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1.
1 INTRODUCTIONSince1980,manyV/Fe/Sheterometallicsulfurclustercompoundshavebeenreported.RauchfussetalobtainedtwokindsofV/Fe/Scompounds[1]using(CH3C5H4)2V2S4asanorganometallicligand,oneis(MeCp)2V2Fe2(NO)2S4withacubanelikestructureandanotheris(MeCp)2V2S4Fe(NO)2and(MeCp)2V2S4…  相似文献   

2.
IntroductionSinceK pfdiscoveredthatdicyclopentadi enyltitaniumdichlorideexhibitedantitumouractionin1979,1alargenumberofcyclopentadienyltitaniumcom plexesbearingdifferentsubstituentshavebeensynthe sized .2 ,3Theexperimentaldatarevealedthat (Cp) 2 TiX2(X =halogen ,p…  相似文献   

3.
1 INTRODUCTIONAsatypeofimportanceprecursor,alotoforganolanthanidechloridecomplexeshavebeensynthesizedandstructurallycharacterized[1].Thebimetalliccomplexescontainingalkalimetal,Cp2Ln(μCl)2M(L)(Cp=η5C5H5orC5Me5;M=Li,Na;L=THF,TMEDA),isamainstructuretype.Inthecourseo…  相似文献   

4.
IntroductionSingleelectrontransferinaromaticnucleophilicsub stitutionhasattractedmuchattentioninrecentyears .Inadditiontothewell knownSRN1mechanismreportedbyBunnett,1manyotheractivatedaromaticsystems ,i .e .,nitroarylhalides ,dinitrobenzenes ,etc .,havebeenre p…  相似文献   

5.
AnticancerDrugs(V)─—SynthesisofEtoposideDerivativesTIANXuan,YANZe-qun,LIJin-xinandCHENYao-zu(NationalLaboratoryofAppliedOrgan...  相似文献   

6.
IntroductionItiswellknownthatyttriumcanbeusedinmanyfields ,suchasmetallurgy ,ceramics ,lasersandelectron ics ,especiallyinfluorescentmaterialswhoseneedforhighpurityyttriumoxideisincreasing .InChina ,there sourceofyttriumisrich ,andthehighpureyttriumisbe ingo…  相似文献   

7.
1 INTRODUCTIONStudiesofthecoordinationchemistryofzinc(II)havearousedmoreandmoreinterestinlastdecadeinviewoftheirbiologicalmodelingapplica tions[1 ,2 ] andsolid statematerials[3 ,4] .WehavebeeninterestedinthestudyoftransitionmetalcomplexesofN oxopyridine 2 thiol(…  相似文献   

8.
IntroductionIsodonenanderianus (Hand . Mazz .)H .W .Li(Labiatae) ,widelydistributedinthesouthernpartsofYunnanProvince ,hasbeenusedinChinesetraditionalfolkmedicineasanti inflammatoryanddetoxifiedagent.1Previousphytochemicalinvestigationhasshownthepres enceofaser…  相似文献   

9.
RamanSpectraofLaserCrystalsNABandNYABandtheLigandVibrationsofTheirActiveIons¥HongShui-Li(DepartmentofPhysics,FuzhouUniversity...  相似文献   

10.
In-situThinLayerSpectroelectrochemicalStudyoftheRedoxMechanismaddIntermediateforVitaminB_2inAqueousSolutionIn-situThinLayerSp?..  相似文献   

11.
The activation of bovine liver arginase, which catalyzes the hydrolysis of L‐arginine to L‐ornithine and urea, by glycine was studied by thermokinetic methods at 37°C in 40 mmol·L?1 sodium barbiturate‐HCl buffer solution (pH 9.4). Results of this experiment indicate that an appropriate concentration of glycine can enhance the activity of arginase, and the relative activation rate reached its maximum value, 74%, when the concentration of glycine in reaction system was 1 mmol·L?1 and the initial concentration of arginine was 5 mmol·L?1. With the increase of substrate concentration, the relative activation rate decreased in a definite glycine concentration. Michealis constant Km of reaction decreased from 5.53 to 3.31 mmol·L?1 and inhibition constant of product L‐ornithine Kp increased from 1.18 to 3.73 mmol·L?1 when glycine concentration was 1 mmol·L?1. For these reasons one possible activation mechanism of arginase by glycine was suggested that the activation effect results from the competition of glycine and arginine to enzyme activity position. When one or two of the activity positions of arginase are occupied by glycine, it is propitious for the enzyme to complex with substrate and obstruct L‐ornithine from combining with enzyme, and when all of the activity positions are occupied by glycine, the activation effect vanishs and the inhibition effect appears.  相似文献   

12.
The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer (10 mmol·L^-1) at pH 7.4. The results suggest that mercuric ion can bind to C- and N-terminal binding sites of apoCopC, and the conditional binding constants were calculated to be kN=(6.79± 1.12)× 10^6 mol^-1·L and kc=(3.06±0.05)× 10^5 mol^-1·L. Using urea as a chemical agent, the conformational stabilities of apoCopC and HgN^2+ -CopC-Hgc^2+ were monitored by fluorescence spectrum in Hepes buffer (50 mmol·L^-1) at pH 7.4. The free energy of stabilization is (14.69±0.85) and (16.66±0.55) kJ.mol^-1, respectively. HgN^2+ -CopC-Hgc^2+ is more stable than apoCopC.  相似文献   

13.
《Analytical letters》2012,45(10):1783-1795
The behavior of seven hydroxy anthraquinone derivatives was studied by capillary zone electrophoresis and micellar electrokinetic chromatography. The effects of buffer pH (6.5–10.8) and sodium dodecyl sulfate concentration (10–20 mmol L?1) on the effective mobilities of the analytes and their separation were tested. A comparison of the two optimized separation systems showed that micellar electrokinetic chromatography was superior as it permits separation of all the seven analytes within 15 min, using 15 mmol L?1 sodium dodecyl sulfate in 10 mmol L?1 tetraborate buffer, pH 8.5, at a voltage of 20 kV. The calibration curves were linear in the concentration range from 5.0 · 10?7 to 5.0 · 10?4 mol L?1 for most of the analytes, at a detection wavelength of 254 nm. LOD and LOQ values of the analytes were in the ranges of 2.10 · 10?7–1.28 · 10?6 mol L?1and 6.99 · 10?7–4.25 · 10?6 mol L?1, respectively. The proposed separation conditions were applied to determination of 1,2-dihydroxy anthraquinone (alizarin) and 1,2,4-trihydroxy anthraquinone (purpurin) in Rubia tinctorum aglycone and of the recently described 1-acetyl-2,4,5,7-tetrahydroxy-9,10-anthraquinone and 1-acetyl-2,4,5,7,8-pentahydroxy-9,10-anthraquinone in the mycelium of fungi Geosmithia lavendula.  相似文献   

14.
A micellar electrokinetic capillary chromatography method with electrochemical detection (MECC‐ED) has been developed for the simultaneous determination of eight phenolic additives, including propyl gallate (PG), tert‐butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) in cosmetic products. Method development involved optimization of the working electrode, the pH value of running buffer, the concentration of sodium dodecyl sulfate (SDS), the separation voltage, and the sample injection time. Under the optimum conditions, all analytes can be well separated within 26 min at the separation voltage of 18 kV in a 9 mmol·L?1 sodium dodecyl sulfate (SDS) ?60 mmol·L?1 borate running buffer (pH 8.0). A 300 μm diameter carbon disk electrode generated good response at +0.90 V (vs. SCE) for all analytes. Linearity of the present method was over three orders of magnitude of analyte concentration with detection limits (S/N=3) ranging from 1.1×10?7 to 1.2×10?6 g·mL?1 for all analytes. This proposed method has been successfully applied to the simultaneous determination of the above additives in commercial cosmetics, and the assay results were satisfactory.  相似文献   

15.
A method based on capillary electrophoresis with electrochemical detection has been developed for the separa-tion and determination of epicatechin,kaempferol,chlorogenic acid,4-hydroxybenzoic acid,quercetin and proto-catechuic acid in hawthorn for the first time.The effects of working electrode potential,pH and concentration ofrunning buffer,separation voltage and injection time on CE-ED were investigated.Under the optimum conditions,the analytes could be separated in a 60 mmol·L~(-1) borate buffer(pH 8.7)within 21 min.A 300 μm diameter carbondisk electrode has a good response at 0.95 V(vs.SCE)for all analytes.The response was linear over three ordersof magnitude with detection limits(S/N=3)ranging from 3×10~(-8) to 2×10~(-7) g·mL~(-1) for the analytes.The methodhas been successfully applied to the analysis of real sample,with satisfactory results.  相似文献   

16.
A new (8‐hydroxyquinolin‐2‐yl)methylene picolinohydrazide derivative ( L ) has been successfully synthesized and characterized. The probe L displays high selectivity to Co2+ in CH3CN/HEPES (1:1, /, 10 mmol·L?1, pH=7.4) with a fluorescence "ON‐OFF" response. The Co2+ ion recognition event possesses some distinct features including rapid response, high selectivity and sensitivity, good anti‐interference ability and being applicable within a wide pH range. Based on job's plot and ESI‐MS studies, the 1:1 binding mode was proposed. The binding constant of L and Co2+ is 1.63×108 L·mol?1 and the detection limit is 1.15 µmol·L?1. Natural water samples experiments revealed that probe L can be potentially applied to the detection of Co2+ in real environment.  相似文献   

17.
In the one compartment electrochemical cell 2‐hydroxy‐2‐p‐tolyl‐butyric acid methyl ester was electrosynthesized by electrochemical carboxylation of p‐methylpropiophenone in the presence of carbon dioxide. Under galvanostatic conditions, the electrocarboxylation was influenced by supporting electrolytes, cathode materials, the current density, passed charge and temperatures. Application scope of the eletrocarboxylation system was then examined, and an excellent yield of 97% was obtained when the electrolysis was carried out in DMF‐0.1 mol·L?1 TEABr solution using cheap and environmentally benign nickel as the cathode under a controlled current density of 5.0 mA·cm?2 until 2.8 F·mol?1 charge passed through the cell at ?10°C. The electrochemical behavior of p‐methoxylacetophenone has been studied on the glassy carbon electrode by cyclic voltammetry and the probable mechanism was proposed accordingly.  相似文献   

18.
采用毛细管电泳-电化学检测法(CE-ED)同时分离测定了中药杠板归中的阿魏酸、香草酸、槲皮素、咖啡酸、原儿茶酸等主要生物活性成分的含量。考察了工作电极电位、运行缓冲液的pH值和浓度、分离电压和进样时间等实验参数对实验结果的影响。在优化的实验条件下,以直径300 μm的碳圆盘电极为工作电极,检测电位为+0.95V(vs. SCE),在10mmol/L磷酸盐(pH 9.2)的运行缓冲溶液中,五个分析物能够在17min内实现很好的基线分离,被测物浓度与峰电流在3个数量级呈良好的线性,检测限(S/N=3)范围从7.1×10-8 到 9.3×10-8g mL-1。该方法已应用于实际样品的分析,样品处理简单,获得了令人满意的结果。  相似文献   

19.
When the concentration of dodecyl benzene sulfonic acid sodium salt (SDBS) is 0.7 mmol·L?1, the electrochemical and electrochemiluminescence (ECL) intensity of Ru(bpy)32+‐chlorpheniramine maleate (CPM) system at the Au electrode were studied. The results showed that compared with the absence of SDBS, enhancement of the ECL intensity was 14‐fold at Au electrode. Base on this, an ECL method was established for efficient and simple determination of CPM at Au electrode. Under the optimum experimental condition, the enhanced ECL intensities had good linear relationship with the concentration of CPM in the range of 1.0×10?4–1.0×10?7 mol·L?1, and a linear regression equation was obtained as follows: I (counts)=48.805×106c+394.03 (r=0.9975), the detection limit for CPM was 1.4×10?8 mol·L?1. The RSD for 5 times determinations of 1.0×10?5 mol·L?1 CPM was 3.2%. The results of recovery test were between 96.3%–102.5%, and the RSD of recovery test (n=5) was 2.7%. In addition, eleven kinds of tertiary amines‐Ru(bpy)32+ systems were investigated in the absence and presence of SDBS. The results showed that the enhancement of SDBS on ECL intensity of tertiary amines‐Ru(bpy)32+ systems was universal.  相似文献   

20.
XU  Jiming  HAN  Wenxia  YIN  Qifan  SONG  Jie  ZHONG  Hui 《中国化学》2009,27(11):2197-2202
The direct electrochemistry of glucose oxidase (GOD) was achieved based on the immobilization of GOD on a natural nano‐structural attapulgite (ATP) clay film modified glassy carbon (GC) electrode. The immobilized GOD displayed a pair of well‐defined quasi‐reversible redox peaks with a formal potential (E0′) of ?457.5 mV (vs. SCE) in 0.1 mol·L?1 pH 7.0 phosphate buffer solution. The peak current was linearly dependent on the scan rate, indicating that the direct electrochemistry of GOD in that case was a surface‐controlled process. The immobilized glucose oxidase could retain bioactivity and catalyze the oxidation of glucose in the presence of ferrocene monocarboxylic acid (FMCA) as a mediator with the apparent Michaelis‐Menten constant Kappm of 1.16 mmol·L?1. The electrocatalytic response showed a linear dependence on the glucose concentration ranging widely from 5.0×10?6 to 6.0×10?4 mol·L?1 (with correlation coefficient of 0.9960). This work demonstrated that the nano‐structural attapulgite clay was a good candidate material for the direct electrochemistry of the redox‐active enzyme and the construction of the related enzyme biosensors. The proposed biosensors were applied to determine the glucose in blood and urine samples with satisfactory results.  相似文献   

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