检索结果-南通市图书馆

Low-temperature superplasticity of β-stabilized Ti-43Al-9V-Y alloy sheet with bimodalγ-grain-size distribution

Journal of Materials Science & Technology 2021年第36期95卷 225-236页

作者： Yu Zhang Shuai Chang Yuyong Chen Yuchao Bai Cuiling Zhao Xiaopeng Wang Jun Min Xue Hao Wang Department of Mechanical Engineering Faculty of EngineeringNational University of Singapore9 Engineering Drive 1Singapore 117575Singapore Department of Materials Science and Engineering Faculty of EngineeringNational University of Singapore9 Engineering Drive 1Singapore 117576Singapore State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China

The superplasticity of Ti-43Al-9V-0.2Y alloy sheet hot-rolled at 1100℃was systematically investigated in the temperature range of 750-900℃under an initial strain rate of 10^(-4)s^(-1).A bimodalγgraindistribution microstructure of Ti Al alloy sheet,with abundant nano-scale or sub-micronγlaths embedded insideβmatrix,exhibits an impressive superplastic *** inhomogeneous microstructure shows low-temperature superplasticity with a strain-rate sensitivity exponent of m=0.27 at 800℃,which is the lowest temperature of superplastic deformation for Ti Al alloys attained so *** maximum elongation reaches~360%at 900℃with an initial strain rate of 2.0×10^(-4)s^(-1).To elucidate the softening mechanism of the disorderedβphase during superplastic deformation,the changes of phase composition were investigated up to 1000℃using in situ high-temperature X-ray diffraction(XRD)in this *** results indicate thatβphase does not undergo the transformation from an ordered L2;structure to a disordered A2 structure and cannot coordinate superplastic deformation as a *** on the microstructural evolution and occurrence of bothγandβdynamic recrystallization(DR)after tensile tests as characterized with electron backscatter diffraction(EBSD),the superplastic deformation mechanism can be explained by the combination of DR and grain boundary slipping(GBS).In the early stage of superplastic deformation,DR is an important coordination mechanism as associated with the reduced cavitation and dislocation density with increasing tensile *** DR can relieve stress concentration arising from dislocation piling-up at grain boundaries through the fragmentation from the original coarse structures into the fine equiaxed ones due to recrystallization,which further effectively suppresses apparent grain growth during superplastic *** the late stage of superplastic deformation,these equiaxed grains make GBS prevalent,which can effectively avoid intergranu

关键词： Titanium aluminides Hot-rolled alloy sheet Bimodal microstructure In situ high-temperature XRD Superplasticity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructure and dielectric properties of BaTi_4 O_9 (f)/0.64 BaTi_4 0_9+0.36 BaPr_2 Ti_4 O_(12) composites

引用

Journal of Harbin Institute of Technology(New Series) 2003年第3期10卷 265-268页

作者：宋英王福平姜兆华 Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Electronics Science and Technology Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 Chinahe microstructure dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD) Transmission electron microscopy (TEM) LCR meter method and X-ray photoelectron spectroscopy (XPS). The results show that the system is composed of BaTi_4O_9 and BaPr_2Ti_4O_(12) two phases. Pr ions are distributed in the BaWi_4O_9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi_4O_9/BaTi_4O_9. The content of Ti~(3+) and Ti~(2+) decrease in the BPT system composites due to the addition of BaTi_4O_9 fibers which improved the dielectric properties of the system. BPT10 sample with 10% BaTi_4O_9 fibers has the best dielectric properties in the system its ε_r = 64 tan δ= 1×10~(-4)(at 1 MHz) and it may be a potential candidate for microwave dielectric ceramics.

The microstructure, dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS). The results show that the system is composed of BaTi_4O_9 and BaPr_2Ti_4O_(12) two phases. Pr ions are distributed in the BaWi_4O_9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi_4O_9/BaTi_4O_9. The content of Ti^(3+) and Ti^(2+) decrease in the BPT system composites due to the addition of BaTi_4O_9 fibers, which improved the dielectric properties of the system. BPT10 sample with 10% BaTi_4O_9 fibers, has the best dielectric properties in the system, its ε_r = 64, tan δ= 1×10^(-4)(at 1 MHz) , and it may be a potential candidate for microwave dielectric ceramics.

关键词： microstructure dielectric properties BaTi_4O_9 fibers composites

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Expanding base editing scope to near-PAMless with engineered CRISPR/Cas9 variants in plants

引用

Molecular Plant 2021年第2期14卷 191-194页

作者： Chengwei Zhang Yao Wang Feipeng Wang Si Zhao Jinling Song Feng Feng Jiuran Zhao Jinxiao Yang Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding Beijing Academy of Agriculture&Forestry SciencesShuguang Garden Middle Road No.9Haidian DistrictBeijingChina

Dear Editor,Base editors(BEs),including cytosine base editor(CBE)and adenine base editor(ABE),have been widely used to generate irreversible nucleotide substitution in plants and ***,their wide applications are largely hindered by the strict NG protospacer adjacent motif(PAM)sequences recognized by Streptococcus pyogenes Cas9(SpCas9)and its engineered variants,such as SpCas9-NG and xCas9(Hua et al.,2019;Ren et al.,2019;Wu et al.,2019;Zhong et al.,2019;Zhang et al.,2020).Most recently,it was reported that three new SpCas9 variants,SpCas9-NRRH,SpCas9-NRTH,and SpCas9-NRCH,could recognize non-G PAMs(NRNH,where R is A or G and H is A,C,or T)in human cells(Miller et al.,2020).Meanwhile,SPRY,another new SpCas9 variant,was developed to greatly expand the editing scope of BEs to nearly PAMless(Walton et al.,2020).In this study,we generated a series of efficient BE toolkits and almost achieved C-to-T mutation without PAM restriction except for NTG PAM,and largely expanded A-to-G mutation scope in stable transformed rice,providing a reference for application in other plants.

关键词： base irreversible transformed

来源：

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

Effect of Ti−6Al−4V particle reinforcements on mechanical properties of Mg−9Al−1Zn alloy

引用

Transactions of Nonferrous Metals Society of China 2022年第10期32卷 3238-3249页

作者： Huan LUO Jian-bo LI Jun-liu YE Jun TAN Muhammad RASHAD Xian-hua CHEN Sheng-li HAN Kai-hong ZHENG Tian-tian ZHAO Fu-sheng PAN College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Department of Chemical Sciences Bernal InstituteUniversity of LimerickLimerick V94T9PXIreland Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China Chongqing Institute of Quality&Standardization Chongqing 400023China

Mg−9Al−1Zn(AZ91)magnesium matrix composites reinforced by Ti−6Al−4V(TC4)particles were successfully prepared via powder metallurgical *** yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)showed a mountain-like tendency with the increase of the TC4 *** mechanical properties of AZ91 magnesium matrix composites reached the optimal point with TC4 content of 10 wt.%,realizing YS,UTS,and EL of 335 MPa,370 MPa,and 6.4%,*** improvement of mechanical properties can be attributed to the effective load transfer from the magnesium matrix to the TC4 particles,dislocations associated with the difference in the coefficient of thermal expansion,good interfacial bonding between the Mg matrix and TC4 particles,and grain refinement strengthening.

关键词： magnesium matrix composites powder metallurgy mechanical properties strengthening mechanisms

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

第9届国际古海洋学大会在上海成功召开

引用

海洋地质与第四纪地质 2007年第5期27卷 84-84,98页

作者：第9届国际古海洋学大会组委会第9届国际古海洋学大会组委会

由同济大学海洋地质国家重点实验室和中国综合大洋钻探计划(IODP-China)主办的第9届国际古海洋学大会(ICP9),2007年9月3-7日在上海光大会展中心国际大酒店成功召开(图1).来自31个国家或地区近500名古海洋学家齐聚一堂,交流、展示全球大... 详细信息

由同济大学海洋地质国家重点实验室和中国综合大洋钻探计划(IODP-China)主办的第9届国际古海洋学大会(ICP9),2007年9月3-7日在上海光大会展中心国际大酒店成功召开(图1).来自31个国家或地区近500名古海洋学家齐聚一堂,交流、展示全球大洋基础研究成果,探讨未来海洋环境、资源研究前景.

关键词：上海光大会展中心古海洋学国际综合大洋钻探计划国家重点实验室海洋地质同济大学研究成果

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A SIMPLE PROOF OF THE INEQUALITY FFD (L)≤11/9 OPT(L)+1, ■L FOR THE FFD BIN-PACKING ALGORITHM

引用

Acta Mathematicae Applicatae Sinica 1991年第4期7卷 321-331页

作者：越民义 Institute of Applied Mathematics Academia Sinica Beijing Forschungsinstitut fur Diskrete Mathematik Bonnhe first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L letOPT(L) denote the minimal number of bins into which L can be packed and let FFD(L)denote the number of bins used by FFD. Johnson showed that for every list L FFD(L)≤11/9OPT(L)+4. His proof required more than 100 pages. Later Baker gave a much shorterand simpler proof for FFD(L)≤11/9OPT(L)+3. His proof required 22 pages. In this paperwe give a proof for FFD(L)≤11/9 OPT(L)+1. The proof is much simpler than the previousones.

The first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L, letOPT(L) denote the minimal number of bins into which L can be packed, and let FFD(L)denote the number of bins used by FFD. Johnson showed that for every list L, FFD(L)≤11/9OPT(L)+4. His proof required more than 100 pages. Later, Baker gave a much shorterand simpler proof for FFD(L)≤11/9OPT(L)+3. His proof required 22 pages. In this paper,we give a proof for FFD(L)≤11/9 OPT(L)+1. The proof is much simpler than the previousones.

关键词： A SIMPLE PROOF OF THE INEQUALITY FFD L FOR THE FFD BIN-PACKING ALGORITHM BIN OPT

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 expression in early focal cerebral infarction following urokinase thrombolysis in rats

引用

Neural Regeneration Research 2012年第17期7卷 1325-1330页

作者： Yuqiang Song Hongli Zou Guofeng Wang Hongxia Yang Zhaohong Xie Jianzhong Bi Department of Neurology the Affiliated Hospital of Medical College Qingdao University Qingdao 266003 Shandong Province China Qingdao Central Hospital Qingdao 266042 Shandong Province China Qingdao No. 9 People＇s Hospital Qingdao 266003 Shandong Province China The Second Hospital of Shandong University Jinan 255000 Shandong Province China

Activity of matrix metalloproteinase-9 increases following cerebral ischemia/reperfusion, and is associated with cerebral microvascular permeability, blood-brain barrier destruction, inflammatory cell infiltration and brain edema. Matrix metalloproteinase-9 also likely participates in thrombolysis. A rat model of middle cerebral artery infarction was established by injecting autologous blood clots into the internal carotid artery. At 3 hours following model induction, urokinase was injected into the caudal vein. Decreased neurological severity score, reduced infarct volume, and increased expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 were observed in the cerebral cortex 24 hours after urokinase thrombolysis. These results suggest that urokinase can suppress damage in the acute-early stage of cerebral infarction.

关键词： cerebral infarction urokinase thrombolysis matrix metalloproteinase-9 tissue inhibitor ofmetalloproteinase-1 neural regeneration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

“7”彩梦想“9”在路上--河南电视台新农村频道(第9频道)创办7周年的思考

引用

当代电视 2013年第6期 39-40页

作者：张克宣河南电视台新农村频道(第9频道)

6月，对于河南乃至全国来说，是意味着丰收、快乐的6月；6月，对于河南电视台新农村频道来说，更是值得骄傲的、寄托着光荣与梦想的6月。2006年6月9日，河南电视台新农村频道以响亮的呼号，和着一亿中原儿女对三农宣传的期望、承载着频... 详细信息

6月，对于河南乃至全国来说，是意味着丰收、快乐的6月；6月，对于河南电视台新农村频道来说，更是值得骄傲的、寄托着光荣与梦想的6月。2006年6月9日，河南电视台新农村频道以响亮的呼号，和着一亿中原儿女对三农宣传的期望、承载着频道所有员工的电视之梦，阔步走来，从最初的白手起家到今时的发展壮大，成绩喜人。

关键词：河南电视台农村频道梦想创办

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Physical Diagnostic Examinations of Cavernous Pulmonary Tuberculosis in the 19th and 21st Centuries

引用

Infectious Diseases & Immunity 2024年第2期4卷 99-100页

作者： Volodymyr Berezutskyi Department of Family Medicine of Postgraduates Faculty and Propedeutic of Internal Medicine Dnipro State Medical UniversityVernadsky AV.9Dnipro 49000Ukraine.

To the editor,Physical examination was first introduced as an effective diagnostic tool in pulmonology after the publication of the 1819 treatise“De l’Auscultation médiate”by the French physician and inventor of the stethoscope,Rene Laennec(1781–1826).Throughout the 19th century,followers of Laennec improved physical examination,making it possible to diagnose hydrothorax[pneumothorax,consolidation,or lung cavities with sizes“not less than that of a walnut.”[1]However,during the 20th and 21st centuries,physicians gradually lost interest in physical diagnoses;this is particularly true in the diagnosis of pulmonary *** tuberculosis,colloquially termed“consumption,”was an epidemic in Europe in the 19th century,when it became the most common cause of *** tuberculosis was the most common autopsy finding.[1]According to modern concepts,tuberculosis progresses from initial infection to tissue necrosis,causing pulmonary cavity formation.[2]

关键词： tuberculosis diagnosis cavity

来源：

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

Elevated plasma level of matrix metalloproteinases-9 and its significance in patients with abdominal aortic aneurysms

引用

Journal of Medical Colleges of PLA(China) 2003年第5期18卷 305-307页

作者：马中 Joerg.HECKENKAMP Jan.BRUNKWALL 陈江浩陈美芬 Department of Vascular Surgery Xijing HospitalFourth Military Medical UniversityXi'an 710033China Vascular Surgery Center Colonge University HospitalColonge 50924Germany . Conclusion: Apparent elevation of plasma concentration of MMP-9 in the AAAs and its dramatic decrease after being treated implicated that MMP-9 might play an important role in the formation and development of AAAs. Meanwhile to investigate the changes of MMP-9 level of AAAs could provide an practical way to facilitate the earlier diagnosis and long term surveillance for AAAs. More importantly pharmacologic prevention and treatment of AAAs in which the MMP-9 serves as effective target might be possible in the future.

Objective: To investigate the changes of the plasma level of MMP-9 (Matrix Metalloproteinase-9, MMP-9) in the patients with abdominal aortic aneurysms (AAAs) before and after the treatment, and evaluate the significance of MMP-9 in the pathogenesis of AAAs. Methods: Blood samples of 35 patients with AAAs and 10 patients with the arterial occlusive diseases (AODs) , which enrolled into the Vascular Surgery Center of Colonge University Hospital from February to August of 2002, were collected before and one month after surgical repair or less-invasive endovascular exclusion. The plasma concentrations of MMP-9 of all the collected samples were measured by means of enzyme-linked immunosorbent assay(ELISA), and compared between the two groups patients at different time point. Results: The mean plasma concentration of MMP-9 of AAAs was significantly higher than that of AODs prior to treatment [(90.3±9.1) ng/ml vs (23.6±7.3) ng/ml, P0.05)] before and after the surgical bypass operation. However, in the patients with AAAs the plasma concentration of MMP-9 was apparently decreased one month after the surgical repair or endovascular exclusion compared with before [(28.6±8.4) ng/ml vs (90.3±9.1) ng/ml, P9 concentration was seen between two groups after the both being successfully treated [(28.6±8.4) ng/ml vs (25.3±5.8) ng/ml, P>0.05]. Conclusion: Apparent elevation of plasma concentration of MMP-9 in the AAAs and its dramatic decrease after being treated implicated that MMP-9 might play an important role in the formation and development of AAAs. Meanwhile, to investigate the changes of MMP-9 level of AAAs could provide an practical way to facilitate the earlier diagnosis and long term surveillance for AAAs. More importantly, pharmacologic prevention and treatment of AAAs, in which the MMP-9 serves as effective

关键词： abdominal aortic aneurysms ( AAAs ) matrix metalloproteinases ( MMPs ) arterial occlusive dieases (AODs)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：