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排序方式: 共有1615条查询结果,搜索用时 15 毫秒
1.
Young-Soo Lee Do-Hyeon Park Hee-Taik Kim Kyong-Ok Yoo 《Korean Journal of Chemical Engineering》1995,12(1):23-28
Much SO2, another perilous air pollutant, was emitted during the oxidative regeneration of sulfided sorbent by H2S. In order to prevent emission of SO2, we carried out oxidative regeneration with the physical mixture of CaO and sulfided sorbent and investigated the effect
of regeneration temperature and oxygen concentration on the reactivity of CaO with S02. The effluent gases were analyzed by G.C. and the properties of sorbent were characterized by XRD. SEM, TG/DTA and EPMA.
Deterioration of reactivity of CaO with S02 resulted in increment of emission of SO12 due to the structural changes of CaO above 750°C and that at 850°C was more severe. Furthermore EPMA and XRD analysis revealed
that product layer diffusion through the solid product, CaSO4, was the rate limiting step for CaO sulfidation. The reaction of CaO w:.th SO2 was first order approximately and that was accelerated by high O2 concentration. 相似文献
2.
Francesco Donsì Stefano Cimino Almerinda Di Benedetto Raffaele Pirone Gennaro Russo 《Catalysis Today》2005,105(3-4):551-559
The oxidative dehydrogenation of ethane is carried out in short contact time reactors over Pt and LaMnO3 based catalysts supported on a large number of different ceramic substrates (45, 60 and 80 ppi foam monoliths and 200, 400, 600, 900 and 1200 cpsi honeycomb monoliths). Experimental results, obtained under the same conditions at varying the C2H6/O2 ratio, showed that the highest performance in terms of ethylene selectivity and yield is always attained on LaMnO3 catalysts. Furthermore, the results are significantly influenced by the morphology and cell density of the support, with 45 and 60 ppi foams and 400 and 600 cpsi honeycombs giving the best performance. The experimental results are explained by means of geometrical and fluid dynamic considerations on the support, and by means of a 2D mathematical model, which clearly indicates an optimal intermediate cell density for maximising ethylene selectivity and yield. 相似文献
3.
上海市吴淞工业区大气PM2.5水溶成分的元素分析及细胞毒性研究 总被引:1,自引:0,他引:1
通过ICP-MS测定了上海市吴淞地区大气PM2.5水溶成分金属元素含量,通过四唑盐(MTT)测定细胞存活率,通过超氧化歧化酶(SOD)和丙二醛(MDA)两个指标测定细胞氧化损伤,琼脂糖凝胶电泳测定细胞内DNA损伤,流式细胞仪(Flow cytometry)检测细胞凋亡和周期等实验研究了大气PM2.5水溶成分的细胞毒性.实验结果表明:PM2.5可溶成分中Zn元素含量最高,PM2.5在一定浓度范围内能导致细胞死亡,引起细胞的氧化损伤,影响DNA的复制,阻碍细胞增殖,但没有诱导细胞凋亡.PM2.5中可溶金属离子对细胞毒性表现为联合作用. 相似文献
4.
Edwin Ramaroson Gilbert Blanchard Michel Che Jean-Michel Tatibouët 《Catalysis Letters》1992,15(4):393-400
The oxidative dimerisation of propene to 1,5-hexadiene has been investigated on Bi-Zn-O catalysts. The Bi48ZnO73 phase, observed in the catalysts calcined at 700 ° C is an active and selective catalyst for the formation of 1,5-hexadiene. The best catalytic performance (1,5-hexadiene selectivity 64%) has been obtained at 525 ° C, with a propene to oxygen ratio of 26, on a catalyst formed by Bi48ZnO73 with a small excess of ZnO. 相似文献
5.
Jos L. Neira Ana Cmara-Artigas Jos Gins Hernndez-Cifre María Grazia Ortore 《International journal of molecular sciences》2021,22(6)
The histidine phosphocarrier protein (HPr) kinase/phosphorylase (HPrK/P) modulates the phosphorylation state of the HPr protein, and it is involved in the use of carbon sources by Gram-positive bacteria. Its X-ray structure, as concluded from crystals of proteins from several species, is a hexamer; however, there are no studies about its conformational stability, and how its structure is modified by the pH. We have embarked on the conformational characterization of HPrK/P of Bacillus subtilis (bsHPrK/P) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, small-angle X-ray-scattering (SAXS) and dynamic light-scattering (DLS)). bsHPrK/P was mainly a hexamer in solution at pH 7.0, in the presence of phosphate. The protein had a high conformational stability, with an apparent thermal denaturation midpoint of ~70 °C, at pH 7.0, as monitored by fluorescence and CD. The protein was very pH-sensitive, precipitated between pH 3.5 and 6.5; below pH 3.5, it had a molten-globule-like conformation; and it acquired a native-like structure in a narrow pH range (between pH 7.0 and 8.0). Guanidinium hydrochloride (GdmCl) denaturation occurred through an oligomeric intermediate. On the other hand, urea denaturation occurred as a single transition, in the range of concentrations between 1.8 and 18 µM, as detected by far-UV CD and fluorescence. 相似文献
6.
以三聚氰胺、偏钒酸铵、硼酸为前驱体,通过煅烧法制备V2O5/g⁃C3N4催化剂。采用XRD、FT⁃IR、XPS、SEM和BET等技术对催化剂的结构与形貌进行表征。以V2O5/g⁃C3N4为催化剂,乙腈为萃取剂,H2O2为氧化剂对模拟油中二苯并噻吩(DBT)的脱除进行考察。探究了反应温度、催化剂质量、萃取剂体积、n(H2O2)/n(S)以及不同硫化物等因素对脱硫效果的影响。在模拟油体积为5.0 mL、萃取剂乙腈体积为3.0 mL、n(H2O2)/n(S)=8、催化剂质量为0.02 g、反应温度为30 ℃和反应时间为60 min的最佳条件下,DBT的脱除率达到91.9%,经过5次催化剂再生后脱硫率仍可以达到85.7%。 相似文献
7.
Kasturi Markandran Jane Wenjin Poh Michael A. Ferenczi Christine Cheung 《International journal of molecular sciences》2021,22(9)
The role of regulatory light chains (RLCs) in cardiac muscle function has been elucidated progressively over the past decade. The RLCs are among the earliest expressed markers during cardiogenesis and persist through adulthood. Failing hearts have shown reduced RLC phosphorylation levels and that restoring baseline levels of RLC phosphorylation is necessary for generating optimal force of muscle contraction. The signalling mechanisms triggering changes in RLC phosphorylation levels during disease progression remain elusive. Uncovering this information may provide insights for better management of heart failure patients. Given the cardiac chamber-specific expression of RLC isoforms, ventricular RLCs have facilitated the identification of mature ventricular cardiomyocytes, opening up possibilities of regenerative medicine. This review consolidates the standing of RLCs in cardiac development and disease and highlights knowledge gaps and potential therapeutic advancements in targeting RLCs. 相似文献
8.
Seungmin Ahn Hoyoung Jung Prof. Dr. Jung-Min Kee 《Chembiochem : a European journal of chemical biology》2021,22(2):319-325
Protein phosphorylation is one of the most studied post-translational modifications (PTMs). Despite the remarkable advances in phosphoproteomics, a chemically less-stable subset of the phosphosites, which we call the crypto-phosphoproteome, has remained underexplored due to technological challenges. In this Viewpoint, we briefly summarize the current understanding of these elusive protein phosphorylations and identify the missing pieces for future studies. 相似文献
9.
周忠清 《化学反应工程与工艺》1995,(3)
探讨了采用Mo-Sb-O复合氧化物催化剂,由甲醇的氧化酯化反应合成甲酸甲酯。文中考察了反应温度、催化剂晶格、接触时间对甲醇转化率的影响,测试了催化剂性能,扼要探讨了该催化反应的机理。 相似文献
10.
The cobalt(II) chloride-catalyzed oxidative cleavage of -methylstyrene with oxygen in t-BuOH gives acetophenone and formaldehyde in good yield. The competing reactions between C=C cleavage and formation of polymeric products are strongly affected by the solvent, cobalt catalyst and concentration used, as well as the reaction temperature. A free radical mechanism involving a cyclic peroxide intermediate is proposed to give the cleavage products. Oxidation of various alkenes using CoCl2/t-BuOH/O2 system shows that only activated styrenes can be oxidized effectively. The reactivity of various styrenes and their selectivity towards giving cleavage products or polymers are strongly influenced by the electronic and steric properties of the substrate. 相似文献