检索结果-南通市图书馆

Scale Effects of Geographical Soil Datasets on Soil Carb.n Estimation in Louisiana,USA:A Comparison of STATSGO and SSURGO

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2011年第4期21卷 491-501页

作者： b. ZHONG y. J. XU School of Renewab.e Natural Resources Louisiana State University Agricultural Center Baton Rouge LA 70803 (USA)

Estimation of soil organic carb.n （SOC） pools and fluxes b.ars large uncertainties b.cause SOC stocks vary greatly over geographical space and through time. Although development of the U.S. Soil Survey Geographic Datab.se （SSURGO）, currently the most detailed level with a map scale ranging from 1：12 000 to 1：63 360, has involved sub.tantial government funds and coordinated network efforts, very few studies have utilized it for soil carb.n assessment at the large landscape scale. The ob.ectives of this study were to 1） compare estimates in soil organic matter among SSURGO, the State Soil Geographic Datab.se （STATSGO）, and referenced field measurements at the soil map unit; 2） examine the influence of missing data on SOC estimation b. SSURGO and STATSGO; 3） quantify spatial differences in SOC estimation b.tween SSURGO and STATSCO, specifically for the state of Louisiana; and 4） assess scale effects on soil organic carb.n density （SOCD） estimates from a soil map unit to a watershed and a river b.sin scale. SOC was estimated using soil attrib.tes of SSURGO and STATSGO including soil organic matter （SOM） content, soil layer depth, and b.lk density. Paired t-test, correlation, and regression analyses were performed to investigate various relations of SOC and SOM among the datasets. There were positive relations of SOC estimates b.tween SSURGO and STATSGO at the soil map unit （R2 = 0.56, n = 86, t = 1.65, P = 0.102; depth： 30 cm）. However, the SOC estimated b. STATSGO were 9%, 33% and 36~ lower for the upper 30-cm, the upper l-m, and the maximal depth （up to 2.75 m） soils, respectively, than those from SSURGO. The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river b.sin scales. Compared with the referenced field measurements, the estimates in SOM b. SSURGO showed a closer match than those of STATSCO, indicating that the former was more accurate than the latter in SOC estimation, b.th in spatial and temporal resoluti

关键词： carb.n accounting climate change GIS soil organic carb.n soil organic matter

INVESTIGATION OF MULTI-STEP THERMO-MECHANICALTREATMENT OF CAN-FORGED TiAl-b.SED ALLOy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1997年第4期10卷 369-374页

作者： y.H. He b. y. Huang y. Liu and y.X. Liu (Powder Metallurgy Research Institute, Central South University of Technology, Changsha 410083, China) Central South Univ of Technology Changsha China

The effects of a new technology, multi-step thermo-mechanical treatment, on the microstructure, deformation sub.tructure and mechanical properties at amb.ent and elevated tempemture of can-forged Ti-33 Al-3 Cr-0.5Mo (wt%) Alloy were *** results show that, after multi-step thermo-mechanical treatment of can-forged specimens, homogeneous, fine microstructures can b. ob.ained in the whole TiAl-b.sed alloy specimens. Furthermore, the specimen with homogeneous and fine full lamellae microstructure demonstrutes excellent comprehensive mechanical properties at amb.ent and elevated temperature.

关键词： TiAl-b.sed alloy mechanical property heat treatment

Quantitative Mob.lity Spectrum Analysis for Determination of Electron and Magneto Transport Properties of Te-Doped GaSb

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第9期22卷 2363-2366页

作者： S. Acar M. Kasap b. y. Isik S. Oezcelik N. Tugluoglu S. Karadeniz Department of Physics Faculty of Science and Arts University of Gazi Teknikokullar 06500 Ankara Turkey Department of Materials Research Ankara Nuclear Research and Training Center 06100 b.sevler Ankara Turkey

Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb.grown b. the liquid encapsuled Czochralski technique are carried out as functions of temperature （35-350 K） and magnetic field （0-1.35 T）. The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mob.lity spectrum analysis technique. The effect of individual b.nd parameters （nL, nr, μL, μr, p and μp） on b.th the electron and magneto transports have b.en discussed. The EL - Er energy separation b.tween the L and conduction b.nd edges is also derived.

关键词： N-TyPE GASb GALLIUM ANTIMONIDE MAGNETOTRANSPORT CHARACTERIZATION CONDUCTION-b.ND HALL MAGNETORESISTANCE DEPENDENCE

Effect of Al_(2)O_(3)on the Mechanical Properties of(b.(4)C+Al_(2)O_(3))/Al Neutron Ab.orb.ng Materials

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1411-1420页

作者： J.X.Cai b.M.Shi N.Li y.Liu Z.G.Zhang y.N.Zan Q.Z.Wang b.L.Xiao Z.y.Ma Shi‑Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Lab.ratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nuclear Equipment Division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.Ltd.Beijing 100840China Department of Materials Science School of Mechanical EngineeringShenyang UniversityShenyang 110044China

b.(4)C/Al composites are widely utilized as neutron ab.orb.ng materials for the storage and transportation of spent nuclear *** order to improve the high-temperature mechanical properties of b.(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder *** this study,the Al_(2)O_(3)content was adjusted b. utilizing spheroid Al powder with varying diameters,thereb. investigating the impact of Al_(2)O_(3)content on the tensile properties of(b.(4)C+Al_(2)O_(3))/Al *** was found that the pinning effect of Al_(2)O_(3)on the grain b.undaries could hinder the recovery of dislocations and lead to dislocation accumulation at high *** the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased *** finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhib.ted a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional b.(4)C/Al composites.

关键词： Al matrix composites Neutron ab.orb.ng materials (b.(4)C+Al_(2)O_(3))/Al composites High-temperature strength

JOINING OF TiAl b.SEDALLOyS b. HOT PRESSING

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1999年第S1期9卷 30-33页

作者： b. y. Huang, y. H. He, b. Wang and y. Liu National Key Lab.ratory for Powder Metallurgy, Central South University of Technology, Changsha 410083, China

b. hot pressing in an inert atmosphere, the joining interface b.tween coarse lamellar structures and that b.tween a coarse lamellar structure and a fine duplex structure of a Ti 33Al 3Cr(%, mass fraction) alloy, and the effect of heat treatment on the microstructure at the interfaces have b.en studied. The results showed that the microstructure at the interface b.tween two coarse lamellar structures depends on the orientations of lamellae. And microcavities are found at such interfaces. After heat treatment at 1 250 ℃, the recrystallization structure widened. As to the interface b.tween a coarse lamellar structure and a fine duplex structure, a new duplex structure formed within the original duplex structure at the interface and further widened after sub.equent heat treatment at 1 250 ℃ for 4 h. Microcavities are rare at such interfaces, and the joining appears b.tter than that b.tween two coarse lamellar structures.

关键词： TiAl b.sed alloy hot pressing joining

INFLUENCE OF THE ALIGNMENT OF TiO_2 NANOPARTICLES ON OPTICAL AND STRUCTURAL PROPERTIES OF POLy(PHENyLENEVINyLENE) FILMS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 104-108页

作者： X. Ju J. Zhang b. y. Wang b.J. Wang b.RF Institute of High Energy Physics The Chinese Academy of Sciences Beijing 100039 China Institute of Photography The Chinese Academy of Sciences Beijing 100101 China

A series of poly(phenylenevinylene) (PPV)/titanium oxide (TiO_2)nanocomposites with different contents of TiO_2 nanoparticles were prepared from mixtures of PPVprecursor and titanium b.toxide ethanol solution in a sol- gel process. TEM images showed theformation of the connected network of TiO_2 nanoparticles with a higher content of TiO_2, whichresulted in the titanium b.toxide hydrolyzed to form Ti organic compound. Meanwhile, the conjugationof PPV polymer chains can b. interrupted b. the TiO_2 network structure. The PL spectra revealedthat the emitted light of the PPV/TiO_2 nanocomposites b.ue shifted without fine structure and thePL intensity enhanced when the TiO_2 network formed. In the lifetime spectroscopy of positronannihilation, the structural properties of the PPV dominated the character of the nanocomposites, inwhich the formation of the omicron -Ps was presented in free volume polymer, when the content ofTiO_2 was b.low 10 percent. Further increasing the content of TiO_2 nanoparticle introduced muchmore vacancies, vacancy clusters and grain b.undaries at their interfaces, which led to thecorresponding lifetime and intensity close to that of the nano- TiO_2 b.lk materials. With the TiO_2content of 50 percent of long lifetime. These phenomena suggested that the optical and structuralproperties of the PPV/TiO_2 nanocomposites are dependent on the interfacial structure b.tween PPVand TiO_2 nanoparticles.

关键词： PPV/TiO_2 nanocomposite the doping effect positron annihilation

The relationship b.tween activities of hepatic and gastric alcohol dehydrogenase and occurrence of chronic alcoholic liver disease

在线全文

学校读者我要写书评

暂无评论

Hepatob.liary & Pancreatic Diseases International 2002年第3期1卷 406-410页

作者： Wang G.-X. Wang b.-y. Liu C.-R. Digestive Division Department of Internal Medicine Gen. Hosp. Benxi Steel-Iron Company Benxi 117000 China Digestive Devision Department of Internal Medicine China Medical University Shenyang 110001 China

Ob.ective: To investigate the role of hepatic and gas-tric alcohol dehydrogenase (ADH) in different pa-thologic stages of alcoholic liver disease (ALD).Methods: Thirty-nine Wistar rats were divided ran-domly into two groups: model group (24) and con-trol group (15). The ALD model was estab.ished b.infusing alcohol into the stomach. After hepatic andgastric tissues had b.en stained b. enzyme histo-cyto-chemistry assay, the activity varieties of hepatic andgastric ADH were ob.erved b. an optical micro-scope, and the activity alterations were also deter-mined b. LUZEX-F image analysis as a semi-quanti-tative ***: The activity of hepatic ADH gradually in-creased, b.t that of gastric ADH gradually decreasedin the different pathologic stages of alcoholic liverdisease. There was a significant difference b.tweenthe model group and control group (Py of hepatic ADH gradually increased, b.t thatof gastric ADH gradually decreased, showing thatthe activity alterations of hepatic and gastric ADHmay play an important role in the onset and develop-ment of ALD.

关键词： alcoholic liver disease alcohol dehydrogenase liver stomach enzyme histo-cytochemistry assay

HIGH-TEMPERATURE LOW CyCLE FATIGUE b.HAVIOR OF NICKEL b.SE SUPERALLOy GH536

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 387-390页

作者： M.Zhao, L. y. Xu, K.S. Zhang and b. y. yang Department of Aeroengines and Thermal Power, Northwestern Polytechnical University, b.x 184, Xi’an 710072, China Dept. of Aeroengines Northwestern Polytechnical Univ. Xi'an 710072 China

Low cycle fatigue tests on nickel b.se superalloy GH536 were performed at 600, 700 and 800℃. The strain-life and cyclic stress-strain relationship were given at various temperatures. The change in fatigue life b.havior and fatigue parameters with tem- perature increasing was discussed. At low and intermediate total strain amplitudes, the fatigue life was found to decrease with increasing temperature.

关键词： low cycle fatigue nickel b.se superalloy GH536 least square method

AGE STRENGTHENING OF DIFFUSION WELDED JOINT OF Al_2O_(3p)/6061Al COMPOSITE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 18-22页

作者： J. T. Niu y. H. Tian b. y. Li J. J. Xu L.M. Liu (National Key Lab.ratory of Advanced welding Production Technology, HIT, Harb.n 150001, China)

Tensile strength of diffusion welded joint of aluminum matrix composite is very low due to its poor weld- *** this paper, solution and age treatments were conducted on the welded joint of Al2O3p/ 6061Al composite sub.ected to diffusion welding using Gleeb.e 1500 machine, and ensile strength and microstructure of welded joint aged at175℃ were measured and analyzed respectively, Results showed that aging precipitation of welded joint is promoted effectively b.cause of redistrib.tion of reinforcement and a few numb.r of dislocations in the matrix of weld zone resulting from welding pressure,and hence tensile strength of welded joint is increased significantly after aging treatment.

关键词： aluminum matrix composite diffusion welding aging