Variations of sulfur and carbon isotopes in seawater during the Doushantuo stage in late Neoproterozoic

The Doushantuo Formation of the Sinian System in the Yangtze area is the first sedimentary stratigraphic unit after the Neoproterozoic Snowball Earth event[1], named the Nantuo Glaciation in south China. There are not only phosphorite and manganese mineralized beds[2], but also a series of biome which represents the biological radiation in Neoproterozoic[3] found in this formation. It is important to study the palaeoenvironment and the early biological evolution implied in the Doushantuo …     

用电化学方法研究烯丙基硫脲在不同温度下对碳钢的缓蚀性及吸附机理的初步探索

利用电化学方法测定了缓蚀剂烯丙基硫脲在不同温度和不同浓度下的缓蚀性，初步探索了缓蚀剂烯丙基硫脲的吸附机理，并比较了不同条件下缓蚀剂烯丙基硫脲和苯基硫脲缓蚀作用的差异，初步分析了缓蚀剂分子的结构对缓蚀性的影响。     

夏季西北太平洋等位势密度面上的副热带逆流

用P-矢量诊断方法对西北太平洋等位势密度面上的地转环流进行了研究;所用的资料是美国海军0.5°× 0.5°水平分辨率的月平均温度和盐度资料,该资料源自美国海军收集的 1930～1997年期间的实测数据.计算结果不仅显现出西北太平洋等位势密度（σθ）面上的主要流系,如北赤道流、黑潮和黑潮逆流等,而且还特别清楚地揭示出副热带逆流.主要讨论夏季（6月份）副热带逆流的分布特征.6月份,副热带逆流弯弯曲曲连续地自西向东流动;在较浅的σθ面上,副热带逆流的源地向西可以一直追溯到巴士海峡以东大约122°E左右;随着σθ的增加,副热带逆流的源头和流核均向北向东迁移,但主要部分仍位于18°～23.5°N,即北回归线附近.在海面至σθ=25.8 kg/m3之间均存在副热带逆流.位势涡度分布清楚地表明,副热带逆流流核位于副热带模态水南边界的上面.     

柠檬酸对溶胶-凝胶法制备羟基磷灰石粉体的影响

为改善以Ca(NO) 3·4H2 O和 (CH3O) 3PO为前驱体、采用溶胶凝胶法制备羟基磷灰石(HAP)粉体的颗粒较大 ,尝试加入螯合剂柠檬酸 (C6H8O7) ,研究其对HAP粉体特征的影响 .SEM结果显示柠檬酸的加入使得粉体粒度明显变小 ,进一步在TEM观察 ,可以发现HAP粉体尺寸约为 5 0nm .XRD和FTIR分析表明柠檬酸的加入可使更多的CO2 -3 以B型替代的方式进入HAP结构中 ,并引起HAP晶格微畸变     

Cloning and expression of ophc2, a new organphosphorus hydrolase gene

The amino acid sequences of N-terminal and internal peptide of OPHC2, purified from Pseudomonas pseudoalcaligenes strain C2-1 in our lab, are determined. The full-length organphosphorus hydrolase gene ophc2 is cloned by PCR using the degenerate primers designed according to the sequences and future inverse PCR. The ophc2 gene is 975 bp long with G C content of 63%, comprising one open reading frame encoding a polypeptide of 324 amino acids with a molecular weight of 36 kD. The nucleotide sequence of ophc2 shows low homologies with those organphosphorus hydrolase genes deposited in GenBank, one of which exhibits the highest homology of 46.4% with ophc2. The organphosphorus hydrolase protein expressed in E. coli bears normal bioactivity.     

Long-chain alkenones in sulfate lakes and its paleoclimatic implications

Long-chain alkenones are ubiquitous in marinesediments. The relationship between alkenone unsatura-tion and temperature has been proved by field studies andcultures of E. huxleyi[1] and G. oceanica[2]. As an idealproxy for sea surface paleotemperature estimation, theU37 index is widely applied to reconstructing paleotem- K 'perature in most oceanographic settings[3—10]. The suc-cessful progresses in the ocean invoked the researchers’attention to the study of LCAs in the liminic system.Cr…     

桔子砂囊悬浮果蔬天然饮料的研制

本文运用正交试验设计的方法,对桔子砂囊悬浮果蔬饮料的悬浮技术进行了研究,解决了悬浮技术难题,确定了本饮料的工艺流程和配方。     

不相交Steiner三元系组的齐次嵌入

本文讨论了不相交Steiner三元系组{X,A_i)|1≤i≤n}的齐次嵌入问题,并完整地解决了n=3时,不相交Steiner三元系组的齐次嵌入.     

一种自校正广义预测控制算法

本文运用自适应原理,在广义预测控制(GPC)算法的基础上,设计了一种自校正GPC算法。该算法具有计算量小,鲁棒性较强的特点。文未给出了仿真实例。     

离散群范数级数Σ｜g｜￣（－s）的收敛性

本文通过对双曲空间Ｈ￣（ｎ＋１）的一些性质的研究，运用双曲格，点定理得到了为上有限子群时ｃａｒｄ｛ｇ∈Ｇ：｜ｇ｜＜ｔ｝的估计式，并从此出发研究了级数收敛性。对的一般离散子群，运用另一方法解决了范数级数收敛性的问题。从而将Ａ．Ｆ．Ｂｅａｒｄｏｎ关于二维离散群的结果推广到了ｎ维Ｍｏｂｉｕｓ群