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1.
林璋  王琛 《电子显微学报》1999,18(1):106-110
观察生物体内DNA凝聚参与物--亚精胺对DNA的凝缩作用将有利于深入理解DNA在体内的紧密存储机制。本文采用原子力显微镜(AFM)研究了在不同的DNA浓度下亚精胺-DNA凝聚体的形态变化,研究表明:随着体系中DNA浓度的变化,亚精胺将诱导DNA形成两种类型的凝的,当λ-DNA浓度低于1ng/μl, 精胺可诱导λ-DNA形成一种特殊的结构--环形凝聚体,其体积与单个λ-DNA的体积近似,当λ-DNA  相似文献   

2.
激光对DNA作用的损伤效应   总被引:1,自引:0,他引:1  
用Nd(3+):YAGQ开关二倍频激光分别照射λ-DNA/HindⅢ,鱼-DNA,小牛-DNA和酵母-RNA,在相同的激光剂量条件下,观察不同激光照射时间对DNA的作用。测定了DNA的UV谱,讨论了激光辐照导致DNA链断裂的分子机制.  相似文献   

3.
本文研究了新型陶瓷刀具材料JX-2-Ⅰ(Al_2O_3/SiCp/SiCw)的力学性能,同A(Al_2O_3)、AP(Al_2O_3/SiCp)、AW(Al_2O_3/SiCw)和Jx-1(Al_2O_3/SiCw)材料相比,JX-2-Ⅰ具有较高的抗弯强度(σ_(bb))和断裂韧性K_(Ic);研究结果表明,在JX-2-Ⅰ陶瓷刀具材料中确实存在增韧补强的协同作用,陶瓷刀具材料JX-2-Ⅰ的主要增韧机理是界面解离、裂纹偏转和晶须拔出。  相似文献   

4.
本文利用TEM研究了新型复相陶瓷刀具材料Jx-2-Ⅰ的界面结构,结果表明,在Jx-2-Ⅰ中Al_2O_3/SiCw(氧化铝/碳化硅晶须)界面和Al_2O_3/SiCp(碳化硅颗粒)界面结合良好,形成了具有较高强度的微观结构;发现在SiCw、SiCp和Al_2O_3晶粒上均有位错产生,在SiCp和Al_2O_3上有孪晶产生;分析表明,位错和孪晶的产生均吸收大量的断裂能,提高材料的断裂韧性,改善JX-2-Ⅰ材料的整体性能。  相似文献   

5.
原位TiC-AlN/Al复合材料中AlN/Al界面的微结构的研究   总被引:2,自引:0,他引:2  
本文用透射电镜(TEM)的衍技术和高分辨电镜(HRTEM)研究了用原位固-气-液三态反应法制备的原位TiC-AlN/Al复合材料中AlN颗粒与Al界面的微现组织结构,发现AlN/Al界面两侧晶休的两个晶面存在平行关系;(101)AlN/(111)Al。作者从金属固溶和金属结晶理论出发,分析了AlN/Al界面微结构的形成机制,较好地解决了原位了TiC-AlN/Al昨合材料中界面结合较好的原因。  相似文献   

6.
通过比较Al-Zn合金和Al_2O_(3p)/Al-Zn复合材料的激光重熔组织。分析Al_2O_3颗粒对Al-Zn合金激光快凝组织的影响规律。实验结果表明,Al_2O_3颗粒可以显著细化激光熔区的晶粒。基于凝固界面与颗粒交互作用的理论分析,给出了晶粒细化的临界条件。  相似文献   

7.
首次用光伏方法研究了(GaAs/AlAs)n短周期超晶格中的超晶格类型及其转变问题.不同于其它方法,光伏方法仅涉及到载流子在实空间中的分离及其大小.这种空间分离在Ⅰ类超晶格中为零,而在Ⅱ类超晶格中不为零.(GaAs/AlAs)n短周期超晶格在n=10和11时被指认为Ⅱ类超晶格,在n=15时被指认为Ⅰ类超晶格.与其它大部分实验结果一致.  相似文献   

8.
本文用扫描隧道显微镜(STM)在天气中研究了Cu-27.2wt.%Zn-4.7wt.%Al合金中的贝氏体的精细结构,并与透射电镜(TEM)及扫描电镜(SEM)下的形态进行了比较,发现Cu-Zn-Al合金中贝氏体是由亚片条或亚单元组成,亚单元由超亚单元构成,进而为贝氏体相变机制的再认识提供了重要的实验基础,并在此基础上提出Cu-Zn-Al合金中贝氏体的形成模型。  相似文献   

9.
对1.3μm和1.55μm波长的Si1-xGex波长信号分离器(WSD)和Si1-xGex/Si应变超晶格(SLS)红外探测器的集成结构进行了系统的分析和优化设计.优化结果为:(1)对Si1-xGexWSD,Ge含量x=0.05.波导的脊高和腐蚀深度分别为3μm和2.6μm.对应于λ1=1.3μm和λ2=1.55μm波长的波导脊宽分别为11μm和8.5μm.(2)对Si1-xGex/SiSLS探测器,Ge含量x=0.5.探测器的厚度为550nm,由23个周期的6nmSi0.5Ge0.5+17nmSi组成.  相似文献   

10.
本文论述在常压CVD硅外延系统中,通过e_qP=B-A/T,分别计算出SiH-Cl_3、PCl_3和BCl_3的A和B二常数值。采用低温深冷工艺,进一步提高硅源的纯度,通过控制SiHCl_3的蒸汽压,在晶向为(111)和(100),掺硼电阻率(4~8)×10 ̄(-3)Ω·cm的抛光衬底硅片上,生长出外延层电阻率为350Ω·cm(杂质浓度3.5×10 ̄(13)/cm ̄3),外延层厚度达120μm的p/p ̄+/硅外延片,制成器件的击穿电压可达1000V。  相似文献   

11.
This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.  相似文献   

12.
We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4' -bis(2,2 -diphenyl vinyl)-1,1' - biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/NPBX (20 nm)/CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/NPBX (5 nm)/DPVBi (30 nm)/Alq(30 nm)/LiF(0.5 nm)/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N' -bis- (1-naphthyl)- N,N' -diphenyl -1, 1' -biphenyl-4,4' -diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (PPY)3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.  相似文献   

13.
To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.  相似文献   

14.
本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。  相似文献   

15.
Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.  相似文献   

16.
It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV).  相似文献   

17.
正For a long time,optical and wireless systems/net-works are developed in separate communities witha few attempts for in-depth convergence.In fact,it prom-ises many advantages to combine the optical and wire-less technologies in the levels of systems and networks.Recently,both academia and industry have made manyefforts to enter a new phase of development to take op-tical and wireless systems as fully integrated networks.To provide high bandwidth and reliable service for bothfixed and mobile users,a well-designed network must  相似文献   

18.
正Happy New Year!As we step into a new year,we take a look back at the key feature topics covered in China Communications over the past 12 months and set out our expecta-  相似文献   

19.
正Cloud computing is a novel computing paradigm that utilizes remote cloud resources to achieve a high-performance computation.Cloud provides infrastructure,platform and software as different on-demand services.China has made remarkable progress in cloudbased products and operating system technology.The government,enterprises and research institutions are all active in the development of cloud computing-related projects.Despite the progress,many important problems  相似文献   

20.
正Smart Grid Communications The electric power industry is undergoing profound changes as the industry aims to capture the promise of a smart grid for a sustainable energy future.Enabled by the advanced sensing devices such as Phasor Measurement Units(PMUs),increasingly powerful  相似文献   

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