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61.
JiŘí Kvapil Josef Kvapil Bohumil Perner Michal Košelja Helena Jelínková 《Czechoslovak Journal of Physics》1990,40(11):1283-1287
The methods of growing YAG:Nd crystals with a flat interface and YAP:Nd crystals with a sharp conical interface are described. The form of the interface was controlled by the He and H2O content in the reducing atmosphere composed mainly of Ar and H2 as well as by axial temperature gradient above the melt level. The crystals of 120–180 mm in length were machined to the high-quality slabs. 相似文献
62.
63.
Mariano Giaquinta Giuseppe Modica Jiří souček 《Archive for Rational Mechanics and Analysis》1989,106(2):97-159
Summary In this paper we introduce some new classes of functions, among these a class of weak diffeomorphisms. In these classes we prove by direct methods the existence of minimizers for several kinds of variational integrals. In particular, we prove the existence of one-to-one orientation-preserving maps that minimize suitable energies associated with hyperelastic materials. The minimizers are also proved to satisfy equilibrium equations. Finally radial deformations are discussed in connection with cavitation. 相似文献
64.
Chemically modified electrodes prepared by treating the cobalt tetraphenylporphyrin modified glassy-carbon electrode at 750 degrees (HCME) are shown to catalyze the electrooxidation of hydrazine. The oxidation occurred at +0.63 V vs. Ag/AgCl (saturated potassium chloride) in pH 2.5 media. The catalytic response is evaluated with respect to solution pH, potential scan-rate, concentration dependence and flow-rate. The catalytic stability of the HCME is compared with that of the cobalt tetraphenylporphyrin adsorbed glassy-carbon electrode. The stability of the HCME was excellent in acidic solution and even in solutions containing organic solvent (50% CH(3)OH). When used as the sensing electrode in amperometric detection in flow-injection analysis, the HCME permitted sensitive detection of hydrazine at 0.5 V. The limit of detection was 0.1 ng. The linear range was from 50 ng to 2.4 mug. The method is very sensitive and selective. 相似文献
65.
XinMeiZHENG YanXingQI XiaoMingZHANG JiShuanSUO 《中国化学快报》2004,15(6):655-658
Jacobsen‘s catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times. 相似文献
66.
本文以二苯基甲酮的KBr压片为标样,在Bruker IFS 120HR付里叶变换红外光谱仪上系统考察了该仪器折一些重要操作参数(光源光栏、切趾函数、扫描速度)对光谱质量(信噪比,分辨率)的影响。从而获得了测样时的优化操作条件。 相似文献
67.
Xin Ying ZHANG Xue Sen FAN Hong Ying NIU Jian Ji WANGSchool of Chemical Environmental Sciences Henan Normal University Key Laboratory ofEnvironmental Science Engineering of Henan Education Department Xinxiang 《中国化学快报》2003,(10)
a, a'-Bis(substituted benzylidene)cycloalkanones were efficiently prepared from cycloalkanones and benzaldehydes in [bmim][BF4] by using iron(III) chloride hexahydrate as a catalyst. It is shown that [bmim][BF4] and iron(III) chloride hexahydrate can be quantitatively recovered and be reused effectively for many times. Compared with the known methods, this novel process has the advantage of being an envkonmentally benign process together with good yields and mild reaction conditions. 相似文献
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在聚乙烯醇存在下,用罗丹明B-Mo(V)-SCN~-荧光熄灭法测Mo,能消除过量的SCN-对罗丹明B的熄灭作用。加入聚乙烯醇后体系的荧光熄灭倍数比未加入时大14倍。此法灵敏度高、稳定性好、操作简便,检测下限0.12ng/ml Mo.可用于测水和头发中的钼。 相似文献
70.