东北地区粮食可持续生产能力分异特征及其空间类型

以东北地区110个商品粮基地县为例,构建粮食可持续生产能力评价指标体系,运用因子分析法对其进行综合评价和分析,并依据Q型聚类结果划分强可持续生产能力型、较强可持续生产能力型、较弱可持续生产能力型、弱可持续生产能力型和极弱可持续生产能力型5种空间类型。为促进区域粮食综合生产能力提高提供较为科学的依据。图1,表3,参7。     

Application of mesoscale modeling optimization to development of advanced materials

The rapid development of computer modeling in recent years offers opportunities for materials preparation in a more economic and efficient way. In the present paper, a practicable route for research and development of advanced materials by applying the visual and quantitative modeling technique on the mesoscale is introduced. A 3D simulation model is developed to describe the microstructure evolution during the whole process of deformation, recrystallization and grain growth in a material containing particles. In the light of simulation optimization, the long-term stabilized fine grain structures ideal for high-temperature applications are designed and produced. In addition, the feasibility, reliability and prospects of material development based on mesoscale modeling are discussed.     

加食盐燃烧提高石灰活性的机理研究

采用扫描电子显微镜（ＳＥＭ５０５）观察ＣａＯ晶体结构变化，电子探针测定其成分．发现了加食盐煅烧能够大幅度地提高石灰活性度的原因．这是因为被蒸发的ＮａＣｌ离子扩散渗入ＣａＯ晶体中，使其晶粒结构发生变化，以及晶粒间的气孔率增加，气孔长、定增大的缘故．     

DNA in wheat seeds from European archaeological sites

We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.     

并行遗传算法的新进展

并行遗传算法将并行计算机的高速并行性和遗传算法固有的并行性相结合 ,极大地提升了遗传算法的求解速度和质量 .在主从式、细粒度和粗粒度这三类遗传算法并行化模型中 ,粗粒度模型以其较小的通讯开销和对种群多样化 ,获得了最广泛的应用 .本文概括了基于模式定理和有限状态马尔可夫链的遗传算法理论 ,总结了前人在粗粒度模型下开展的理论分析和实践应用 ,并指出并行遗传算法的研究将向异步化 ,理论化和模型化的方向发展 ,而有限状态马尔可夫链是构建并行遗传算法可执行模型的有力工具.     

黄化大麦的系列研究——Ⅺ南黄大麦的穗部性状

补充报道了南黄大麦的穗部性状,南黄大麦穗的全长、芒长部比原品种长,而穗轴较短,穗粒数少,籽粒不饱满,千粒重轻,产量不高。其原因与叶缘体结构异常有关.     

Al晶界中Ti杂质效应的第一性原理计算

基于局域密度泛函理论,对AlΣ9倾侧晶界中掺杂Ti后超晶胞原子和电子结构的变化用第一性原理的赝势方法进行了模拟计算,进而研究了Ti偏析对Al晶界的影响。计算结果表明,与纯Al晶界相比,引入杂质Ti后,超晶胞的晶界略有膨胀,晶界处的电子密度明显增加,Ti原子与Al原子间形成了较强的具有共价—金属混合性质的化学键,其脆化机制可归于"bond mobility model"。     

铬对铌微合金钢显微组织和热塑性的影响分析

It is well-known that the surface quality of the niobium microalloy profiled billet directly affects the comprehensive mechanical properties of the H-beam. The effects of chromium on the γ/α phase transformation and high-temperature mechanical properties of Nb-microalloyed steel were studied by Gleeble tensile and high-temperature in-situ observation experiments. Results indicated that the starting temperature of the γ→α phase transformation decreases with increasing Cr content. The hot ductility of Nb-microalloyed steel is improved by adding 0.12wt% Cr. Chromium atoms inhibit the diffusion of carbon atoms, which reduces the thickness of grain boundary ferrite. The number fractions of high-angle grain boundaries increase with increasing chromium content. In particular, the proportion is up to 48.7% when the Cr content is 0.12wt%. The high-angle grain boundaries hinder the crack propagation and improve the ductility of Nb-microalloyed steel.     

硼在奥氏体晶界的两种偏聚形式

用PTA方法研究了Fe-30％Ni合金中硼在晶界的偏聚行为。实验表明在550-1200℃保温后用不同方式冷却的试样中存在平衡与非平衡两类硼偏聚,它们各自的形成机制不同,试验条件对它们的影响不同。平衡偏聚在保温时形成,在低温区淬火时起主要作用。在高温加热后,用通常冷却速度淬火时,晶界偏聚主要来源于冷却过程中产生的非平衡偏聚,实际瘁火试样中观察到的硼偏聚是这两类偏聚的叠加。试验指出,Fe-30％Ni合金中偏聚方式有一个转折温度区,这温度受冷却速度影响,在通常冷却速度下,这个转折温度在650～750℃之间。     

PP/CaCO3复合体系力学性能研究

改变CaCO3含量、CaCO3种类、偶联剂用量、CaCO3与滑石粉的配比等，对PP／CaCO3复合材料力学性能进行了研究与分析。结果表明：CaCO3用量、种类及滑石粉和偶联剂用量均对体系力学性能有影响。