同位旋非对称核物质性质与扩展的BHF方法(Ⅴ)三体核力对质子和中子单粒子势的影响

在扩展的同位旋相关的Brueckner Hartree Fock理论框架内 ,研究了三体核力对同位旋非对称核物质中质子与中子的单粒子势及其同位旋依赖性的影响 .

Ba同位素的截面测量

用 60MeV/u18O离子轰击天然铀靶 ,通过2 38U( 18O ,X)反应产生钡的放射性同位素 .使用放射化学分离方法从被照射过的铀靶中分离出Ba ,用HPGeγ射线探测器测量Ba样品的γ射线谱 ,经对所得时间累计谱的处理和分析得到了Ba同位素的产生截面 ,并观察到Ba同位素分布中的双峰分布现象 .

基于ImIQMD模型对准裂变和核子集团的研究

本文基于改进的同位旋相关的量子分子动力学(ImIQMD)[1]模型对于反应系统48Ca+208Pb准裂变机制进行了研究。通过计算俘获截面、准裂变碎片质量分布等，并与实验结果进行了比较，我们认为ImIQMD模型对低能重系统准裂变反应的描述基本是合理的。 并合模型是判定碎片的经典模型，但是应用这个模型来判定核子集团会遇到一些困难，因为碎片之间往往相互离得较远，而核子集团之间相互距离相比之下很近。本文第四章对此给出了详细的讨论，提出了对原算法的改进，以及新的算法。 微观动力学模型的发展使得我们可以更细致地了解物理过程之中核子的运动，但是对于重系统而言，直接在核子尺度上来讨论具体的物理问题是十分繁杂的，因为不但核子数众多，而且核子间还存在强烈的相互作用。在这种情况下，根据研究需要定义核子集团的判定标准，而后得到核子集团分布，不但可以使“新的组成”数目减少，而且相互之间的作用强度也会下降，这就降低了处理的繁杂程度，并且与实验现象可以更接近。本文在第四章之中基于这个思想讨论了一些问题

黄土丘陵区次降雨下的山坡道路侵蚀特征分析

黄土丘陵区是水土流失治理的重点区,由于大规模以植被恢复重建的生态建设和以石油资源开发引起的山区道路建设对本地区侵蚀环境和侵蚀动力机制产生了巨大影响,坡面水土流失与道路水土流失对比发生了新变化,在坡面侵蚀得到初步治理的新环境下,水土流失源于道路侵蚀则上升为主要地位。本文分析了2005年7月2日次降雨引起的支道山路(植物路)、干道山路、石油运输道路和农林草地小区、小支沟的径流、泥沙系统监测结果,提出在本次降雨条件下,三类道路的产沙强度分别为:支道山路500 t.km-2、干道山路3163 t.km-2和运油道路13500 t.km-2,而农林草地下垫面的产沙强度则仅为:5.68~184.38 t.km-2,道路产沙强度远大于农林草地的产沙强度,道路产沙量占流域总产沙量的42%。而灌草地侵蚀产沙仅占流域的26.7%。进而提出黄土高原丘陵区水土流失治理应该重点放在道路防蚀的观点,成果有助于社会主义新农村建设。

黄土高原典型土壤剖面土壤颗粒组成分形特征

采集从北向南依次分布的干润砂质新成土(神木)、黄土正常新成土(延安)和土垫旱耕人为土(杨陵)等典型土壤剖面0～200cm土层土样,通过测定土样颗粒体积分形维数及基本性质,以期阐明黄土高原典型土壤颗粒体积分形特征及其与土壤基本性质间的相关性。结果表明,从南到北,土壤颗粒体积分形维数呈下降趋势,而不同土层土壤颗粒体积分形维数差异不显著。土垫旱耕人为土、黄土正常新成土和干润砂质新成土表层(0～10cm)颗粒体积分形维数分别为2.723±0.024、2.609±0.077和2.589±0.025,表层以下(10～200cm)颗粒平均体积分形维数分别为2.729±0.034、2.584±0.054和2.558±0.034;颗粒体积分形维数与<0.01mm的物理性黏粒及<0.002mm的黏粒体积百分含量呈极显著正相关关系,与0.002～0.05mm的粉粒和>0.05mm的砂粒体积百分含量呈极显著负相关关系,与粉粒的显著性较小,而土壤中物理性黏粒体积百分含量与土壤全氮、有机碳及矿物固定态铵均达到极显著正相关关系,而砂粒体积百分含量与上述土壤基本性质均呈极显著负相关关系。

油松水源保护林人工诱导更新与定向恢复机理

以油松水源保护林为对象,进行人工诱导更新与定向恢复机理研究。结果表明,在郁闭林分内油松更新苗密度平均为5 375株.hm-2,更新苗年龄为1~2年,而在人工Gap“效应岛”样地内,更新苗密度平均为17 062.5株.hm-2,其中1~2年、3~4年、5~6年生更新苗分别占73.44%,13.97%和12.59%;生长季光照强度在0、1.5和2.0 m三个不同高度梯度上,在Gap内部的平均值分别为289.0×100、542.0×100和589.0×100 lux,在对照林分内分别为139.0×100、146.0×100和246.0×100lux;从夏季观测到的空气温度平均值日变化分析,在白天Gap内的温度高于郁闭林分内部,温差可差2~3℃,在夜间Gap内的温度低于郁闭林分内,温差可差0.5~1℃;在白天6:00~11:00,人工Gap“效应岛”内空气湿度明显低于郁闭林分内,在其它时间段大致相当;对于同一层次土壤而言,Gap内的土壤温度明显高于郁闭林分内且变化幅度大,在0、10和20 cm三个梯度上Gap与郁闭林分相比土壤温度最大差值分别可达10、5和2℃;0~10、10~20和20~30 cm三个层次平均土壤含水量在Gap内分别为16.9%1、5.1%和12.3%,在郁闭林分内分别为14.6%、12.5%和9.9%。总体上比较二者的光照强度、空气温度、空气湿度、土壤温度、土壤水分等有显著差异,因此人工Gap“效应岛”的创建是诱导其内部微环境因子变化的基础,也是油松水源保护林定向恢复更新的机理之所在。

玉米施用长效肥料增产效果研究

长效肥料具有肥效期长、肥料利用率高、提高产量等优点。同时,长效肥料用于基施可免去追肥工序,省工省力,增加效益。本文通过玉米施用长效肥料,探索对玉米的增产效果。试验结果表明玉米施用长效肥料可增加玉米产量7.28%～11.44%,增加产值589～817元/hm2,增产增收效果明显,具有广泛的应用价值。

Synthesis and fluorescent property of NH4Y1.9Eu0.1F7 nanoparticles with the temperature effect on the morphology

Sphere NH4Y1.9Eu0.1F7 nanoparticles were successfully synthesized by a hydrothermal method at 180 degrees C for 10 h. SEM and TEM images show the particles are spheres and have lots of hollows in them. The mean particle size is about 60 nm. The shape and size of the particles can be controlled by changing temperature and time of reactants. The luminescent property of the sample indicates that strong emission peaks of the Eu3+ ions are located at about 589 and 612 mm.

Syntheses, structures, and magnetic properties of two novel three-dimensional frameworks built from M4O4 cubanes and dicyanamide bridges

Two novel coordination polymers Ni-4(CH3O)(4)(CH3OH)(4)(dca)(4) (1) and Co-4(CH3O)(4)(CH3OH)(4)(dca)(4) (2) have been synthesized by solvethermal reaction. X-ray single-crystal analysis reveals that the two complexes are isostrutural and possess 3D frameworks that are built from the M4O4(M= Ni (1) and Co (2)) cubanelike building blocks linked by dicyanamide (dca) bridges. The temperature dependence of the magnetic susceptibility was measured and the DC experiment data were fitted using the Heisenberg spin Hamiltonian.

Preparation of KMgF3 and Eu-doped KMgF3 nanocrystals in water-in-oil microemulsions

In this study, KMgF3:Eu2+ luminescent nanocrystals (NCs) were prepared in water/cetyltrimethylammonium bromide (CTAB)/2-octanol microemulsions. The KMgF3:Eu2+ NCs were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), fluorescence spectrum, infrared spectroscopy (IR) and elementary analysis. The results showed that the size of the KMgF3:Eu2+ NCs was hardly affected by water content and surfactant (CTAB) concentration. The emission spectrum showed that the position of the 362 nm peak is due to the K+ sites substituted Eu2+. Two emission peaks located at 589 and 612 nm can be attributed to Eu3+, which exist at two different types of Eu3+ centers: one is Eu3+ at a K+ site, the other is clustering of Eu3+ ions in the interstices of KMgF3 host lattice.

The relationship between the thermal expansions and structures of ABO(4) oxides

The linear thermal expansion coefficients of ABO(4) compounds are determined and the expansion tendency is analyzed from the chemical bond viewpoint. All chemical bonds contributions are involved. The contributions from different chemical bonds are compared with each other and the origin of the expansion behavior of ABO(4) oxides is revealed that the A-O bonds expansions dominate the compound expansion. The calculated expansion coefficients agree satisfactorily with the experimental data. By analyzing the expansion regularity the range of the expansion coefficients can be qualified. The thermal expansion coefficients of some ABO(4) compounds having not been measured are predicted and discussed.

Miscibility, crystallization and mechanical properties of PPC/PBS blends

In this paper, melt blends of poly(propylene carbonate) (PPC) with poly(butylene succinate) (PBS) were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), tensile testing, wide-angle X-ray diffraction (WAXD), polarized optical microscopy and thermogravimetric analysis (TGA). The results indicated that the glass transition temperature of PPC in the 90/10 PPC/PBS blend was decreased by about 11 K comparing with that of pure PPC. The presence of 10% PBS was partially miscible with PPC. The 90/10 PPC/PBS blend had better impact and tensile strength than those of the other PPC/PBS blends. The glass transition temperature of PPC in the 80/20, 70/30, and 60/40 PPC/PBS blends was improved by about 4.9 K, 4.2 K, and 13 K comparing with that of pure PPC, respectively; which indicated the immiscibility between PPC and PBS. The DSC results indicated that the crystallization of PBS became more difficult when the PPC content increased. The matrix of PPC hindered the crystallization process of PBS. While the content of PBS was above 20%, significant crystallization-induced phase separation was observed by polarized optical microscopy. It was found from the WAXD analysis that the crystal structure of PBS did not change, and the degree of crystallinity increased with increasing PBS content in the PPC/PBS blends.