55 resultados para 855

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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对非理想界面的三相复合材料,提出了计算弹性应力场的微观力学模型,在适当的简化假设下,对带界相的颗粒增强和纤维增强复合材料,得到了应力场的计算公式。以剪切载荷为例给出了数值例子。给出的数值结果表明非理想界面对三相复合材料应力场的影响

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We propose a new method to increase the resolution of an optical system by modifying part of the spatial-frequency spectrum, viz., displacing the lower-frequency light to a high-frequency band, which makes the central maximum in the diffraction pattern narrower and increases the depth of focus. Simulation results show that this kind of apodizer (the term apodization was originally used to describe ways to reduce the sidelobes of the PSF, but in this paper, we use it in a wider sense) is superior to the phase-shifting ones. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

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共光路外差干涉仪具有很高的分辨率.但因为安装、调试误差会产生非线性误差.影响系统的测量精度。着重分析了在共光路外差干涉仪中由激光光源的椭圆偏振化和沃拉斯顿棱镜的安装方位角误差同时存在的情况下,引起的频率混叠综合误差的大小及变化规律。结果发现其造成的非线性误差可达2.2nm,同时还发现两者造成的误差在某些情况下存在一定程度的相互抵消作用。讨论了提高测量系统精度的有效措施,对正确设计和调试激光外差测试系统、提高测量系统精度具有重要意义。

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用气相平衡扩散(VTE)法在α-偏硼酸钡单晶衬底上成功地制备出β-偏硼酸钡薄膜。使用X射线衍射技术(XRD)测试了样品的衍射峰,并比较了不同温度、不同保温时间、不同衬底方向对薄膜的影响。

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植物激素乙烯作为一种信使分子调节控制果实完熟。ACC合成酶是植物体内乙烯生物合成途径的限速酶,其反义RNA的表达将能有效地抑制乙烯的生物合成而延缓果实完熟,利用反转录PCR技术克隆获得了ACC合成酶多基因家族成员之一LE-ACC2阅读框架约1.7kb的cDNA,经酶切图谱和序列分析鉴定无误后,反向连入植物表达载体pBin437中构建成组成型表达ACC合成酶反义RNA的双元载体。经农杆菌途径转化番茄“丽春”品种,获得了60株抗卡那再生杭株,PCR检测证明有6株为转基因植株,Southern杂交和Northern杂交分析进一步确证了外源基因的插入及其转录活性。反义番茄果实的乙烯释放受到明显抑制,表现出更好的耐储保鲜特性,并且与对照相比,在果实品质上没有明显差别。大田培育Fl和F2代转化番茄植株,反义番茄纯合品系的筛选工作正在进行之中。 同时,本研究利用已经获得的ACC合成酶和PG的cDNA克隆,构建了两个嵌合转化基因载体pPGACC1、pPGACC10,它包括1300bp的ACC合成酶cDNA编码序列,并分别含有反向与正向的250bp的5’端PG基因片断。酶切图谱和序列分析鉴定无误后,以pBin437为植物表达载体构建了双元载体pBPGACC1和pBPGACC10,分别表达PG正义RNA和反义RNA,并均表达ACC合成酶反义RNA。经农杆菌转化番茄子叶,植株的再生培育有待进行。通过对转基因植物的分析,我们期望阐明用单一嵌合基因表达载体通过反义抑制与抑制作用实现对内源两同源基因——PG和ACC合成酶下降调节的可能性,并可望得到具有更好耐储效果且品质优良的番茄品系。

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胜坨地区位于东营凹陷北部,北部以胜北大断层为界,南至东营凹陷中央。 在古近纪,该区北部陈家庄凸起遭受强烈剥蚀,物源十分充足,接受了大量古近 系沉积,发育形成规模最大的砂砾岩扇体。胜北断层下降盘砂砾岩体的有利勘探 面积近100 km2。从近期钻井情况看,砂砾岩体之间相互独立、横向连续性差, 储层非均质性极强。因此,对砂砾岩体的认识一直不够深入,几年来一直没能在 勘探上有大的突破。高分辨率层序地层学的理论在90 年代被引入中国后,使众 多学者对中国陆相盆地的研究有了新的理论认识,在渤海湾盆地开展了广泛的研 究。 本论文应用高分辨率层序地层学的理论及方法,建立研究区层序地层格架, 开展沉积体系及其储层特征研究。结合地震、岩心、测井和录井四种资料进行高 分辨率层序地层单元界面的识别。在地震剖面中自下而上,划分了两个三级层序: 沙四上和沙三下层序,同时借助初次湖泛面和最大湖泛面识别各层序内的体系 域。在层序界面识别的基础上,对研究区四口深井T764、T765、T766、T767 进 行

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本发明涉及一种基于8位单片机的电源远程控制器。一种高精度直流电源远程控制器,包括有单片机(1),单片机(1)的地址总线(10)连接地址译码器(3)和数据储存器(4),其主要特点是还包括有地址译码器(3)的译码输出端分别作为数据储存器(4)、数模转换电路(5)、多路独立模数转换电路(6)、状态量输入电路(7)和开关量输出电路(8)的片选地址;单片机(1)的8位数据总线(9)分别连接数据储存器(4)、数模转换电路(5)、多路独立模数转换电路(6)、状态量输入电路(7)、开关量输出电路(8);单片机(1)的串行口与通信接口电路(2)连接。本发明的优点是实现了对高精度高稳定度直流稳流或稳压电源的远程分布控制。各功能模块运行稳定,开发不同的控制软件,达到相应的控制目的;控制数据通信可靠,控制命令响应正确,具有良好的抗干扰能力;远控基准长期稳定度高。

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系统发育研究已是澄清所有进化历史问题的必由之路.选择合适的分子标记以及最大限度地挖掘和利用其所包含的系统发育信息是构建可靠的系统发育树的关键.等位基因杂合子(Intra-individual allele heterozygotes,IIAHs)是核基因内含子作为系统发育研究中的分子标记时常常出现的现象.如何挖掘并利用其中所包含的系统发育信息成为近年来系统发育学的研究热点.文章从此现象的产生、杂合子的分离以及现有的研究方法3个方面详尽概述,阐述了IIAHs及其在系统发育分析中的最新研究进展.

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A new nortriterpenoid, 20-hydroxymicrandilactone D (1) and a novel lignan glycoside, lancilignanside A (2) were isolated from leaves and stems of Schisandra lancifolia, together with three known nortriterpenoids (3-5) and nine known phenolics (6-14). The structures of new compounds 1 and 2 were determined by detailed analysis of their 1D and 2D NMR spectra, and chemical evidences. In addition, compounds 1-2, 6-7, and 9-11 showed anti-human immunodeficiency virus (HIV)-1 activities with 50% effective concentration (EC50) in the range of 3.0-99.0 mu g/ml. Compound 12 was not bioactive in this assay with EC50 more than 200 mu g/ml.

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To investigate germline development and germ cell specification, we identified a Dazl homolog (CagDazl) from gynogenetic gibel carp (Carassius auratus gibelio). Its cDNA sequence and BAC clone sequence analyses revealed the genomic organization conservation and conserved synteny of the Dazl family members and their neighborhood genes among vertebrates, especially in fish. Moreover, a polyclonal antibody specific to CagDazl was produced and used to examine its expression and distribution throughout germline development at protein level. Firstly, ovary-specific expression pattern of CagDazl was confirmed in adult tissues by RT-PCR and Western blot. In addition, in situ hybridization and immunofluorescence localization demonstrated its specific expression in germ cells, and both its transcript and protein were localized to germ plasm. Then, co-localization of CagDazl and mitochondrial cloud was found, confirming that CagDazl transcript and its protein are germ plasm component and move via METRO pathway during oogenesis. Furthermore, the CagDazl is abundant and continuous throughout germline development and germ cell specification including primordial germ cell (PGC) formation, oogonium differentiation, oocyte development, and embryogenesis, and the dynamic distribution occurs at different development stages. The data suggest that maternal CagDazl might play an important role in gibel carp PGC formation. Therefore, CagDazl is a useful and specific marker for tracing germ plasm and germ cell development in the gynogenetic gibel carp. In addition, in comparison with previous studies in sexual reproduction species, the continuous and dynamic distribution of CagDazl protein in the germ plasm throughout the life cycle seems to have significant implication in sex evolution of vertebrates. J. Exp. Zool. (Mol. Deu. Euol.) 312B:855-871, 2009. (C) 2009 Wiley-Liss, Inc.