掺杂对纳米ZnO粉末晶粒度和结构的影响

研究了用化学共沉淀方法分别制备的掺杂Bi,Sb,Co,Cr,Mn和多元掺杂对纳米ZnO粉末晶粒度和相结构的影响,发现经500℃／h热处理后,掺Bi,Mn,Co和Cr的粉末晶粒度没有明显变化,而掺Sb的ZnO粉末晶粒度随Sb含量的增加而减小;掺Bi的粉末除主晶相ZnO外还有BiOCl相,掺Sb的粉末有主晶相和尖晶石相,所掺Mn,Co,Cr均固溶于主晶相ZnO;多元掺杂晶粒度均为30nm,相为主晶相和尖晶石相。     

Lasing on pyroclastic rocks: A case study of <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating on Moshishan Group,eastern Zhejiang Province

It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. ^40Ar/^39gAr incremental heating results on groundmass selected from the samples show that the age spectra are meaningless geologically. However, singe crystal total fusions of CO2 lasing on the sanidine separates could yield rational 4^40Ar/^39Ar results and distinguish their sources in this study. Timing on three formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this paper. The lowermost portion of the Chawan Formation gives an age of 113.7±0.3 Ma; the lower part of the Xishantou Formation was formed 116.4±0.4 Ma ago and the bottom of the Gaowu Formation took its shape at 118.4±0.4 Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations.     

低频电磁铸造过程中温度场的形成机理

通过理论解析研究了电磁场引起铸造过程中温度场改变的原因,并通过在铸造过程中连续测温的方法进行了实验验证.结果表明,低频电磁铸造对温度场产生影响的主要原因是低频电磁场引起熔体强制对流.强制对流对熔体产生强烈的搅拌作用,促进了熔体内部的热交换,加强了熔体与结晶器壁(石墨环)以及熔体和固液界面的传热,使熔体温度场非常均匀,接近于同一温度.研究还发现,低频电磁铸造过程对浇注温度不敏感,改变浇注温度,结晶器内熔体温度变化不大.     

南阳粮食总产量的灰色预测研究

通过南阳市粮食总产量摆动序列的综合信息,应用灰色理论建立了粮食生产的DGM(2,1)参数优化数学模型,经比较,预测模型结果明显优于常规的DGM(2,1)模型,进一步提高了该模型的预测精度和适用性.应用模型对南阳未来几年的粮食总产量作出预测,为有关部门制定合理的经济政策提供理论依据.     

反向凝固过程中铸带厚度及晶粒度的预测

基于人工神经网络建立了反向凝固过程中的性质预测模型，实现了对铸带厚度和新相层晶粒度的全面预测；探讨了凝固过程中的主要工艺参数对上述性能的综合影响。为反向凝固性能的综合预测提供了简便的新手段。     

车站计算机联锁设备抗扰度检测的研究

考虑到铁路信号设备抗干扰的特殊性 ,在对铁路现场电气化铁道干扰及设备有关数据进行理论分析的基础上 ,提出了计算机联锁设备在电源谐波、共地阻抗耦合、输入和输出电路耦合、数据通信方面的抗扰度检测项目和等级要求 .同时提出了测试方法 ,以评估受试设备的抗干扰性能 .     

建设优质专用小麦商品粮生产基地之浅见

分析了闻喜县优质专用小麦生产中存在的问题，提出只有通过进行管理机制的创新、采取切实可行的措施解决生产中的实际问题，才能建设好全国优质专用小麦商品粮生产基地。     

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。     

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.