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1.
利用Tersoff势和分子动力学方法研究了初始动能为500eV的硼粒子注入金刚石的微观行为.结果表明:单个500 eV的硼原子注入后金刚石仍保持长程有序结构;表面层原子向内驰豫,邻近表达层的其他各层原子向外驰豫,表面层与近表层原子的间距减少了15%,而第2层原子与第3层原子之间的间距增加了1.5%;硼原子穿透到表面层下0.4nm处,然后再向表面扩散;表面层产生0.4 MPa的压应力.  相似文献   

2.
利用Tersoff势和分子动力学方法研究了初始动能为500eV的硼原子注入金刚石的微观行为.结果表明:硼注入后产生温度为5000K的热峰,其寿命为0.18ps;同时产生了半径为0.45nm的局部非晶化区域,三重配位原子数占该区域原子数的7%.硼原子以B〈110〉分裂间隙的形式存在于金刚石结构中.  相似文献   

3.
应用HP4192A低频阻抗分析仪测量了低压ZnO压陶陶瓷的复电容曲线,研究了烧结温度对复电容曲线压低角的影响规律,探讨了晶粒边界耗习层中电子陷阱的种类和起因,并对电子陷阱的特征参数进行了表征。实验发现:在低压ZnO压敏陶瓷中存在两种非理想的Deblye驰豫现象,对于每一种驰豫,其复电容曲线存在压低现象,且其压低角随着烧结温度的升高而迅速减小,在低压ZnO压敏陶瓷的耗尽层区域内存在两种电子陷阱,它们分别位于导带底0.209eV和0.342eV处,其中0.209eV处的陷阱能级对尖于本征施主Znj^x的二次电离,而0.342eV处的陷阱能级对应于氧空位V0的一次电离。  相似文献   

4.
采用考虑 d电子相互作用的spd紧束有闪矿结构的半导体(CuCl的体能带,用形势散射理论方法计算了驰豫的CuCl(110)表面电子结构,给出了表面投影带结构和表面波矢分辨的层态密度,计算结果表明,表面驰豫主要是表面层p-p和p-d的重新杂化而引起的。  相似文献   

5.
本文用高温扩散方法制成了硼皮金刚石,其表面层硼的厚度小于0.1μm,并测得人造淡黄色金刚石,含硼金刚石和硼皮金刚石的动态起始氧化温度分别为675℃,813℃和924℃。由人造金刚石的Auger测量结果表明,在人造金刚石的内部约含有2%的氧。由于它的存在而降低了人造金刚石的抗氧化性与抗压强度。  相似文献   

6.
利用基于密度泛函理论的第一性原理方法研究了Ni1-xPtx(111)和Ni1-xPtx(001)表面合金的功函数.计算结果表明,Pt原子掺杂在表面层时对功函数影响较大,而且表面层Pt原子掺杂后的合金结构最为稳定;对于Ni1-xPtx(001),当表面层Pt原子的覆盖度从0增加到100%时,功函数近线性增加了0.6eV;而对于Ni1-xPtx(111),当表面层Pt原子的覆盖度从0增加到25%时,功函数增加了0.22eV,覆盖度从25%增加到100%时,功函数却几乎不再变化.上述结果表明,表面层合金化对功函数有重要影响,而金属功函数又强烈依赖于表面取向.  相似文献   

7.
本文用第一原理性的密度泛函理论,对6H-SiC(0001)(3×3) 表面再构的原子结构进行了研究.总能计算表明,再构层中的Si原子存在扭转现象,扭转角度为5.4°;无扭转的驰豫模型是一个能量的亚稳结构,它的形成能比扭转模型的高0.7 eV.  相似文献   

8.
主要介绍硼掺杂金刚石膜的生长.采用热灯丝CVD法在硅上制备金刚石薄膜,采用三氧化二硼制备硼掺杂金刚石膜.利用拉曼光谱分析硼掺杂金刚石膜的生长情况.结果表明:硼的掺杂质量分数随生长时间延长而增大;利用SEM观察硼掺杂金刚石膜的表面晶粒变小;利用银浆在掺杂金刚石膜表面制备电极,测试电流随温度升高而变大.  相似文献   

9.
在双能级模型及凝聚态物质的低频涨落,耗散和驰豫行为的统一理论基础上,研究了非晶合金Fe50Ni30B20于480K退火2h以后,在250-350K范围的磁后效谱,计算得到红外发散指数n=0.11,特征驰豫时间τ∞=2.8×10^-17S.在驰豫峰温处,计算的表观激活能E为1.7eV,此结果与实验很好地一致。计算结果表明,对此非晶合金,磁后效是由于B原子跳跃引起Fe-B,Ni-B原子对的局域重排而导  相似文献   

10.
在单电子Hartree-Fock近似的基础上采用扩展离子方法研究RGS中原子型的激子驰豫及所导致的激发态原子解吸机理.研究表明激子──晶格相互作用在解吸过任中起着重要作用.研究结果是位于表面的及表现下一层的原子型激子,可通过空腔解吸机理导致激发态Ne原子的解吸,却不可能导致激发态Kr原子的解吸,这与它们的体内a-STE周围能否形成空腔有关.此外,对解吸原子的发光研究结果与实验符合得较好.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

15.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

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