratio, the fine β phase precipitates dispersively during aging which hardens the alloy. The two different kinds of mechanisms (the softening one and the hardening one) decide the hardness variation of the alloy with 9/1 Ni-to-Fe ratio mentioned above. 展开更多
关键词 w-NI-FE Tungsten heavy alloys Ni-to-Fe ratio Strain aging β phase
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超超临界HR6W钢TIG焊接残余应力和变形有限元预测
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作者 陈勇 《今日制造与升级》 2021年第5期40-42,53,共4页
采用钨极氩弧焊接(TIG)方法对超超临界HR6W钢厚板进行对接焊接,采用数值模拟方法分析焊接过程温度场,预测焊缝残余应力和焊接变形分布。结果表明,随着焊接道次增多,焊接变形逐渐增大,焊接变形为典型的角变形,以焊接线为中心线,呈对称分... 采用钨极氩弧焊接(TIG)方法对超超临界HR6W钢厚板进行对接焊接,采用数值模拟方法分析焊接过程温度场,预测焊缝残余应力和焊接变形分布。结果表明,随着焊接道次增多,焊接变形逐渐增大,焊接变形为典型的角变形,以焊接线为中心线,呈对称分布,最大变形不超过1mm;随着焊接道次的增加,焊缝平均拉应力和压应力均先增大,后减小;焊缝中部区域存在残余压应力,焊缝首端和末端区域存在残余拉应力。 展开更多
关键词 超超临界hr6w 数值模拟 焊接变形 残余应力
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进气歧管喷水对发动机燃烧性能的试验研究
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作者 叶坦 王雷 曹永 《机械科学与技术》 CSCD 北大核心 2024年第1期45-53,共9页
为研究进气歧管喷水技术对汽油发动机热效率的提升潜力,基于一台研究型单缸汽油发动机,采用试验的手段对比研究了不同的喷水比例、不同的负荷工况及不同的压缩比下进气歧管喷水对发动机燃烧性能的影响。结果表明,采用进气歧管喷水技术... 为研究进气歧管喷水技术对汽油发动机热效率的提升潜力,基于一台研究型单缸汽油发动机,采用试验的手段对比研究了不同的喷水比例、不同的负荷工况及不同的压缩比下进气歧管喷水对发动机燃烧性能的影响。结果表明,采用进气歧管喷水技术可有效降低发动机的爆震趋势,随着喷水比例的增加,CA50逐渐提前,燃料的滞燃期及燃烧持续期增加,同时伴随着传热损失逐渐增加。相比于无喷水(w/o PWI)的结果,喷水的引入虽然导致未燃损失增加,但有利于排气能量损失大幅降低,最终反应到经济性的表现为热效率随着喷水比例的增大呈先增加后降低的趋势,油耗率的表现同热效率的结果相反;此时最佳的净指示热效率(GITE)为43.1%,相比于w/o PWI的结果升高了2.5%;最佳的净指示油耗率(GISFC)为197.9 g/(kW·h),相比于w/o PWI的结果降低了11.8 g/(kW·h)。高负荷运用喷水技术将达到更显著的热效率改善及油耗改善效果;同时,喷水技术的引入使得发动机高压缩比的应用成为可能。 展开更多
关键词 进气歧管喷水 喷水比例 负荷 压缩比 燃烧性能
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环境样品中铀的HR-ICP-MS测定 被引量:9
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作者 梁帮宏 李兵 +3 位作者 孙鹏 李已才 陈云明 杨彬 《化学研究与应用》 CAS CSCD 北大核心 2016年第1期134-138,共5页
高分辨电感耦合等离子体质谱法(HR-ICP-MS)是痕量元素分析的有效手段。本文采用HR-ICP-MS对环境样品(土壤、底泥、茶叶、地表水)中铀浓度和同位素比值进行了测定。土壤、底泥、茶叶样品采用微波消解法进行溶解;水样采用45μm滤膜过滤后... 高分辨电感耦合等离子体质谱法(HR-ICP-MS)是痕量元素分析的有效手段。本文采用HR-ICP-MS对环境样品(土壤、底泥、茶叶、地表水)中铀浓度和同位素比值进行了测定。土壤、底泥、茶叶样品采用微波消解法进行溶解;水样采用45μm滤膜过滤后直接测定。实验对样品制备、仪器参数设定、记忆效应消除、质量歧视效应修正等进行了探索,建立了环境样品中痕量铀浓度和同位素比值测定方法。土壤制样过程中铀的加标回收率为97.7%,铀检出限0.51ng·L^(-1)。 展开更多
关键词 hr-ICP-MS 微波消解 环境样品 同位素比值
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高分辨率气体同位素质谱法测定氢同位素丰度
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作者 武超 胡石林 +3 位作者 任英 刘艳 张宾永 王宇菲 《质谱学报》 EI CAS CSCD 北大核心 2024年第5期647-655,共9页
氢同位素丰度的准确定量对验证氢同位素分离装置的分离效果非常重要,为此,本研究建立了高分辨率气体同位素质谱(HR-IRMS)法测量全范围氢同位素丰度。确定了质谱的线性进样压强范围4~33 Pa与三原子离子产生率的影响因素,三原子离子产生... 氢同位素丰度的准确定量对验证氢同位素分离装置的分离效果非常重要,为此,本研究建立了高分辨率气体同位素质谱(HR-IRMS)法测量全范围氢同位素丰度。确定了质谱的线性进样压强范围4~33 Pa与三原子离子产生率的影响因素,三原子离子产生率与进样压强的平方成正比,与离子源加速电压负相关,加速电压应大于8 V;通过自制标准气体制备装置,配制了平衡态的氢同位素标准气,并校正了进样系统分馏效应和各组分灵敏度的差异,验证了该质谱进样方式为严格的分子流进样。采用所建立的方法测量低、中、高不同氘丰度的样品气体。结果表明:对于天然氘丰度的样品,测量外精度小于1%;对于中、高丰度的样品,测量外精度小于0.5%;测量值与标称值吻合良好。与低分辨率的质谱分析方法相比,该方法简单可靠、无需解析质量重叠峰、测量结果准确性不依赖于样品中氢同位素的平衡程度。 展开更多
关键词 氢同位素 高分辨率气体同位素质谱(hr-IRMS) 全丰度范围 灵敏度 三原子离子
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各相体积比对W/O/W复合乳状液性质的影响 被引量:8
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作者 魏慧贤 钟芳 麻建国 《食品与机械》 CSCD 北大核心 2007年第6期35-38,47,共5页
目的:研究用两步乳化法制备W/O/W型复合乳状液时,第一相体积比(内水相与油相的体积比)、第二相体积比(初乳与外水相的体积比)对W/O/W型复合乳状液性质的影响;方法:采用两步乳化法制备W/O/W型复合乳状液,固定制备工艺条件,改变第一相体... 目的:研究用两步乳化法制备W/O/W型复合乳状液时,第一相体积比(内水相与油相的体积比)、第二相体积比(初乳与外水相的体积比)对W/O/W型复合乳状液性质的影响;方法:采用两步乳化法制备W/O/W型复合乳状液,固定制备工艺条件,改变第一相体积比和第二相体积比的数值制备初乳和复乳,用离心分层稳定性评价复乳的稳定性,初乳的离心稳定性、黏度和复乳的粒度分布被测定;结果:随着第一相体积分数增大,初乳黏度增大,初乳和复乳的离心稳定性都提高,但是内水相的体积分数达到65%时,初乳表现出凝胶的外观,所制备的复乳的稳定性反而降低,当内水相的体积分数增加到70%的时候,初乳转相形成O/W型乳状液,不能进一步制备复乳;随着第二相体积分数的增大,复乳黏度线性增大,复乳滴的体积平均粒径减小,复乳的离心稳定性提高。初乳中内水相与油相的适宜的体积比及复乳中初乳和外水相的适宜体积比皆为1∶1左右。 展开更多
关键词 w/O/w型复乳 第一相体积比 第二相体积比 黏度 粒径 离心稳定性
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敞开体系法合成W-MCM-41介孔催化剂及其性能 被引量:4
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作者 张晓丽 杨春艳 +2 位作者 李敏艳 王向宇 郑修成 《应用化学》 CAS CSCD 北大核心 2010年第6期695-699,共5页
以十六烷基三甲基溴化铵为模板剂、正硅酸乙酯为硅源、钨酸钠为钨源,采用敞开体系法制备了W-MCM-41介孔催化剂样品。利用多种表征手段对其进行了表征,考察了投料中硅与钨摩尔比对W-MCM-41结构和催化环己烯氧化性能的影响。研究发现,所制... 以十六烷基三甲基溴化铵为模板剂、正硅酸乙酯为硅源、钨酸钠为钨源,采用敞开体系法制备了W-MCM-41介孔催化剂样品。利用多种表征手段对其进行了表征,考察了投料中硅与钨摩尔比对W-MCM-41结构和催化环己烯氧化性能的影响。研究发现,所制W-MCM-41介孔催化剂样品均保持着MCM-41的介孔结构,而且表现出较好的催化性能,其中硅与钨摩尔比为30时所制的W-MCM-41样品催化活性最高。 展开更多
关键词 敞开体系法 w-MCM-41 硅与钨摩尔比 结构表征 环己烯氧化
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