首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 890 毫秒
1.
金属趋细颗粒的微波吸收特性   总被引:3,自引:0,他引:3  
分析了金属超细粒的吸波机制,在稳频、稳幅和线路匹配情况下,采用波导系统在5~12GHz频率范围内对样品进行了测试,结果表明:金属超细颗粒弥散系的微波吸收在粒度、涂层的厚度及配制方式有关。  相似文献   

2.
根据热力学统计理论证明,当计入量子尺寸效应时,由颗粒的尺寸及颗粒表面曲率决定的压力而引起振动谱的重整化,使半径为R的球形金属超细颗粒的德拜温度发生变化。随着颗粒尺寸的减小,颗粒的德拜温度与大块金属德拜温度的比值将减小,当颗粒的尺寸足够大时,其德拜温度趋近于大块金属的德拜温度。  相似文献   

3.
利用主应力法,结合金属超塑性力学方程,推出了金属超塑性正挤压变形力的计算式;对Tang S提出的金属超塑性挤压模型进行了订正和改进,采用锌铝共析合金对理论计算公式进行了实验验证。  相似文献   

4.
一种新的多金属超富集植物--圆锥南芥(Arabis paniculata L.)   总被引:29,自引:0,他引:29  
野外调查和营养液培养试验表明,圆锥南芥(Arabis Paniculata L.)具有超量富集Pb/Zn/Cd的能力,是国内首次发现的Pb/Zn/Cd多金属超富集植物,它的出现填补了国内多金属超富集植物的空白,为重金属复合污染土壤的植物修复提供了新的种质资源.  相似文献   

5.
考虑空洞演化效应的金属超塑性变形理论   总被引:3,自引:0,他引:3  
根据金属超塑性变形时一般出现严重空洞化的特点,对金属板料超塑性变形时的屈服准则、空洞长大模型、材料损伤动力学方程、起塑性极科的受拉(包括双向受拉)失稳过程和先稳时的成形极限计算方法,起塑性极科成形极限图的预测以及自由胀形和充模胀形等具体起塑成形工艺考虑空洞演化效应的工艺计算与分析等问题进行了系统全面的研究.从而形成了考虑空洞演化效应的金属起塑性变形理论体系。对考虑空洞演化效应的金属起塑性变形理论中的基本问题作了扼要介绍。  相似文献   

6.
为研究洪峰过境堤基发生管涌时内部细颗粒运动及迁出规律,采用变水头模拟洪水,对间断级配无黏性土进行室内管涌试验。以常水头下管涌规律作为对照组,使用彩砂追踪管涌过程中细颗粒的迁移,依据试验结果对不同细颗粒含量和不同孔隙比试样的渗透系数、细颗粒流失量等进行了分析。结果表明:变水头作用下,细颗粒在下降段存在逆流运动;细颗粒流失主要集中在下游,相同试验条件下,变水头流失的细颗粒比常水头多,迁移通道贯通范围大;细颗粒含量越大,孔隙比越小,在水头循环后最大破坏水力梯度差越大,细颗粒流失越严重。  相似文献   

7.
用磁控溅射法制备了Fe/Cu一维准周期磁性金属超晶格样品,并借助X射线衍射技术进行了结构研究,然后,仿照周期金属超晶格的研究方法,引入准周期调制函数,对实验结果进行理论处理,标定了各衍射主峰和卫星峰的指数,并计算了相应的衍射矢量值,对择优生长晶面间距的变化进行了计算,计算结果与实验结果相符.  相似文献   

8.
为了研究燃烧源产生细颗粒在过饱和条件下的长大特性,设计了基于冷气流与热水接触形成过饱和环境的生长管来促进细颗粒的长大.利用热风保温的方式防止测量窗口水汽的凝结,从而实现了直接测量细颗粒长大后的液滴粒径分布.利用实验系统研究了热水温度、初始颗粒浓度、气体流量对细颗粒长大特性的影响.实验结果表明:热水温度的上升对细颗粒的长大影响非常明显;而细颗粒的初始浓度增加则不利于细颗粒的长大;气体流量的增大在一定范围内对细颗粒的长大影响较小,而流量大于4 L/min时,则影响较大.在最优的实验条件下,平均粒径为0.197μm的细颗粒长大为5.411μm.  相似文献   

9.
对于金属超晶格中的无序,提出一种简化的Hamilton模型,用Anderson局域化理论研究了这种模型的电子态并计算了迁移率边位置。  相似文献   

10.
基于roBDD的细颗粒度动态污点分析   总被引:1,自引:0,他引:1  
研究了细颗粒动态污点分析的瓶颈所在,提出一种基于roBDD的细颗粒度离线污点分析方法。实验结果表明该方法能够显著提高细颗粒度污点分析的性能,并减低内存需求,为进一步扩大细颗粒度污点分析的应用提供了途径。  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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号