摘要:

AbstractDuring gelation, the time dependence of the apparent viscosity has been used to analyze the kinetics of the gelation of polyacrylamide (PA) sol with chromium (III) ions. The investigations have stablished the following facts: Before gelation the relation between the viscosity, η, of Cr(III)‐PA sol and the PA concentration is η =f([PA]) = 2.36×1015[PA]3.15and the rate equation of gelation in the steady‐state stage during gelation is expressed asVn=ksf([PA]) [PA]2[Cr(

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130202

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe development of the instrumentation of a scanning electrochemical microscopy (SECM) is presented. The core of the SECM sensing system is constructed based on piezo‐bimorph scanners, a mechanical micropositioner of multi‐dimensional adjustment and ultramicroelectrodes. The control of the electrochemical cell and the SECM system is realized by a battery powered bipoteniostat and analog control circuits respectively with the control of a microcomputer work station. The demonstrations of SECM experiments are given on both a standard IDA sample and a silver electrode. Discussions on the resolution and quality of SECM image are m

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130203

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractSolubilities of ternary systems Li+,K+/SO2‐4‐H2O (1) and Li+,Mg2+/SO42‐‐H2O (2) were investigated by isothermal method at 25°C. Physico‐chemical properties of solutions, such as density, refractive index, viscosity, conductivity and pH, were determined. Phase diagram of the system (1) consists of three solubility branches and three crystallization fields corresponding to K2SO4, Li2SO4·H2O and LiKSO4. LiKSO4is an incongruent compound, and its transition point is estimated graphically to be 45.5–46.0°C. No solid solution of LiKSO4with Li2SO4·H2O was found in the system. The system (2) is a simple eutonic type. Pitzer model of electrolyte solution was used to check the obtained solubilities. Data comparison gives good agreement. Two equations were used to correlate density, refractive index of the solution with its composition. Differences between measured and calculated values are less than 0.6% for density, 0.15%

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130204

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe photovoltaic effects of chlorophyll‐a(chla) and the effects of stearic acid, egg phosphatide and cholesterol on those were investigated by means of measuring the photoinduced potentials of SnC2/chla electrodes. Because of the formation of liquid crystal states, appropriate concentrations of stearic acid and egg phosphatide added in a certain system could increase the photovoltaic effects of chla. Cholesterol always decreased the photovoltaic effects of chla because there was no liquid crystal state formed with i

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130205

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of alkali metals (Na+,K+) on the exchange degree of Hβ zeolite under different conditions and the conversion ofα(orβ)‐methylnaphthalene over the alkalized zeolites were studied. The results showed that the H+of Hβzeolite is totally replaced by the Na+of NaCl solution, while partially exchanged by the K+of KCl solution, there is an exchange equilibrium between the H+and K+for Hβzeolite (Si/Al=17.23) and the value of equilibrium is 88.39. The exchange degree also increases with increasing the Si/Al of the samples. It was suggested that these results are attributed to the electrostatic field in the pore of Hβ zeolite and the nature of zeolite and the properties of alkali metal. The isomerization ofα(orβ)‐methylnaphthalene is the main reaction over the samples and it is more favour on the proper acid‐base sites

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130206

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this paper theoretical studies were performed on artemisinin (qinghaosu) derivatives with semiempirical quantum chemical methods AMI and PM3. The antimalarial activity ‐logChas an obvious correlation with the net charge of C(16) and bond orders of bonds O(1)‐C(10), O(2)‐C(6), O(1)‐O(2) and O(5)‐C(16). According to the calculation results, we derived structure‐activity relationship, presented the probable pharmacophore of qinghaosu derivatives and the interaction fashion between the drugs and the plasmodi

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130207

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper reports calculations of the rate of isomerization of HCN→HCN based on the theory of Gary and Rice as extended by Zhao and Rice. The major task is to determine the effect of intramolecular energy transfer on the prediction of the rate of isomerization. Both the full three‐dimensional (3D) system and the reduced two‐dimensional (2D) system obtained from freezing CN bond at 1.159 A are analyzed to check the validity of the freezing bond approximation. Meanwhile, RRKM rates are calculated to test RRKM choice of the transition state by comparing to Gary‐Rice three‐state model. The comparison shows that the rates from 2D model and 3D model are differing up to 20% with 2D rates consistently larger. The intramolecular energy transfer modifies the isomerization rate for HCN system up to 30% that is modestly small by the expectation. The isomerization rate predicted from RRKM theory is greater than those of Gary‐Rice three‐state model theory up to 65%, and it overstimates the rates under all considerations, including the contribution from intramolecular energy transfer, for the studied system by about

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130208

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe titled complex has been synthesized by the reaction of sodium sulfo‐salicylate with lanthanum and yttrium perchlorate. The crystal structure has been determined by single crystal X‐ray diffractometry. The crystal is monoclinic with space groupC2/c. The unit cell parameters are as follows:a=16.289(8),b=18.323(8),c=22.044(8) Å, β=106.34(2)°, V=6314(6) Å3, Z=4 andDc=1.764 g/cm3. The structure was solved by direct method. The least‐square refinement based on 3776 observed reflections [F>6σ(F)] converged to a finalR=8.6% and F(000) is 3548. Yttrium ion with eight‐coordinate is located in central of the molecule, the two lanthanum ions with ten‐coordinate are located at the two sides of yttrium ion. There are two positions for Na in the molecule, one is in theC2axis with six coordinate, the other one is in a general position with f

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130209

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe strength of basic sites has been measured by pyrrole‐IR on alkali metal cation exchangedβand X zeolites, as well as NaOH loaded Naβ. The influence of cation type and the structure of zeolites on their basicity has been studied. The acidic and basic properties of the samples were investigated by NH3‐TPD and isopropanol reaction. It was shown that the strength of basic sites on samples could be characterized by the shift of vnhband in the pyrrole‐IR spectra. The framework oxygen charges were calculated from the Sanderson electronegativity. The changes in basic properties with various alkali metal cation are consistent with the changes of local oxygen charges of the zeolite fr

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130210

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA convenient derivatization method of amino acids with l‐fluoro‐2,4‐dinitrobenzene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded phase column with a simple linear gradient elution consisting of aqueous buffer and methanol. The eluate was detected by common ultraviolet absorption detector at 360 nm. The detection limits of amino acids were as low as 10 picomole. This method has been successfully applied to assay amino acid injection liquor used in hospital. It has good reproducibility and precision. The procedures avoid the requirements of particular derivative equipment and analyzer employed in conventional amino acid ana

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130211

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY