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991.
以水合肼和硼氢化钾为共还原剂制备了四元合金催化剂Ni-Cu-Co-La,并将其应用于乙腈催化加氢反应.采用X射线衍射、X射线光电子能谱、透射电镜和H2程序升温脱附对催化剂进行了表征,考察了催化剂组分对乙腈选择性加氢制乙胺催化性能的影响.结果表明,Cu,Co和La的加入均不同程度地提高了催化剂的活性和选择性,在反应压力1.8 MPa,反应温度120℃,反应时间1 h的条件下,乙腈转化率和乙胺选择性分别为100%和98.24%,优于使用Raney Ni、非晶态Ni-B和Co-B合金催化剂时的结果. 相似文献
992.
993.
A series of ferrocene‐containing liquid‐crystalline polyphosphonates with an even number of methylene groups are reported. All the polymers gave birefringent melts. The mesophase was identified as transparent with an increase in the spacer. The effects of pendant substitution and the spacer were studied with thermogravimetric analysis and differential scanning calorimetry. The effects of the phosphonate group in the spacer and the ferrocene ester group in the mesogen were examined. The presence of a steplike mesogenic structure and a pendant phenyl group in the spacer led to reductions in the glass‐transition and melting temperatures. The ferrocene moiety in the mesogen might be one of the reasons for the increased thermal stability and decreased liquid crystallinity. An energy‐minimized structure for the mesogenic and spacer segments was created with computer‐modeling programs, and it suggested the reason for the reductions in the glass‐transition and melting temperatures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2256–2263, 2002 相似文献
994.
The structure of the complex, [Fe2(II)Fe2(III)(HCOO)10(C6H7N6)n, (1) exhibits a neutral two-dimensional layer network of alternating iron(II) and iron(III) ions, bridged equatorially by formate groups. All iron atoms are octahedrally coordinated, with iron(III) coordinating axially to one gamma-picoline and one formate group, while the iron(II) centers interact axially with two gamma-picoline groups, above and below the layer plane. The complex crystallizes in the triclinic space group P1 at all studied temperatures [at 120 K, the cell dimensions are: a = 10.228(1), b = 12.071(1), c = 12.072(1) A, alpha = 89.801(2), beta = 71.149(2), gamma = 73.371(2) degrees]. An intralayer antiferromagnetic exchange interaction of J = -2.8 cm(-1) between iron(II) and iron(III) was observed in the magnetic studies. Decreasing the temperature to close to 20 K causes a magnetic-ordering phenomenon to occur and a low-temperature phase with a long-range antiferromagnetic spin orientation appears. The magnetic phase transition was confirmed by M?ssbauer spectroscopic studies at temperatures above and below the critical temperature. Structural information of 1 from synchrotron X-ray diffraction data collected at room temperature and 16 K suggests that the antiferromagnetic ordering is caused by an enhanced pi-pi interaction between chi-picoline groups from adjacent layers. 相似文献
995.
Suzdalev I. P. Buravtsev V. N. Maksimov Yu. V. Zharov A. A. Imshennik V. K. Novichikhin S. V. Matveev V. V. 《Russian Chemical Bulletin》2003,52(9):1950-1958
Magnetic phase transitions of the first and second order were revealed by Mössbauer spectroscopy in nanosystems of - and -ferric oxides and metallic europium subjected to shear stress (240°) under high pressure (20 kbar). For - and -ferric oxide nanoclusters, the Curie (Neel) points decreased to 300 K, whereas for nanostructured europium the Neel point increased from 90 to 100 K. The thermodynamic model of magnetic phase transitions predicting a change in the character of magnetic phase transitions and a decrease (increase) in the critical Neel (Curie) points in nanoclusters was developed. The type of magnetic phase transitions and the change in the critical points were caused by defects in nanoclusters, whose maximum concentration was observed for the clusters with the 20—50 nm size range. 相似文献
996.
建立了反相高效液相色谱法监测人口服地尔硫艹卓缓释片后血药浓度。血样用正己烷-氯仿-异丙醇混合溶剂(60405)提取后,以C18化学键合硅胶为固定相,甲醇-水-三乙胺为流动相,安定为内标,在239nm波长处定量检测。血药浓度在15~300μg/L范围内线性关系良好,最低检测浓度为3μg/L。批内(n=7)及批间(n=5)测定相对标准偏差分别小于6.8%和8.4%,回收率为91%~104%。监测了8名健康人口服盐酸地尔硫艹卓缓释片后的不同时间的血药浓度变化,计算了有关的药代动力学参数。 相似文献
997.
AN Ya XU Jun ZHANG Jin HU Changgang LI Ganzuo WANG Zhining WANG Zhongni ZHANG Xiaoyi & ZHENG Liqiang . Key Lab of Colloid Interface Chemistry for State Education Ministry Jinan China . College of Science Guizhou Normal University Guiyang China 《中国科学B辑(英文版)》2006,49(5)
The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, 2H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA′ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively. 相似文献
998.
合成了系列卟啉乙酸合锰配合物9个,其中6个为未见文献报道的新化合物.用UV,1HNMR,IR,MS,元素分析等表征确证了配合物的结构,总结了锰与卟啉类配体配合的IR,UV,1HNMR判据.采用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能,发现8个配合物具有液晶性.考察了烷氧基链长、配位金属离子和分子空间结构对液晶性能的影响. 相似文献
999.
A series of methacrylamide-based C16 monolithic columns were prepared and characterized to determine how their porous structural properties and chromatographic behavior are affected by the percentages of functional monomer, base monomer, and cross-linker in the polymerization solution. Baseline separation of 6 neutral compounds can be readily obtained in an optimized column. Furthermore, the effects of organic additive in the mobile phase, operating voltages, and temperature on retention behaviors and separation efficiencies were also studied. The separation mechanism is also discussed. High column efficiency and good reproducibility indicate that the monolithic columns hold considerable promise. 相似文献
1000.
Poly ionic liquid 1-ethyl 3-(2-methacryloyloxy ethyl) imidazolium iodide (PEMEImI) as a single-ion conductor was designed and synthesized. When appropriate amount of suitable plasticizers, I2 and polyacrylonitrile (PAN) were incorporated into it, the complex formed gel polymer electrolyte. Chemical structure, thermal behavior and ionic conductive properties of the gel polymer electrolyte were investigated by Raman spectra, UV-Vis spectra, differential scanning calorimetry (DSC), and complex impedance analysis, respectively. For the new gel polymer electrolyte, the ionic conductivity of about 1 × 10−3 S cm−1 at room temperature was achieved. 相似文献