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1.
蓝 Ia超新星是迄今天文学家已知的校准得最好的标准烛光 ,峰值光度弥散仅为 0 .11mag.将近处距离已知的蓝 Ia超新星匹配到远处哈勃流样本中 ,便可获得哈勃常数的估计值 .当前的数据显示哈勃常数为H0 =( 55.3± 5.3) km· s-1· Mpc-1.  相似文献   

2.
在水-乙醇及水-二氧六环混合溶剂体系中,用pH电位滴定法,测定了新β-酮螯合剂1-苯基-3-甲基-4-(α-呋喃甲酰基)-5-吡唑酮(简称HA)在不同有机溶剂含量(x)时的酸离解常数(K_a),建立了K_a与x的关系式,通过外推,求出HA在纯水中的酸离解常数pK_a=4.18±0.02(I=0.10,t=25±0.5℃),采用两相滴定法,测定了HA在七种有机溶剂与水相间的两相分配常数。用Hildebrand正规溶液理论解释了实验结果,进而建立了溶度参数(δ)与两相分配常数的关系式:log K_d=log(1000d/M)+3.07-0.248(δ-9.80)~2,式中d和M分别是溶剂的密度及摩尔质量。  相似文献   

3.
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   

4.
我们用流动微波放电—化学发光方法首次测定了O(~3p)原子与环戊酮分子在303—503K温度范围内的反应速率常数,反应速率常数与温度关系为k=3.79±1.41×10~(-11)exp(-18.6±1.5kJ·mol~(-1)/RT)cm~3·molecule~(-1)·s~(-1)O(~3p)原子由流动微波放电产生,利用检测其与NO反应生成NO_2~*的化学发光强度的方法来检测O(~3p)浓度。此外,还就这类反应速率常数与环形分子结构关系进行了讨论。  相似文献   

5.
紫外吸光光度法测定厚朴酚及和厚朴酚的解离常数   总被引:5,自引:2,他引:5  
 根据光度法测定酸解离常数的原理,采用紫外分光光度法测定了厚朴酚与和厚朴酚的解离常数(pKa),并用计算机和统计方法作数据处理.实验测得厚朴酚的解离常数pKa1为7.10±0.11,pKa2为10.58±0.36,和厚朴酚的pKa1为9.64±0.03,pKa2为10.71±0.21.方法简便,结果可靠准确.  相似文献   

6.
为解决木质框架土壤渗滤系统(WFSI)在处理干清粪养猪废水时的设计高度问题,构建了高度为1.2 m的WFSI反应器。在表面水力负荷为0.08,0.2和0.32 m3·(m2·d)-1,氨氮负荷为27.3±6.0,88.5±9.4,122.7±7.4,28.1±3.7,114.9±10.3 g·(m3·d)-1等条件下运行了WFSI反应器,并根据扩散理论和水流在反应器的流态推出了氨氮浓度与滤层高度间的函数关系式。通过对沿程土壤层中的含水率和氨氮浓度的测量和函数拟合,得到了含水量沿程变化和氨氮浓度沿程变化的经验公式。利用经验公式对氨氮浓度与滤层高度间的函数关系式进行求解,并得到了系统构造常数。通过对比五种运行条件得到的系统构造常数,验证了本研究得到的氨氮浓度与滤层高度间的函数关系是较为可信的。  相似文献   

7.
本文用分光光度法研究了钛(Ⅳ)—磺基水物酸—柠檬酸/酒石酸/苹果酸竞争体系中络合物的形成。测定了柠檬酸钛、酒石酸钛、苹果酸钛络合物的组成及稳定常数。结果表明:在PH3.7时、钛(Ⅳ)与柠檬酸形成1:1无色络合物,其lgβ_1=9.95(±0.04),钛(Ⅳ)与酒石酸形成两种无色络合物,其组成比分别为1:1和1:2,lgβ_1=7.81(±0.03),lgβ_2=10.35在PH3.5时,钛(Ⅳ)与苹果酸形成1:1无色络合物,其lgβ_1=8.49(±0.04)并用金属指示法等对结果进行了验证。  相似文献   

8.
用流动放电—化学发光方法测定O(~3p)原子和丙烯醇分子化学反应速率常数.在293K—473K 范围内,反应速率常数的Arrhenius 形式为k=(6.41_(-0.61)~(+0.67))×10~(-11)exp[-(6.4±0.3)kJ·mol~(-1)/RT]cm~3·molecule~(-1)·s~(-1)并对该反应的反应机理进行了讨论.  相似文献   

9.
在水溶液中鈷和吡啶,3-甲基吡啶,4-甲基吡啶形成紅色的1:1絡离子。由光密度及pH的测定,計算了在离子强度0.5,pH05—6,钴离子和配位体浓度比1:1到1:7的范围內鈷和吡啶,3-甲基吡啶,4-甲基吡啶的絡合平衡常数K_1分別为12±1,13±1,及23±1各配位体的絡合常数的对数与共和氢离子締合常数的对数成正比关系,logK_1/logK_B=0.20。  相似文献   

10.
熊胆缓释胶囊的溶出度和生物利用度   总被引:1,自引:0,他引:1  
为了减少服药次数,方便病人和医护人员,用缓释阻滞剂制备熊胆缓释胶囊。高效液相色谱外标定量法测定熊胆中特有成分熊去氧胆酸(UDCA)的含量,建立校正曲线及方法学考察。用RC-3D溶出仪,转篮法测定12颗胶囊溶出度。家兔16只分成两组,分别灌胃口服熊胆缓释颗粒和熊胆原药100mg/5mL生理盐水液。设定时间点采血后测出血浆中UDCA含量,绘制血药浓时曲线。3P87软件计算曲线峰下面积AUC缓,AUC原和各自的转运速率常数K缓和K原,用公式[AUC缓K缓(/AUC原·K原)]×100%,得出相对生物利用度F。实验结果是(1)体外溶出度按取样时间点为序(h)是05、1、2、4、6、8、10、12、14、16、18、20。累积溶出百分率(%)为1837、2945、3578、4267、4986、5734、6912、7642、8867、9612、9673、9748。(2)血药浓时曲线在设定时间点(h)1、3、6、9、12、24、36、48,缓释组的浓度(μg·mL-1±SD)59159±2748,68826±4279,66278±3964,60207±3717,54964±4459,61480±4775,51573±6009,42462±4522。原药组41334±2291,67522±4635,51498±4987,37518±4175,36644±3933,35464±2986,25870±1914,22318±2693。曲线峰下面积(AUC缓和AUC原)[μg·mL-1·h)]分别是89852664,35164555,两组清除相转运速率常数K缓和K原分别是(h-1)003、0089。(3)计算出相对生物利用度F为7680%。表明熊胆缓释胶囊有好的体外溶出度和较高的体内生物利用度,可提供48h服药一次,达到缓释目的。  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.
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   

14.
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   

15.
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   

16.
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   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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