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971.
采用水热法合成了配位聚合物[Co2(HBTC)2(H2O)6]·C4H10N2·2H2O}n(H3BTC为1,3,5-均苯三羧酸,C4H10N2为哌嗪),通过X射线单晶衍射、红外光谱和荧光光谱进行表征,并用TGA研究了该配位聚合物的热稳定性.晶体属三斜晶系,P1空间群,a=1.05437(9)nm,b=1.05485(9)nm,c=0.71482(5)nm,α=102.4623(28)°,β=91.3500(42)°,γ=111.0186(29)°,V=0.72018(10)nm3,Mr=764.37,Dc=1.762g·cm-3,Z=1,μ(MoKα)=1.25mm-1,F(000)=394,R=0.0307,wR=0.0815.晶体的基本构建单元中包含2个Co()中心、2个配位的HBTC分子和6个配位的水分子.基本构建单元通过相互链接形成具有“Z”型结构的一维配位聚合链,链间通过两种不同的氢键(O—H…O和N—H…O)相互作用,进而形成具有三维骨架结构的微孔晶体,微孔大小为0.71nm×0.82nm.荧光光谱表明,常温下用λex=312nm的光激发后,配位聚合物在329nm处出现强烈的荧光发射. 相似文献
972.
Lee JC Chang SW Liao CC Chi FC Chen CS Wen YS Wang CC Kulkarni SS Puranik R Liu YH Hung SC 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(2):399-415
A novel and convenient route for the synthesis of biologically potent and rare L-hexose derivatives from D-glucose is described. Conversion of diacetone-alpha-D-glucose (14) into 1,2:3,5-di-O-isopropylidene-beta-L-idofuranose (19) was efficiently carried out in two steps. Orthogonal isopropylidene rearrangement of compound 19 led to 1,2:5,6-di-O-isopropylidene-beta-L-idofuranose (27), which underwent regioselective epimerization at the C3 position to give the L-talo- and 3-functionalized L-idofuranosyl derivatives. Hydrolysis of compound 19 under acidic conditions furnished 1,6-anhydro-beta-L-idopyranose (35) in excellent yield, which was successfully transformed into the corresponding L-allo, L-altro, L-gulo, and L-ido derivatives via regioselective benzylation, benzoylation, triflation and nucleophilic substitution as the key steps. Applications of these 1,6-anhydro-beta-L-hexopyranoses as valuable building blocks to the syntheses of 4-methylcoumarin-7-yl-alpha-L-iduronic acid and the disaccharide moieties of bleomycin A(2) as well as heparan sulfate are highlighted. 相似文献
973.
Method for the synthesis of m-and p-isomers of 4-[2-(ethynylphenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides by the cross-coupling of 4-[2-(3-iodophenyl)vinyl]-and
4-[2-(4-iodophenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides with (trimethylsilyl)acetylene followed by desilylation
was elaborated. The reactions at the CH-fragment of the ethynyl group were performed. The Mannich reaction proceeds with the
loss of a spin label, whereas the oxidative homocoupling, with its retention.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2051–2054, October, 2007. 相似文献
974.
《Surface and interface analysis : SIA》2003,35(5):483-488
Titanium‐implanted CaTiO3 film was prepared and then characterized by x‐ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) before and after immersion in Hanks' solution for 7 days. An as‐prepared specimen contained a small amount of Ar implanted during sputtering, although the pressure was as low as 10?4 Torr. Even though Ar convolution increased with an increase in the relative Ti ion dose, most of the convoluted Ar was not from the Ar gas used for Ti ion production but rather was from the Ar gas used for sputtering the CaTiO3. During Ti implantation, the CaTiO3 films were ion‐etched by Ti ions. The composition of the CaTiO3 film was not changed to any great degree by the Ti implantation, however its properties changed considerably. After immersion in Hanks' solution, the thickness of the specimen not implanted with Ti decreased the most whereas the [Ca]/[P] ratio, which was nearly unity before exposure, decreased significantly, becoming 0.23 on the Ti‐implanted specimen prepared at 200 W and 0.13 on the Ti‐implanted specimen prepared at 50 W. It was also observed by XPS that the ratio [Ca]/[P] was ~1.9 for all Ti‐implanted specimens after immersion in Hanks' solution for 7 days. Judging from the binding energies of Ca 2p3/2 and P 2p electrons and the [Ca]/[P] ratio, it was suggested that a hydroxyapatite‐like substance had formed on the surfaces of the Ti‐implanted specimens after immersion in Hanks' solution. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
975.
对130℃下1,3 二烯基 1,1,3,3 四甲基二硅氧烷(DVDS)/苯乙烯(St)的溶液环化共聚合动力学进行了研究.根据低转化率(<10%)的共聚物组成及环状结构比例,通过参数估计方法,求得环化率与竞聚率,分别为r1=0102、r2=348、rc=00210、Kc=381mol/L、K′c=0389mol/L,同时得到它们95%置信概率的联合置信区间及其交互影响的联合置信区间.表明DVDS的反应活性较St低,其非环状结构自由基具有较强的分子内环化反应能力;环的位阻效应使环状结构DVDS自由基的活性低于其非环状结构自由基. 相似文献
976.
When food containing fat is treated by ionizing radiation, a group of 2-alkylcyclobutanones is formed. These components contain the same number of carbon atoms as their precursor fatty acids and the alkyl group is located in ring position 2. Thus, from palmitic acid 2-dodecylcyclobutanone is derived. To date, there is no evidence that the cyclobutanones occur in unirradiated food. Therefore, these components cannot be considered inherent to food, and for questions pertaining to risk assessment of irradiated food it would be advisable to determine the genotoxic and toxic potentials of cyclobutanones. Measurements of DNA damage in cells exposed to 2-dodecylcyclobutanone, employing the single cell microgel electrophoresis technique, have been carried out. In vitro experiments using rat and human colon cells indicate that 2-docylcyclobutanone in the concentration range of about 0.30 – 1.25 mg/ml induces DNA strand breaks in the cells. Simultaneously, a concentration related cytotoxic effect is observed as was determined by trypan blue exclusion. To which extent these in vitro findings are of relevancy for the in vivo human exposure situation needs to be investigated in further studies. In vivo tests in rats are in progress. 相似文献
977.
CuO/CeO2和CuO/Al2O3催化剂的催化性能 总被引:13,自引:0,他引:13
本文以CO氧化为模式反应考察了CeO2和Al2O3负载氧化铜催化剂的氧化活性,运用XRD和TPR技术研究了催化剂的还原性能和物相结构,结果表明:载体性质对负载CuO催化剂的CO氧化活性有很大影响,CuO/CeO2催化剂活性明显高于CuO/Al2O3催化剂.催化剂的还原特性随载体不同而不同.同时发现,热处理对催化剂铜物种的存在形式,晶粒大小、还原特性及其催化活性有明显影响,CuO/Al2O3催化剂活性下降的主要因素是生成了活性较低的CuAl2O4相,而CuO/CeO2催化剂活性下降是由于CuO和CeO2发生烧结,晶粒变大 相似文献
978.
Summary Lattice parameter values were determined for the ternary B 2-phase in the Al-Co-Ga system, and it was found that a continuous solid solution exists between -AlCo and -CoGa. Phase boundaries of the ternary phase at 1 100 K were derived from the variation of the lattice parameter with composition.
Über die ternäre B 2-Phase im System Al-Co-Ga
Zusammenfassung Im Bereich der ternären B 2-Phase im System Al-Co-Ga wurden die Werte des Gitterparameters bestimmt; es stellte sich heraus, daß eine durchgehende feste Lösung zwischen -AlCo und -CoGa besteht. Die Phasengrenzen der ternären Phase bei 1 100 K wurden aus der Änderung des Gitterparameters mit der Zusammensetzung abgeleitet.相似文献
979.
The photophysical behaviour of rhodamine 6G and coumarin 1 has been studied in a range of aqueous micellar media. Resonance energy transfer is demonstrated in dilute (10?5 M) solutions and the location of the dye molecules in the micelle deduced from fluorescence lifetimes. A highly efficient, energy transfer dye laser is reported for dyes in micellar matrices. 相似文献
980.
The structure elucidation and 1H and 13C assignments of the new triterpenes 3beta-palmitoxy-7beta-hydroxyolean-12-ene (1) and its hydrolysis product 3beta,7beta-dihydroxyolean-12-ene (2) and 3beta-sn-glyceroyl-(1'-palmitoxy)urs-12-ene (3), isolated from the aerial parts of Cladocolea grahami (Loranthaceae), are reported. 相似文献