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751.
介绍了基于碳纳米管与聚苯胺纳米纤维的两种氨气传感器的制备与测试,综合运用两种传感器,兼顾了高灵敏度和大范围测量两项互相制约的要求.使用近场电纺技术制备单根聚苯胺纳米纤维传感器,对1×10-6氨气灵敏度达到2.7%,比较了聚苯胺纳米纤维结构和薄膜结构的响应特性.纳米纤维的立体结构可提升传感器性能.使用双向电泳技术制备碳纳米管传感器,对浓度大于20× 10-6 (V/V)的氨气有良好的线性响应.分析了主要功能材料的微结构,阐述了制备技术,比较了响应特性,分析了纤维中气体三维扩散模型,通过计算和测试值,表明响应时间与纤维直径存在反相关性. 相似文献
752.
在本文中,我们将介绍运用第一性原理计算包含非谐效应或势能面锥形交叉情况下内转换速率的最新工作。我们同时计算了包含非谐效应的分子吸收和发射光谱,以检验量子化学方法计算得到势能面的准确性。势能面的锥形交叉对内转换过程的影响是学界广泛关注的焦点。本文将介绍如何在内转换速率计算的过程中考虑势能面锥形交叉的影响,并将之运用于吡嗪分子。本文运用绝热近似理论处理了另外一个重要的无辐射过程,分子的振动驰豫过程,并将这个理论应用于水二聚体和苯胺的振动弛豫速率的计算。 相似文献
753.
A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate.Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z-selectivity.A free radical mechanism has been proposed to account for the formation of the products. 相似文献
754.
The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain. 相似文献
755.
The hydrothermal reaction of ZnO with benzene‐1,4‐dicarboxylic add gave Zn·BDC·2H2O (1) and Zn‐BDC·H2O (2) (BDC = benzene‐1, 4‐dicarboxylate), respectively. Polymer 1 (C4H4O3ZH0.5) shows a one‐dimensional zigzag chain structure built up from the alternate connection of tetrahedral ZnO4 and BDC units. Polymer 2 (C4H3O2.5Zn0.5) possesses a three‐dimensional framework containing infinite zigzag Zn·Zn·Zn pseudochains generated by five‐coordinate zinc centers and a rectangular channel system including three groups of different straight channels along the [001], [010] and [60–1] directions. The two metal‐organic polymeric compounds exhibit strong photoluminescent emission bands at 402 nm (λex = 260 nm) (for 1) and at 344 nm and 385 nm (λex = 279 nm) (for 2) in the solid state at room temperature. 相似文献
756.
757.
Dong Yu ZHAO Sheng Hua YANG Ming HU Xue Yi MA* Department of Chemistry National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2003,14(2)
Andrographolide (Andro) (Figure 1) is a diterpene lactone isolated from Andrographis paniculate Nees1. It has showed several biological activities including analgesic, antipyretic and anti-inflammatory effects2. However, its poor water solubility and unstability towards oxygen restrained its application. In pharmaceutics, b-CD is used to increase solubility and stability3. We have prepared the inclusion compound of Andro/b-CD (Figure 2) under microwave irradiation4. It has been found… 相似文献
758.
A New Bibenzyl Glycoside from Dendrobium moniliforme 总被引:1,自引:0,他引:1
Chun Sheng ZHAO Wei Min 《中国化学快报》2003,14(3):276-277
A new bibenzyl glycoside has been isolated from the stems of Dendrobium moniliforme (L.) Sw.(Orchidaceas).Its structure has been identified on the basis of spectroscopic and chemical methods. 相似文献
759.
ChuanChunZOU ShuJieHOU PingShengLEI XiaoTianLIANG 《中国化学快报》2003,14(4):361-364
Two spirostanol saponins(gracillin and dioscin)which have the typical sugar moieties were synthesized facilely by a general approach. 相似文献
760.
Chun Chun ZHANG Wei ZENG Jian Zhang LI Sheng Ying QIN* Department of Chemistry Sichuan University Chengdu 《中国化学快报》2003,(6)
It is well known that the study on biomimetic oxygen carriers not only has important theoretic significance to discover the mechanism of reversible bonding, activating oxygen as well as the oxidation reaction in organism, but also has potential application in separating oxygen from air and realizing the high efficiency and selectivity of catalytic oxidation reaction under a mild condition1. Metal- porphyrin and metal- phthalol- gaunine have been extensively used as biomimetic oxygen carriers u… 相似文献