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941.
考察了反应温度、气体空速和进料中CH4:O2比值对Mo2C/Al2O3催化的POM反应制合成气的影响.结果发现较高的温度具有较高的甲烷转化率、CO和H2的选择性;而在较低的温度下,对CO的选择性比对H2的影响更大.反应气体的空速较小时对于甲烷的转化率、CO和H2的选择性是有利的;而在较高的气体空速下,氢气的选择性则更低.进料中CH4:O2比值稍高于2:1时有利于获得高的甲烷转化率、CO和H2的选择性.并且还可以增加催化剂的稳定性.当CH4:O2比值低于2:1时.甲烷转化率、CO和H2选择性随反应的进行急剧下降.而当此比值调整到高于2:1时.转化率和选择件都可以得到恢复。 相似文献
942.
Ken-ichi Ogu 《Journal of fluorine chemistry》2003,124(1):69-80
Treatment of allylic alcohols with hexafluoropropene-diethylamine adduct (PPDA) afforded N,N-diethyl-2-fluoro-2-trifluoromethyl-4-alkenamides which were formed by the Claisen rearrangement of intermediary 2-alkenyl-1-diethylamino-2,3,3,3-tetrafluoro-1-propenyl ethers. Although (E)-allylic alcohols gave two diastereomeric products in about 1:1 ratio, (Z)-allylic alcohols gave the corresponding product as a single diastereomer. 相似文献
943.
Sorel Tchewonpi Sagu Eva Landgrber Michal Rackiewicz Gerd Huschek Harshadrai Rawel 《Molecules (Basel, Switzerland)》2020,25(24)
Sorghum is of growing interest and considered as a safe food for wheat related disorders. Besides the gluten, α-amylase/trypsin-inhibitors (ATIs) have been identified as probable candidates for these disorders. Several studies focused on wheat-ATIs although there is still a lack of data referring to the relative abundance of sorghum-ATIs. The objective of this work was therefore to contribute to the characterization of sorghum ATI profiles by targeted proteomics tools. Fifteen sorghum cultivars from different regions were investigated with raw proteins ranging from 7.9 to 17.0 g/100 g. Ammonium bicarbonate buffer in combination with urea was applied for protein extraction, with concentration from 0.588 ± 0.047 to 4.140 ± 0.066 mg/mL. Corresponding electrophoresis data showed different protein profiles. UniProtKB data base research reveals two sorghum ATIs, and P81367; both reviewed and a targeted LC–MS/MS method was developed to analyze these. Quantifier peptides ELAAVPSR ( P81368) and TYMVR ( P81367) were identified and retained as biomarkers for relative quantification. Different reducing and alkylating agents were assessed and combination of tris (2 carboxyethyl) phosphine/iodoacetamide gave the best response. Linearity was demonstrated for the quantifier peptides with standard recovery between 92.2 and 107.6%. Nine sorghum cultivars presented up to 60 times lower ATI contents as compared to wheat samples. This data suggests that sorghum can effectively be considered as a good alternative to wheat. P81368相似文献
944.
Novel visible-light-driven photocatalyst of NiO/Cd/g-C3N4 for enhanced degradation of methylene blue
《Arabian Journal of Chemistry》2020,13(6):5810-5820
Novel NiO/Cd/g-C3N4 photocatalysts were synthesized using a green and straightforward microwave-assisted method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), the Brunauer–Emmett–Teller (BET) method, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and ultraviolet–visible spectroscopy (UV–Vis). The ternary NiO/Cd/g-C3N4 nanocomposites were evaluated for the degradation of methylene blue (MB) at room temperature under the visible light irradiation. Experimental results revealed that the weight percent of cadmium had a remarkable effect on the photodegradation efficiency. The NiO/Cd/g-C3N4 (0.1%) sample exhibited superior activity in the degradation reaction. The activity of this nanocomposite was about 4.5 and 3.25 fold higher than those of the pure g-C3N4 and NiO/g-C3N4 samples in the degradation of MB, respectively. The enhanced photocatalytic activity was attributed to the low energy gap, increased absorption capacity of the visible light, and efficient suppression of the recombination of photogenerated electron-hole pairs. A detailed photocatalytic mechanism over the nanocomposite of NiO/Cd/g-C3N4 (0.1%) was proposed with superoxide radical anion O2– as the main reactive species. The stability of the nanocomposite was confirmed after four consecutive runs as well. 相似文献
945.
采用XRD表征了水蒸气和磷联合改性的HZSM-5沸石分子筛的结构.通过NH3-TPD和N2吸附脱附研究了样品的酸性和比表面.采用正庚烷的裂化反应研究了样品的裂化活性,研究结果表明,磷改性样品与母体样品相比,经过水蒸气处理后显示出较高的酸量和正庚烷裂化活性.上述结果首次用模型簇和计算量子化学方法进行了解释.采用Gaussian94软件包和PM3半经验量子化学方法对模型簇进行了全优化和频率分析.计算结果显示磷改性后样品的脱铝补硅反应热大于母体样品脱铝补硅反应热,从而显示出磷对骨架的稳定化作用. 相似文献
946.
5α,11-二羟基-2-氧代桉烷-3-(5α-Hydroxy—isopterocarpolone,1)是由贾忠建等于1996年从中药南牡蒿中首次分离得到的一种桉烷型倍半萜类天然产物.桉烷型倍半萜类化合物广泛分布于天然植物中,具有较好的昆虫拒食、抑制细胞繁殖和植物生长调节等多种生理活性.天然产物1的合成研究尚未见报道. 相似文献
947.
The Diels-Alder reaction of protonated N-benzyl imine of methyl glyoxylate with cyclopentadiene in different solvents gave mixtures of exo/endo adducts. The exo/endo selectivity of the reaction was elucidated by NMR experiments. Theoretical calculations by means of density functional theory (DFT) at the B3LYP/6-31G(d) level have also been performed to elucidate the molecular mechanism of this reaction. The DFT results suggest a highly asynchronous concerted mechanism, which in turn can explain the preferred exo stereoselectivity of the reaction. Inclusion of solvent effects enhances the exo selectivity, and this effect increases with the polarity of the solvent, in good agreement with the experimental findings. 相似文献
948.
2-(8-羟基喹啉-5-磺酸-7-偶氮)-1,8-二羟基-3,6-萘二磺酸与牛血清白蛋白的相互作用 总被引:5,自引:0,他引:5
用平衡透析法和分光光度法研究了 2 (8 羟基喹啉 5 磺酸 7 偶氮 ) 1,8 二羟基 3,6 萘二磺酸与牛血清白蛋白 (BSA)在酸性溶液中的结合反应 ,认为 8Q5SAC与BSA之间的结合力是以静电引力为主的非共键作用力 ,并探讨了其结合模型。在 2 98K下 ,测得这一反应的最大结合数为 35~ 40 ,结合常数为 6 .1× 10 5L mol。还研究了溶液基本条件如酸度和离子强度等对 8Q5SAC与牛血清白蛋白分子复合物形成的影响 ,在pH =3.34条件下 ,标准工作曲线的线性范围为 0 .2 0~ 46 .90mg L。 相似文献
949.
On dehydration of La[Co(CN)6]·5H2O, the color of the complex, changes from white to pale blue at around 230°C. Heating the pale blue specimen, the color changes
to deep blue at around 290°C. This deep blue specimen is easily rehydrated to a pink one. As reported previously, in the pale
blue specimen, Co3+ ions are situated in the center of the D4h crystal field formed by six CN- ions.
The deep blue specimen is due to the presence of [Co(CN)4]2- ions in which Co2+ was situated in a Td coordination field formed by four CN- ions and the Co-C bond length is 1.67 Ĺ. The pink species corresponded to trans-[Co(CN)4(H2O)2]2- and the bond lengths of Co-C and Co-O are 1.89 and 1.85 Ĺ, respectively.
The Raman spectra of the complex observed at 25°C displays two bands at 2157 and 2176 cm-1 associated with the vibration of C-N bond, and the band of 2157 cm-1 was split into two bands, 2150 and 2156 cm-1, at around 100°C. When the complex was heated to around 230°C, three new bands were observed at 2103, 2116 and 2141 cm-1.
The bands of 2103 and 2116 cm-1 were assigned to the stretching vibration of C=N bonding to Co2+. The band of 2141 cm-1 was assigned to the stretching vibration of the inverted CN- as follows: Co-C=N-La→Co-N=C-La. The activation energy for the inversion of CN- was estimated as 67 kJ mol-1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
950.
Highly crystalline I-rich type Cladophora cellulose, which had been kept in never-dried condition, was treated in 60wt% sulfuric acid at 100°C, for 1–48h. The cellulose microcrystals thus obtained were analysed by X-ray diffractometry, FT-IR, and transmission electron microscopy. The I component was found to be more degraded than the I component. The cellulose I/I ratios of the samples acid-treated for 0, 24, and 48 h were about 8:2, 6:4, and 4:6, respectively. After the acid treatment, the microcrystals became narrower in width, and very sharp at their ends. These results indicate that the I phase is mostly located at the surface of the microcrystals, which is morphologically more susceptible to the acid treatment. 相似文献