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931.
The synthesis and mesomorphic properties of a homologous series of N-(3-hydroxypropyl)-4-alkoxylsalicylaldimine, N-(3-hydroxypropyl)-4-(4′-alkoxybenzoxy)salicylaldimine, and their dicopper(II) and di-oxovanadium(VI) complexes are reported. Copper complexes exhibited monotropic smectic A phases; however, vanadyl complexes showed no mesomorphism. A systematic comparison revealed that the meso-genie behaviors of these bimetallic complexes are induced by the weak intermolecular force and determined mainly by the central metal. The effects on the structural variations near the metal central cores and side chain density are also discussed. 相似文献
932.
偶氮胂酸型荧光试剂测定铝的研究 总被引:10,自引:1,他引:10
比较了5种新试剂及偶氮胂-I的铝铬合物的荧光性能,讨论了试剂结构与性能之间的关系。试验出7-〔(4-甲基-2-胂酸基苯)偶氮〕-8-羟基喹啉-5-磺酸为铝的优良荧光试剂,并用其测定茶叶、含茶叶饲料,以及大白鼠排泄物中的铝和水样中的铝,结果满意。 相似文献
933.
以内型3,3-二甲基-2-降冰片基乙醛(1)与叔丁胺反应制得醛亚胺(2),依次和溴化乙基镁,碘乙烷反应制得内型2-(3,3-二甲基-2-降冰片基)丁醛的亚胺(4),再经水解得内型2-(3,3-二甲基-2-降冰片基)丁醛(5)。后者经与乙二醇缩醛化及氧化分别制得该醛的缩醛(6)及羧酸(7)。这些化合物均为新化合物,经纯化后进行了结构分析,并对其质谱进行了讨论。 相似文献
934.
We study the early stage coagulation kinetics for a charged colloidal dispersion which is here modeled by an effective two-body colloid-colloid potential. The colloidal system was physically prepared by choosing sets of colloidal parameters varying in particular the Hamaker constant and the particle's size. The kinetics of coagulation process was driven by the addition of an indifferent electrolyte and assumed to proceed in two quasi-steady steps. In the first step, colloidal particles are destabilized by the presence of a second potential minimum to diffuse from a bulk-stabilized liquid phase to a flocculated phase. In the second step, we assume that different entities are found in the second potential minimum. The entities comprise secondary dimers, secondary dimers undergoing redispersion, and monomers still in singlet states. If, under favorable condition, this kind of interaction-driven diffusive motion continues, a fraction of the secondary dimers will be induced to undergo primary dimers formation in the first deep minimum. Whether or not the latter process occurs is determined either energetically by the potential barrier falling below a prescribed value, say of 15k(B)T, or/and the second potential minimum becoming negligibly small (with a magnitude coagulation transition and would throw a fresh light on the use of both the energy and the kinetic criteria for understanding the colloidal stability such as those observed in the liquid-liquid coexistence. 相似文献
935.
936.
降香黄檀和印度紫檀中微量元素的研究 总被引:1,自引:0,他引:1
运用ICP-AES法测定了呀约降香的基源植物降香黄檀和印度檀心材中14种无机元素含量,发现它们之间含量相近的元素为Cr,Mn,Ti,Fe,含量差别较大的元素有Sr,Co,Ca等。 相似文献
937.
Yao-Pin Yen Kuei-Ta Chen Shu-Chiu Lee Chu-Chi Shen Ching-Cheng Lai R. S. H. Liu 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):109-114
Products from photoirradiation of 4,5-cycloalkanopyrazoles have been isolated and characterized. The simpler product mixtures relative to the parent systems are in agreement with the hypothesis that the extra carbocyclic ring could reduce the possible number of reaction pathways. Relative reactivities and secondary photoreaction pathways have also been determined. 相似文献
938.
Lai TS Lee SK Yeung LL Liu HY Williams ID Chang CK 《Chemical communications (Cambridge, England)》2003,(5):620-621
With a highly encumbered manganese porphyrin as catalyst, significant improvements in regioselectivity towards less substituted C-C double bond in diene epoxidation were attained by simply adding organic bases as axial ligand. 相似文献
939.
[structure-see text]A series of fluorene-dithia[3.3]paracyclophane copolymers was synthesized by Suzuki coupling reactions of suitable precursors. Transannular pi-pi interactions altered the electronic and optical properties of the polymer backbone significantly. A large red shift in the emission spectrum of the unsubstituted polymer was accompanied by enhanced photoluminescence (PL) efficiency. Substitution in the cyclophane unit resulted in PL quenching. 相似文献
940.
Summary In Lai and Stout [7] the upper half of the law of the iterated logarithm (LIL) is established for sums of strongly dependent stationary Gaussian random variables. Herein, the upper half of the LIL is established for strongly dependent random variables {X
i} which are however not necessarily Gaussian. Applications are made to multiplicative random variables and to f(Z
i
) where the Z
i
are strongly dependent Gaussian. A maximal inequality and a Marcinkiewicz-Zygmund type strong law are established for sums of strongly dependent random variables X
i
satisfying a moment condition of the form E¦S
a,n
¦pg(n), where
, generalizing the work of Serfling [13, 14].Research supported by the National Science Foundation under grant NSF-MCS-78-09179Research supported by the National Science Foundation under grant NSF-MCS-78-04014 相似文献