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Rare Earth Materials Activate Diesel Oil
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作者 黄丽容 金宗哲 +1 位作者 王毅 王圣威 《Journal of Rare Earths》 SCIE EI CAS CSCD 2005年第S1期70-73,共4页
The properties of rare earth materials activated diesel oil such as temperature, density and hydroxylic radical were discussed. Rare earth materials including minim thorium oxide powders which had radioactivity were m... The properties of rare earth materials activated diesel oil such as temperature, density and hydroxylic radical were discussed. Rare earth materials including minim thorium oxide powders which had radioactivity were mainly composed of rare earth waste-residue powders. Under the radiation catalysis of rare earth materials, molecules of diesel oil can be transformed into activated molecules, the collision frequency increases among molecules, and temperature raises a little higher than usual. When temperature is higher, the interaction force between molecules is lessened, distance between molecules is shortened. The volume is increased and the density is decreased. A large amounts electrons and negative ions are produced by rare earth materials, which leads to the signals of hydroxylic radical stronger that means rare earth materials can activate diesel oil and can improve the activity of diesel oil. 展开更多
关键词 rare earth materials ACTIVITY hydroxylic radical TEMPERATURE density
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Geochemical characteristics and growth suitability assessment of Scutellaria baicalensis Georgi in the Earth's critical zone of North China 被引量:1
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作者 LI Xia WEI Xiao-feng +4 位作者 WU Jin YIN Zhi-qiang WAN Li-qin SUN Hou-yun AN Yong-long 《Journal of Mountain Science》 SCIE CSCD 2022年第5期1245-1262,共18页
Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment.The quantitative evaluation of element migration in the Earth’s critical zone is a challeng... Geochemical differentiation of soils has a series of consequences on plant and places pressure on the ecological environment.The quantitative evaluation of element migration in the Earth’s critical zone is a challenging task.In this study,two demonstration study areas of Scutellaria baicalensis Georgi were selected,and multiple chemical weathering indexes,chemical loss fraction,mass migration coefficients and biological enrichment coefficient method were used to assess the ecological and geochemical suitability.The results show that for the element of Fe,Zn,Se,Cu,Co,Ni,Mo and Ge,the degree of weathering and soil maturation,were greater in the rhyolitic tuff area than in the Plagioclase gneiss area.In both research sites,the heavy metal level of samples in Scutellaria baicalensis Georgi did not exceed the standard limits.The plagioclase gneiss region’s surface soil environment was more alkaline,and the content of soil organic matter was lower,resulting in a higher bioenrichment intensity of Ge,Co,Cu,and Se elements in Scutellaria baicalensis Georgi than in the rhyolite-tuff area.The elements of Cd,Nb,Mo,Pb and As are considerably enriched in the soil of the plagioclase gneiss area but lost by leaching in the soil of the rhyolite tuff area,which is connected to the interplay of elemental abundance and human impact in the parent materials.This study provides a good example of how to assess growth suitability of Chinese medicinal materials in the Earth’s critical zone. 展开更多
关键词 earths critical zone Biogeochemistry characteristics Weathering mechanism Element migration Chinese medicinal materials Chengde
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The Influence of Alkaline Earth Elements on Electronic Properties ofα-Si3N4 via DFT Calculation
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作者 张剑文 HUANG Zhifeng +3 位作者 YIN Ziqian LI Meijuan CHEN Fei 沈强 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2020年第5期863-871,共9页
We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alka... We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alkaline earth metal elements results in structural expansion when they were doped into theα-Si3N4 lattice.Formation energies of the doped structures indicate that dopants prefer to occupy the interstitial site under the nitrogen-deficient environment,while substitute Si under the nitrogen-rich environment,which provides a guide to synthesizingα-Si3N4 with different doping types by controlling nitrogen conditions.For electronic structures,energy levels of the dopants appear in the bottom of the conduction band or the top of the valence band or the forbidden band,which reduces the bandgap ofα-Si3N4. 展开更多
关键词 FIRsT-PRINCIPLEs density functional theory calculations alkaline earth elements dopedα-si3N4 photoluminescence material crystal structure electronic structure
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利用SG-C053超导重力仪检测智利8.8级地震激发的地球自由震荡 被引量:3
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作者 刘子维 郝洪涛 +1 位作者 韦进 李辉 《大地测量与地球动力学》 CSCD 北大核心 2011年第B06期43-45,50,共4页
利用SG-C053超导重力仪的观测资料,研究了2010年2月27日智利Ms8.8地震引发的球形自由振荡0S0~0S48的所有基频振型,检测结果与PREM模型的理论值相比,二者基本相符。
关键词 超导重力仪 地球自由振荡 功率谱密度 智利Ms8.8地震 PREM模型
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S掺杂促进Fe/N/C催化剂氧还原活性的实验与理论研究 被引量:3
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作者 陈驰 张雪 +2 位作者 周志有 张新胜 孙世刚 《物理化学学报》 SCIE CAS CSCD 北大核心 2017年第9期1875-1883,共9页
向Fe/N/C非贵金属催化剂中再引入S掺杂是进一步提高其氧还原催化活性的有效方法。为了探究活性提高的原因,本文以三聚氰胺-甲醛树脂为前驱体,氯化钙为模板,氯化铁为铁源,通过添加硫氰化钾(KSCN)来控制热解催化剂的S掺杂量。通过对比分... 向Fe/N/C非贵金属催化剂中再引入S掺杂是进一步提高其氧还原催化活性的有效方法。为了探究活性提高的原因,本文以三聚氰胺-甲醛树脂为前驱体,氯化钙为模板,氯化铁为铁源,通过添加硫氰化钾(KSCN)来控制热解催化剂的S掺杂量。通过对比分析催化剂的物化性质,结合密度泛函理论(DFT)计算,分析S掺杂促进Fe/N/C催化剂氧还原活性的原因。透射电子显微镜(TEM)和N_2吸脱附等温线测试结果表明,S元素可抑制含铁纳米粒子的形成,促使形成多孔碳结构,提高比表面积。X射线光电子能谱(XPS)结果表明,适量S前驱体可实现较高的S掺杂含量,得到最优的活性,过量的S反而会导致Fe和S的掺杂量同时降低,影响活性。DFT计算结果表明在Fe-N_4大环中引入S掺杂,可增强O_2分子和中间体OOH与Fe-N_4结构中的Fe的相互作用,促进形成Fe―O键,从而导致O―O键的键能显著降低,为后续反应O―O键的断裂提供可能,促进ORR反应的进行。 展开更多
关键词 氧还原反应 非贵金属催化剂 Fe/N/C材料 s掺杂 密度泛函理论
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稀土元素与In共掺对SnO_2导电性能影响的第一性原理研究 被引量:6
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作者 张颖 王景芹 康慧玲 《人工晶体学报》 CSCD 北大核心 2017年第11期2147-2153,共7页
AgSnO_2触头材料中的SnO_2近乎绝缘,为了提高触头材料的电性能提出了稀土材料La、Ce、Y和In共掺杂的方法。采用基于密度泛函的第一性原理对SnO_2以及单掺杂稀土元素的SnO_2和共掺稀土元素和In的SnO_2晶胞进行能带和态密度的计算。结果表... AgSnO_2触头材料中的SnO_2近乎绝缘,为了提高触头材料的电性能提出了稀土材料La、Ce、Y和In共掺杂的方法。采用基于密度泛函的第一性原理对SnO_2以及单掺杂稀土元素的SnO_2和共掺稀土元素和In的SnO_2晶胞进行能带和态密度的计算。结果表明:掺杂后的材料仍旧是直接带隙半导体材料,都具有热稳定性,共掺杂可以进一步使得导带底、价带顶向费米能级附近移动,进而窄化带隙;共掺杂比单掺的电子有效质量小,电导率大,其中Y和In共掺杂的导电性最好。共掺杂比单掺稀土元素更能提高AgSnO_2触头材料的导电性,为触头材料的发展提供了理论依据。 展开更多
关键词 触头材料 能带和态密度 第一性原理 稀土与In共掺杂 电导率
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A_3BGa_3Si_2O_(14)类晶体的旋光特性研究
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作者 魏爱俭 王宝林 袁多荣 《中国稀土学报》 CAS CSCD 北大核心 2006年第4期507-509,共3页
报道了La3Ga5SiO14(LGS)同构物掺杂性改进后,用提拉法生长出A3BGa3Si2O14(A=Ca2+,Sr2+;B=Nb5+,Ta5+)系列的4种晶体。此类稀土晶体均为单轴晶,属三方晶系,32点群。采用改造过的分光光度计研究了这类晶体的透过率、旋光角、旋光率色散,并... 报道了La3Ga5SiO14(LGS)同构物掺杂性改进后,用提拉法生长出A3BGa3Si2O14(A=Ca2+,Sr2+;B=Nb5+,Ta5+)系列的4种晶体。此类稀土晶体均为单轴晶,属三方晶系,32点群。采用改造过的分光光度计研究了这类晶体的透过率、旋光角、旋光率色散,并与LGS进行了比较。透射率光谱显示,ABGS类晶体在大于294 nm的可见光谱区和红外区是透明的,透过率均大于LGS。偏振光透过率曲线显示这类晶体自然旋光率较大,结果表明,这4种晶体的旋光率均大于LGS,其中SNGS旋光为最大,在波长0.30μm处,ρ=240.75(°).mm-1;在0.633μm处,ρ=34.73(°).mm-1。根据实验结果计算了这类晶体的波尔兹曼系数,与文献结果吻合很好。 展开更多
关键词 无机非金属材料 晶体生长 A3BGa3si2O14系列晶体 旋光率 波尔兹曼系数 稀土
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基于碾压应力的土石坝料压实质量控制方法
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作者 何素飞 华天波 +3 位作者 杜智毅 李新雨 刘欣 霍苗 《水力发电》 CAS 2024年第8期44-51,102,共9页
坝料压实质量是土石坝施工质量控制的关键内容。在长河坝填筑现场进行碾压应力测试,建立土应力与坝料干密度关系模型,得出对应压实密度标准的土应力控制值;构建Midas三维有限元分析模型,模拟坝料碾压过程中的应力动态变化,根据土应力控... 坝料压实质量是土石坝施工质量控制的关键内容。在长河坝填筑现场进行碾压应力测试,建立土应力与坝料干密度关系模型,得出对应压实密度标准的土应力控制值;构建Midas三维有限元分析模型,模拟坝料碾压过程中的应力动态变化,根据土应力控制值来判断坝料压实质量。研究结果表明:坝料土应力与干密度之间存在较强的线性关系,其线性模型平均决定系数为0.9;对应坝料干密度控制标准,反滤料1上层、中层、下层土体的应力控制值分别为1.465、1.064、0.773 MPa,反滤料3上层、中层、下层的土体应力控制值分别为0.926、0.774、0.664 MPa;运用构建的Midas模型实时监测碾压应力变化,可知反滤料1和反滤料3分别在振碾6遍和8遍后整体达到压实密度标准。 展开更多
关键词 土石坝料 振动碾压 压实质量 土应力 干密度 Midas模型
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Characterization of Y_2O_2S∶Eu ^(3+), Mg^(2+), Ti^(4+) Long-Lasting Phosphor Synthesized by Flux Method 被引量:8
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作者 王育华 王治龙 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第1期25-28,共4页
Long-lasting phosphor Y2O2S : Eu^3+ , Mg^2+ , Ti^4+ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased w... Long-lasting phosphor Y2O2S : Eu^3+ , Mg^2+ , Ti^4+ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu2O3 content in Y2O2S: Eu^3+ (0.01 ≤ x ≤0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y2O2S: Eu^3 + crystal structure, Eu^3+ ions only replaced Y^3 + ions' places in which it posited center position of c axis. With the increase of Eu2O3 content, the position of the strongest emission peak changed from 540 nm (5D1→^ 7F2 transition) to 626 nm (^5Do→^7TF2 transition), and the maximum intensity was obtained when x = 0.09 in Y2O2S: Eu^3+ (0.01 ≤x ≤0.10). This is due to the environment of trivalent europium in the crystal structure of Y2O2S. Doping with Mg^2+ or Ti^4+. ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg^2 + and Ti^4 + ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd·m^-2). Thus the LLP mechanism was analyzed. 展开更多
关键词 Y2O2s Eu^3 Mg^2 Ti^4 flux method long-lasting phosphorescence material rare earths
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From the Beginning of the World to the Beginning of Life on Earth 被引量:3
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 2021年第4期1503-1523,共21页
Hypersphere World-Universe Model (WUM) is, in fact, a Paradigm Shift in Cosmology [1]. In this paper, we provide seven Pillars of WUM: Medium of the World;Inter-Connectivity of Primary Cosmological Parameters;Creation... Hypersphere World-Universe Model (WUM) is, in fact, a Paradigm Shift in Cosmology [1]. In this paper, we provide seven Pillars of WUM: Medium of the World;Inter-Connectivity of Primary Cosmological Parameters;Creation of Matter;Multicomponent Dark Matter;Macroobjects;Volcanic Rotational Fission;Dark Matter Reactors. We describe the evolution of the World from the Beginning up to the birth of the Solar System and discuss the condition of the Early Earth before the beginning of life on it. 展开更多
关键词 Hypersphere World-Universe Model Law of Conservation of Angular Momentum Dark Epoch Volcanic Rotational Fission Luminous Epoch Dark Matter Particles Macroobject shell Model Dark Matter Core Medium of the World Dark Matter Fermi Bubbles Galactic Wind solar Wind Intergalactic Plasma Macroobjects Gravitomagnetic Parameter Impedance Energy density Gravitational Parameter Hubble’s Parameter Temperature of Microwave Background Radiation Inter-Connectivity of Primary Cosmological Parameters Dark Matter Reactor Early earth Formation of earth Origin of Moon Continental Crust of earth earths Atmosphere and Oceans Origin of Life
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Study on Optical Activities of A3BGa3Si2O14 Crystals
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作者 Wei Aijian Wang Baolin Yuan Duorong 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第4期391-391,共1页
Four crystals with the general formula of A3BGa3Si2O14 (A = Ca^2+, Sr^2+; B=Nb^5+ , Ta^5+) grown by using the Czoehralsky technique were reported. They are all uniaxial and belong to 32 point group. Their transm... Four crystals with the general formula of A3BGa3Si2O14 (A = Ca^2+, Sr^2+; B=Nb^5+ , Ta^5+) grown by using the Czoehralsky technique were reported. They are all uniaxial and belong to 32 point group. Their transmission, rotatory angle and specific rotation dispersion were investigated by speetrophotometer and compared with LGS. The transmission spectra show that they are transparent in the visible wavelength region beyond 294 nm and infrared region, and their transmission are all larger than that of LGS.The transmission spectra between parallel polasizers show that they have large optical activities which are larger than that of LGS. Of the four crystals, Sr3NbGa3Si2O14 has the largest optical activity : 240.75 (°)·mm^-1 at 0.30 μm wavelength, 34.73 (°) ·mm^-1 at 0. 633 μm wavelength. The Bohzmann's coefficients of these crystals were calculated, which were in good agreement with earlier measurement in other reference. 展开更多
关键词 inorganic non-metallic materials crystal growth A3BGa3si2O14 crystal optical activity boltzmann's coefficients rare earths
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Observations and modelling of the travel time delay and leading negative phase of the 16 September 2015 Illapel,Chile tsunami
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作者 Peitao Wang Zhiyuan Ren +4 位作者 Lining Sun Jingming Hou Zongchen Wang Ye Yuan Fujiang Yu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第11期11-30,共20页
The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics ... The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami(DART)sites and 29 coastal tide gauge stations.The results revealed systematic travel time delay of as much as 22 min(approximately 1.7%of the total travel time)relative to the simulated long waves from the 2015 Chilean tsunami.The delay discrepancy was found to increase with travel time.It was difficult to identify the LNP from the near-shore observation system due to the strong background noise,but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean.We determined that the LNP for the Chilean tsunami had an average duration of 33 min,which was close to the dominant period of the tsunami source.Most of the amplitude ratios to the first elevation phase were approximately 40%,with the largest equivalent to the first positive phase amplitude.We performed numerical analyses by applying the corrected long wave model,which accounted for the effects of seawater density stratification due to compressibility,self-attraction and loading(SAL)of the earth,and wave dispersion compared with observed tsunami waveforms.We attempted to accurately calculate the arrival time and LNP,and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event.The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model.Taking all of these effects into consideration,our results demonstrated good agreement between the observed and simulated waveforms.We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP,which is observed for tsunamis that have propagated over long distances frequently.The travel time delay between the observed and corrected simulated waveforms is reduced to<8 min and the amplitude discrepancy between them was also markedly diminished.The incorporated effects amounted to approximately 78%of the travel time delay correction,with seawater density stratification,SAL,and Boussinesq dispersion contributing approximately 39%,21%,and 18%,respectively.The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event.In contrast,the seawater stratification only reduced the tsunami speed,whereas the earth’s elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations.This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival,and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami.These results also support previous theory and can help to explain the observed discrepancies. 展开更多
关键词 2015 Chilean tsunami travel time delay leading negative phase numerical modeling corrected long wave earths elasticity loading seawater density stratification Boussinesq dispersion
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Two-Dimensional Organometallic TM3–C12S12 Monolayers for Electrocatalytic Reduction of CO2
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作者 Jin-Hang Liu Li-Ming Yang Eric Ganz 《Energy & Environmental Materials》 2019年第3期193-200,共8页
Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investig... Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investigate the electrocatalytic performance of the first transition metal series TM3–C12S12 monolayers on CO2 using spin-polarized density functional theory.The calculations show that M3–C12S12 exhibits excellent catalytic activity and selectivity in the catalytic reduction in CO2.The main reduction products of Sc,Ti,and Cr are CH4.V,Mn,Fe and Zn mainly produce HCOOH,and Co produces HCHO,while CO is the main product for Ni and Cu.For Sc,Ti,and Cr,the overpotentials are>0.7 V,while for V,Mn,Fe,Co,Ni,Cu,Zn,the overpotentials are very low and range from 0.27 to 0.47 V.Therefore,our results indicate that many of the M3–C12S12 monolayers are expected to be excellent and efficient CO2 reduction catalysts. 展开更多
关键词 density functional theory electrocatalytic reduction of CO2 organometallic TM3-C12s12 Monolayers single atom catalyst two-dimensional materials
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B_(4)C-PrB_(6)/CeB_(6)汽车材料的制备及性能研究
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作者 黄樱 睢利铭 李坤 《矿冶工程》 CAS 北大核心 2023年第6期169-173,共5页
分别以Pr_(6)O11和CeO_(2)为添加剂,采用无压烧结、热压烧结和放电等离子烧结法分别在2200℃、1900℃和1700℃制备了B_(4)C基复合材料,并对其微观结构和力学性能进行了研究。结果表明,通过原位反应形成的PrB_(6)和CeB_(6)可以填充B_(4)... 分别以Pr_(6)O11和CeO_(2)为添加剂,采用无压烧结、热压烧结和放电等离子烧结法分别在2200℃、1900℃和1700℃制备了B_(4)C基复合材料,并对其微观结构和力学性能进行了研究。结果表明,通过原位反应形成的PrB_(6)和CeB_(6)可以填充B_(4)C晶粒之间的孔隙,提高复合材料的致密性;与无压烧结和热压烧结相比,放电等离子烧结制备的复合材料具有更高的致密性;B_(4)C-CeB_(6)复合材料断裂韧性得以提高的原因是实现了高致密以及裂纹沿着CeB_(6)发生了偏转、分枝和桥联,最终延长了裂纹的扩展路径,降低了应力集中。采用放电等离子烧结制备的B_(4)C-CeB_(6)复合材料综合力学性能较好,相对密度、维氏硬度、抗弯强度和断裂韧性分别达到了99.3%、34.7 GPa、451 MPa和4.38 MPa·m^(1/2)。 展开更多
关键词 汽车材料 碳化硼 硼化镨 硼化铈 稀土掺杂 添加剂 制备工艺 断裂韧性 复合材料 致密性
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Some advancements in measurements of physical parameters of earth's material at high temperature and ultrahigh pressure 被引量:3
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作者 XIE Hongsen, ZHANG Yueming, GUO Jie, XU Ji’an, SONG Maoshuang, XU Yousheng and HOU Wei1. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China 2, Institute of Earth Science, Academia Sinica, Taipei, China 《Chinese Science Bulletin》 SCIE EI CAS 1997年第21期1807-1810,共4页
IT is very important to measure physical parameters of minerals, rocks, melts and fluids athigh pressure and high temperature. The data from these experiments can provide materialsfor explanation of geophysical observ... IT is very important to measure physical parameters of minerals, rocks, melts and fluids athigh pressure and high temperature. The data from these experiments can provide materialsfor explanation of geophysical observations on large scale, and information of geochemicalfield. Therefore, we set up measurement methods on elastic wave velocity, electrical conduc-tivity and differential thermal analysis in YJ-3000 ton press fitted with a wedge-type 展开更多
关键词 PHYsICAL PARAMETERs earths materiAL high temperature and nltrahigh pressure.
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Earth's density flattening and hypothesis of latitudinal normal density
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作者 郝晓光 许厚泽 刘大杰 《Science China Earth Sciences》 SCIE EI CAS 2001年第8期673-679,共7页
In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to ... In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to the pole gravity condition and equator gravity condition for the level ellipsoid, latitudinal density distribution function of the level ellipsoid is obtained. It is proved mathematically that latitudinal density of the earth's equator is larger than that of the pole, the earth's density flat-tening calculated preliminarily is 1/322, and hypothesis of the earth's latitudinal normal density is further proposed, so that theoretical preparation for studying the forming cause of the earth gravity in problems such as continent drift, mantle convection, and submarine extension is made well. 展开更多
关键词 latitudinal density density flattening hypothesis of earths latitudinal normal density.
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钨热电子发射材料的研究进展 被引量:18
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作者 郭艳群 聂祚仁 +1 位作者 席晓丽 杨建参 《稀有金属》 EI CAS CSCD 北大核心 2005年第2期200-205,共6页
钨热电子发射材料主要用作微波管、阴极射线管、等离子体装置和电子束设备的阴极,是电子产生的源泉,它的研究与应用已有多年历史。本文详细阐述了钨热电子发射材料的种类、性能特点、发射机制及其应用,总结了它们的发展历史和研究进展,... 钨热电子发射材料主要用作微波管、阴极射线管、等离子体装置和电子束设备的阴极,是电子产生的源泉,它的研究与应用已有多年历史。本文详细阐述了钨热电子发射材料的种类、性能特点、发射机制及其应用,总结了它们的发展历史和研究进展,提出了目前钨热电子发射材料的几个研究方向。稀土氧化物 钨热电子发射材料具有优越的发射性能,并可解决W ThO2 阴极材料的放射性污染,对综合性能更优的复合稀土氧化物钨热电子发射材料需要进一步深入研究。随着纳米技术的发展,纳米复合氧化物 钨热电子发射材料是目前钨热电子发射材料研究的热点。在发射过程中,如何保证发射电流的稳定性、均匀性是热发射研究的又一个研究方向。 展开更多
关键词 热电子发射材料 稀土氧化物 电流密度
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稀土催化材料的应用及研究进展 被引量:25
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作者 詹望成 郭耘 +3 位作者 龚学庆 郭杨龙 王艳芹 卢冠忠 《催化学报》 SCIE EI CAS CSCD 北大核心 2014年第8期1238-1250,共13页
稀土元素具有未充满电子的4f轨道和镧系收缩等特征,当用作催化剂的活性组分或载体时常常表现出独特的催化性能.稀土催化材料的研究和发展为La和Ce等高丰度轻稀土元素的高质、高效利用提供了有效的途径.目前稀土催化材料在石油化工、化... 稀土元素具有未充满电子的4f轨道和镧系收缩等特征,当用作催化剂的活性组分或载体时常常表现出独特的催化性能.稀土催化材料的研究和发展为La和Ce等高丰度轻稀土元素的高质、高效利用提供了有效的途径.目前稀土催化材料在石油化工、化石燃料的催化燃烧、机动车尾气净化、工业废气治理和固体氧化物燃料电池等领域发挥着重要的作用.本文综述了稀土催化材料的应用以及理论研究进展,重点讨论了稀土元素对所涉及催化剂的结构、活性和稳定性等的影响. 展开更多
关键词 稀土催化材料 环境保护 清洁能源 密度泛函理论计算 氧化铈催化
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粗粒筑坝材料密实度的缩尺效应研究 被引量:52
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作者 朱晟 王永明 翁厚洋 《岩石力学与工程学报》 EI CAS CSCD 北大核心 2011年第2期348-357,共10页
针对已有研究成果忽视密实度缩尺效应对粗粒筑坝料力学性质影响的问题,根据双江口300m级土石坝堆石料的原平均设计级配曲线,采用4种不同缩尺方法得到室内干密度极值试验成果,利用粗粒筑坝材料的级配设计母线——Talbot曲线,引入分形几... 针对已有研究成果忽视密实度缩尺效应对粗粒筑坝料力学性质影响的问题,根据双江口300m级土石坝堆石料的原平均设计级配曲线,采用4种不同缩尺方法得到室内干密度极值试验成果,利用粗粒筑坝材料的级配设计母线——Talbot曲线,引入分形几何理论,选取对级配性质较为敏感的Talbot公式的指数n以及反映颗粒形状与粗糙度的因子作为分形指标,解译粗粒料密实度出现缩尺效应的内在原因,为粗粒料级配构成对密实度影响的量化评价提供依据,克服以往只能利用不均匀系数和曲率系数进行模糊评价的缺点。利用PFC2D软件,结合混合法各缩尺比级配进行干密度极值数值试验,研究缩尺效应对粗粒料的相对密度、孔隙率的影响规律,并分析引起其差异的细观机制。 展开更多
关键词 水利工程 土石坝 粗粒料 密实度 缩尺效应 分形几何
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高性能粘结钕铁硼磁体的制备 被引量:6
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作者 李军 刘颖 +1 位作者 高升吉 涂铭旌 《中国稀土学报》 CAS CSCD 北大核心 2004年第3期331-335,共5页
研究了磁选处理、偶联处理、润滑处理、预压成型以及双向压制对粘结NdFeB磁体的密度和磁性能影响规律及机制。研究表明 :磁选可分离磁粉中低矫顽力的磁粉 ;偶联处理可改善磁粉与粘结剂之间的界面 ;减少粘结剂的含量可提高磁体的磁性能 ... 研究了磁选处理、偶联处理、润滑处理、预压成型以及双向压制对粘结NdFeB磁体的密度和磁性能影响规律及机制。研究表明 :磁选可分离磁粉中低矫顽力的磁粉 ;偶联处理可改善磁粉与粘结剂之间的界面 ;减少粘结剂的含量可提高磁体的磁性能 ;粒度配合可减少磁体中的孔隙 ;润滑处理可提高磁体的成型性 ;预压成型和双向压制可提高磁体的密度。采取上述工艺制备了密度为 6.5 2g·cm- 3,磁性能达到 10 9kJ·m- 3的粘结NdFeB磁体。 展开更多
关键词 金属材料 粘结NDFEB磁体 高性能 密度 稀土
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