检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

TC4表面激光熔覆硬质复合涂层组织与性能

华南理工大学学报（自然科学版） 2024年第3期52卷 10-17页

作者：付宇明马顺芯刘绍峰郑立娟燕山大学机械工程学院河北秦皇岛066004

TC4凭借比强度高、耐腐蚀性好、质量轻等一系列优点,被广泛应用于航空航天领域,但其摩擦系数大、耐磨性差等缺点极大地限制了其应用范围,针对TC4硬度低、耐磨性差等缺点,采用4 kW大功率Laser4000半导体激光器,选用过渡族难熔碳化物Hf.、... 详细信息

TC4凭借比强度高、耐腐蚀性好、质量轻等一系列优点,被广泛应用于航空航天领域,但其摩擦系数大、耐磨性差等缺点极大地限制了其应用范围,针对TC4硬度低、耐磨性差等缺点,采用4 kW大功率Laser4000半导体激光器,选用过渡族难熔碳化物Hf.、taC和ZrC作为增强相,以H13钢基粉末作为基粉,利用激光熔覆技术在TC4表面制备了不同比例的钢基金属-陶瓷硬质涂层。之后利用扫描电镜(SEM)、EDS能谱仪、D/max-2500/PC型X射线衍射仪(XDR)等试验手段对不同比例涂层的宏观形貌、显微组织、物相组成和涂层元素分布等进行对比分析,利用Qness型号维氏显微硬度计测试涂层硬度并分析熔覆试样截面微观硬度变化规律,利用MMU-5G型端面摩擦磨损试验机研究了不同材料组分涂层的摩擦磨损性能,研究结果表明:试件熔覆层与基材形成了良好的冶金结合,熔覆层组织形态主要以枝晶组织以及块状组织为主,各熔覆层的主要物相中均含有TiC,随着三元陶瓷粉末含量的增加,MC的含量也随之增加,当碳化物混合粉末添加量为15%(质量分数)时,熔覆层中检测到Hf.(0.8)ta_(0.2)f._(2)三元合金相。当三元陶瓷粉添含量为10%(质量分数)时,熔覆层晶粒最为细小,涂层平均硬度最高,平均硬度约为763.43 HV,是基材硬度的2.29倍,当三元陶瓷粉末含量为5%(质量分数)时涂层的耐磨性最好,相对耐磨性为25%。

关键词： TC4钛合金激光熔覆金属陶瓷涂层过渡族碳化物

A common property of.R(E,f. and B(R^n,R^m) and a new method f.r seeking a path to connect two operators

在线全文

学校读者我要写书评

暂无评论

Science China mathematics 2010年第10期53卷 2605-2620页

作者： ma Zhaof.ng ma JiPu Zhejiang Inst Commun Dept Informat & Management Hangzhou 311112 Zhejiang Peoples R China Harbin Normal Univ Tseng Yuan Rong Funct Anal Res Ctr Harbin 150025 Peoples R China

Given two Banach spaces E,f.let B(E,f. be the set of.all bounded linear operators f.om E into f.and R(E,f. the set of.all operators in B(E,f. with f.nite *** is well-known that B(Rn) is a Banach space as well as an algebra,while B(Rn,Rm) f.r m = n,is a Banach space but not an algebra;meanwhile,it is clear that R(E,f. is neither a Banach space nor an ***,in this paper,it is proved that all of.them have a common property in geometry and topology,i.e.,they are all a union of.mutual disjoint path-connected and smooth submanif.lds (or hypersurf.ces).Let Σr be the set of.all operators of.f.nite rank r in B(E,f. (or B(Rn,Rm)).In f.ct,we have that 1) suppose Σr∈ B(Rn,Rm),and then Σr is a smooth and path-connected submanif.ld of.B(Rn,Rm) and dimΣr = (n + m)r-r2,f.r each r ∈ [0,min{n,m});if.m = n,the same conclusion f.r Σr and its dimension is valid f.r each r ∈ [0,min{n,m}];2) suppose Σr∈ B(E,f.,and dimf.= ∞,and then Σr is a smooth and path-connected submanif.ld of.B(E,f. with the tangent space taΣr = {B ∈ B(E,f. : BN(A)-R(A)} at each A ∈Σr f.r 0 r f.r seeking a path to connect two operators can hardly apply here.A new method and some f.ndamental theorems are introduced in this paper,which is development of.elementary transf.rmation of.matrices in B(Rn),and more adapted and simple than the elementary transf.rmation *** addition to tensor analysis and application of.Thom’s f.mous result f.r transversility,these will benef.t the study of.inf.nite geometry.

关键词： operator of f.nite rank smooth Banach submanif.ld matrix

持续负荷冲击下AnSBBR运行性能及群落结构响应

在线全文

学校读者我要写书评

暂无评论

中国环境科学 2024年第1期44卷 140-149页

作者：王泽于莉芳马芷萱郑兰香刘然刘甜西安建筑科技大学环境与市政工程学院陕西西安710055 宁夏大学生态环境学院宁夏银川750021 中国葡萄酒产业技术研究院宁夏银川750021

以厌氧序批式生物膜反应器(AnSBBR)处理葡萄酒生产废水,考察反应器在持续负荷冲击下的运行特性及群落结构响应.结果显示,持续负荷冲击的前13d(29~41d),反应器运行稳定;因逐渐增加的氢分压和挥发性脂肪酸(Vf.s),到56d时系统稳定性降低(Vf...

以厌氧序批式生物膜反应器(AnSBBR)处理葡萄酒生产废水,考察反应器在持续负荷冲击下的运行特性及群落结构响应.结果显示,持续负荷冲击的前13d(29~41d),反应器运行稳定;因逐渐增加的氢分压和挥发性脂肪酸(Vf.s),到56d时系统稳定性降低(Vf./ta=0.72),乙酸比产甲烷活性(Sma)降低46.2%,但氢利用速率(HUR)增加69.2%,辅酶f.20浓度增加11.9%.在42d时仅外层的Slime-EPS浓度明显增加(34.1%);在56d时TB-EPS和LB-EPS浓度增加61.3%和62.8%,其PN/PS比值增加197.8%和126.0%,负荷冲击诱导EPS分泌大量的应急性蛋白类产物,其电活性物质提高了系统的电子传递活性(35.5%).Illumina MiSeq显示,负荷冲击下Desulf.vibrio、Ruminococcus和Geobacter等产酸菌丰度降低,而Methanobacterium丰度由32.2%增至50.9%.生物膜系统通过逐级EPS分泌和强化还原CO_(2)产甲烷来响应持续负荷冲击的影响.

关键词：厌氧序批式生物膜反应器负荷冲击胞外聚合物代谢活性群落结构

鲁西地区沂南金矿床成因:硫化物矿石与围岩稀土和微量元素的制约

在线全文

学校读者我要写书评

暂无评论

地质通报 2024年第6期43卷 896-913页

作者：李亚东马明蔡文艳高继雷张照录孙祥彪山东省第一地质矿产勘查院山东济南250100 山东省富铁矿勘查技术开发工程实验室山东济南250100 山东理工大学资源与环境工程学院山东淄博255000 自然资源部战略性金属矿产找矿理论与技术重点实验室/中国地质大学(北京) 北京100083 呼伦贝尔山金矿业有限公司内蒙古呼伦贝尔022357

沂南金矿床为鲁西地区典型的矽卡岩型矿床,产于早白垩世中酸性杂岩与新太古界—寒武系接触带及其附近。本次利用岩/矿石稀土和微量元素组成,示踪成矿物质来源及成矿流体地球化学性质。结果显示,成矿的闪长玢岩负Eu异常不显著,且早矿化... 详细信息

沂南金矿床为鲁西地区典型的矽卡岩型矿床,产于早白垩世中酸性杂岩与新太古界—寒武系接触带及其附近。本次利用岩/矿石稀土和微量元素组成,示踪成矿物质来源及成矿流体地球化学性质。结果显示,成矿的闪长玢岩负Eu异常不显著,且早矿化阶段发育大量磁铁矿,暗示早阶段成矿流体具有氧化性特征。晚(金)矿化阶段的黄铁矿和黄铜矿相对富集轻稀土元素和高场强元素,负Eu异常显著,Ce异常不明显,且Hf.Sm、Nb/La值大于1,显示含f.的还原性流体特征。矿石的Y/Ho、Zr/Hf.Nb/ta值变化较大,且黄铁矿Co/Ni>10,表明成矿流体源于岩浆水和大气降水的混入。矿石与赋矿围岩具有相似的稀土元素配分模式和微量元素地球化学行为,且具有相同范围/趋势的微量元素比值,说明沂南杂岩体和碳酸盐岩提供了必要的成矿物质。综上,沂南金矿床的成矿过程得到了较好的约束,同时也对区域范围内金矿成因有一定指示意义。

关键词：黄铁矿和黄铜矿稀土和微量元素成矿流体成矿物质来源沂南金矿鲁西地区

同方期刊数据库

经皮耳迷走神经电刺激对缺血性卒中患者的康复疗效观察

在线全文

学校读者我要写书评

暂无评论

同济大学学报（医学版） 2024年第3期45卷 404-410页

作者：马丽封亮赵曦余斌同济大学医学院上海200092 同济大学附属养志康复医院麻醉疼痛康复科上海201600

目的探讨不同频率的经皮耳迷走神经电刺激(transcutaneous auricular vagus nerve stimulation,taVNS)结合康复运动对缺血性卒中患者康复疗效的影响。方法选取2023年6月—10月同济大学附属养志康复医院神经内科收治的80例缺血性脑卒中... 详细信息

目的探讨不同频率的经皮耳迷走神经电刺激(transcutaneous auricular vagus nerve stimulation,taVNS)结合康复运动对缺血性卒中患者康复疗效的影响。方法选取2023年6月—10月同济大学附属养志康复医院神经内科收治的80例缺血性脑卒中后伴上肢偏瘫患者,随机分为taVNS 0 Hz(n=20)、taVNS 30 Hz组(n=20)、taVNS 300 Hz组(n=20)、taVNS 3000 Hz(n=20)组,4组均接受常规康复训练,同时增加不同频率的taVNS刺激,根据患者耐受情况调整ta-VNS治疗强度,每次30 min,每日1次,连续治疗14 d。在假刺激组中,只夹电极但不给与刺激。分别记录治疗前、治疗30 d、治疗45 d后简式f.gl-Meyer(f.8})运动功能评分。结果治疗前4组f.8}评分无显著差异(f.0.195,P=0.900);重复测量方差分析结果显示,治疗30 d及45 d后,4组f.8}评分均较治疗前显著提高(PtaVNS 300 Hz组治疗45 d后的f.8}评分最优(48.81±20.30);不同治疗方案在治疗30 d前后、治疗45 d前后f.8}指标的差值均具有差异(PtaVNS 300 Hz组治疗45 d前后的f.8}评分差值最大(9.81±1.69),具有临床意义。结论taVNS结合康复运动能促进缺血性卒中患者的运动功能康复,taVNS 300 Hz治疗组效果最优。

关键词：缺血性卒中经皮耳迷走神经电刺激康复

SMOOTH AND PATH CONNECTED BANACH SUBmaNIf.LD Σ_r Of.B(E,f. AND A DIMENSION f.RMULA IN B(R^n,R^m)

在线全文

学校读者我要写书评

暂无评论

Analysis in Theory and Applications 2008年第4期24卷 395-400页

作者： Jipu ma Harbin Normal University/Nanjing University China

Given two Banach spaces E, f. let B（E, f. be the set of.all bounded linear operators f.om E into f. ∑r the set of.all operators of.f.nite rank r in B（E, f., and ∑r^# the number of.path connected components of.∑r. It is known that ∑r is a smooth Banach submanif.ld in B（E,f. with given expression of.its tangent space at each A ∈ ∑r. In this paper, the equality ∑r^# = 1 is proved. Consequently, the f.llowing theorem is obtained： f.r any nonnegative integer r,∑r is a smooth and path connected Banach submanif.ld in B（E, f. with the tangent space ta∑r = {B E B（E,f. ： BN（A） belong to R（A）} at each A ∈ ∑r if.dim f.= ∞. Note that the routine method can hardly be applied here. So in addition to the nice topological and geometric property of.∑r the method presented in this paper is also interesting. As an application of.this result, it is proved that if.E = R^n and f.= R^m, then ∑r is a smooth and path connected submanif.ld of.B（R^n,R^m） and its dimension is dim ∑r = （m ＋ n）r- r^2 f.r each r, 0≤r 〈 min{n,m}.

关键词： operator of.f.nite rank smooth Banach submanif.lcl path connectivity perturbation analysis of.generalized inverse

Mineralization of.the Lianhuashan Sn-polymetallic deposits associated with dynamic metamorphism:Constraints f.om cassiterite geochemistry and U-Pb geochronology

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2023年第7期66卷 1664-1677页

作者： Jun WANG Liming WANG Shuang YAN Yong ma Diankui XU CAS Key Laboratory of.Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of.Mineral Physics and materials Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of.Chinese Academy of.Sciences Beijing 100049China Geology Bureau f.r Nonf.rrous Metal of.Guangdong Province Guangzhou 510080China Nonf.rrous Geological Exploration Institute of.Guangdong Province Guangzhou 510080China Nonf.rrous Metal Geological Bureau of.Guangdong Province 931 Battalion Shantou 515041China

The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the tashan,Xianshuili,and ***,the metallogenic mechanism of.these deposits remains hotly *** this paper,two types of.cassiterites(Cst1 and Cst2)have been identif.ed in the Xianshuili and Jiangxikeng Sn deposits,which are hosted in the biotite-mylonite and garnetcordierite-muscovite blastomylonite,*** euhedral Cst1(0.50–1.8 mm)coexists with biotite,f.ldspar,and *** is platy and zoned with a mosaic *** subhedral to anhedral Cst2(0.02–0.35 mm)coexists with metamorphic minerals such as garnet and cordierite,and it is characterized by well-developed porosity and has no ***-situ U-Pb dating of.the Cst1 and Cst2 yielded ages of.149.5±1.0 ma(MSWD=1.6,n=45)and 125.1±2.3 ma(MSWD=4.5,n=43),***1 is most likely to be related to the intermediate-f.lsic magmatism that f.rmed Gaojiping Group,whereas Cst2 has relatively high ta,Nb,f.,and W contents with obvious rare earth tetragroup ef.ect,and may have f.rmed by the late Early Cretaceous dynamic *** presented here,when combined with regional geology and geochemistry,led us to suggest that the Mesozoic intermediate-f.lsic volcanic rocks in the LMB are signif.cantly enriched in Sn and f.with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related *** the late Early Cretaceous period,due to the NW-dipping subduction of.the paleo-Pacif.c plate,the intermediate-f.lsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization,migration,and precipitation in the regional ductile shear zones,and eventually generating Sn *** propose that areas beneath Xianshuili and Jiangxikeng have great potential f.r discovery of.new Sn *** f.ndings likely of.er practical importance to regional geological

关键词： Lianhuashan metallogenic belt(LMB) Sn-polymetallic deposit Cassiterite U-Pb geohronology Dynamic metamorphism

Geochronology,Geochemistry and Sr-Nd-Pb Isotopic Study of.the Wulong f.ower-Like Glomerophyric Diorite Porphyry(Central China):Implications f.r Tectonic Evolution of.Eastern Qinling

在线全文

学校读者我要写书评

暂无评论

Journal of.Earth Science 2018年第5期29卷 1203-1218页

作者： Yuxiang Zhu Lianxun Wang Changqian ma Chao Zhang Ke Wang School of.Earth Sciences China University of GeosciencesWuhan 430074China Institut f.r Mineralogie Leibniz Universitat HannoverCallinstr.330167 HannoverGermany

The Wulong diorite porphyry displays a very unusual f.ower-like glomerophyric texture and is thus well-known as a gemstone type of.＂Luoyang peony stone＂ f.r non-geologists. Hereby, we present a comprehensive study in terms of.petrography, zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotope. The rock exposed as small-scale dykes in the f.eld, intruding in the Archean migmatized biotite- plagioclase genesis at the southern margin of.the North China Craton. It exhibits typical porphyrite texture with plagioclase and amphibole as dominant and subdominant phenocrysts, respectively. The diorite porphyry rocks contain 51 wt.%-59 wt.% SiO2, belonging to medium-K calc-alkaline rock series. They are characterized by enrichment of.large ion lithophile elements （LILEs, e.g., Ba） and depletion of.high f.eld-strength elements （Hf.Es, e.g., Nb, ta, Zr and Hf., resembling island arc magmatic rocks. They show high initial Sr isotopic ratios （0.710 7-0.715 8）, low eNd（t） values （-9.9 to -13.3） and variable initial Pb isotopic ratios （206pb/204Pb vary f.om 17.3 to 19.3）, similar to the coeval intermediate and maf.c magmatic rocks of.adjacent region. These geochemical f.atures indicate that the Wulong diorite porphyry is likely to originate f.om an enriched mantle with contamination of.crustal materials. Zircon U-Pb dating results reveal a magma crystallization age of.480-A3 ma, consistent with the summit of.the magmatic events of.the Qinling orogenic belt and ref.ecting the northernmost Paleozoic magmatic activity of.the belt. This may indicate the inf.uence of.northward subduction of.Paleotethyan oceanic slab can extend a distance of.ca. 200 km to the north and reach Luoyang-Songshan region in the East Qinling Orogen.

关键词： Early Paleozoic North China Craton geochronology diorite porphyry Wuloug f.owerlike glomerophyric texture.

云英岩在开放与封闭岩浆体系中成因差异性的对比研究——以南岭成矿带四个代表性含钨和含锂矿床为例

在线全文

学校读者我要写书评

暂无评论

岩石学报 2024年第9期40卷 2905-2924页

作者：龚磊郭春丽于淼郑义张斌武陈振宇马星华许以明中南大学长沙410083 成矿作用与资源评价自然资源部重点实验室中国地质科学院矿产资源研究所北京100037 自然资源部深地科学与探测技术实验室中国地质科学院北京100094 湖南省矿产资源调查所郴州423000

云英岩是花岗质岩浆成岩和成矿过程中常见的岩石类型,也是有色和稀有金属元素的主要赋矿体。目前对其成因主要有三种认识:由花岗质熔体与外界流体交代而成、花岗质熔体与岩浆出溶热液相互作用的产物、以及高度富Li-f.特殊中酸性岩浆岩... 详细信息

云英岩是花岗质岩浆成岩和成矿过程中常见的岩石类型,也是有色和稀有金属元素的主要赋矿体。目前对其成因主要有三种认识:由花岗质熔体与外界流体交代而成、花岗质熔体与岩浆出溶热液相互作用的产物、以及高度富Li-f.特殊中酸性岩浆岩。为了进一步阐明云英岩的形成机制,本研究聚焦南岭成矿带晚侏罗世(166~145ma)包括淘锡坑石英脉型W矿床、柿竹园矽卡岩-云英岩型W-Sn-Mo-Bi-f.床、茅坪石英脉-云英岩型W-Sn-Li矿床、香花铺花岗岩型W-ta-Nb-Li矿床在内的四个花岗质岩浆-液热矿床,通过对侵入岩体的花岗岩、云英岩化花岗岩和云英岩中不同类型云母的EMPA和LA-ICP-MS分析,发现:(1)淘锡坑和柿竹园W矿床中云英岩的云母为多硅白云母,而茅坪和香花铺含W-Li矿床中云英岩的云母为铁锂云母;(2)淘锡坑和柿竹园从低分异花岗岩→高分异花岗岩→云英岩,其SiO 2、Al 2O 3含量并未呈现一直增加或降低的趋势,而是出现一个转折;而茅坪和香花铺云母中的上述主量元素变化趋势一致,未出现转折,说明它们在岩浆演化上具有一定的差异性;(3)淘锡坑和柿竹园中云母的Ba含量突然增加表明有外界流体加入,而茅坪和香花铺云母中的Ba含量保持不变,说明体系基本维持在封闭状态。本研究认为,导致上述差异性的原因是由于淘锡坑和柿竹园的钨矿体是在开放体系下,花岗质熔体与外来流体发生相互作用而形成的;茅坪云英岩钨锂矿是在半封闭体系下熔体-流体共存阶段形成的,主要为岩浆自身出溶热液且有少量大气降水加入;而香花铺锂矿是在几乎全封闭体系下由岩浆与自身出溶热液相互作用的产物。本研究提出钨和锂元素的富集均需要岩浆经历高度分异作用,岩浆体系是否开放是形成何种矿产的重要条件。

关键词：云英岩云母微量元素矽卡岩型钨矿石英脉型钨锂矿花岗岩型锂矿晚侏罗世南岭成矿带