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131.
Secondary benzylic or allylic trimethylsilyl ethers are oxidized at room temperature to the corresponding ketones in good yields using aqueous 70% t-BuOOH and catalytic amounts of a mixture of Ph3SiOH and CrO3. 相似文献
132.
This work presents the characteristics of a high frequency ion source operating on a low energy, 150 keV accelerator. The
latter is to be used as a neutron generator and its design is based on a theoretical analysis which shows that if the axial
potential in an electrostatic electrode system is made to increase with four thirds the power of axial distance, inward electric
forces will compensate space charge forces tending to blow up the beam. This results in a simplified acceleration tube much
shorter and of higher gradient than the conventional acceleration columns. The ion source itself is an ordinary type using
axial extraction of the beam, and its main properties investigated are the beam current and beam quality (or emittance). Dependence
of the two on different parameters is investigated in a series of tests. 相似文献
133.
134.
Dr. Emile R. Engel Dr. Abdelaziz Jouaiti Charl X. Bezuidenhout Prof. Mir Wais Hosseini Prof. Leonard J. Barbour 《Angewandte Chemie (International ed. in English)》2017,56(30):8874-8878
A non-interpenetrated metal–organic framework with a paddle-wheel secondary building unit has been activated by direct thermal evacuation, guest exchange with a volatile solvent, and supercritical CO2 drying. Conventional thermal activation yields a mixture of crystalline phases and some amorphous content. Exchange with a volatile solvent prior to vacuum activation produces a pure breathing phase with high sorption capacity, selectivity for CO2 over N2 and CH4, and substantial hysteresis. Supercritical drying can be used to access a guest-free open phase. Pressure-resolved differential scanning calorimetry was used to confirm and investigate a systematic loss of sorption capacity by the breathing phase as a function of successive cycles of sorption and desorption. A corresponding loss of sample integrity was not detectable by powder X-ray diffraction analysis. This may be an important factor to consider in cases where flexible MOFs are earmarked for industrial applications. 相似文献
135.
Rodríguez de Castro Antonio Agnaou Mehrez Ahmadi-Sénichault Azita Omari Abdelaziz 《Transport in Porous Media》2019,130(3):799-818
Transport in Porous Media - With X-ray computed tomography still being flawed as a result of limitations in terms of spatial resolution and cost, toxic mercury intrusion porosimetry (MIP) is... 相似文献
136.
A simple theoretical model is proposed in order to represent gas–liquid slug flows in inclined ducts of arbitrary shape. To cite this article: A. Dyment, A. Boudlal, C. R. Mecanique 332 (2004). 相似文献
137.
138.
Houmam A Muhammad H Chahma M Koczkur K Thomas DF 《Chemical communications (Cambridge, England)》2011,47(25):7095-7097
4-Nitrophenyl sulfenyl chloride was used as a new precursor for the formation of densely packed aromatic SAMs on gold. The adsorption involves the reductive dissociation of the S-Cl bond. A well-ordered row structure corresponding to a √3 × 4 phase with a molecular area of 27.8 ?(2) is obtained. 相似文献
139.
We introduce multiple Dedekind–Rademacher sums, in terms of values of Bernoulli functions, that generalize the classical Dedekind–Rademacher sums. The aim of this paper is to give and prove a reciprocity law for these sums. The main theorem presented in this paper contains all previous results in the literature about Dedekind–Rademacher sums. 相似文献
140.
Nabil Kallel Nejib Ihzaz Sami Kallel Ahmed Hagaza Mohamed Oumezzine 《Journal of magnetism and magnetic materials》2009,321(15):2285-2289
The structural, magnetic and transport properties of La0.5Sr0.5MnO2.88 and La0.5Sr0.5Mn0.5Ti0.5O3 samples have been investigated systematically. Indeed, this series has been considered to understand the influence of physical parameters such as oxygen deficiency and titanium doping effect in undoped La0.5Sr0.5MnO3 sample. Ceramic material based on La0.5Sr0.5MnO2.88 exhibits interesting behaviours of charge-ordering (CO), ferromagnetic (FM) states and a good conductivity down to the lowest temperatures. The substitution of Ti for Mn destroyed drastically the CO, damaged the motion of itinerant eg electrons and changed the local parameters of perovskite cell. A change of the structure from tetragonal to rhombohedral symmetry is observed causing a weakening of double-exchange interaction. The experiment results show that the suppression of the CO is sensitive to the variety of Mn3+/Mn4+ ratio. In a field of 8 T at 10 K, FM and CO phase can be evaluated to be ∼20:80 according to the μexp/μcal ratio for La0.5Sr0.5MnO2.88, whereas the CO state is suppressed for La0.5Sr0.5Mn0.5Ti0.5O3 sample, FM and anti-ferromagnetic (AFM) phase are coexisted and evaluated to be ∼54:46, respectively. 相似文献