检索结果-南通市图书馆

Selective Deactivation of Gibberellins below the Shoot Apex is Critical to Flowering but not to Stem Elongation of Lolium

引用

Molecular Plant 2008年第2期1卷 295-307页

作者： rod W. King Lewis n. Mander Torben Asp Colleen R MacMillan Cheryl A. Blundell Lloyd T. Evans CSIRO Plant Industry Canberra ACT 2600 Australia Research School of Chemistry Australian National University Canberra ACT 0200 Australia Department of Genetics and-Biotechnology University of Aarhus 4200 Slagelse Denmark Present Address: EnSIS PO Box E 4008 Kingston ACT 2604 Australia

Gibberellins （GAs） cause dramatic increases in plant height and a genetic block in the synthesis of GA1 explains the dwarfing of Mendel＇s pea. For flowering, it is GAs which is important in the long-day （LD） responsive grass, Loliurn. As we show here, GA1 and GA4 are restricted in their effectiveness for flowering because they are deactivated by C-2 hydroxylation below the shoot apex. In contrast, GAs is effective because of its structural protection at C-2. Excised vegetative shoot tips rapidly degrade [14C]GA1, [14C]GA4, and [14C]GA20 （〉80% in 6 h）, but not [14C]GAs. CoincidentaUy, genes encoding two 2β-oxidases and a putative 16-17-epoxidase were most expressed just below the shoot apex （〈3 mm）. Further down the immature stem （〉4 mm）, expression of these GA deactivation genes is reduced, so allowing GA1 and GA4 to promote sub-apical stem elongation. Subsequently, GA degradation declines in florally induced shoot tips and these GAs can become active for floral development. Structural changes which stabilize GA4 confirm the link between florigenicity and restricted GA 2β-hydroxylation （e.g. 2α-hydroxylation and C-2 di-methylation）. Additionally, a 2-oxidase inhibitor （Trinexapac Ethyl） enhanced the activity of applied GA4, as did limiting C-16,17 epoxidation in 16,17-dihydro GAs or after C-13 hydroxylation. Overall, deactivation of GA1 and GA4 just below the shoot apex effectively restricts their florigenicity in Loliurn and, conversely, with GAs, C-2 and C-13 protection against deactivation allows its high florigenicity. Speculatively, such differences in GA access to the shoot apex of grasses may be important for separating floral induction from inflorescence emergence and thus could influence their survival under conditions of herbivore predation.

关键词： flowering shoot apices Shoots Gallium Lolium plant height Deactivation G(A1) ganglioside Apex APEX1 protein, human Gibberellins stem elongation

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

Molecular Dynamics Simulation of Tensile Deformation and Fracture of γ-TiAl with and without Surface Defects

引用

Journal of Materials Science & Technology 2016年第10期32卷 1033-1042页

作者： h.n.Wu D.S.Xu h.Wang R.Yang Institute of Metal Research Chinese Academy of Sciences

Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single *** results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.

关键词： Intermetallic compounds Superdislocation Fracture Surface defects Molecular dynamics

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

神秘飞行计划

引用

2019年

作者： rod neilsen

来源：南通市图书馆图书评论

学校读者我要写书评

暂无评论

Influence of alloying elements on microstructure and microhardness of Mg-Sn-Zn-based alloys

引用

Transactions of nonferrous Metals Society of China 2010年第12期20卷 2246-2252页

作者： W. L. ChEnG S. PARK W. n. TAnG B. S. YOU B. h. KOO School of nano ＆ Advanced Materials Engineering Changwon National University Changwon 641-773 South Korea Light Metals Research Group Korea Institute of Materials Science （KIMS） Changwon 641-831 South Korea

The phase evolution in （88%-91%）Mg-8%Sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPhAD method and simulations were used in precise selection of the chemical composition. The influence of the addition of different alloying elements such as A1, Mn and Ce on the microstructure and microhardness of Mg-8%Sn-l%Zn-based alloys was investigated. Combined addition of A1 and Mn shows features distinct from separate addition of A1 or Mn. Additions of l%AI and l%Mn to base alloy result in the formation of massive A1-Mn phase in a-Mg matrix grains. Addition of Ce element can refme the second eutectic precipitates and form intermetallic compounds with Sn. Fine rod-like Sn-Ce phase presents mainly on the grain boundaries and plays a role in inhibiting grain growth. The effects of alloying elements on Vickers microhardness and indentation size effect of base alloy were examined.

关键词： magnesium alloys alloying elements CALPhAD method hardness indentation size effect

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

Application of a new reagent for analysis of oxygen presence in a lowcarbon steel wire rod

引用

Journal of Iron and Steel Research International 2021年第6期28卷 729-738页

作者： M.I.Dávila-Pérez h.J.Vergara-hernández O.Vázquez-Gómez F.Reyes-Calderón E.López-Martínez J.M.Salgado-López national Technology of Mexico/T.I.of Morelia Morelia 58120MichoacanMexico national Council for Science and Technology COnACYT Mexico City 03940Mexico Isthmus University Santo Domingo TehuantepecOaxaca 70760Mexico Engineering and Industrial Development Center CIDESI Santiago de Queretaro 76125QueretaroMexico

A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire *** failure zone was analyzed by comparison using three different attack reagents:alkaline sodium chromate(ASC),ASC with hydrogen peroxide and amyl alcohol,and a solution of nitric acid in ethyl *** reagents were applied in samples in the failure zone,showing different types of zones in regions with internal and superficial defects such as carbides,pores,cracks,deformation,and detachment zones,indicating the possible presence of *** areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer,which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon,aluminum,and iron;this is associated with the presence of oxygen in the oxide *** was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides,while the nitric acid solution only identified the steel *** modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life,and therefore,its application must be carried out at the time of preparation.

关键词： Etching Alkaline sodium chromate Oxide presence Internal defect

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

Synthesis of Barium nickel Titanium Oxide Stabilized by Citric Acid

引用

Modeling and numerical Simulation of Material Science 2013年第1期3卷 23-27页

作者： K. Y. Chew M. Abu Bakar n.h.h. Abu Bakar nanoscience Research Laboratory School of Chemical Sciences Universiti Sains Malaysia 11800 USM Pulau Pinang Malaysia.

Barium nickel titanium oxide particles (Ba2niTi5O13) were synthesized in the presence of citric acid by using a two step sol-gel method followed by calcination. The addition of citric acid as a stabilizer (mole ratio of 0.5, 1.0, 2.0, 4.0) resulted in the formation of Ba2niTi5O13 particles with various morphology (i.e. sphere, cube, rod). These various morphology changes were deduced to be caused by citric acid that tends to absorbed on certain dimension of the Ba2niTi5O13 particles when different concentration of citric acid was added. Besides that, the growth of Ba2niTi5O13 particles from incorporation of bulky micelles which act as a protective 'shell' that control particle sizes by attaching on the surfaces of particles.

关键词： Barium nickel Titanium Oxide Citric Acid Morphology

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

Model acupuncture point:Bone marrow-derived stromal stem cells are moved by a weak electromagnetic field

引用

World Journal of Stem Cells 2016年第10期8卷 342-354页

作者： Artem n Emelyanov Marina V Borisova Vera V Kiryanova Laboratory of high Laser and Magnetic Technology North-Western State Medical University Training Laboratory of Physical Chemistry Institute of ChemistrySt. Petersburg State University Department of Physical Therapy and Rehabilitation North-Western State Medical University

AIM To show the existence of a structural formative role of magnetic fields(MFs) with respect to biological objects by using our proposed model of an *** We introduced a magnetised 10-100 μT metal rod(needle) into culture dishes with a negatively charged working surface and observed during 24 h how cells were arranged by MFs and by electrical fields(EFs) when attached. Rat and human bone marrow-derived stromal stem cells(r BMSCs and h BMSCs), human nonadherent mononuclear blood cells, nCTCs and A172 cells, and Escherichia coli(E. coli) were evaluated. The dish containing BMSCs was defined as the model of an acupoint. r BMSCs proliferative activity affected by the needle was investigated. For investigating electromagnetic field structures, we used the gas discharge visualisation(GDV) *** During 24 h of incubation in 50-mm culture dishes, BMSCs or the nonadherent cells accumulated into a central heap in each dish. BMSCs formed a torus(central ring) with an inner diameter of approximately10 mm only upon the introduction of the needle in the centre of the dish. The cells did not show these effects in 35- or 90-mm culture dishes or hydrophobic dishes or rectangular cuvettes. nCTCs and A172 cells showed unstable the effects and only up to two weeks after thawing. Moreover, we observed that the appearance of these effects depended on the season. In winter, BMSCs showed no the effects. GDV experiments revealed that the resonant annular illumination gradually formed from 10 to 18-20 s in polar solutions with and without cell suspension of BMSCs, nCTCs and E. coli when using circular 50-mm dishes, stimulation at 115 V and switching of the electrode poles at 1 kh z. All these data demonstrate the resonant nature of the central ring. Significant influence of MFs on the rB MSC proliferation rate was not *** BMSCs can be moved by MFs when in the presence of a constant EF and MF, when the cells are in the responsive functional state, and whe

关键词： Stem cell movement Magnetic targeting Acupuncture Model acupoint Frizzled-related protein Biology resonance Cytoplasm movement Glycocalyx

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

比较经桡动脉冠状动脉支架置入术后当日出院并仅快速推注阿昔单抗与夜间留院治疗并快速推注及输注阿昔单抗的随机研究

引用

世界核心医学期刊文摘(心脏病学分册) 2007年第6期 27-28页

作者： Bertrand O.F De Larochellière R rodés-Cabau J 黄欣 h■pital Laval Institut Universitaire de Cardiologie et de PneumologieL' Université Laval2725 CheminSte FoyQue.G1V 4G5Canada .Dr.

背景:系统化使用冠状动脉支架及血小板聚集抑制剂极大地改善了经皮冠状动脉介入治疗的短期疗效。经桡动脉冠状动脉介入治疗伴随发生出血并发症的低风

关键词：阿昔单抗并发症并发病疾病冠状动脉支架置入经桡动脉输注推注

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

用于梁式泵采油的带状抽油杆

引用

国外石油机械 1996年第2期7卷 44-50页

作者：郑津侪 h. n. hensley 东北输油管理局机械厂科研所

带状抽油杆(Ribbon rod)是一种可盘绕的连续纤维抽油杆,一般规格为:1.45 in×0.212 in(36.83 mm×5.38 mm)。带状抽油杆可以盘绕在直径10ft(3.05 m)、宽6 in(0.15m)的滚筒上。该杆类似于玻璃纤维抽油杆,需与钢杆组合用于井下。该杆的性... 详细信息

带状抽油杆(Ribbon rod)是一种可盘绕的连续纤维抽油杆,一般规格为:1.45 in×0.212 in(36.83 mm×5.38 mm)。带状抽油杆可以盘绕在直径10ft(3.05 m)、宽6 in(0.15m)的滚筒上。该杆类似于玻璃纤维抽油杆,需与钢杆组合用于井下。该杆的性能可以利用波动方程数学模型进行设计和分析。带状抽油杆已经过十多年的实验室与现场的成功试验。这种抽油杆具有无接箍、耐腐蚀、轻质的特点。本文介绍了带状抽油杆的新材料、新结构、新设计,以及在实验室和现场的试验结果。采用带状抽油杆的梁式泵举升系统比选用其它抽油杆具有更高的开采速度。

关键词：抽油杆采油游梁式泵抽油机机械采油

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

Mismatch between calf paternity and observed copulations between male and female reindeer:Multiple mating in a polygynous ungulate?

引用

Current Zoology 2023年第4期69卷 377-384页

作者： Keenin R.Coombs Robert B.Weladji Ostein holand Knut h.rodc Department of Biology Concordia University7141 Sherbrooke St.WestMontrealQCH4B1R6Canada Department of Animal and Aquacultural Sciences Norwegian University of Life SciencesOluf Thesens vei 61433ÅsNorway Faculty of Veterinary Medicine Norwegian University of Life SciencesVeterinærbygningenElizabeth Stephansens vei 15N-1430ÅsNorway

In polygynous systems,such as that exhibited by reindeer Rangifer tarandus,mate choice can be difficult to disentangle from male intrasexual competition because male behavior may constrain female *** mating may provide an avenue for female mate choice,though it is difficult to identify using behavioral estimators *** techniques address this issue by affording ecologists an opportunity to reassess mating systems from a genetic *** assessed the frequency and possible explanations for multiple mating in reindeer using a genetic approach to determine the success of observed copulations in a semi-domesticated herd in Kaamanen,*** and genetic data were synthesized with population characteristics over a 7-year period to test the hypothesis that,if present,polyandry in reindeer is driven by sexual harassment from sub-dominant *** observed multiple mating in 42%of females,with as many as 60%exhibiting multiple mating in certain *** found no evidence that multiple mating resulted from sexual harassment by sub-dominant males,suggesting that it is likely a deliberate strategy among *** rate of copulations into paternities varied with male size,with smaller males more likely to experience mismatch than larger *** preference for larger males persisted despite the occurrence of multiple mating,possibly suggesting a mechanism for cryptic post-copulatory *** suggest further research to delineate the possible influence of cryptic post-copulatory selection and multiple mating to defend against infertility in exhausted males.

关键词： female choice mate choice mating systems polyandry reproductive success sexual selection

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

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

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

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：