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81.
用三丁基氯化锡与戊二羧酸二钠以2:1摩尔比反应,合成了双(三丁基锡)戊二羧酸酯,并用元素分析、红外光谱、核磁共振氢谱及X-射线单晶衍射进行了表征和结构测定。X-射线单晶衍射法测定表明,化合物属单斜晶系,空间群为Cc,晶胞参数:a=13.984(3),b=16.164(3),c=16.894(3)A,β=107.457(3)°,V=3642.9(11)A3,Z=4,C29H60O4Sn2,Dc=1.251g/cm3,μ=1.394 mm-1,R=0.0500,wR=0.0874,F(000)=1416。晶体结构中存在2种化学环境不同的三角双锥构型的锡原子,由于配体中2个羧基在不同方向的交联作用,使化合物呈现三维立体骨架结构,并且在骨架结构中存在沿a、b、c轴3个方向伸展的规则的大环直孔道。 相似文献
82.
83.
J. P. Osleeb S. J. Ratick P. Buckley K. Lee M. Kuby 《Annals of Operations Research》1986,6(6):161-180
The formulation and use of a mixed integer mathematical programming location-allocation model, the Coal Logistics System (COLS), is presented in this study. COLS is used to evaluate the potential for reducing water-borne coal transportation costs, and concomitantly the costs of delivering coal to European markets. This cost reduction is accomplished through the use of supercolliers which would require the dredging of channels at selected ports or the use of offshore loading sites at East and Gulf Coast ports or both. The model developed and the analysis presented in this paper are intended to aid in the determination of the location and extent of these activities, and to indicate the size of the potential reduction in the costs of U.S. export coal. In order to be able to accommodate these deeper draft vessels at East and Gulf Coast ports, expensive improvements would need to be undertaken which may include the deepening of harbor channels to the depths required for 120 000 dead weight ton (dwt) or larger supercolliers. Since dredging requires large initial investments and has significant long-term maintenance costs, excess capacity could represent an inefficient use of both U.S. revenues and the ports' own funds. The use of offshore loading moorings to permit the topping off of supercolliers by self-unloading colliers at the deepwater sections of harbor channels has been proposed as a way of reducing trans-ocean transportation costs and avoiding the large investments and time delays associated with dredging activities. The Coal Logistics System was modified and extended to enable the evaluation of these two port improvement options to be undertaken in a consistent and realistic manner. 相似文献
84.
There are many organic pollutants in the environment, such as polychlorinated biphenyl, polycyclic aromatic hydrocarbons, dichlorodiphenyl-trichloroethane (DDT), and polychlorinated naphthalene. These organic pollutants are persistent,liposoluble and easily cumulated in organism; consequently, the potential toxicity will be high. Risk assessment of industrial chemicals is currently carried out using scanty experimental data, because many of these chemicals have very little or no test data. S… 相似文献
85.
IntroductionInthepastseveralyears ,considerableprogresshasbeenachievedincontrollingtheassemblyofindividualbuildingblocksintostructureswithspecifictopologiesandinterestingpropertiessuchasmolecularrecognition ,ionexchangeandselectiveguestinclusion .1 3 Itis… 相似文献
86.
《European Polymer Journal》2002,38(11):2133-2141
Superswelling acrylamide (AAm)/maleic acid (MA) hydrogels were prepared by free radical polymerization in aqueous solution of AAm with MA as comonomer with some multifunctional crosslinkers such as trimethylolpropane triacrylate and 1,4-butanediol dimethacrylate. AAm/MA hydrogels were used in experiments on swelling and adsorption of a water-soluble monovalent cationic dye such as Basic Blue 17 (Toluidin Blue). As a result of dynamic swelling tests, the influence of relative content of MA on the swelling properties of the hydrogel systems was examined. AAm/MA hydrogels were swollen in the range 1660-6050% in water, while AAm hydrogels swelled in the range 780-1360%. Equilibrium water content of AAm/MA hydrogels were calculated in the range 0.8873-0.9837. Water intake of hydrogels followed a non-Fickian type diffusion. The uptake of the cationic dye, BB-17 to AAm/MA hydrogels is studied by batch adsorption technique at 25 °C. In the experiments of the adsorption equilibrium, S-type adsorption in Giles's classification system was found. The binding ratio of hydrogel/dye systems was gradually increased with the increase of MA content in the AAm/MA hydrogels. 相似文献
87.
Clemens C. Freyhardt Michael Wiebcke Jürgen Felsche Günter Engelhardt 《Journal of inclusion phenomena and macrocyclic chemistry》1994,18(2):161-175
Single-crystal X-ray structure analyses of N(nPr)4[B5O6(OH)4][B(OH)3]2,1, and N(nBu)4 [B5O6(OH)4][B(OH)3]2,2, reveal that these materials are novel clathrates, the isotypic host structures of which are three-dimensional assemblies of hydrogen-bonded [B5O6(OH)4]– ionsand B(OH)3 molecules. The assembly of only the pentaborate anions is a distorted (i.e., along [102] elongated) fourconnected diamond-related network. The N(nPr)
4
+
and N(nBu)
4
+
ions are trapped within the complex three-dimensional channel systems of the host frameworks. Both1 and2 crystallize monoclinically with space groupP21/c andZ=4. The cell constants are:1:a=13.592(5),b=12.082(2),c=17.355(6) Å, =106.60(2)° (298K);2:a=13.874(3),b=12.585(1),c=17.588(4) Å, =107.04(1)° (238 K). The results obtained by both11B and13C MAS NMR spectroscopy are discussed. Thermogravimetric studies under a flowing inert-gas atmosphere suggest that water, stemming from polycondensation of the hydrous borate species, is released from the clathrates at ca. 443 K (1) and 398 K (2) before the decomposition of the organic cations starts at ca. 603 K (1) and 603 K (2).Author for correspondence.
Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82172 (82 pages). 相似文献
88.
The novel complex [K(18-C-6)]2[Cd(mnt)2][18-C-6-18-crown-6,nmt=1,2-dicyanoethene-1,2-dithiolate,C2S2-(CN)2^2-] was synthesized and characterized by elemental analysis,IR spectrum and X-ray diffraction analysis.The complex displays two-dimensional network structure of [K(18-C-6)] complex segments and [Cd(nmt)2] complex segment bridged by S-K-S,S-K-N and N-K-N interactions between adjacent[K(18-C-6)] and [Cd(mnt)2]units. 相似文献
89.
两组份互穿网络聚合物的合成研究 总被引:1,自引:0,他引:1
以蓖麻油聚氨酯和聚醚聚氨酯的不同重量比与光敏剂、催化剂、稀释剂、促进剂所组成的多相体系为反应物,分别在紫外光照射和加热的条件下合成网络Ⅰ和网络Ⅱ的互穿网络聚合物(IPN)。改变网络Ⅱ聚醚聚氨酯中各组份的摩尔比制得系列样品。红外光谱,应力-应变曲线和动态力学性能测定发现,样品的力学性能与两组份重量比和网络Ⅱ中不同组成都存在着一定关系。这些结果,为该体系IPN的合成和应用提供了一定依据。 相似文献
90.
Poly(N-isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM-containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature-sensitive microspheres. 相似文献