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1.
利用两相滴定法在(25±0 5)℃下测定了仲壬基苯氧基乙酸(CA-100)在水中的溶解度S,离解常数Ka,以及庚烷中的二聚常数K2和水-庚烷两相间的分配常数Kd.实验测得S=1 30×10-4mol/L,Ka=2 94×10-4,K2=3 29×102,Kd=4 15×102.  相似文献   

2.
本文用VPO 法证实P_(507)在癸醇中以单体形式存在的基础上,用电导滴定法测定了水相中萃取剂总浓度S,并用pH 两相滴定法测定了P_(507)在水一癸醇体系中的电离常数K_α、两相分配常数Kd 和两相电离常数K_(αE).测定值:S=5.30×10~(-5)M; pKα=3.88;1gKd=3.18; pK_(αE)=7.06.  相似文献   

3.
利用在线分光光度法对Fenton试剂降解活性黑5模拟废水进行褪色行为研究,考察了FeSO4初始浓度、H2O2初始浓度、pH值、反应温度等因素对活性黑5褪色过程的影响规律.结果表明,Fenton氧化过程分为两个拟一级动力学过程,反应前期褪色速率常数(k1)和反应后期褪色速率常数(k2)相差约5倍.增大Fe2+的初始浓度和体系温度能够增加k1和去除率,且k1与Fe2+初始浓度线性相关,反应活化能为3.451 kJ/mol;H2O2初始浓度和pH值存在最佳值,分别为2.118 mmol/L和3.  相似文献   

4.
试验结果表明,中蜂(Apis cerana Smith)和意蜂(Apis mellifera Linnaeus)的乙酰胆碱酯酶(AchE)对底物乙酰硫代胆碱的反应性质具有明显的不同。中蜂的AchE的反应初速度和反应进程曲线的线性相关时间范围分别是0.027(OD_(412)值/min,0.8头)和0—10分钟,而意蜂则分别为0.012和0—15分钟。米氏常数值和最大反应速度值,中蜂分别为6.25mmol/L和0.105(OD_(412)值/min,0.4头),意蜂分别为0.862和0.015(仅为中蜂的13.8%和14.3%)。中蜂和意蜂AchE对残杀威的双分子速率常数值(K_i),氨基甲酰化常数(K_2)、解离常数(K_d)以及I_(50)值没有明显的差异。但是,对敌百虫的反应确明显不同,K_i、K_2、K_d和I_(50)值分别相差2.70、1.39、1.94和5.64倍。说明中蜂和意蜂AchE对氨基甲酸酯类化合物和有机磷类化合物的反应是不同的。  相似文献   

5.
1.主要研究结果和创新之处 (1)利用牛肾上腺皮质束、网状带细胞(BAC细胞)培养,放射性同位素受体结合标记,首次证明本地黄牛BAC细胞表面分布有机能性碱性成纤维细胞生长因子(FGF2)的高、低亲和力受体。它们高亲和力受体(具有酪氨酸激酶活性)的数目为4500个/细胞,低亲和力受体(硫酸乙酰肝素蛋白多糖HSPG)数目为28000个/细胞。两种受体的平衡解离常数(Kd)分别为23.5和381.9pm;转化生长因子β1(TGFβ1)和促肾上腺皮质激素(ACTH)刺激均可增加BAC细胞表面的FGF2受体数目。前者增加的高、低亲和力受体数目分别为6500个/细胞和140000个/细胞(Kd分别为3.151×10~(-11)mol/l  相似文献   

6.
(1) 以纤维蛋白溶酶原(PG)为底物,H—uk的Km值为L—uk的一半。但以CTN为底物时,H—uk和L—uk的Km值很接近,分别为5×10~(-4)M和4×10~(-4)M。 (2) 在PH7.5—9.0范围内,改变氢离子浓度只影响两种尿激酶水解CTN的最大反应速度V,而Km保持不变。由此断定k_(-1)>>k_2。Km是平衡常数的倒数。以pH对logV作图,求得H—uk和L—uk活性中心可解离基团的PK很接近,分别为7.65和7.85。 (3) ∈—氨基已酸(E-ACA)对两种尿激酶都呈现典型的竞争性抑制作用。EACA对H—uk的Ki为0.8×10~(-2)M,对L—uk的Ki为1.5×10~(-1)M。来源不同的天然胰蛋白酶抑制剂对两种尿激酶都不抑制。 (4) 观察了温度对K_m和k_2的影响,计算了平衡反应和活化过程的各种热力学常数。 (5) 从所得动力学和热力学结果推测,两种分子形式尿激酶的活性中心性质相同,但二者的构象却很不相同,H—uk的结构更有利于进行反应,由此推测H—uk是尿激酶的天然形式,L—uk是前者的降解产物。  相似文献   

7.
为优化钒电池电解液配比和设置合理的充放电制度,需弄清自由钒离子活度和离子对的解离常数及其热力学性质.研究了电导法测定在298.15 K时水溶液中VOSO4.3.53H2O(s)的电导率,利用Origin数据拟合求出极限摩尔电导;采用改进的Ostwald稀释定律和改进的Davies方程求解活度系数,进而求得溶液的真实离子强度;采用Fuoss方法求解硫酸氧钒离子对的解离常数.经过数据处理得到298.15 K时硫酸氧钒极限摩尔电导率Λ0为203.2520325 S.dm2.mol-1,硫酸氧钒离子对的解离常数Kd为0.001 961 62,为电池性能有关的热力学性质提供了基础数据.  相似文献   

8.
运用NMR技术对叔丁基氯在60%丙酮水溶液中的水解动力学机理进行了研究。该水解反应为准一级反应,其速率常数k=(1.34±0.2)×10~(-4)/s,反应的半衰期为τ_(1/2)=k_1~(-1) In2=5284s。  相似文献   

9.
本文采用CCSD(T)/aug-cc-pVTZ//B3LYP/6-311+G(2df,2p)方法构建了HO_2+ClO反应体系的单、三重态反应势能剖面,并对该反应主通道的速率常数进行了计算研究.结果表明,HO_2+ClO反应中存在4条抽氢通道R1(HOCl+~1O_2)、R2(HOCl+~3O_2)、R3(HCl+~1O_3)和R4(HCl+~3O_3)以及2条抽氧通道R5(OOCl+HO)和R6(OClO+HO),其中抽氢通道R2(HOCl+~3O_2)和R3(HCl+1O3)的能垒比其它四个通道的能垒降低了9.08~42.90kcal·mol-1,是标题反应的优势通道.采用传统过渡态理论并结合Wigner校正对优势通道R2(HOCl+~3O_2)和R3(HCl+~1O_3)在240~425K范围内的速率常数进行了计算.计算结果表明,通道R2(HOCl+3 O2)的速率常数比R3(HCl+~1O_3)的对应值大了3~5个数量级,表明标题反应的速率主要取决于通道R2(HOCl+~3O_2).此外在298 K时,通道R2(HOCl+3O2)的速率常数为2.76×10-15 cm3·molecule-1·s-1,与实验值较为吻合.  相似文献   

10.
本文应用交流胆抗法测定Zn(Ⅱ)/Zn体系在微酸性硫酸盐溶液中的交换反应速度常数.根据电荷转移电阻(R_(ct))计算得交换反应速度常数(k)为(3.1±0.5)×10~(-5)ms~(-1).k值与转速无关,表明Zn~(2+)离子从本体溶液向电极表面的扩散不参与界面上的交换速度过程.  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 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   

13.
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   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
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   

16.
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   

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.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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