首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
采用电渗法研究了几种电解质溶液对铝阳极氧化多孔膜界面性能的影响.结果表明,含有F-,SiO2-3,PO3-4,S2O2-3和酒石酸根等的电解质溶液,使多孔膜的等电点pHIEP由原来的9.20分别移至3.40,3.30,4.30,3.90和3.80,膜的带电性能发生了相应的变化.多孔膜带电性能的变化有利于常温封闭液中的金属离子进入多孔膜内,同时F-,S2O2-3还可通过与膜内H+,H2O等的相互作用,使膜孔内pH升高,从而加速金属离子在膜内的水解沉积,促进常温封闭的进行.  相似文献   

2.
掺铜TiO2的制备及其光催化降解铝试剂1的研究   总被引:4,自引:1,他引:4  
采用sol-gel法和高温灼烧制备了掺杂不同量的Cu^2 的TiO2/glass膜及纳米TiO2颗粒.研究了其对铝试剂的光催化降解过程,并由紫外吸收光谱对降解的中间产物进行了初步探讨.结果表明掺杂量为0.07%的Cu^2 时,光催化活性最佳.结合压电传感技术在线检测了不同气体氛围对TiO2光催化剂催化效果的影响,定量说明O2有利于光催化,而N2对其有抑制作用.  相似文献   

3.
利用电子束沉积方法在玻璃基底上制备了TiO2薄膜及zr掺杂TiOz薄膜.采用拉曼光谱仪和分光光度计对膜的结构和吸收光谱进行了表征;研究结果表明:退火温度为773K时,沉积得到的Ti02薄膜为锐钛矿结构的薄膜;Zr掺杂锐钛矿型TiO2,导致带隙减小,掺杂后在350—450nm附近的光吸收系数增大,TiO2的吸收带产生红移,增强了TiO2的光催化活性;1%掺杂量对光的吸收系数于大5%的掺杂量.  相似文献   

4.
利用脉冲激光沉积法,在氧气氛下(氧分压为20 Pa)以硅为基体制备了ZnO:Al透明导电膜.靶材选用(ZnO)1-x(Al2O3)x陶瓷靶,沉积过程中基体温度保持在600℃.通过对膜进行霍尔效应测量及SEM、XRD测试分析,研究了靶材中的化学配比(掺杂比)对膜的电学特性的影响.结果表明:掺杂比影响着膜的电学性能和膜的结晶状况.掺杂铝的质量分数为1.37%时所获得的ZnO薄膜具有最小的电阻率.  相似文献   

5.
我们用PECVD方法制备出SnO_2薄膜,透射电镜TEM分析表明沉积温度由高到低时,SnO_2膜从多晶态转变为非晶态,并且其电阻率随之增加;沉积时氧气流量增加时,SnO_2的电阻率增加。  相似文献   

6.
复合氧化物气敏材料的制备与特性   总被引:2,自引:0,他引:2  
用固相反应法及共沉淀法制备了LaNiO3系与LaCoO3系复合氧化物,讨论了掺杂TiO2、V2O5、SnO2、Sb2O3等对材料结构的影响.以及材料结构与气敏性质的关系,发现选择合适的掺杂物与掺杂量及适宜的热处理温度,可获得具有理想敏感特性的复合材料  相似文献   

7.
采用胶体化学方法制备了SnO_2.ZnO微粒的水溶胶和有机溶胶,实验结果表明,SnO_2·ZnO胶体存在着明显的量子尺寸效应。应用L-B膜技术制备了SnO_2·Zno纳米微粒/硬脂酸交替L-B膜,用原子力显微镜观察了SnO_2·ZnO纳米微粒/硬脂酸交替L-B膜的形貌。通过加热除去硬脂酸后的SnO_2·ZnO膜有好的气敏性及对酒精的选择性。  相似文献   

8.
本研究利用α-Al_2O_3为原料,添加粘结剂、成型助剂、成孔剂,采用注浆成型,通过固态烧结技术制备了不同规格的多孔性微孔膜管。制备的基质管孔隙率在40~50%,平均孔径0.8~2.0μm,微滤层的孔隙率在30~45%,平均孔径0.1~0.5μm,并具有一定的机械强度。文中分析了影响膜管成型的因素及成孔烧结的机制,探讨了成孔剂和烧成温度对膜的结构、孔径、渗透系数、孔隙率的影响,实验发现加入成孔剂可大大提高了膜的渗透性能,是制取大通量膜材的方法之一,同时发现温度是影响膜性能的重要因素,合理的烧成温度与粘结剂、骨科有很大的关系。  相似文献   

9.
研究了铝的不同掺杂工艺和掺杂量对草酸钴结构和形貌的影响.通过工艺1可让纳米级铝化合物基本分布在草酸钴晶粒外面,而应用工艺2则让铝进入草酸钴晶格中.用费氏粒度仪测量样品的粒度;X射线衍射仪测晶型结构;扫描电镜观察形貌.结果表明,使用工艺1不会改变草酸钴的结构而应用工艺2只需掺入少量铝即可使草酸钴由α-晶型转变为β-晶型.随着草酸钴中铝掺杂量的增加,掺杂草酸钴的粒度增大,而草酸钴的外形轮廓不发生明显改变.  相似文献   

10.
报道了MOCVD生长的高铝值AlxGaAs(x≥0.7)中的非故意碳掺杂.实验研究了Ⅴ/Ⅲ比、生长温度、生长压力、生长速率对载流子浓度的影响,实验发现:碳掺杂主要取决于Ⅴ/Ⅲ比、生长压力、生长速率.在650℃到760℃之间,生长温度对碳掺杂没有太大影响.  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.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
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   

19.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

20.
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   

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-23

京公网安备 11010802026262号