Tổng hợp tài liệu Khoa Học Tự Nhiên tham khảo cho học sinh, sinh viên.
The effect of the reaction temperature was then investigated varying from 80oC to 120oC, using 0.2 mol% catalyst in DMF, and in the presence of K3PO4 as the base. It was decided to use 0.2 mol% instead of 0.5 mol% of the bentonite-Pd2+ catalyst for the reaction as the difference in reaction rates was not considerable. Experimental results sh...
6 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 512 | Lượt tải: 0
The connection of the sugars part to C-3 of the aglycone was confirmed by the correlation of an anomeric proton (δH 4.54) and C-3 position (δC 79.1) in the HMBC spectrum. This carbohydrate consisted of one disubstituted glucose and two terminal rhamnose moieties. The linkage positions of the sugars were determined by HMBC spectrum. According...
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This indicated that the 2-azido compounds did not exist, but instead of the fused heterocycle, namely tetrazolo[1,5-a]quinoline. The typical signal for all protons of the compound 5 appeared in 1H NMR spectra. Methyl group in the position 5 on the quinoline ring component had chemical shift in the upfield region at δ =~2.75 ppm (as singlet)....
7 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 454 | Lượt tải: 0
4. Conclusion 2D arrays of Cu nanodisks were fabricated in high quality by RF-sputtering Cu onto AAO templates, then removing the pore wall from them. The fabricated 2D array of Cu nanodisks showed different surface plasmon resonance peaks in the spectral range from 400 nm to 1400 nm. That is promising for SERS application. The enhancement effe...
5 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 417 | Lượt tải: 0
SEM image of Fe2O3/AB (Fig. 4) is quite different to that of Fe2O3@C (Fig. 2). It is impossible to distinguish Fe2O3 and AB particles. This suggests that Fe2O3 and AB was mixed relative uniformly. Comparison of the CV results of the Fe2O3@C electrode (Fig. 3) with those of Fe2O3/AB electrode at corresponding ratio of Fe2O3 and AB (Fig. 5) indica...
7 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 472 | Lượt tải: 0
In summary, the present study has shown that Y3Fe5-xInxO12 (x = 0 ÷ 0.7) powders with size between 50 – 100 nm were fabricated using the sol-gel method. The single phase structural was observed for x as large as 0.6. At x = 0.7, a small amount of orthoferrite YFeO3 appears (~ 2%). The value of lattice constant increases with increasing x. Our re...
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In summary, we have successfully synthesized NiFe2O4/ZnO core/shell nanoparticles by using a combination of hydrothermal and co-precipitation methods. In the sample, NiFe2O4 and ZnO phases were crystallized completely. Grains were observed to be a set of these phases. Magnetization of the core was enhanced significantly in the case that the NiFe...
9 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 576 | Lượt tải: 0
In this work, microstructure and dynamic properties of large model of silica liquid at pressures ranging from 0 to 20 GPa were investigated in detail. Results reveal that the structure of SiO2 liquid consists of structural units SiOx (x = 4, 5, 6) and OSiy (y = 2,3). At ambient, the number of SiO4 and OSi2 unit is domain. Upon compression, the f...
9 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 587 | Lượt tải: 0
In this work, a model for the effective excess charge in a capillary QˆvR as well as in porous media REV Qˆv is developed for arbitrary pore scales. The results of QˆvR and QˆvREV as a function of the capillary radius, electrolyte concentration and permeability predicted from the obtained model are then compared with those from [19]. The compar...
11 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 443 | Lượt tải: 0
We have successfully prepared the CaCu3Ti4O12 materials by a ceramic technology and investigated its electric and optical properties. The sample exhibited a high dielectric constant (~52,000) at room temperature and showed almost the same first-order phonon bands as were observed in the previous studies. The results showed that the compound was ...
6 trang | Chia sẻ: honghp95 | Ngày: 01/12/2020 | Lượt xem: 649 | Lượt tải: 0
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