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1.
将一个新理论——正、负能谱(PNES)热力学理论应用于白矮星系统的力学平衡问题,对白矮星初期淡化阶段的力学平衡进行了详细的分析.虽然应用PNES热力学理论所得出的结论与原有的理论结果一致.但是PNES理论的基本原理和思路与原有的理论完全不同,按照原有理论,白矮星系统只是一种电子系统,氮离子系统只被视为约束电子系统的外部约束条件.显然原有理论不能反映白矮星的实际状态,因为白矮星并不是一个电子系统而是一个由电子子系和氯离子子系组成的复合系统.因此,对白矮星的力学平衡问题和演化问题都必须以由电子子系和氮离子子系组成的复合系统来进行研究.本文应用这一新理论(PNES热力学理论),以复合系统的观点研究了白矮的力学平衡问题.  相似文献   

2.
反应精馏过程设计不同于常规精馏 ,利用变换组成变量 ,可借助常规精馏设计类似的方法简化设计反应精馏过程 对于平衡化学反应和速率较慢的两种类型反应 ,设计方法一般不同 前者 ,平衡化学反应对相平衡有较大影响 ;而后者 ,由于反应速率较慢 ,塔板上 (或塔内 )持液量对反应有较大影响 数学模拟可预测反应精馏过程的操作状况 平衡级模型由于简单 ,对它的研究起步较早、也较深入 非平衡级模型可以较精确地模拟板式塔及填料塔的反应精馏过程  相似文献   

3.
用密度泛函理论(DFT)B3LYP方法,在6 311 G 基组水平上,计算了反应XCOOH(X=F,Cl,Br)HX CO2.优化了反应物 中间体 过渡态和产物的几何构型,并用频率分析和内禀坐标法(IRC)验证了各鞍点构型和反应路径,计算了不同温度(200 15~450 15K)下慢反应经零点能校正的活化热力学量、反应过程热力学改变量、正逆反应的速率常数和频率因子以及平衡常数,得到了各反应的动力学信息.  相似文献   

4.
在胺与卤代烷产生的烷基化反应中,生成的胺盐与胺之间存在着质子转移平衡,所得产物为复杂的混合物,用此法制备叔胺产率较低。相转移催化为一新的实验方法,它能改变许多传统化学反应的进程。本文研究了选用适当的相转移催化剂参与由胺与卤化烷制备叔胺的反应,并对某些反应条件进行了探索,找到了影响叔胺产率的因素。  相似文献   

5.
用 CO 还原 FexOy(主要是指 FeO 和 Fe_3O_4),是高炉炼铁的主要化学反应之一。人们用间接还原度 r_c。来衡量这个反应的发展程度,它的大小直接关系着高炉能耗的高低。因为与直接还原相比,间接还原的缺点是还原剂耗量较大:基于 FexOy CO 反应的热力学平衡,还原剂 CO 并不能被完全利用,剩余的 CO 与还原生成的 CO_2组成平衡气相。所谓还原剂过量倍数 n 是指总的还原剂供给量相当于已被利用的 CO 的倍数,它的倒数则  相似文献   

6.
以甲苯和间苯二甲酰氯(IPC)为原料,经傅-克酰基化反应,合成1,3-二(4-甲基苯甲酰基)苯(DMBB),产率85%;将DMBB在KMnO4/吡啶/水体系中氧化合成中间体1,3-二(4-羧基苯甲酰基)苯(DMBA),产率96%;DMBA和氯化亚砜反应以91%的产率合成一种新型的芳二酰氯--1,3-二(4-甲酰氯苯甲酰基)苯(DMBC),三步总收率为74%.产物结构经FT-IR、1H NMR、元素分析等技术表征确认,DSC分析表明目标产物具有较高的纯度.  相似文献   

7.
探讨了Bal31核酸酶在无Ca(Ⅱ)体系中能否依赖稀土离子La(Ⅲ)从两端降解线性DNA分子.发现了 1 mmol/L 的La(Ⅲ)能激活Bal31核酸酶, 从而快速酶解线性DNA.表明了Ca(Ⅱ)并不是文献中所说的唯一能激活Bal31核酸酶的离子. 用液相色谱(HPLC)分别检测Ca(Ⅱ)、La(Ⅲ)体系的酶解产物,结果表明:虽然后者酶解CG 碱基对的速率只约为前者的60%.但两体系对AT碱基对的酶解速度相近.  相似文献   

8.
目的系统探讨和分析蒙日几何学派和高斯几何学派的微分几何思想。方法历史分析、比较研究和文献考证。结果曲面可以用立体的边界与孤立的二维薄膜两种方式验证。前者是制图工程师看待曲面的方式,属于蒙日几何学派的观点;后者是测地员考虑方式,属于高斯几何学派的观点。结论蒙日几何学派和高斯几何学派相辅相成,推动了微分几何的发展。  相似文献   

9.
一步室温固相化学反应法合成CuO纳米粉体   总被引:9,自引:0,他引:9  
研究了以CuSO4·5H2 O ,CuCl2 ·2H2 O ,Cu(NO3) 2 ·3H2 O ,Cu(gly) 2 ·H2 O与NaOH为反应物 ,用一步室温固相化学反应合成CuO纳米粉体的 4个反应体系 ,用透射电镜 (TEM)和X射线衍射 (XRD)对产物进行表征 .表明产物CuO(Ⅱ )化合物与NaOH经室温固相化学反应得到单斜晶纳米CuO .另还从研磨方式、反应配比及反应体系等方面对影响产物粒径大小及分散性的因素进行了探讨  相似文献   

10.
对二甲醚自热重整制氢体系进行了热力学计算和分析,探讨了反应体系的理论最大能效以及达到热力学平衡时产物等的变化情况,分析了水醚摩尔比、氧醚摩尔比、反应温度等因素对体系平衡组成的影响.分析发现,固定水醚摩尔比时,二甲醚自热重整理论完全反应可在某一氧醚摩尔比下达到自热平衡点,此时反应能量效率最高;重整反应在水醚摩尔比为2.0~4.0、氧醚摩尔比为0.4~0.5以及温度为150~350℃的条件下,产物中氢气摩尔分数高于50%,氢气产率高于80%,产物中一氧化碳摩尔分数低于5%,反应理论最大能效高于85%.  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.
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   

15.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

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