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排序方式: 共有196条查询结果,搜索用时 31 毫秒
1.
Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH3NO),N-methylformamide (C2H5NO),NN-dimethylformamide (C3H7NO),NN-dimethylacetamide (C4H9NO), 1,4-dioxane (C4H8O24), succinimide (C4H5NO2) and solutions of acetamide (C2H5NO) and benzoic acid (C7H6O2) in 1,4-dioxane (C4H8O2) have been determined by narrow beam γ-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental
values of mass attenuation coefficients of these compounds have been used to calculate effective atomic numbers and electron
densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions. 相似文献
2.
tert-Butyl 2-hydroxyalkyl sulfides, prepared by reaction of epoxides with 2-methylpropane-2-thiol, are converted directly to 1,3-oxathiolanes upon treatment with pivalaldehyde and boron trifluoride diethyl etherate in the presence of thioanisole. 相似文献
3.
Adarsh Kumar A. K. Bose Prof. S. P. Mushran 《Monatshefte für Chemie / Chemical Monthly》1975,106(4):863-869
The oxidation kinetics of cycloheptanone by chloramine-T in alkaline media has been investigated. A mechanism involving the formation of an intermediate by the interaction between the enolic anion of cycloheptanone and chloramine-T in a slow step followed by its interaction with another molecule of chloramine-T in a fast step leading to products has been proposed. The scheme satisfactorily accords with the observed stoichiometry, negligible influence of ionic strength and a positive dielectric effect. Various rate parameters have been computed and 1.2-cycloheptanedione identified as the end product.With 2 Figures 相似文献
4.
Summary Bifunctional methylenebis(diphenylphosphine oxide) (mdpo) on reaction with iron(III) perchlorate forms the complex, [Fe(mdpo)3](ClO4)3 · H2O. This has been characterized through elemental analysis, i.r., far-i.r., u.v. and visible spectroscopy and by x-ray diffraction, magnetic moment, molar conductance and e.s.r. data. The e.s.r. spectrum consists of five lines with transitions from: ¦–5/2¦–3/2¦–3/2¦–1/2, ¦–1/2¦+1/2¦+1/2¦+3/2 and ¦+3/2¦+5/2 centred at a g-value of 2.00. On the basis of these studies, a chelated octahedral structure has been assigned to the cation, [Fe(mdpo)3]3+. 相似文献
5.
Following the newly-discovered UV absorption spectrum of Br2Si, its reactions with oxygen and nitric oxide in the gas phase have been quantitatively investigated using the flash photolysis-kinetic
absorption spectroscopy technique. The room temperature bimolecular rate constants are:
相似文献
6.
Sarjit S. Sandhu Miss Sukhvinder Baweja Swarn S. Parmar 《Transition Metal Chemistry》1980,5(1):299-302
Summary Ten complexes of nickel(II) and cobalt(II) witho-phenylenebis(diphenylarsine), (pdpa) ando-phenylenebis(di-p-tolylarsine), (pdta) have been synthesised. The stoichiometry of complexes is markedly dependent upon the reaction temperature, thus reaction atca. 0° gives the M(A-A)2X2 chelates, [M = Ni, X = Br, (A-A) = pdpa; M = Ni, X = I, (A-A) = pdpa, pdta; M = Co, X = CNS, (A-A) = pdpa] whereas at higher temperatures the M(A-A)X2 chelates [M = Ni, X = Br, I, (A-A) = pdpa, pdta; M = Co, X = CNS, (A-A) = pdpa or pdta] are obtained. The Ni(A-A)2I2 compounds can be converted into Ni(A-A)I2 by boiling under reflux in n-BuOH; the conversion can be reversed by cooling a CH2Cl2 solution of the latter at or below 0°. Stereochemical assignments of all the new complexes have been made on the basis of room temperature eff values, molar conductance, i.r. and u.v. data. 相似文献
7.
The method for determination of chlorpyrifos is validated and dissipation behaviour of residue in scented rose and percent transfer in different products is described. GC-electron-capture detection with a HP-1, 30 m x 0.53 mm, 3.0 microm capillary column and nitrogen at 1 ml/min was used in the study. Plant matrices studied were: leaves, flowers, soil, rose water, absolute and concrete. Detector response linearity and sensitivity, limit of detection and determination, percent recovery were determined based on area response (mm2) of the standard. Analytical field and laboratory samples (rose water by hydro-distillation of the flowers, concrete and absolute by hexane extraction and condensation) were analysed for evaluation of the method. Samples were extracted with acetone, partitioned with water, saturated sodium chloride solution and dichloromethane. The organic layer was rotary-evaporated to 2 ml for cleanup with silica-carbon column. The column was eluted with dichloromethane-toluene-acetone (10:2:2, v/v/v) and the derived solution was rotary-evaporated to 5 ml for end analysis. Matrix enhancement effect was observed for leaf and soil samples for which corrective approach was followed to compensate for overestimation of the residue. Limit of detection for chlorpyrifos standard was 0.05 mg/l with good linearity of detector response (R2 = 0.99). Percent recovery ranged from 78 to 117% in different plant matrices (fortification level 1, 4 and 8 mg/l). Dissipation behaviour showed that chlorpyrifos was below detection limit by the 12th day of application on the scented rose with half life of 3.40 days on leaves and 3.10 days on flowers at 0.1% dosage. Percent transfer studies showed that 5.71, 46.91 and 38.80% of the residue from flowers was transferred to rose water, concrete and absolute, respectively. 相似文献
8.
The thermal decompositions of alkaline earth tris(oxalato)ferrates(III) (Mg, Ca, Sr and Ba) have been studied by Mössbauer spectroscopy and other techniques. During the thermal decomposition, dehydration occurs first, followed by reduction to iron(II) species, and oxides and ferrites (MFeIIIO4) are then formed at higher temperature. In the case of strontium tris(oxalato)ferrate(III), strontium ferrite (SrFeIVO4) is formed at 700°.
Zusammenfassung Die thermische Zersetzung von Tris(oxalato)ferraten(III) der Erdalkalimetalle (Mg, Ca, Sr, Ba) wurde durch Mössbauer-Spektroskopie und andere Techniken untersucht. Im Verlaufe der thermischen Zersetzung verläuft zunächst die Dehydratisierung, gefolgt von der Reduktion zu Eisen(II)-Species. Oxide und Ferrite (MFeIIIO4) werden danach bei höheren Temperaturen gebildet. Strontium-tris(oxalato)-ferrat(III) geht bei 700 °C in Strontiumferrit (SrFeIVO4) über.
() () , , ë . , , MFeIIIO4. 700° SrFeIVO4.相似文献
9.
Marva Sandhu Hafiz Muhammad Irfan Shahid Ali Shah Madiha Ahmed Iffat Naz Muhammad Akram Humaira Fatima Ayesha Shuja Farooq 《Molecules (Basel, Switzerland)》2022,27(14)
Oxidative stress (OS) and c-Jun N-terminal kinase (JNK) are both key indicators implicated in neuro-inflammatory signalling pathways and their respective neurodegenerative diseases. Drugs targeting these factors can be considered as suitable candidates for treatment of neuronal dysfunction and memory impairment. The present study encompasses beneficial effects of a naturally occurring triterpenoid, friedelin, against scopolamine-induced oxidative stress and neurodegenerative pathologies in mice models. The treated animals were subjected to behavioural tests i.e., Y-maze and Morris water maze (MWM) for memory dysfunction. The underlying mechanism was determined via western blotting, antioxidant enzymes and lipid profile analyses. Molecular docking studies were carried out to predict the binding modes of friedelin in the binding pocket of p-JNK protein. The results reveal that scopolamine caused oxidative stress by (1) inhibiting catalase (CAT), peroxidase enzyme (POD), superoxide dismutase (SOD), and reduced glutathione enzyme (GSH); (2) the up-regulation of thiobarbituric acid reactive substances (TBARS) in mice brain; and (3) affecting the neuronal synapse (both pre- and post-synapse) followed by associated memory dysfunction. In contrast, friedelin administration not only abolished scopolamine-induced oxidative stress, glial cell activation, and neuro-inflammation but also inhibited p-JNK and NF-κB and their downstream signaling molecules. Moreover, friedelin administration improved neuronal synapse and reversed scopolamine-induced memory impairment accompanied by the inhibition of β-secretase enzyme (BACE-1) to halt amyloidogenic pathways of amyloid-β production. In summary, all of the results show that friedelin is a potent naturally isolated neuro-therapeutic agent to reverse scopolamine-induced neuropathology, which is characteristic of Alzheimer’s disease. 相似文献
10.
A new and efficient method for the rearrangement of oximes 1 has been achieved by a simple reaction of a ketoximes with bismuth trichloride under microwave irradiation in the solid state. 相似文献