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1.
T. S. KRISHNAN 《Mineral Processing and Extractive Metallurgy Review》2013,34(1):53-67
Beryllium and beryllium compounds find wide variety of applications in diverse industries. Low density, high strength, and attractive nuclear properties like low neutron absorption cross section and high scattering cross section have created great interest in the metal for space, aeronautical, and nuclear applications. The extraction technology of beryllium is now fairly well established and significant progress has also been made in the powder metallurgy fabrication of the metal. Conventional fabrication methods like rolling, wire drawing, extrusion etc. have not been found quite suitable for beryllium because of its low ductility. This paper presents an overview of the extraction processes and the fabrication methods presently employed for beryllium metal and alloys. The various applications are described and the prospects and constraints in the large scale utilization of beryllium in industry are analysed. 相似文献
2.
ДрицМ .Е .[1,2 ] reportedthatscandium ,com paringwiththeotherrareelements ,isthemosteffec tiveadditiontopromotethestrengthofaluminumal loys .Thestrengthofas extrusionAl 6 5Mgalloyrodcontaining 0 .2 %Screaches 4 0 0MPa (σb)and 2 5 0MPa (σ0 .2 ) ,higherthanAl 6 5Mgalloywithoutscandiumonetime .Willey[3] fromAluminumCompa nyofAmericapatentedthefirstaluminumscandiumalloyin 1971.Since 70′soflastcentury ,theformerSovietUnionengagedcompletelyresearchonthepro ductionandapplicationofalum… 相似文献
3.
Plates of A1-6Mg alloys with and without scandium were prepared by semi-continuous cast, homogenization,hot-rolled, cold-rolled and annealing. Based on studying of effects of temperature and time on hardness and conductivity during homogenization, it was found that homogenization of ingot with Sc and Zr can result in dispersion strengthening.Recrystallization temperature of alloys was studied by hardness method and optical metallographic method. Staring recrystallization temperature of A1-6Mg alloys with Sc and Zr is 375℃, increasing by 150℃ than AI-6Mg alloys without Sc and Zr. Mechanical properties (δb,δ0.2,δ) of hot-rolled alloy with Sc and Zr are 400 MPa, 280 MPa and 18% ; cold-rolled and anneal alloy with Sc and Zr are 420 MPa, 310 MPa and 12% respectively. 相似文献
4.
Fear Jessica M.; Champion Jennifer E.; Reeslund Kristen L.; Forehand Rex; Colletti Christina; Roberts Lori; Compas Bruce E. 《Canadian Metallurgical Quarterly》2009,23(5):762
The present study examined the role of children and adolescents’ perceptions of self-blame specific to interparental conflict and children and adolescents’ coping behaviors in the context of parental depression as predictors of internalizing and externalizing symptoms in a sample of 108 youth (age 9–15 years old) of parents with a history of depression. Higher levels of current depressive symptoms in parents were associated with higher levels of interparental conflict and higher levels of internalizing symptoms in children and adolescents, and interparental conflict was positively associated with both internalizing and externalizing symptoms in children/adolescents. Consistent across a series of multiple regression models, children and adolescents’ perceptions of self-blame and use of secondary control coping (acceptance, distraction, cognitive restructuring, positive thinking) were significant, independent predictors of both internalizing and externalizing symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Earlier May, China Electricity Council made forecast to the nationwide power supply and demand for the 2nd quarter of 2007 . 相似文献
6.
pHPotentiometricStudyonRareEarthsandCalciumBinaryandTernaryComplexeswithDLMalicAcidandLHydroxyprolineWangRuiyao(王瑞瑶),GaoF... 相似文献
7.
~~China's imports and exports of nickel and cobalt by category~~ 相似文献
8.
G Litscher G Schwarz E Eger I Hadolt E Mahla KH Tscheliessnigg 《Canadian Metallurgical Quarterly》1998,43(6):158-163
There is a steady progress in the development of artificial heart and circulatory assist devices. There is also no doubt that further advances in energy systems, materials, and electronics will provide for smaller and more reliable electrically driven blood pumps, but the present engineering design appears to be adequate to provide devices satisfactory for initial clinical use. Due to problems in the availability of suitable donor hearts, the concept of replacing the natural heart with an artificial heart as a "bridge to transplantation" has gained attention in recent years. The present paper shows technical and clinical aspects of multivariable electrophysiologic neuromonitoring in a patient with an artificial heart assist device in the intensive care unit. The data (EEG, 40 Hz brain oscillations, brainstem auditory- and somatosensory evoked potentials) are discussed with respect to the influence of the artificial heart on their quality and reliability. Reasons for artifacts and problems of interpretation are shown. 相似文献
9.
Li Huili~ Yu Ning~ * Sun Zhenyan~ Ji Jingwen~ Chen Jianjun~ Ren Xinjian~ 《中国稀土学报(英文版)》2006,24(5):640-640
~~Internal Friction and Profile of Property and Structure of PD_3 and PD_3RE Rail Steels 相似文献
10.
Viscosity and Viscosity Estimate Model of Fluoride-free and Titanium-Bearing Mold Fluxes 总被引:1,自引:0,他引:1
The relationship between the binary basicity (CaO/SiO2),TiO2,Na2O,Li2O,MgO,MnO,B2O3 and viscosity for fluoride-free and titanium-bearing mold fluxes were systematically researched. The rotating cylinder method was employed in the experiment to measure the viscosity of the slag. The results indicate that Li2O, B2O3 and Na2O play major roles in decreasing viscosity, especially Li2O, which is the most effective flux, while MgO and MnO exert little influence on viscosity. Meanwhile, it can be concluded that with increasing TiO2 content, the viscosity of fluoride-free and titanium-bearing mold fluxes increases at first but then falls when the amount of TiO2 is greater than 6.0%. Based on large amounts of experimental statistics of the viscosity of fluoride-free and titanium-bearing mold fluxes, an available model in literature for predicting the mold-slag viscosity was modified. This modified model can be used to predict the viscosity of fluoride-free and titanium-bearing mold fluxes. In fact, the predicted values approximate the observed values with a ±10.6% average deviation. Compared with the classical models,the average deviation is higher and it was found that the modified model can be used to estimate the viscosity of fluoride-free and titanium-bearing mold fluxes. 相似文献
11.
The Bax-0.05MgAl10O16 x :Eu0.05^2 (0.88≤ x≤ 1.02) phosphors with different Ba^2 content and the Ba0.85MgAl10O16.94:Eu0.05^2 phosphors with different fluxes (BaF2, MgF2, AlF3, BaCl2, MgCl2, AlCl3, H3BO3)were prepared by high temperature solid-state reaction method and their luminescence characteristics were studied under 254 nm excitation and vacuum ultraviolet (VUV) excitation. With the increase of the Ba^2 content, there is an increase in the emission intensity, and when x = 0.94, it reaches a maximum. Then, as the Ba^2 content increases, the emission intensity slowly falls. The fluorides have better flux-effects than chlorides and H3BO3. The possible mechanism in the process of particle growth was discussed when fluorides were used as fluxes. The effect of the activator concentration on this system was also investigated. The quenching concentration is 0.13 mol in per mole host. 相似文献
12.
A finite-element formulation is developed for analyzing flutter instability and buffeting response of long-span bridges and their interaction. The flutter derivatives, instead of the indicial functions used by previous researchers, are applied in the random parametric excitation (RPE) analysis. This application makes finite-element formulation possible and results in much less computational effort in RPE analysis than those of previous analyses. With the finite-element program developed in the present study, as many modes as desired can be easily included in the flutter and buffeting analyses. Users have the choice of RPE or eigenvalue method for flutter analysis and RPE or spectral method for buffeting analysis. 相似文献
13.
The interactions of La(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), and Yb(Ⅲ) with cytosine, 5-bromocytosine, 5-azacytosine and 5-flurocytosine as primary ligands (L) and guanine (A) as secondary ligand for both binary (1:1) as well as ternary (1:1:1) systems were investigated by potentiometric equilibrium measurements at 25, 35 and 45 ℃ in aqueous solution (ionic strength, μ=0.1 mol·dm-3 NaNO3). The stability constants of the binary (1:1) and ternary (1:1:1) metal-ligand complexes follow the following order La<Pr<Nd<Sm<Eu>Gd<Dy>Yb. Results also indicate that the ternary lanthanide complexes of La(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), and Yb(Ⅲ) are more stable than corresponding binary lanthanide complexes. The enthalpy (Δhof) and entropy (Δsof) changes for the formation of binary and ternary complexes were calculated from temperature coefficient data. The ΔΔSof values are positive for all the metal ligand systems. The negative ΔΔHof values indicate the extra stability of the ternary complexes by the exothermic enthalpy changes (ΔΔSof=ΔTSof-ΔBSof and ΔΔHof=ΔTHof-ΔBHof where ΔTSof, ΔTHof and ΔBSof, ΔBHof are the entropy and enthalpy values associated with the ternary and binary complexes, respectively). It was also proposed that the guanine is bonded to metal ions through N1/C6=O and N7 whereas cytosine and its derivatives are bonded through N3 atoms in ternary complexes. 相似文献
14.
Interaction between Eu-phenylalanine and DNA Using Cyclic Voltammetry and UV Spectroscopy 总被引:5,自引:0,他引:5
InteractionbetwenEuphenylalanineandDNAUsingCyclicVoltammetryandUVSpectroscopyShenHebai(沈鹤柏),KuaiLiheng(蒯丽衡),NiLihua(倪丽华),... 相似文献
15.
A. Grigor'ev 《Metallurgist》1975,19(5):339-343
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17.
Essia Hannachi Yassine Slimani Muhammad Nawaz R.Sivakumar Zayneb Trabelsi R.Vignesh Sultan Akhtar Munirah A.Almessiere Abdulhadi Baykal Ghulam Yasin 《中国稀土学报(英文版)》2023,41(5):682-688
Yttrium(Y) and cerium(Ce) co-doped ZnO nanoparticles(NPs) were synthesized via the simple sol-gel auto-combustion route.The effect of Ce and Y doping on the structure,morphology,optical,Zeta potential,and photocatalytic activities of ZnO NPs was examined by Fourier transform infrared(FTIR)spectrometer,X-ray diffraction(XRD),transmission electron microscope(TEM),UV-vis spectrophotometer,and Zetasizer instrument.XRD data show that the fabricated samples crystallize into a hexagonal wurtzite struct... 相似文献
18.
┌─────────────┬───────────────┬─────────────┐│Name │lmPo代 │ExPort ││ ├───────┬───────┼──────┬──────┤│ │Quant勺 │V匕IUe │Quan幼fy │V白.U6 │├─────────────┼───────┼───────┼──────┼──────┤│Silver Powder │125,729223 │24,971,146 │1,757.190 │248,1 61 │├─────────────┼───────┼───────┼──────┼──────┤│Unwrought 5.扮erl … 相似文献
19.
Itiswellknownthatreductionofparticlesizeofcrystallinesystemcanresultinremarkablemodifica tionoftheirpropertieswhicharedifferentfromthoseofbulkbecauseofhighsurfacetovolumeratioandquan tumconfinementeffectofnanometermaterials .In1994 ,Bhargavaetal .reportedthatradiativetransi tionrateofMn2 ionsinZnSnanocrystalincreasedsixorderincomparisonwithbulkone[1] .Despitethisre sultwasstronglycriticizedlater ,studiesonnanosizedluminescentsemiconductorattractedgreatinter ests[2~ 4 ] .Sincecompoundsofra… 相似文献
20.
Recently, five domestic lead and zinc produc-ers, including the Huludao Zinc Smelter,Zhuzhou Torch Group Limited, China MetalsLingnan, Baiyin Nonferrous Metals Co., Ltd.and Shuikoushan Co., Ltd., have submitted ajoint proposal to the central government inrespect of the fast growth of lead and zincimport, demanding that the preferential taxpolicy on the border trade of lead and zinc berescinded so as to provide a fair and equal tradeenvironment for international and domesticbusinesses of the industry. 相似文献