Role of Lithium in Multicomponent Oxide Catalysts for Oxidative Coupling of Methane

The effect of Li content in a series of multicomponent oxides LixLa0.5Ti0.5 For methane oxidative coupling has been studied. The catalytic activities of LiLa0.5Ti0.5 catalyst before and after washing with boiling water have been compared. The surface and

锂在甲烷氧化偶联多元氧化物催化剂中的作用

考察了不同Li含量对LixLa0．5Ti0．5系氧化物催化剂的甲烷氧化偶联催化性能的影响；比较了水洗前后LiLa0．5Ti0．5氧化物催化剂的催化活性，并通过XRD、IR、XPS和BET等方法时催化剂进行表征。确认了Li在含稀土、过渡金属多元氧化物中的作用。其中，表面Li的作用是缩小催化剂的比表面积，覆盖表面深度氧化活性位，提高C2选择性；体相Li的作用是部分取代Ti3+进入LaTiO3晶格形成LaTi1-yLiyO3-λ活性相，产生甲烷氧化偶联Li+－O-－Ti3+缺陷簇。（注：LixLa0．5Ti0．5和LiLa0．5Ti0．5表示该系列氧化物催化剂制备时的各金属元素的配比。用来表示催化剂的名称，并不表示实际存在的物相，以下类同，下面出现时，不再加以说明。

THE CLEAVAGE REACTION OF THE MO-MO TRIPLE BOND - THE CRYSTAL-STRUCTURES OF MOLYBDENUM COMPLEXES [CPMO(CO)(2)(C(5)H(4)NS)], [CPMO(CO)(2)(C(9)H(6)NS)]O=PPH(3) AND [CPMO(CO)(2)(S(2)CNME(2)]

The reactions of [Cp2Mo2(CO)4] (1) with 2,2'-dipyridyl disulphide (C5H4NS-)2, 8,8'-diquinolyl disulphide (C9H6NS-)2 and tetramethyl thiuram disulphide (Me2NC(S)S-)2 in toluene solution resulted in the cleavage of the Mo-Mo triple bond to yield molybdenum complexes [CpMo(CO)2(C5H4NS)] (2), [CpMo(CO)2(C9H6NS)] (3) and [CpMo(CO)2(S2CNMe2)] (4), respectively. The molecular structures of 2, 3 . O=PPh3 and 4 were determined by X-ray diffraction studies. Crystals of 2 are monoclinic, space group P2(1)/n, with Z = 4, in a unit cell of dimensions a = 6.448(1), b = 12.616(2), c = 14.772(2) angstrom, beta = 92.85(1)-degrees. The structure was refined to R = 0.028 and R(w) = 0.039 for 1357 observed reflections. Crystals of 3 . O=PPh3 are triclinic, space group P1BAR, with Z = 2, in a unit cell of dimensions a = 11.351(3), b = 13.409(3), c = 9.895(2) angstrom, alpha = 94.59(2), beta = 90.35(2), gamma = 78.07(2)-degrees. The structure was refined to R = 0.033 and R(w) = 0.037 for 3260 observed reflections. Crystals of 4 are monoclinic, space group P2(1)/a and Z = 4 with a = 12.468(5), b = 7.637(2), c = 13.135(4) angstrom, beta = 96.62(3). The structure was refined to R = 0.032 and R(w) = 0.042 for 1698 observed reflections. Each of complexes 2-4 contains a cyclopentadienyl ligand, a cis pair of carbonyls and a chelate ligand (S,N donor or S,S donor). All the compounds have distorted square-pyramid structures.

SYNTHESIS AND CRYSTAL-STRUCTURE OF HETEROPOLY MOLYBDOSILICIC LANTHANIDE K10H3[PR(SIMO11O39)2].18H2O

The intensity data of the title complex were collected at a low temperature of -90-degrees-C. The compound crystallizes in the monoclinic space group P2(1)/n, a = 17.504(2), b = 27.323 (5), c = 21.616(4) angstrom, beta = 104.49 (2)degrees, Z = 4. The structure was solved by Patterson and Fourier techniques and refined by least-squares to an R = 0.088 for 8320 independent reflections. The central Pr ion is bonded to eight oxygen atoms from two molybdosilicic heteropoly ligands to form a square antiprism. The Pr-O average distance is 2.44 (2) angstrom. Both molybdosilicic heteropoly ligands are of a defective alpha-Keggin structure.

稀土钼硅杂多酸根配合物K_(10)H_3[Pr(SiMo_(11)·O_(39))_2]·18H_2O的合成及晶体结构

本文采用低温技术,在—90℃的干燥氮气保护下,收集标题化合物晶体的衍射数据,用重原子法解出结构。P2_1/n空间群,a=17.504(2),b=27.323(5),c=21.616(4),β=104.49(2)°,z=4.8320个衍射参与精修,最后的R值为0.088。中心离子Pr(Ⅲ)同2个钼硅杂多酸根中的8个氧原子键合,形成正方反棱柱配位多面体。Pr—O的平均键长为2.44(2)。钼硅杂多酸根配体具有缺位的α型Keggin结构。

热浸镀钢材在海水中的氢渗透行为及其对材料力学性能的影响

氢渗透和拉应力的联合作用对海洋环境中的热浸镀钢材的安全构成潜在威胁，本文以当前应用最广泛的三种商业化热浸镀钢材（Galvanized、Galfan和Galvalume）为研究对象，采用边界元方法计算了三种镀层缺陷周围的电场分布；设计了专用子母配套双电解池并测试了氢渗透电流密度曲线，比较了镀层氢渗透抑制性能及存在缺陷时的自渗氢倾向，并结合镀层成分及结构进行了分析；推导了氢渗透过程相关公式，建立了适合于评价镀层材料氢渗透行为的TANG-LI模型并计算了控制氢渗透相关过程的动力学参数；通过SSRT比较、分析了镀层材料充氢与无充氢条件下的应力－应变行为，并配合断口的显微分析，探讨了海水中带缺陷镀层的氢渗透行为对钢材基体力学性能的影响，结果表明： ⑴海水中三种镀层钢材缺陷处的阴极电位负于析氢电位，能够发生析氢反应而析出氢原子； ⑵ Galvanized镀层对氢渗透的抑制能力较弱，Galfan镀层完好时能明显抑制外部氢的进入，两者存在缺陷时都能产生额外的氢；Galvalume镀层具有很强的氢渗透抑制能力，而且当其存在缺陷时无自渗氢行为；镀层铝含量越高，完整镀层的氢渗透抑制能力越强，缺陷镀层自渗氢能力越弱。 ⑶Galvanized镀层在海水中的氢渗透能降低基体材料的强度并使得其断裂方式由韧性变为准解理，从而加大了材料发生氢脆的倾向；Galfan镀层的氢渗透行为能降低材料的强度但不会改变其韧性断裂方式；Galvalume缺陷镀层则对材料的强度和韧性断裂方式都不能造成影响。

Characteristics of the microzooplankton community in Jiaozhou Bay, Qingdao, China

The species composition and abundance of microzooplankton at 10 marine and five coastal stations (Hongdao, Daguhe, Haibohe, Huangdao and Hangxiao) in the Jiaozhou Bay (Qingdao, China) were studied in 2001. The microzooplankton community was found to be dominated by Tintinnopsis beroidea, Tintinnopsis urnula, Tintinnopsis brevicollis and Cvdonellopsis sp. The average abundance of microzooplankton was highly variable among stations. Specifically, the abundance of microzooplankton was higher at inshore stations and lower in the center of the bay (St. 5), bay mouth (St. 9) and outside the bay (St. 10). The highest average annual densities (346 ind./L) was observed at St. 3, while the lowest (55 ind./L) was at St. 10. Two abundance peaks were recorded in May (324 ind./L) and February (300 ind./L). The distribution of microzooplankton in three sampling layers at the 10 stations was relatively homogenous and the abundance decreased slightly as the water depth increased. At coastal stations, the highest average annual density was recorded at Hongdao Station (677 ind./L), followed by Daguhe Station (616 ind./L), Haibohe Station (400 ind./L), Huangdao Station (275 ind./L) and Hangxiao Station (73 ind./L). Furthermore, a 24-h sampling analysis conducted at Hangxiao Station revealed that the microzooplankton assemblages were characterized by a bimodal diel vertical migration pattern, with the highest densities occurring at dusk (154 ind./L), followed by dawn (146 ind./L), noon (93 ind./L) and midnight (77 ind./L). The density of microzooplankton in the Jiaozhou Bay was in the middle range of the densities of temperate coastal waters worldwide.

Corrosion resistance of hot-dipped zinc and zinc alloy coated sheet steels under offshore atmospheric environment

The application of hot-dipped zinc and zinc-aluminum alloy coatings were introduced. Exposure tests of the steels with these coatings were conducted in the offshore atmosphere in Qingdao and Xiamen for 12 years separately. Effects of the coating thickness, alloy composition and atmospheric environment on the corrosion performance were studied. Results of the onsite exposure tests were compared with the results of a previous indoor salt spray accelerated corrosion tests. The study supports that zinc-aluminum alloy coatings are useful in providing better corrosion resistance and can be further developed for future applications.

Chemical Constituents of Nitraira tangutorum Seed from Qaidam Basin

Six compounds were isolated from the 75% ethanol extract of Nitraria tangutorum seed.On the basis of spectroscopic methods including 1H NMR,13C NMR and ESI-MS and comparison with literature,their structures were elucidated as daucosterol(1),4-hydroxypipecolic acid(2),quercetin(3),allantoin(4),1,2,3,4-tetrahydro-1-methyl-β-carboline-3-carboxylic acid(5) and L-tyrosine(6).Compounds 1,2,3,5 and 6 were isolated from Nitraria tangtorum for the first time.

珠芽蓼果实营养成分分析

本文对珠芽蓼果实的营养成分进行了分析.结果表明,珠芽蓼果实含有丰富的蛋白质、总糖、氨基酸和矿质元素,是一种值得有效开发的野生植物资源.

藏药细穗香薷挥发性化学成分的研究

研究细穗香薷(Elsholtzia ianthina)的挥发油成分.采用水蒸气蒸馏法提取,用气相色谱质谱联用技术进行分析,用面积归一法计算出有关的相对含量,鉴定出45个化合物,主要的挥发油化学成分为三环[4.3.1.13,8]十一烷-1-醇,2,3,5,6-四甲基酚,共占挥发油总量的56.29%.

款冬的胚胎学

系统报道了中藏药款冬大小孢子的发生、雌雄配子体发育和胚胎的发育过程。药壁发育双子叶型; 绒毡层发育接近菊科中的“The Com os bip innatus”型; 成熟花粉为3 细胞型; 单珠被, 薄珠心, 倒生胚珠；具发达的珠被绒毡层；胚囊发育4 孢子型, 接近五福花(A d ox a)型胚囊。受精作用属于有丝分裂前配子体融合类型。胚乳发育为核型。胚胎发育为紫菀型千里光变型。讨论了该种胚胎学特征的生态学及系统学意义。

夏季自然水体与大气界面间气态总汞的交换通量

利用动力学通量箱法与高时间分辨率大气测汞仪的联用技术, 在瑞典西南的Kristineberg海洋观测站(KMRS)和Knobesholm的Hovgårdsån河分别测定了夏季海水和河水表面与大气间汞的交换通量. 在夏季, 河水和海水都是大气汞的源. 河水和海水表面与大气间汞的交换通量在夏季具有一致的昼夜变化规律, 白天由水体向大气排汞且在正午达到最大值; 夜间排汞量相对较小且有时会出现大气汞向水体沉降. 河水与大气间汞的交换通量与光照强度呈线性正相关关系, 与大气相对湿度呈线性负相关性, 同时还与水体温度存在指数相关性. 海水与大气间汞交换通量只与光照强度存在良好的线性正相关关系. 水体中溶解态气汞的过饱和是水体汞向大气释放的驱动力.