检索结果-南通市图书馆

Chin.se Journ.l Of Geochemistry 2009年第3期28卷 248-257页

作者： Ekere E. Ukwan. barth n. ekwueme Departmen. of Geology P.M.B. 1115CalabarNigeria

The trace elemen.s characteristics of the migmatitic gn.isses (biotite-garn.tan. horn.len.e-biotite), gran.lite facies rocks (charn.ckitic gn.isses) an. meta-peridotite in.the area of Southwest Obudu Plateau in.icate that the area exhibits a high degree of geochemical variability. Compatible trace elemen.s (n. an. Cr) are comparatively high in.the gran.lite facies rocks an. meta-peridotite. n. ran.es from 28×10-6 to 266×10-6 whilst Cr ran.es from 62×10-6 to 481×10-6 for the gran.lite facies rocks (charn.ckitic gn.isses), an. for the meta-peridotite n. varies between.2045×10-6 an. 2060×10-6. In.ompatible trace elemen.s show a higher variability in.these rocks. The rocks in.the area of Southwest Obudu Plateau gen.rally are characterized by the high con.en.ration. of Ba, Ce, Sr, Rb, Ga, n., Cr, Co, Zr, Pr an. moderate con.en.ration. of Cu, Sm an. Th. The available data show that the charn.ckitic gn.isses are of lower crustal origin. The en.ichmen. of the meta-peridotite in.compatible trace elemen.s suggests the primitive man.le would be the source region. with slight con.amin.tion.durin. ascen.. These diverse origin. collaborate the tecton.c settin. of the area as shown.by discrimin.tion.diagrams. The diverse tecton.c settin.s ran.e from arc to collision.l. Alkalin. to sub-alkalin. magmatism in.the area was probably con.emporan.ous with the tecton.c even.s that occurred in.the area durin. the Proterozoic.

关键词：元素地球化学麻粒岩相高原地区岩石西南尼日利亚构造特征东南部

Min.ralization.of pegmatites in.parts of the Oban.Massif,Southeastern.n.geria:A prelimin.ry an.lysis

在线全文

学校读者我要写书评

暂无评论

Chin.se Journ.l Of Geochemistry 2009年第2期28卷 146-153页

作者： Kin.sley A.Ero ekwueme barth n. Departmen. of Geology University of CalabarP.O.Box 3651 Unical Post OfficeCalabarNigeria

The Oban.Basemen. Massif of southeastern.n.geria is composed of metamorphosed rocks in.ludin. phyllites, schists, gn.isses an. amphibolites cut by pegmatitic dykes of varyin. len.th an. thickn.ss, which in.ruded the metamorphic rocks. Prelimin.ry geochemical study an. an.lysis of these pegmatites from western.Oban.Massif at Uyan.a, Akwa Ibami, Iwuru I, Iwuru Ⅱ an. Igbofia showed that the pegmatites are highly albitized. This is in.on.sisten. with earlier postulation. that the pegmatites in.this part of n.geria are barren. In.ices of fraction.tion.such as Ba/Rb, K/Rb, n./K, K/Cs, K/Ba reveal that the pegmatites are min.ralized an. differen. discrimin.tion.plots show that they are en.iched in.Li, Be, Sn. Ba, Ta, n., Cs, Sn.an. Zn. Rare metal in.icative elemen.s such as Ta, n., Rb, Cs, an. Sn.are en.iched in.the pegmatites, con.irmin. that the pegmatites are min.ralized.

关键词：尼日利亚地块矿化化学研究稀有金属变质岩岩石包东南部

Sin.le zircon.evaporation.ages: Eviden.e for the Mesoproterozoic crust in.the southeastern.n.gerian.basemen. complex

在线全文

学校读者我要写书评

暂无评论

Chin.se Journ.l Of Geochemistry 2012年第1期31卷 48-54页

作者： Ekere E.Ukwan. barth n.ekwueme Alfred Krn.r Departmen. of Geology University of CalabarEtta AgborP.M.B.1115 CalabarNigeria In.titut fur Geowissen.chaften Universitat MainzGermany

The Ukwortun. area of the Obudu Plateau exposes high-grade metamorphic rocks of upper amphibolite to gran.lite facies. Zircon.grain. from three location. of Southwest Obudu Plateau were dated by the Pb-Pb datin. method. This sin.le zircon.radiometric datin. method con.irms the occurren.e of Mesoproterozoic crust in.the southeastern.n.geria basemen. complex. The pyroxen. gn.iss (gran.lite facies) sample from Biereberi n.ar Ukpe yielded a mean.age of 2061.4±0.4 Ma, suggestin. the presen.e of Paleoproterozoic crust. The combin.d 207Pb/206Pb ratios from the garn.t-biotite gn.iss in.the area gave a mean.age of 1794.4±0.4 Ma. This further con.irms the pres-en.e of Paleoproterozoic crustal compon.n.s within.the Obudu Plateau. The Mesoproterozoic (1548.8±0.5 Ma) an. n.oproterozoic (619.8±0.9 Ma) ages were obtain.d from two population. of zircon.grain. from the leucogran.te in.Okordem, Southwest Obudu. These "sign.tures" collaborate the occurren.e of Mesoproterozoic ages in.the Afar region.an. Cameroon.basemen.s alon. with the southeastern.n.gerian.basemen. complex, con.titutin. the major portion.of the West Cen.ral African.mobile belt. The zircon.age of 1794.4±0.4 Ma may probably be the maximum deposition.l age of the meta-sedimen. (garn.t-biotite gn.iss) an. the age of 1548.8±0.5 Ma may be in.erpreted as the time of emplacemen. of the gran.toid. The n.oproterozoic age (619.8±0.9 Ma) probably records the metamorphic even. that was prevalen. durin. the Pan.African.period an. thus affected the area.

关键词：单颗粒锆石平均年龄地壳成分中元古代尼日利亚地下室东南部证据

Petrogen.sis an. geotecton.c settin. of the Pan.African.basemen. rocks in.Bamen.a Massif, Obudu Plateau, southeastern.n.geria: Eviden.e from trace elemen. geochemistry

在线全文

学校读者我要写书评

暂无评论

Chin.se Journ.l Of Geochemistry 2006年第2期25卷 122-131页

作者： UKAEGBU V.U ekwueme B.n Departmen. of Geology University of Port Harcourt Port Harcourt Nigeria Departmen. of Geology University of Calabar Calabar Nigeria

The rocks of the Obudu Plateau ran.e from high-grade metagreywacke-pelite sequen.e to metaign.ous (gran.tic to tholeiitic) an. polymagmatic (calc-alkalin. gran.tic to olivin. tholeiitic) ign.ous rocks. Several co-varian.e diagrams an. other parameters in.icate that the trace elemen.s of rocks in.southern.Obudu Plateau exhibit systematic variation. an. suggest highly heterogen.ous protoliths. The tecton.c settin. of the rocks in.icates riftin. an. collision.l to n.n.orogen.c emplacemen.s in.ocean.c to en.ialic en.iron.en.s. The calc-alkalin. an. tholeiitic n.ture of the magmatism as well as the greywacke-pelite sequen.e is suggestive of an.An.ean.type con.in.n.al en.iron.en..

关键词：微量元素岩石成因论地壳构造花岗岩橄榄石

Petrogen.tic sign.fican.e of rare-earth elemen. behavior in.the basemen. rocks of southern.Obudu Plateau, Bamen.a Massif, southeastern.n.geria

在线全文

学校读者我要写书评

暂无评论

Chin.se Journ.l Of Geochemistry 2005年第2期24卷 129-135页

作者： UKAEGBU V.U. ekwueme B.n. Departmen. of Geology University of Port Harcourt Port Harcourt NigeriaDepartment of Geology University of Calabar Calabar Nigeria.

Rock samples represen.in. various ign.ous an. metamorphic rocks of southern.Obudu Plateau were an.lyzed for rare-earth elemen. (REE) behavior by ICP-MS. Results of the an.lyses in.icate a ran.e of REE abun.an.es an. distin.tive pattern. from highly fraction.ted pattern. with n.gative Eu an.malies in.gran.tic rocks to relatively low abun.an.es an. less REE fraction.ted flat pattern. with little Eu an.maly in.some paragn.isses, schists, en.erbites an. dolerites to un.raction.ted pattern. with positive Eu an.malies in.some paragn.isses an. charn.ckites. Over all, there are low to high ∑REE con.en.s with n.gative to positive Eu an.malies. The ratios of differen. parameters, especially La/Yb an. Ce/Yb, show behaviors con.isten. with crustal to man.le derivation. The heterogen.ity of REE abun.an.es an. REE pattern. reflects man.le to crustal petrogen.tic variation. of differen. rock suites on.the Plateau. The LREE con.en. is higher than.the HREE con.en. in.the highly differen.iated rocks, as eviden.ed by their La/Yb, Ce/Yb an. La/Sm ratios, which are n.rmally higher in.residual products than.in.primary melts. The domin.n.ly in.ermediate n.ture of the source rock of the orthogn.isses is suggested by the gen.rally low {∑REE}. The gran.tes en.iched in.LREE an. depleted in.HREE an. some of the charn.ckites with n.gative Eu an.malies were probably formed by partial meltin. an. crystallization.

关键词：稀土元素地球化学丰度 Obudu高原变质岩

Quality vs. quan.ity of publication. in.n.n.techn.logy field from the People’s Republic of Chin.

在线全文

学校读者我要写书评

暂无评论

Chin.se Scien.e Bulletin 2008年第8期53卷 1272-1280页

作者： Ron.ld n. KOSTOFF Ryan.B. barth Clifford G. Y. LAU Office of n.val Research 875 N. Randolph St. Arlington 22217 VA USA DDL-OMn. En.in.erin. LLC 8260 Greensboro Drive Suite 600 McLean VA USA In.titute for Defen.e An.lyses 4850 Mark Center Drive Alexandria VA USA

This study evaluates tren.s in.quality of n.n.techn.logy an. n.n.scien.e papers produced by au- thors from the People’s Republic of Chin. (PRC). The metric used to gauge quality is ratio of highly cited n.n.techn.logy papers to total n.n.techn.logy papers produced in.sequen.ial time frames. The USA is both the most prolific n.n.techn.logy publishin. coun.ry an. most represen.ed coun.ry on.highly cited n.n.techn.logy papers (both in.absolute n.mbers of highly cited papers an. highly cited papers relative to total publication.) over the 1998―2003 time frame, based on.the SCI/SSCI databases. Some of the smaller hi-tech coun.ries have relatively high ratios (~2) of highly cited papers to total publication. (e.g. Den.ark, n.therlan.s, Switzerlan.). Coun.ries that have exhibited rapid growth in.SCI/SSCI n.n.techn.logy paper production.in.recen. years (e.g. PRC, South Korea) had ratios an.order of magn.tude less than.that of the USA for 1998, but by 2003 had in.reased to about 20% that of the USA (~2.5). PRC an. South Korea have climbed in.the publication. ran.in.s from 6th an. 9th in.1998, re- spectively, to 2n. an. 6th in.2005, respectively. PRC’s ratio mon.ton.cally in.reased from 0.16 to 0.45 over the 1998―2003 period, an. South Korea’s ratio in.reased from 0.11 to about 0.6 over that same period, in.icatin. their papers are gettin. more an. more citation. proportion.tely. Thus, un.er rapid growth con.ition., PRC an. South Korea have been.able to in.rease their share of participation.in.highly cited papers. As of 2003, PRC an. South Korea have ratios comparable to n.tion. like Japan. Fran.e, Italy, an. Australia but n.t yet approachin. those of the highly cited coun.ries. n.n. of the top ten.publication. producin. in.titution. are from the USA, while all of the top ten.highly cited publica- tion. producers are from the USA. Over the 1998―2003 time period, the top six total publication. pro- ducin. in.titution. (globally) remain.d the same, with Chin.se Academy of Scien

关键词：纳米技术纳米科学引用分析中国

Optimizin. n.trogen.Use Efficien.y for n.-Till Corn.Production.by Improvin. Root Growth an. Capturin. n._(3)-n.in.Subsoil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2016年第4期26卷 474-485页

作者： Eduardo F. CAIRES Ren.to ZARDO FILHO Gabriel barth Helio A. W. JORIS Departmen. of Soil Scien.e an. Agricultural En.in.erin. State University of Ponta Grossa Ponta Grossa 84030-900 Green.Circle Growers 51051 US FIighway 20 Oberlin OH 44074 ABC Foun.ation.Research an. Agricultural Developmen. Castro 84165-700

Subsoil acidity restricts root growth an. reduces crop yields in.man. parts of the world. More than.half of the fertilizer n.trogen.n. applied in.crop production.is curren.ly lost to the en.iron.en.. This study aimed to in.estigate the effect of gypsum application.on.the efficien.y of n.fertilizer in.n.-till corn.Zea mays L.) production.in.southern.Brazil. A field experimen. examin.d the effects of surface-applied gypsum(0, 5, 10, an. 15 Mg ha^(-1)) an. top-dressed ammon.um n.trate(n._4n._3)(60, 120, an. 180 kg n.ha^(-1)) on.corn.root len.th, n.uptake, an. grain.yield. A green.ouse experimen. was con.ucted usin. un.isturbed soil column. collected from the field experimen. site to evaluate n._3-n.leachin., n.uptake, an. root len.th with surface-applied gypsum(0 an. 10 Mg ha^(-1)) an. top-dressed n._4n._3(0 an. 180 kg n.ha^(-1)). Amelioration.of subsoil acidity due to gypsum application.in.reased corn.root growth,n.uptake, grain.yield, an. n.use efficien.y. Applyin. gypsum to the soil surface in.reased corn.grain.yield by 19%–38% an. partial factor productivity of n.PFPn. by 27%–38%, depen.in. on.the n.application.rate. Results of the un.isturbed soil column.green.ouse experimen. showed that improvemen. of n.use efficien.y by gypsum application.was due to the higher n.uptake from n._3-n.in.the subsoil as a result of in.reased corn.root len.th. Our results suggest that amelioratin. subsoil acidity with gypsum in.a n.-till corn.system could in.rease n.use efficien.y, improve grain.yield, an. reduce en.iron.en.al risks due to n._3-n.leachin..

关键词： ammon.um n.trate grain.yield n.uptake n.trate leachin. partial factor productivity of n.trogen soil acidity

Cure Characteristics an. Mechan.cal Properties of Pin.apple Leaf Fibre Filled n.tural Rubber

在线全文

学校读者我要写书评

暂无评论

Journ.l of Min.rals an. Materials Characterization.an. En.in.erin. 2018年第6期6卷 601-617页

作者： Chin.n.e C. ekwueme Isaac O. Igwe Departmen. of Polymer an. Textile En.in.erin. Federal University of Technology Owerri Nigeria

The cure characteristics an. mechan.cal properties of n.tural rubber filled with pin.apple leaf fibre (PLF) were studied at differen. filler con.en.s an. particle sizes. The PLF was characterized for filler properties while carbon.black (n.30) served as the referen.e filler. The n.tural rubber vulcan.zates were compoun.ed on.a two-roll mill. Results showed that PLF (300 μm) filled n.tural rubber vulcan.zates exhibited the highest maximum torque (Tmax) (47.04 lb-in. at filler con.en., 10 phr amon. the filler particle sizes in.estigated. The min.mum torque (Tmin. of the vulcan.zates gen.rally in.reased with the in.rease in.filler con.en.s an. particle sizes. The scorch times of the rubber vulcan.zates did n.t vary with fibre con.en. while the cure times of PLF (300 μm) filled rubber vulcan.zates decreased with filler con.en.. The ten.ile stren.th (TS) of PLF (150 μm) filled n.tural rubber vulcan.zates gen.rally in.reased with the in.rease in.filler con.en. whereas the ten.ile modulus of the rubber vulcan.zates decreased steadily with in.reasin. filler particle size at filler con.en.s, 5 an. 30 phr. The elon.ation.at break (EB) of the rubber vulcan.zates exhibited n. gen.ral order of variation.with filler con.en. an. particle size, an. was gen.rally greater than.that of un.illed n.tural rubber. The flexural stren.th of the rubber vulcan.zates in.reased with in.reasin. filler particle size at filler con.en.s, 20 an. 40 phr. The addition.of PLF an. carbon.black improved the compression.stren.th of the rubber vulcan.zates, an. which for PLF (300 μm) an. CB fillers gen.rally in.reased with the in.rease in.filler con.en.. The study has demon.trated the en.an.emen. of properties of n.tural rubber vulcan.zates on.in.orporation.of PLF in.o n.tural rubber, however, the property en.an.emen.s obtain.d were less than.those recorded for CB filled n.tural rubber vulcan.zates.

关键词： n.tural Rubber Pin.apple Leaf Fibre Carbon Black Mechan.cal Properties Cure Characteristics

Validation.of the clin.cal tuberculosis screen.n. algorithm used in.n.gerian.n.tion.l tuberculosis con.rol programme for screen.n. people livin. with HIV

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

Health 2013年第11期5卷 1737-1741页

作者： Emman.el n. Aguwa Chika n. On.asigwe Joseph n. Chukwu Dan.el C. Oshi Charles C. n.afor Babatun.e I. Omotowo An.e C. n.u An.hon. O. Meka Osa-Eloka C. ekwueme n.achukwu C. Ugwun.a Moses C. An.im Departmen. of Commun.ty Medicin. University of Nigeria Nsukka Nigeria Departmen. of Commun.ty Medicin. University of Nigeria Nsukka Nigeria German.Leprosy an. Tuberculosis Relief Association Enugu Nigeria

Backgroun.: In.high HIV prevalen.e, tuberculosis diagn.sis is challen.in.. Some coun.ries hen.e use clin.cal algorithms to screen.for tuberculosis in.People Livin. with HIV (PLHIV). Objectives: The aim of the study was to validate the n.tion.l algorithm for clin.cal tuberculosis screen.n. of person. livin. with HIV who atten. comprehen.ive HIV clin.cs. Methods: A cross-section.l study of PLHIV who presen.ed with cough of at least 2 weeks duration.between.2009 an. 2011 at St Patrick’s Hospital, Ebon.i State, n.geria. Sputum smear microscopy for acid fast bacilli was obtain.d from the participan.s. Results: Three hun.red an. twelve PLHIV were studied: 146 (46.8%) males an. 166 (53.2%) females. On.y 55 (17.6%) of the participan.s had smear positive pulmon.ry tuberculosis. Weight loss (c2 = 2.33;P = 0.127), hemoptysis (c2 = 0.03;P = 0.864), n.ght sweats (c2 = 1.52;P = 0.218), fever (c2 = 3.49;P = 0.06), an.rexia (c2 = 0.49;P = 0.484), chest pain.(c2 = 2.48;P = 0.115), breathlessn.ss (c2 = 0.63;P = 0.426) were n.t sign.fican. in.PLHWA with/without pulmon.ry tuberculosis. Cough, fever, n.ght sweat an. weight loss combin.d gave a sen.itivity of 97.0%, specificity of 10.9%, n.gative predictive value (n.V) of 93.3% an. positive predictive value (PPV) of 21.8%. Con.lusion. Fin.in.s suggest that though n.tion.l screen.n. algorithm is a valid tool to screen.for tuberculosis in.PLHIV, it will lead to man. false positive results.

关键词： HIV Tuberculosis PLHIV Screen.n. Tool Validation

En.-Use Properties of Pin.apple Leaf Fibre Filled n.tural Rubber

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

Journ.l of Min.rals an. Materials Characterization.an. En.in.erin. 2019年第6期7卷 435-445页

作者： Chin.n.e C. ekwueme Isaac O. Igwe An.kwute O. Vivian Departmen. of Polymer an. Textile En.in.erin. Federal University of Technology Owerri Nigeria

The effects of in.orporatin. pin.apple leaf fibre (PLF) as a filler on.the en.-en. properties of n.tural rubber vulcan.zates were studied at differen. filler con.en.s an. particle sizes. The pin.apple leaf fibre was used within.filler con.en.s, 0 to 40 phr at the followin. filler particle sizes, 75, 150 an. 300 μm. The PLF was characterized for filler properties while carbon.black (n.30) served as the referen.e filler. The n.tural rubber vulcan.zates were compoun.ed on.a two-roll mill. Results showed that the abrasion.resistan.e of filled n.tural rubber vulcan.zates was gen.rally higher than.that of the un.illed n.tural rubber vulcan.zate at filler con.en., 5 phr, an. for PLF (150 an. 300 μm) an. carbon.black filled n.tural rubber vulcan.zates, the abrasion.resistan.e decreased within.filler con.en., 5 to 20 phr after which it in.reased with filler con.en.. CB exhibited better abrasion.resistan.e in.the vulcan.zates than.PLF at filler con.en.s greater than.20 phr. The hardn.ss of filled n.tural rubber vulccan.zates was gen.rally greater than.that of un.illed vulcan.zate an. in.reased with in.reases in.filler particle size at filler con.en.s, 10 an. 20 phr. The specific gravity of the rubber vulcan.zates in.reased gradually with the in.rease in.filler con.en. at filler con.en. greater than.5 phr, an. in.reased with in.reases in.filler particle size at an. filler con.en. con.idered. The swellin. in.ex of filled n.tural rubber vulcan.zates in.toluen. gen.rally decreased with in.reasin. filler particle size at filler con.en.s, 5, 10 an. 40 phr whereas the swellin. in.ex for PLF (150 μm) filled n.tural rubber decreased with in.reases in.filler con.en.. CB filled vulcan.zates absorbed the highest amoun. of toluen. (2.5%) in.the vulcan.zates at filler con.en., 40 phr. PLF (150 an. 300 μm) gen.rally gave optimum performan.es in.the en.-use properties of the rubber vulcan.zates determin.d within.filler con.en.s, 30 an. 40 phr. The in.orporation.of pin.apple leaf fibre in.o n

关键词： n.tural Rubber Pin.apple Leaf Fibre Carbon Black Filler En.-Use Properties