γ-Fe2O3/Ni2O3复合纳米微粒基二元磁性液体的制备及场致光透射特性

介绍了由强磁γ-Fe2O3/Ni2O3复合纳米微粒和弱磁Fe5O7(OH)·4H2O纳米微粒构成的二元磁性液体的制备方法,并用X射线衍射仪、透射电子显微镜、振动样品磁强计分别对这两种微粒的晶体结构、表面形貌及其磁性进行了表征.同时测量了单元磁性液体和二元磁性液体在平行于激光照射方向且具有不同梯度外磁场作用下场致光透射强度的弛豫变化,揭示了二元磁性液体有不同于单元磁性液体的特征弛豫时间,并从微观结构上分析了产生弛豫时间差异的原因.     

粗酶制剂对雏鹅消化器官发育的影响

选用１８只７日龄雏鹅,随机分成对照组和试验两组,饲以大麦（占４５％）基础日粮,试验组添加０．１％的Ｂｉｏｋｙｏｗａ粗酶制剂。实验期为７－２１日龄,２１日龄时宰杀,称量消化腺和消化道重量,并测定小肠食糜上清液的粘度。结果显示：与对照组相比较,试验组雏鹅胰腺和肝脏的相对重量较对照组分别轻３１．２５％（Ｐ〈０．０１）和９．７５％（Ｐ〈０．０５）,胃（肌胃＋腺胃）较对照组低１０．７９％（Ｐ〈０．０５）,十     

组培枣苗基因组DNA提取方法及其含量的比较

本文以组培二倍体木枣、四倍体变异苗和二倍体京枣苗为供试材料,采用琼脂糖凝胶电泳和紫外分光光度检测技术,研究了不同提取方法对其叶片基因组DNA的提取效果。结果表明,CTAB法提取枣叶片DNA的效果优于SDS法,表现为蛋白质杂质干扰少,DNA结构完整、纯度与得率高;用不同方法提取的样液中DNA片段的大小和分布是不同的,以改进的CTAB法提取的样液中大片段的DNA分子较多,所以在其底部分布较多,而用SDS法提取的样液中小片段的DNA分子较多,故在其上部分布较多;电泳时不同的加样量获得的DNA带也有较大差异,试验选出CTAB法提取样液的适宜的加样量为5μL（7.485μg）,SDS法提取样液的适宜的加样量为4μL（5.988μg）;枣品种间DNA的含量明显不同,木枣四倍体的DNA含量（3.074μg/μL）相当于组培木枣二倍体（1.497μg/μL）的2倍,也明显地高于京枣二倍体（2.182μg/μL）。这些结果为枣树遗传种质资源的研究奠定了一定的科学与技术基础。     

青海高原东部农业区建设用地扩张驱动力分析

利用土地利用现状调查与变更调查统计数据,结合历年统计年鉴的社会经济数据,分析了青海高原东部农业区1996-2005年建设用地扩张过程与特点,定量分析建设用地变化的驱动因素。研究结果表明：建设用地的外延扩张迅速,非农建设占用耕地的现象较为突出。各类社会经济驱动因素中,逐步上升的二三产业比重、不断增长的人口压力和城镇化水平...     

完善农村小额信用贷款体制促进广西农村经济发展

农村小额信用贷款对农村经济发展所起的作用越来越大,农村合作金融机构是农村小额信用贷款的主要经营者,但农村小额信用贷款具有金额小、户数多、风险大、管理成本高等弱点,使农村小额信用贷款经营者的经济效益低和承担的风险大.文章提出了拓宽支农资金来源、加快农村信用环境建设、建立支农贷款补偿机制和激励机制、加快推进涉农担保体系建设、积极推进涉农金融机构信贷管理方式创新和产品创新、提高农业产业化水平、降低农户经营风险等六项措施促进农村小额信用贷款体制建设.     

Spatial heterogeneity of soil water content in the reversion process of desertification in arid areas

Sandy soils in arid,rain-fed environments have low and limited water content,which is a principal factor limiting vegetation development,and a key constraint controlling the structure and functions of the ecological systems in arid areas.The spatial heterogeneity of soil water content is a major soil property,and a focus of soil science and hydrology.On the southern edge of the Tengger Desert,sample plots were selected from mobile sand dunes in desertified lands that had been enclosed for 5,15 and 25 years,respectively.This study explored the dynamic and spatial heterogeneity of soil water content in these different layers of soil that were also in the reversion process of desertification.The results showed that the soil water content of the mobile sand dunes was highest when in the initial stages of the reversion process of desertification,while the soil water content in the 0-20 cm,20-40 cm and 40-60 cm layers of soil was 1.769%,3.011%,and 2.967% respectively,presenting a restoring tendency after 25 years of enclosure.There were significant differences,as a whole,in the soil water content among different restoration stages and different soil layers,respectively.Changes in soil water content,in different soil layers,at different restoration stages,exhibited exponential or spherical patterns.The spatial distribution of soil water content exhibited a mosaic patch pattern with obvious spatial heterogeneity.The ratio of the heterogeneity of spatial autocorrelation to gross spatial heterogeneity was greater than 50%.The gross spatial heterogeneity of the 0-20 cm layer of soil improved gradually,while those of the 20-40 cm and 40-60 cm layers improved initially,then weakened in the reversion process of desertification.This study revealed that restoration with sand-binding vegetation reduced soil water content,and increased its spatial heterogeneity in arid areas.However,after 25 years of vegetation-soil system restoration,the soil water content started to increase and its spatial heterogeneity started to weaken.These results will further benefit the understanding of the ecological mechanism between soil water and sand-binding vegetation.     

The Characterization of Heavy Metals in the Grapevine (Vitis vinifera) Cultivar Rkatsiteli and Wild Blackberry (Rubus fruticosus) from East Serbia by ICP-OES and BAFs

Inductively coupled plasma optical emission spectroscopy, in combination with calculation of various biological factors, was used in this study not only for a simple illustration of the present status of some essential and non-essential metals such as copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As), and cadmium (Cd) in the grapevine cultivar Rkatsiteli and wild blackberry from East Serbia but also for the estimation of plant bioaccumulation potentials. Great majority of detected metal concentrations were in normal ranges except in few cases: Zn concentrations were at the level of deficiency in almost all plant parts, and some Cu and As concentrations were at the levels that could be considered phytotoxic. Biological accumulation factors provided very informative data on metal accumulation and translocation in both plants and pointed to low accumulation rates of metals except in the case of Cu, Zn, and As in some wild blackberry tissues.     

物理教学中研究性学习的探讨

文章结合物理学科的特点,提倡在物理教学中开展研究性学习,强调教师应指导学生适当选择研究性学习的内容,培养学生研究性学习的兴趣,进而提高学生的创新能力.