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51.
52.
合成了两种新型的固体配合物,其组成为K(BrB15C5)X(X=NCS ̄-或Pic ̄-).钾(Ⅰ)离子不仅能与4’-溴苯并-15-冠-5形成常见的1:2夹心式配合物,而且还能生成稳定的1:1型(M:L)固体配合物. 相似文献
53.
铜(Ⅱ)(溴代苯并—15—冠—5)配合物的研究 总被引:3,自引:2,他引:3
苯并冠醚对碱金属、碱土金属及稀土金属离子具有特殊的配位能力,但它们与溶剂化能量较大的“软酸”过渡金属离子配位较难。通过在冠醚苯环上引入吸电子取代基团减弱冠醚的碱性,是这类过渡金属大环配合物研究的一个重要方面。从模拟金属蛋白中铜(Ⅱ)离子的位置看,铜(Ⅱ)离子冠醚配合物的研究具有一定的意义。本文在过去工作的基础上,合成了高氯酸铜与4′-溴苯并-15-冠-5(L_A)及4′,5′-二溴苯并-15-冠-5(L_R)两种新配合物,并研究了它们的有关物理、化学性质。 相似文献
54.
Xiuying QiaoXueshan Xiao Xianhong WangJian Yang Zhaobin QiuLijia An Wenkui WangZhishen Mo 《European Polymer Journal》2002,38(6):1183-1190
In order to investigate the effect of external field on the crystallization behavior of poly(3-dodecylthiophene) (P3DDT), the samples were recrystallized with different electrostatic field intensity, different pressure and different solidification direction in temperature gradient field. Measurements of differential scanning calorimetry and X-ray diffraction were operated to characterize these samples for analysis. The results suggest that after recrystallization, whether the external field is added or not, a more compact packing of molecular chains in P3DDT could be obtained without the change of the crystal structure model. Moreover, the addition of electrostatic field has greater effects on the crystallization of rigid main chains than on that of flexible side chains. Merely great pressure field can effect the rearrangements of molecular chains greatly. As for the temperature gradient field induced crystallization, different oriented solidification direction will lead to different effects on the compact degree and perfect degree of molecular chains packing. 相似文献
55.
Li W Sun Y Liang W Fitzloff JF van Breemen RB 《Rapid communications in mass spectrometry : RCM》2003,17(9):978-982
Caffeic acid derivatives occurring in black cohosh [Cimicifuga racemosa (L.) Nutt., Actaea racemosa (Ranunculaceae)], some of which may have pharmacological activity, were analyzed using high-performance liquid chromatography (HPLC) electrospray ionization tandem mass spectrometry (ESI-MS/MS) with the aim of developing a methodology for their rapid identification in a complex plant matrix. Based on these studies, structurally characteristic product ions and neutral molecule losses were identified, which were then used during LC/MS/MS with product ion scanning, precursor scanning and constant neutral loss scanning to detect caffeic acid derivatives in a crude extract of black cohosh. Several caffeic acid derivatives were detected, and the identification of six of them were confirmed by comparison with authentic standards including caffeic acid, ferulic acid, isoferulic acid, fukinolic acid, cimicifugic acid A, and cimicifugic acid B. Four other compounds were detected that appeared to be caffeic acid derivatives based on LC/MS/MS retention times, molecular weights, and fragmentation patterns during MS/MS. Since standards were unavailable for these four compounds, they were tentatively identified using LC/MS/MS as cimicifugic acid E, cimicifugic acid F, dehydrocimicifugic acid A, and dehydrocimicifugic acid B. Dehydrocimicifugic acid A and dehydrocimicifugic acid B have not been reported previously to be constituents of black cohosh. 相似文献
56.
Huang H Zhang W Li M Gan Y Chen J Kuang Y 《Journal of colloid and interface science》2005,284(2):593-599
In this paper, we report the use of binary carbon supports (carbon nanotubes (CNTs) and active carbon) as a catalyst layer for fabricating gas diffusion electrodes. The electrocatalytic properties for the oxygen reduction reaction (ORR) were evaluated by polarization curves and electrochemical impedance spectroscopy (EIS) in an alkaline electrolyte. The binary-support electrode exhibits better performance than the single-support electrode, and the best performance is obtained when the mass ratio of carbon nanotubes and active carbon is 50:50. The results from the electrode kinetic parameters indicate that the introduction of carbon nanotubes as a secondary support provides high accessible surface area, good electronic conductivity, and fast ORR kinetics. Furthermore, the effect of CNT support on the electrocatalytic properties of Pt nanoparticles for binary-support electrodes was also investigated by different loading-reduction methods. The electrocatalytic activity of the binary-support electrodes is improved dramatically by Pt loading on CNT carbon support, even at very low Pt loading. Additionally, the EIS analysis results indicate that the process of ORR may be controlled by diffusion of oxygen in the electrode thin film for binary-support electrodes with or without Pt catalyst. 相似文献
57.
近年来,有关过渡金属离子冠醚配合物的研究虽有一些报道,但这些研究所涉及的配体大多数是单取代苯并冠醚,对双取代苯并冠醚配位的研究则很少。为了进一步弄清取代冠醚对过渡金属配位性能的影响,我们研究了混合双取代的苯并-15-冠-5,根据文献[2,3]合成了4′-溴-5′-硝基苯并-15-冠-5,并制得了一种新的配合物FeCl_3·L,经性质证明此配合物是1:1型非溶剂合、不含水的固体配合物,其三个Cl~-离子位丁配合物的外界。 相似文献
58.
Jun Wang Tianjin Zhang Hongying Xia Junhuai Xiang Wenkui Li Shuwang Duo 《Journal of Sol-Gel Science and Technology》2008,47(1):102-106
Compositionally graded Ba1−x
Sr
x
TiO3 (BST) (0 ≤ x ≤ 0.4) thin films were fabricated on Pt/Ti/SiO2/Si and YSZ/Pt/Ti/SiO2/Si substrates by a modified sol–gel technique. The YSZ buffer layer was prepared by RF magnetron sputtering. The microstructure
of the graded BST films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force
microscopy (AFM). The results showed that all the films have uniform and crack-free surface with a perovskite structure. The
graded BST film with an YSZ buffer layer has larger dielectric constant and lower dielectric loss. The leakage current density
of the graded BST film with an YSZ buffer layer lowers two orders than the film without buffer layer. The improved electric
properties of the graded films with an YSZ buffer layer was attributed to the YSZ buffer layer act as an excellent seeding
layer to enhance the graded BST film growth. 相似文献
59.
Sun?Liling?Email author Wu?Tianjiao Wang?Wenkui Zhang?Jun Wataru?Utsumi Taku?Okada 《中国科学G辑(英文版)》2005,48(6):716-722
The phase transitions in Pd40Ni10Cu30P20 bulk metallic glass (BMG) have been studied under high pressure and high temperature (HP & HT) by X-ray diffaction measurements
with synchrotron radiation source. We found that the BMG underwent a phase transitions of amorphous-crystalline-amorphous
at 10 GPa upon heating. The parallel experiments were carried out at 7 GPa, while we did not observe the amorphous-crystalline-amorphous
transitions by increasing temperature. Quenching the melted BMG at 7 GPa, it was found that the phase crystallized from the
melt differed from the primary phase crystallized from the starting amorphous solid upon heating suggesting there existed
a distinct mechanism in two cases. 相似文献
60.
在丙酮介质中合成了4',5'-二溴苯并-15-冠-5分别与碘化钾和硫氰化钾的两种新型固体配合物。元素分析表明配合物的化学组成为K(Br_2B15C5)X(X=I ̄-或NCS ̄-)。通过摩尔电导、红外光谱、X-射线粉末衍射分析对配合物进行了表证。从而证明,钾(Ⅰ)离子不仅容易与4',5'-二溴苯并-15-冠-5形成常见的1:2夹心式配合物,而n还能生成稳定的1:1型固体配合物。 相似文献