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161.
ASemiintegralelectroanalysishasbeenimprovedanddevelopedsinceOldhamlwhofirstintroduceditinl972,andiswidelyaPpliedtoseveralkindsofpolarographicanalysis"'suchaslinearsweepvoltammetry,cyclicvoltammetryandanodicstrippingvoltanunetry.Anewfieldinelectroanalysis,neopolarographicmethod,isformed.Thismethodhasmanyadvantages,forexample,highsensitivity,goodresolvingpower,simPlicityofinstrUmentstructureandlowcost.Itissuitableforthestudyoffastanalysisandfastelectrodereaction.Determinationcanbecarriedouteve… 相似文献
162.
应用灰色系统理论和最小二乘原理,推导出连续GM(1,N)模型,并将该模型用于高效液相色谱中溶质保留行为的预测.研究了烷烃、烷基苯及对羟基苯甲酸酯等化合物的容量因子与流动相组成、容量因子与碳数、保留时间与温度、保留时间与碳数的关系,并建立了相应的数学模型,经验证,预测结果良好. 相似文献
163.
164.
A series of 2-cyano-3-methylthio-3-substituted methylaminoacrylates were synthesized as herbicidal inhibitors of photosystem Ⅱ (PSⅡ) electron transport, in order to estimate the effect of fluorine atom, pyridyl group, chirality and ester chain on activity. The important intermediate 2-fluoro-5-aminomethylpyridine was synthesized with high yield. The bioassay results showed that most of rifle compounds had high herbicidal activity in postemergence treatment. The introduction of an a-methyl into the 3-substituted methylamino could improve the activity notably. The replacement of hydrogen by chlorine or fluorine group and phenyl by pyridyl group showed different effects, and at the same time, the ester chain affected the activity too. 相似文献
165.
溶剂聚合膜pH电极作内电极的气敏电极的研究 总被引:1,自引:0,他引:1
研究了以中性载体为活性物的石墨内导平头溶剂聚合膜(SPM)pH电极作内电极的二氧化碳和氨气敏电极。电极的性能取决于中性载体的特性,其中以菸酸十八酯为内电极膜活性物的二氧化碳气敏电极和以二辛基十八胺为活性物的氨气敏电极性能较佳。二氧化碳气敏电极用作丙酮酸脱羧酶酶电极的原电极,其性能院于传统的以玻璃pH电极作内电极的二氧化碳气敏电极。 相似文献
166.
A new method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace Sc and Y, based on gaseous compound introduction into the plasma as their thenoyltrifluoroacetone (TTA) complexes by electrothermal vaporization was developed. Using the reagent TTA as chemical modifier can not only enhance the analytical signals, but also reduce the vaporization temperature. At a temperature of 1,000 °C the trace Sc and Y can be vaporized completely into ICP. The factors affecting the formation of the chelate and its vaporization behavior, such as drying time, vaporization temperature/time, reaction medium and the amount of TTA, were investigated in detail. Under the optimized conditions (drying temperature/time 100 °C/10 s, vaporization temperature/time 1,000 °C/4 s), the limits of detection for Sc and Y were 19 pg and 34 pg (3), respectively, and the relative standard deviations for Sc and Y were 4.2% (c
Sc=0.2 g mL–1; n=7) and 2.6% (c
Y=0.5 g mL–1; n=7). The linear ranges of the calibration graphs cover three orders of magnitude. The method was applied to the analysis of the biological reference materials (GBW 07602, bush branches and leaves; GBW 07604, poplar leaves), and the results obtained were in good agreement with the certified values. 相似文献
167.
This phase was discovered following direct fusion of the elements in welded Nb tubes at 550 degrees C and equilibration at 300 degrees C for 1 week. Single-crystal X-ray diffraction analysis reveals that KNa(3)In(9) crystallizes in an orthorhombic system (Cmca, Z = 8, a = 9.960(1) A, b =16.564(2) A, c = 17.530(2) A, 23 degrees C). The structure contains a three-dimensional indium network built of layers of empty In(12) icosahedra that are each 12-bonded and interconnected by 4-bonded indium atoms that also form zigzag chains. All cations bridge between cluster faces or edges, and their mixed sizes appear critical to the stability of this particular structure, which does not occur in either binary system. Both empirical electron counting and EHTB band structure calculations on the macroanion indicate that the bonding in this structure is closed-shell, whereas resistivity and magnetic susceptibility measures show that the compound is a moderately poor metal. 相似文献
168.
IntroductionCatal}ticrcactionsaffcctcdb}'diffosionaIlimitationincatal}'stporcshavcbccnextensive1}dcaltx`ithinlit.rat.rcll~5I.Scvcraltcchniqucsonthcspccialcase0fFischcr-Tropschs}'nthcsis(FTS)t\crcapplicdtocxplorcthebchaviorofthiscatal}ticrcactionundercxpcrimcntalandopcrationaIconditionsI3~5l.It`"ouldbeofvaluctoindicatchcrcthatthcseinvcstigationsx"ercmainl}'bascdonthesimplcstkineticsofthcfirstordcrinH2proposedbyAndersonl6]attheearIystages.However-thesetboents,striCtlyspeaking,areinvalidfor… 相似文献
169.
Biochemistry is a branch subject of chemistry, which is the study of chemical structures and processes associated with living organisms. COVID-19 pandemic is a problem for human beings. From the perspective of biochemistry, this paper demonstrates the chemical structure and interactions of SARS-CoV-2's spike protein and its receptor (human angiotensin converting enzyme 2), and summarizes the related research progresses. The authors hope to provide insights for the development of COVID-19 vaccine. 相似文献
170.
Synthesis of the third-order nonlinear materials:bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4-naphthaquinone. The materials exhibit larger third-order nonlinear optical susceptibilities χ. 相似文献