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991.
Nikolina L. Petrova Dimitar S. Todorovsky Veselinka G. Vasileva 《Central European Journal of Chemistry》2005,3(2):263-278
Mn-, LaMn- and LaCaMn-citrates were synthesized at 60–120°C in ethylene glycol medium using chlorides or nitrates as metal
sources. Their composition, IR spectra and thermal decomposition were studied. Equimolar La/Mn ratio has been established
in the complex, prepared from chloride solution with the same initial composition of the metals. In the isolated three-metallic
complex the molar ratio of the metals deviates from the composition in the initial solution. The final products of the heating
of Mn- and mixed-metal LaMn-citrates at 1000°C are phase-homogeneous Mn3O4 (hausmannite) and LaMnO3 respectively. Parasitic phase(s) are observed in LaxCa1−xMnyO3, produced from LaCaMn-citrate. 相似文献
992.
Ole Toft Sørensen 《Journal of Thermal Analysis and Calorimetry》2005,80(3):793-794
Summary An enormous development has taken place within the last five years in synchronous teaching over the Internet, i.e. both the teacher and the students are simultaneously in direct communication with each other as in a normal class-room or auditorium. With this concept it is possible to communicate orally, to exchange Power Point Presentations, documents, programmes and live web-camera pictures. It is even possible to use an electronic black board on which both the teacher and the students can work simultaneously. The great advantage with this type of teaching is that it is not restricted to a single class-room/auditorium with limited access, but in a virtual room accessible to everybody in principle all over the world, and which certainly open up new possibilities in teaching. The purpose of this paper is to present and to discuss the concept of virtual class-room teaching, how the system operates in practice, its advantages and, finally, how its inherent limitations can be overcome. 相似文献
993.
The isolation and structural characterisation of the product of addition of HCN to the Schiff base derived from phenyl 2-pyridyl ketone and 3,4-dimethylaniline (Me2 bsb) provides evidence in favour of a mechanism involving nucleophilic attack at the coordinated ligand for reaction of the complex [Fe(Me2bsb)3]2+ with cyanide. 相似文献
994.
MingZhuLIU ShengYiZHANG YuHuaSHEN MingLiangZHANG 《中国化学快报》2004,15(10):1249-1252
Selenium nanoparticles were prepared by a reverse microemulsion system. Sodium selenosulfate was used as selenium source. The results showed that hydrochloric acid concentration and reaction temperature had great influence on the morphology of products. The crystalline selenium nanowires and amorphous selenium nanorods were obtained in given condition. 相似文献
995.
催化燃烧是目前最有效的处理挥发性有机物(VOCs)技术之一. 本文从催化剂活性组分、催化剂载体、有效组分颗粒大小、水蒸汽的影响及催化燃烧反应中的积碳等几个方面, 对近年来催化燃烧处理VOCs的研究进行了总结. 分析表明: 贵金属催化剂的研究主要着重于选择有效的载体和双组分贵金属催化剂; 非贵金属催化剂的研究主要集中在高活性的过渡金属复合氧化物、钙钛矿和尖晶石型等催化剂的研制, 还有这些活性组分粒径大小及载体对催化燃烧VOCs反应活性的影响;此外, 在实际应用中,水蒸汽和催化剂积碳失活等问题对催化燃烧VOCs的反应也有很大影响. 本文的评述将为选择合适的催化燃烧技术处理VOCs污染物提供一定参考. 相似文献
996.
PU大分子单体水溶液性质 总被引:2,自引:0,他引:2
双亲聚合物一般由亲水和亲油 2种链段构成 ,有嵌段型[1,2 ] 和接枝型[3 ] 2种 ,其中通过大分子单体法合成双亲接枝聚合物备受关注[4] 。如以亲水性大分子单体和亲油性小分子单体共聚 ,大分子单体构成共聚物主链上支链 ,具有较大活动性 ,亲水效能高。采用对氯甲基苯乙烯[5] 或甲基丙烯酰氯[6] 与聚氧化乙烯大分子的一端相反应 ,可得到亲水性大分子单体 ,但其分子量及结构变化有限。本文采用常规条件 ,合成了嵌段式水溶性聚氨酯大分子单体 ,其分子量较大 ,共聚接枝的支链较长。利用该大分子单体具有非离子高分子表面活性剂的性质 ,采用无皂乳… 相似文献
997.
Su M Pan Z Dravid VP Thundat T 《Langmuir : the ACS journal of surfaces and colloids》2005,21(24):10902-10906
The formation of a water meniscus between a sharp tip and a solid surface is one of the prevailing requirements for scanning probe microscope (SPM)-based lithographies, such as dip-pen nanolithography (DPN) and conductive tip induced oxidation. The water meniscus functions as a medium for the oxidation of or mass transfer to the solid surface. Here we report a simple, efficient, and effective approach to enhance the local relative humidity and thus increase the size of the water meniscus by bringing a water-containing capillary tube to the proximity of the tip-surface contact area. The enhancement in local relative humidity is confirmed via an increase in the measured tip-surface adhesion forces and the widths of DPN generated parallel lines. Compared to the global control of relative humidity for the whole lithography system, the short distance between the "water reservoir" and the tip-surface contact area enables rapid increase in the local vapor pressure of water, less perturbation, and minimal erosion to the state-of-the-art electronics. As a result, most scanning probe lithography experiments at high relative humidity can now be performed in a reasonable time frame. 相似文献
998.
The crystal structure of 1-[(1'-phenyl-5'-methyl-4'-pyrazolcarbonyl)]-3-methyl thio-5-amino-1H-yl-1,2,4-triazole (C14H14N6OS, Mr = 314.37) has been determined by single-crystal X-ray diffraction analysis. The crystal belongs to triclinic, space group P with a = 8.026(3), b = 8.651(4), c = 11.369(5) (A), α = 89.917(7), β= 89.084(7), γ = 68.470(6)°, V = 734.2(5) (A)3, Z = 2, Dc = 1.422 g/cm3, ( = 0.232 mm-1, F(000) = 328, R = 0.0376 and wR = 0.0890 for 2950 unique reflections. The crystal structure shows the presence of a dimmer with intermolecular N(4)-H(4)…N(3A) hydrogen bonds. 相似文献
999.
1000.
由手性配体α-D-葡萄糖衍生物5,6,7以及薄荷醇(8)和葑醇(9),经 Ulmann偶联反应得到光学活性的(R)-和(S)-6,6′-二硝基联苯-2,2′- 二甲酸(4a),(R)-6,6′-二甲基联苯-2,2′-二甲酸(4b),(R)-1,1′-联萘-2 ,2′-二甲酸(13)。以三个手性膦酰胺16,17,18和CuCl组成的手性络合物为 催化剂,通过2-萘酚直接氧化偶联得到(S)-2,2′-联萘酚(15)。产物4, 13,15具有中等ee值的光学活性。 相似文献