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1.
基于Bragg衍射理论,分析了超环面晶体分析器实现等离子体在子午和弧矢2个方向等比例放大成像的原理,采用云母作为衍射晶体,研制了对激光等离子体进行二维成像的超环面晶体分析器,其子午和弧矢曲率半径分别为290 mm和196 mm,用于衍射成像时的Bragg角度为54°.采用铬靶X射线源辐照金属网格目标,网格的网孔尺寸为200 μm×200 μm,通过超环面晶体分析器对铬靶Kα谱线的衍射,在X射线IP板上得到了网格的二维背光衍射图像,并与球面晶体分析器成像效果进行了对比.实验结果表明,与球面晶体分析器相比,超环面晶体分析器可实现在子午和弧矢2个方向等放大比的X射线背光成像,且分析器具有较高的空间分辨力,当光源尺寸为500 μm,成像放大倍数为1.86倍时,其空间分辨力达到67 μm.  相似文献   

2.
光子带隙结构时域仿真   总被引:1,自引:0,他引:1  
为了研究光子晶体的能带,利用时域有限差分方法对矩形几何结构的光子晶体进行数值仿真.通过分析光子晶体中电磁场的空间分布和随时间的变化,得到了本征模空间分布与光子能带分布之间的规律.然后通过比较不同波矢和不同能带本征模的空间分布,准确地确定了光子晶体的能带.仿真结果有效地验证了本征模理论,为光子晶体新结构设计提供了重要依据.  相似文献   

3.
应用颗粒膜中颗粒自旋波激发和自旋极化激发的色散关系表达式,对Fe-SiO2颗粒膜进行了计算,探讨其色散规律,结果表明:颗粒自旋波激发与温度无关,而自旋极化激发与温度有关,两者的波谱都随波矢增大而增大,且波矢取分离值,不具有块状晶体自旋波色散关系周期性的变化特征.  相似文献   

4.
本文用普遍的压电耦合波动方程,详细研究了6mm类晶体半空间中的表面波问题。当弧矢面与c轴垂直时,获得了一对新的准声表面波的解析解,并证明其中之一是Bleustein—Gyulaev波的精确解。  相似文献   

5.
极性晶体中极化子的性质   总被引:1,自引:0,他引:1  
本文研究极性晶体中极化子的性质,采用微扰法导出了极性晶体中极化子的基态能量和有效质量。在计及电子在反冲效应中发射和吸收不同波矢的声子之间的相互作用时,讨论对极化子性质的影响,结果表明.反冲效应中不同波矢的声子之间的相互作用对极化子自陷能的影响随耦合常数的增加而增大。  相似文献   

6.
根据相位匹配理论,给出三倍频的参数计算公式。详细计算BABF晶体的相位匹配角、非线性有效系数、走离角、允许角随波长变化的理论曲线,得到了对基频波长为1 064 nm和1 342 nmI类相位匹配的三倍频的相位匹配角、非线性有效系数、谐波走离角、允许角,分别为:74.84°、0.348 6×10-12m/V、0.405 3°、6.465 6 mrad.mm-1和50.87°、0.839 8×10-12m/V、1.448 5°、0.589 0 mrad.mm-1。在考虑走离效应的情况下,研究了三倍频转换效率随BABF晶体长度、基频光光斑半径的变化规律。  相似文献   

7.
根据会聚激光束通过平板型样品池弧矢像散的理论计算结果,全面讨论了相关参数对弧矢像散的影响,其结论对实际操作具有重要的指导意义.  相似文献   

8.
对10例(雄5,雌5)成年太行猕猴枢椎进行了全面测量,另算出两项指数,并作了相关分析.结果表明:所有测量指标及两项指数,经t检验,雌雄间没有显著性差异.用矢径、全宽、椎孔矢径与椎孔横径两两组合为6组进行了相关分析,两两均呈正相关;其中矢经与全宽、矢径与椎孔横径、全宽与椎孔横径呈高度相关.并用矢径(X)与全宽(Y)建立了一元线性回归方程:Y=2.234+1.012X.  相似文献   

9.
晶状体核大小的测量及ECCE切口大小的探讨   总被引:7,自引:0,他引:7  
目的测量巩膜隧道切口白内障囊外摘出述摘出的Ⅱ~Ⅴ级晶状体核的大小,探讨巩膜隧道切口白内障囊外摘除术切口的长度。方法将摘出的晶状体核按颜色分为Ⅱ~Ⅴ,测量各级核的直径、厚度、前面弧长、后面弧长。结果106个晶体核平均直径6.81mm,厚度3.47mm,前面弧长7.28mm,后面弧长8.04mm,Ⅱ~Ⅴ级核各数值依次增加。结论Ⅱ~Ⅴ级核的大小依次增大,手术切口的长度要与核的后面弧长相当,Ⅱ、Ⅲ、Ⅳ、Ⅴ级核推荐平均切口弦长分别为7、8、9、10mm。  相似文献   

10.
使用大功率LD抽运Nd:GdYVO4晶体,分别采用连续抽运和脉冲抽运方式,分析对比了1.06μm激光的输出特性.从速率方程出发,对Nd:GdYVO4晶体的热效应对激光输出特性的影响进行了讨论,从理论上得到了连续抽运和脉冲抽运时激光的输入输出关系,理论与实验符合很好.  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.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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   

20.
赵英华 《科技信息》2008,(12):219-220
0.Preface China has long been boasting of its colorful and immense culture which comprises of Taoism,Confucianism and Buddhism.The interwoven influence among the religions on Chinese way of thinking,on the nation's behavior in their social life throughout the long history is beyond list.  相似文献   

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