栉孔扇贝×虾夷扇贝子一代杂种优势的RAPD分析

应用RAPD技术对栉孔扇贝×虾夷扇贝子一代的杂种优势进行了研究,对栉孔扇贝(C)、虾夷扇贝(P)及其正交F1(C♀×P♂)、反交F1(P♀×C♂)共4个群体的RAPD扩增带谱进行了分析。从40个随机引物中筛选出16个扩增带丰富的引物进行扩增,共得到l15条清晰稳定的扩增带,扩增片段大小在200～2000bp之间,其中有82个扩增位点具有多态性,多态性位点比率为71.3%。栉孔扇贝与正反交子代的相对遗传距离分别为0.0852和0.2886;虾夷扇贝与正反交子代的相对遗传距离分别为0.2327和0.0559,杂种子代与两亲本的遗传差异不是对等的,而是偏向各自的母本,系统树、Shannon多样性指数同样证明了这一点。两亲本群体内相似性指数分别为0.8392和0.8451,均大于正交子代的群体内相似性指数,而小于反交子代的群体内相似性指数,表明正交子代群体的遗传多样性水平升高,产生杂种优势;反交降低,未产生明显的杂种优势,与4个群体Shannon遗传多样性指数计算分析结果一致。     

栉孔扇贝和虾夷扇贝杂交子代的细胞遗传学研究

采用基因组荧光原位杂交(GISH)技术,结合改进的染色体滴片和压片法,对栉孔扇贝和虾夷扇贝远缘杂交正、反交子代4-8细胞胚胎及担轮幼虫的染色体构成及其变异进行了研究.结果表明,在染色体数目上,绝大部分正、反交子代早期胚胎的染色体数目为38条,与其双亲一致; 在染色体构成上,绝大部分正、反交子代分别继承了栉孔扇贝和虾夷扇贝各一套染色体,为真正的杂交种,核型也为双亲染色体核型的综合:2n=6m 29(sm,st) 3t;正、反交子代之间在染色体构成上无明显差别,结果说明两种扇贝的属间杂交正反方向均能产生正常的杂交种胚胎,合子中两套染色体具有较强的亲合性.此外,杂交子代在胚胎发育早期还存在较小比例的染色体数目异常、不对称染色体继承等遗传学现象.在群体杂交所产生的正反交子代中还存在极小比例的疑为雌核发育的母本类型个体,但在单对杂交产生的正反交子代中均未见雌核发育的个体.本文就这些异常现象产生的可能原因进行了探讨.     

人工诱导点带石斑鱼性逆转的组织学证据及其机制探讨

对外源混合激素药条肌体埋植法诱导点带石斑鱼提早性逆转的发育过程进行了组织学观察，结果表明：(1)3-5龄的雌鱼能在50-70天内转变为功能性雄鱼，年龄较小的雌鱼性转时间相对长些。(2)性转雄鱼精巢组织的雄性生殖细胞包括：精原细胞、初级精母细胞、精子细胞和精子，精子头部呈球型直径约1．5-2．5μm．尾长12．4-44．5μm，与天然雄鱼相似。(3)人工诱导性转雄鱼可取代天然雄鱼进行人工繁殖。(4)点带石斑鱼的性逆转机制为性类固醇依赖型。外源雄性激素通过抑制“雌性相关基因”的表达，而成为石斑鱼性逆转的启动因子，诱发卵巢退化和精巢的发育，直至精子生成。     

纳米TiO2光催化材料及其应用于环境保护的研究进展

讨论了纳米TiO2光催化材料降解污染物的机理及几种主要降解方式,综述了纳米TiO2光催化材料在环境保护领域中的应用等方面的研究进展,展望了纳米TiO2光催化材料的发展方向和应用前景。     

工人冒险作业时的内在心理结构研究

采用逆转理论及访谈方法，研究发现：煤矿工人在冒险作业时，其内在的心理结构深受文化程度、事故记录的影响。一般来说，文化程度高、非事故组的煤矿工人大都倾向于具有正面的元动机特征（ 内在心理结构） ，如唤醒回避、超前计划、尝试完成活动、服从规章制度及关心他人等，而工龄、工种、用工形式及年龄却很少发生影响     

The effect of the additional biasing on the switching process in pseudo spin-valve structure

The magnetization reversal of the free layer was studied in a pseudo spin-valve Gd-Co/Cu/Co structure prepared by thermal evaporation. The uniaxial magnetic anisotropy in a plane of the film was induced by applying the magnetic field during deposition. The angular dependence of the free Co layer coercivity was observed to be consistent with the Stoner-Wohlfarth rotation model. The switching field of this Co layer was found to be dependent on an additional constant magnetic field, oriented perpendicular to the anisotropy axis in a plane of the multilayered structure. This dependence confirms the possibility of additional regulations of the sensitivity of the spin-valve structure by the application of an appropriate bias field and could be useful for sensor applications.     

Evaluating Relationship of Consistency Ratio and Number of Alternatives on Rank Reversal in the AHP

This article shows the simulation result of the rank reversal phenomenon with respect to the changing values of consistency ratio and the number of alternatives. The simulation result reveals that the number of alternatives and the consistency ratio have significant effect on the occurrence of rank reversal. The more the number of alternatives is, the higher the probability of rank reversal occurrence becomes. The more inconsistent the judgment is, the more likely the rank reversal will occur. This result is based on two-way analysis of variance in which the number of alternatives and the consistency ratio are considered as factors, and the probability of rank reversal occurrence is regarded as the response variable. The number of alternatives of 4 to 7 and the consistency ratios ranging between 0.02 and 0.20 are investigated. The observation is based on the rank reversal that occurs after adding a copy of the best existing alternative.     

Studies on the in vitro and in vivo degradation behavior of amino acid derivative-based organogels

The in vitro degradation behavior of organogel with different gelators based on amino acid was investigated in detail. Two methods were applied in this research: weighting method and high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) method, which was established for the first time. Their degradation behaviors in vivo were investigated by varying the kind and concentration of gelators via subcutaneous implantation. The results showed that the stronger the gelation ability or the higher the gelator concentration, the slower the degradation rate of organogel. Moreover, the organogel prepared by oils with longer alkyl length degraded slower than that of the shorter ones, which also decreased in thermal stability and mechanical strength. The investigation on degradation process showed that the degradation rate was mainly controlled by the collapse of network structure formed by gelators. In conclusion, organogel had a tunable degradation rate through altering the gelator type, oil type and the gelator concentration. It remains a promising candidate for subcutaneous in-situ implant as drug delivery vehicle.     

基于纵向超声导波管道非通透缺陷检测研究

管道经过长期服役后,由于磨损、腐蚀和意外损伤等原因,对管道正常运行产生危害。在实际工况中,小的腐蚀缺陷容易发展成腐蚀穿孔,浅层的小裂纹容易发展成穿透型裂纹,因此探究如何有效检测管道小宽度非通透缺陷是很有必要的。利用ANSYS有限元仿真软件模拟纵向模态导波对管道的周向和斜向非通透缺陷的检测,得到了周向非通透缺陷的反射系数曲线,并证实时间反转法可以显著提高导波对非通透斜裂纹的检测能力。还针对空管和充水管非通透斜裂纹的定位问题进行了研究,结果表明利用时间反转法可以得到缺陷较为精确的周向与轴向位置及大致形状。     

聚硫聚氨酯(脲)的热稳定性

对一系列聚硫聚氨酯(脲)的热降解进行了研究,由异佛尔酮二异氰酸酯(IPDI)、甲苯二异氰酸酯(TDI)、液体聚硫橡胶(LP)以及2,5-二氨基-3,6-二甲硫基甲苯(E300)合成聚硫聚氨酯脲,用TG、DTA、ATR-IR等研究其热降解性能。结果表明,聚硫聚氨酯(脲)的降解分两个阶段。在200℃条件下老化一段时间后,聚硫聚氨酯仍保持大部分力学性能。     

The influence of molybdenum on the degradation resistance of aluminized iron-nickel-base alloys in sulphidizing environments

Since Al₂O₃?forming nickel-and iron-nickel-base alloys are known to be more effective than Cr₂O₃?forming alloys in sulphur-containing gases, several commercial Cr₂O₃?forming alloys have been pack aluminized to establish aluminide coatings for use in mixed-gas environments of high sulphur and low oxygen activity. Results are given for long-term exposures (up to 2500 h) to H₂/1.6%H₂O/1.1%H₂S at 1000°C under thermal-cycling conditions. Uncoated specimens of such alloys are sulphidized completely in very short periods in this environment. Early work indicated that an aluminized molybdenum-containing nickel-base alloy is the most resistant system, so a series of alloys based on nickel and nickel-iron and incorporating various amounts of molybdenum was included in the tests. Most of the aluminized systems showed reasonable resistance for periods of 500 h or more. Subsequently, the protective Al₂O₃ scale broke down following back-diffusion of aluminium into the alloy substrate and depletion of the surface in this element, thereby enabling base metal sulphides to develop rather than the protective oxide to be maintained. The aluminized Inconel 625 system was the most effective, with failure not occurring until after 2000 h, while the corresponding Incoloy 825, Alloy 904L and PK33 systems showed good resistance for 1500 h. These alloys contain 3 to 9 wt% molybdenum and were more resistant than similar alloys containing none of this element. However, aluminized alloys incorporating higher molybdenum concentrations (such as Hastelloy S, Hastelloy B2 and Hastelloy C4) were not as resistant and failed in less than 1000 h. The structures of the various aluminized systems are presented and their performances in the mixed-gas environment are considered in relation to the structures and compositions of the base alloys.     

反应温度对聚苯胺薄膜生长的影响

在不同反应温度条件下采用原位聚合法在石英基片上制备了聚苯胺薄膜．对薄膜样品进行了紫外光谱、SEM、电性能表征。实验结果表明，过高的合成温度会加速聚合反应过程，抑制膜厚的增长，引起薄膜的热降解，进而对样品的导电性产生不良影响。根据生长速率与合成温度的依赖关系，估算了聚合反应的活化能Ea=34.4kJ/mol。