α－Al_2O_3衬底上生长的GaN膜的光学性质

采用金属有机化学气相淀积（ＭＯＣＶＤ）方法生长了α－Ａｌ２Ｏ３衬底上外延的高质量的单晶ＧａＮ薄膜。Ｘ射线衍射光谱与喇曼散射光谱表征了ＧａＮ外延薄膜的单晶结构和单晶质量。透射光谱和光调制反射光谱定出了六角单晶ＧａＮ薄膜的直接带隙宽度和光学参数。     

柴达木盆地北缘侏罗系烃源岩干酪根13C核磁共振研究

柴达木盆地北缘是柴达木盆地三大油气区之一,其源岩为早、中侏罗世煤系地层.烃源岩有机质类型以Ⅲ₁型和Ⅱ型干酪根为主,Ⅰ₂型干酪根仅在局部地区有分布.通过对柴达木盆地北缘侏罗系烃源岩中不同类型干酪根的¹³C核磁共振研究,指出了研究区Ⅰ₂、Ⅱ、Ⅲ₁型干酪根的化学结构特征以及化学结构中“芳构碳”、“油潜力碳”与“气潜力碳”的相对含量,据此从定量分析的角度对不同类型干酪根的生油气贡献作了评价.Ⅰ₂、Ⅱ、Ⅲ₁型干酪根的生烃能力依次减弱,对生油的贡献也依次减弱,且生成油气的比例不同,Ⅰ₂、Ⅱ型干酪根以生油为主,Ⅲ₁型干酪根则以生气为主.     

Use of chemical variation and predation as plant defenses byEncelia farinosa against a specialist herbivore

Larvae of the monophagous herbivore,Trirhabda geminata, selectively eat particular plants and plant parts of its natural host,Encelia farinosa. Measurements of leaf damage and larval positions on branches through time support this observation. Time-lapse movie photography revealed that larvae are sufficiently mobile to search most of a plant in a 48-hr period and that aggregations were the result of larval activity and not directly the result of oviposition. Experiments withT. geminata larvae on artificial diets containing a range of natural concentrations of chemical extracts fromE. farinosa leaves showed that the larvae grew significantly slower and had a lower overall survivorship at the high concentration. Combining the results of all choice tests, larvae appeared unable to distinguish between high- and low-concentration agar diets. Considered individually, larval preferences for natural production concentrations changed as the season progressed. Early-season larvae preferred low-concentration leaves, while late-season larvae preferred high-concentrations. Measurements of chemical and nitrogen content of leaves selected by larvae in the field confirmed this pattern. Percent parasitism in field-collected larvae increased with season as the larval population decreased. This combination of slowed growth and increasing parasitism and predation is a putative defense strategy ofEncelia farinosa to prevent adaptation by a specialist herbivore to the total range of compounds elaborated.     

铂与氢、水和苯分子相互作用的量子化学研究

采用量子化学程序Gaussian98(A.9)从头算的B3LYP方法，全优化计算铂对氢、水和苯的化学吸附作用，得到了3种相关络合物PtX、PtXX和Ptxxx(X=H，H2O或C6H6)的平衡几何构型和电子结构信息，并探讨了这些络合物的成键性质，以及苯环与铂原子之间的分子轨道作用性质。结果表明，苯环与铂原子之间有很强的成键作用，并随着游离氢原子和水分子的参与，作用强度有很大变化。苯分子吸附在金属铂上，它的芳香性得到不同程度的降低，苯环被活化，苯环与铂原子之间形成η^2型π键络合物；水参与作用后，苯环与铂原子之间形成σ络合物；氢和水同时参与作用后，苯环与铂原子之间仅有很弱的π轨道作用。     

烧结钕铁硼永磁体的镍及镍磷合金镀层

综述了钕铁硼永磁体材料的表面电镀镍及化学镀镍磷合金的研究进展，提出了从铵铁硼材料的特殊性来选择恰当的前处理和镀覆工艺，就有获得优质的保护镀层。     

埃及Ain Sukhna Ezz带钢厂的电弧炉

埃及Ain Sukhna Ezz带钢厂的电弧炉是达涅利公司建造的最大的电弧炉之一,由于可选用多种入炉原料,采用最优化熔炼和精炼方法,可在电弧炉上以转炉生产成本生产转炉优质钢种.     

Electron microscope studies of InxGav1−xAs/GaAs/Si grown by metalorganic chemical vapor deposition

The microstructure of In_xGa_1−xAs/GaAs (5 nm/5 nm, x < 0 to 1.0), as grown by a metalorganic chemical vapor deposition two-step growth technique on Si(100) at 450‡C, and subsequently annealed at 750‡C, is investigated using plan-view and cross-sectional transmission electron microscopy. The variations in resultant island morphology and strain as a function of the In content were examined through the comparison of the misfit dislocation arrays and moirés observed. The results are discussed in relation to the ways in which the island relaxation process changes for high In content.     

Defensive allomones in three species ofHypselodoris (gastropoda: Nudibranchia) from the Cantabrian sea

ThreeHypselodoris species,H. villafranca, H. cantabrica, and H. tricolor, have been studied in order to further investigate the defensive strategies of Chromodorididae mollusks from Iberian coasts. All animals possess large amounts of furanosesquiterpenoids, probably derived from their diet of sponges. The products are transferred and stored in specific sites of the mantle (mantle dermal formations, MDFs) to be used as chemical deterrents against predators. Chemical analysis of CantabrianHypselodoris species has led to the characterization of eight sesquiterpenoids. Among these, six have been found previously in both sponges and nudibranchs, while two are new natural products.Hypselodoris species cooccurring in the same area contained comparable mixtures of sesquiterpenoids. However, two populations ofH. cantabrica from different sites of the Cantabrian sea showed different metabolic patterns. All sesquiterpenoids induce feeding deterrence inCarassius auratus and two are also toxic toGambusia affinis.     

流程模拟中分解与切断的计算机处理方法探讨

探讨在化工过程模拟计算中对大系统分解及排出单元模拟优先顺序，找出切断流的最佳切断位置的一种新方法。     

石化行业自动化控制仪表常见故障分析及其处理

介绍化工生产过程中仪表故障及其处理措施。