解决土地碎片化的制度框架设计

为解决土地碎片化问题,采用文献统计和比较分析等研究方法,在对土地碎片化现状、原因与问题分析的基础上,通过总结国内外实践经验,提出了解决土地碎片化的制度框架。研究结果表明,土地碎片化的产生既有自然原因也有制度原因,所带来的问题主要包括:1田埂面积多而导致的耕地资源浪费;2地界纠纷多而导致新技术新产品难以推广;3谈判成本高导致农地资源无法合理进行配置;4机械水平低导致劳动生产率、土地生产率和成本产值率也随之下降等。必须要通过明晰产权关系、构建市场平台、创建新型农业经营体系、推广"良田良种良法"等政策措施来逐步破解中国土地碎片化难题。     

牙鲆耐寒相关基因CIRP、HMGB1的克隆及表达特征分析

为鲆鲽鱼耐低温标记辅助育种研究和应用提供候选基因,并了解耐寒相关基因在低温下的表达图示,作者通过同源克隆以及5?/3?RACE的方法扩增得到了牙鲆(Paralichthys olivaceus)CIRP和HMGB1基因。组织表达谱分析显示,这两个基因在脑、鳃、心脏、肌肉、肝脏、肠等组织均有表达,但HMGB1基因在鳃中表达较弱。低温胁迫后,两基因随着胁迫时间的延长其表达量在肌肉中都出现先上升后下降的趋势:在0~12 h逐渐上升并达到最大值,然后下降恢复至最初水平。但在肝脏和脑组织中的变化趋势却不同,低温胁迫后0~2 h HMGB1基因在脑中的表达量上升至最高,然后下降至最初水平,在肝脏中变化不大。而CIRP基因在低温胁迫后0~2 h在肝脏中表达量处于上升趋势,然后下降至初始水平,在脑中变化不大。由此推测,这两个基因在低温条件下都参与了机体对外界的抵抗,特别是在抵抗外界寒冷的主要组织—肌肉中发挥作用,可能共同参与了机体的免疫反应,对低温胁迫环境下的鱼体进行保护,可以作为鱼类耐低温标记筛选的候选基因。     

高盐诱导太平洋牡蛎(Crassostrea gigas)三倍体的初步研究

初步探讨了利用高盐抑制受精卵第2极体(PB2)的释放的方法诱导太平洋牡蛎(Crassostrea gigas)三倍体。水温25℃条件下,分别进行不同高盐处理(盐度梯度为40、45、50、55、60、65、70、75、80)、不同处理时机(受精卵出现第一个PB1,30%和50%PB1,出现第一个PB2,50%PB2)和不同持续处理时间(10~25min)的实验,通过胚胎孵化率、三倍体诱导率及综合评价指数的分析表明,高盐诱导太平洋牡蛎三倍体的最适方案为:当50%受精卵出第一极体时,以盐度为65的高盐海水处理受精卵20min,三倍体诱导率最高达65.53%。     

Sulfate reducing bioreactor dependence on organic substrates for remediation of coal-generated acid mine drainage: Field experiments

Field experiments were conducted over a 460-day period to assess the efficiency of different mixtures of organic substrates to remediate coalmine-generated acid mine drainage (AMD). Five pilot-scale, flow-through bioreactors containing mixtures of herbaceous and woody organic substrates along with one control reactor containing only limestone were constructed at the Tab-Simco site and exposed to AMD in situ. Tab-Simco is an abandoned coal mine near Carbondale, Illinois that produces AMD with pH ∼2.5 and notably high average concentrations of SO₄ (5050 mg/L), Fe (950 mg/L), Al (200 mg/L), and Mn (44 mg/L). Results showed that the sequestration of SO₄ and metals was achieved in all reactors; however, the presence and type of organic carbon matrix impacted the overall system dynamics and the AMD remediation efficiency. All organic substrate-based reactors established communities of sulfate reducing microorganisms that contributed to enhanced removal of SO₄, Fe, and trace metals (i.e., Cu, Cd, Zn, Ni) via microbially-mediated reduction followed by precipitation of insoluble sulfides. Additional mechanisms of contaminant removal were active in all reactors and included Al- and Fe-rich phase precipitation and contaminant surface sorption on available organic and inorganic substrates. The organic substrate-based reactors removed more SO₄, Fe, and Al than the limestone-only control reactor, which achieved an average removal of ∼19 mol% SO₄, ∼49 mol% Fe, 36 mol% Al, and 2 mol% Mn. In the organic substrate-based reactors, increasing herbaceous content correlated with increased removal efficiency of SO₄ (26–35 mol%), Fe (36–62 mol%), Al (78–83 mol%), Mn (2–6 mol%), Ni (64–81 mol%), Zn (88–95 mol%), Cu (72–85 mol%), and Cd (90–92 mol%), while the diversity of the intrinsic microbial community remained relatively unchanged. The extrapolation of these results to the full-scale Tab-Simco treatment system indicated that, over the course of a 460-day period, the predominantly herbaceous bioreactors could remove up to 92,500 kg SO₄, 30,000 kg Fe, 8,950 kg Al, and 167 kg Mn, which represents a 18.3 wt%, 36.8 wt%, 4.1 wt% and 82.3 wt% increase in SO₄, Fe, Al, and Mn, respectively, removal efficiency compared to the predominantly ligneous bioreactors.The results imply that anaerobic organic substrate bioreactors are promising technologies for remediation of coal-generated AMD and that increasing herbaceous content in the organic substrate matrix can enhance contaminant sequestration. However, in order to improve the remediation capacity, future designs must optimize not only the organic carbon substrate but also include a pretreatment phase in which the bulk of dissolved Fe/Al-species are removed from the influent AMD prior to entering the bioreactor because of 1) seasonal variations in temperature and redox gradients could induce dissolution of the previously formed redox sensitive compounds, and 2) microbially-mediated sulfate reduction activity may be inhibited by the excessive precipitation of Al- and Fe-rich phases.     

Urban fluvial flood modelling using a two‐dimensional diffusion‐wave treatment,part 2: development of a sub‐grid‐scale treatment

This paper develops and tests a sub‐grid‐scale wetting and drying correction for use with two‐dimensional diffusion‐wave models of urban flood inundation. The method recognizes explicitly that representations of sub‐grid‐scale topography using roughness parameters will provide an inadequate representation of the effects of structural elements on the floodplain (e.g. buildings, walls), as such elements not only act as momentum sinks, but also have mass blockage effects. The latter may dominate, especially in structurally complex urban areas. The approach developed uses high‐resolution topographic data to develop explicit parameterization of sub‐grid‐scale topographic variability to represent both the volume of a grid cell that can be occupied by the flow and the effect of that variability upon the timing and direction of the lateral fluxes. This approach is found to give significantly better prediction of fluvial flood inundation in urban areas than traditional calibration of sub‐grid‐scale effects using Manning's n. In particular, it simultaneously reduces the need to use exceptionally high values of n to represent the effects of using a coarser mesh process representation and increases the sensitivity of model predictions to variation in n. Copyright © 2005 John Wiley & Sons, Ltd.     

干密度对击实黄土震陷性影响的试验研究

干密度是表征黄土地基振密、挤密处理后土体紧密程度的一个重要物理指标。本文通过对不同干密度的非饱和击实土样的震陷试验,研究了干密度对击实黄土震陷性的定量影响规律,建立了击实黄土的震陷曲线方程,得到了不同振次下干密度与震陷系数的定量关系。文中提出了由干密度算不同振次和任一动应力下击实黄土震陷系数的经验公式,并为黄土地基抗震陷处理初步提供了干密度波速、标贯和孔隙比等方面的标准。     

蒙脱石热处理产物的微结构变化研究

本文对广东和平蒙脱石及其热处理产物进行了化学分析、差热和热重分析、X射线粉末衍射分析、红外吸收光谱分析、扫描电镜、原子力显微镜及魔角旋转核磁共振等研究。结果表明,蒙脱石在热处理温度为126℃-148℃时,主要脱出吸附水和层间水,这一脱水过程是可逆的。当热处理温度达到659℃时,蒙脱石八面体片中的羟基开始脱失,但层状结构仍然保持,这种羟基的脱失过程对应着八面体片中Al^Ⅵ向Al^Ⅳ的转变。当温度达到900℃时,蒙脱石的层状结构完全被破坏,并有新的矿物相μ-堇青石产生。当温度为1200℃时,则出现方英石及莫来石相。当热处理温度达到1350℃时,方英石及莫来石的含量略有减少,并出现较多的含铁堇青石相。     

原子吸收分光光度法测定肉类样品中微量的铜铅锌镉

采用原子吸收法对肉类样品微量铜铅锌镉进行测定，重点对样品的前处理进行实验，拟订测试操作规程和仪器测量最佳条件，实验证明本法操作简便，准确快速，结果满意。     

STUDY ON EUTROPHICATION CONTROL FOR SOUTH LAKE IN CHANGCHUN

ＳＴＵＤＹＯＮＥＵＴＲＯＰＨＩＣＡＴＩＯＮＣＯＮＴＲＯＬＦＯＲＳＯＵＴＨＬＡＫＥ　ＩＮＣＨＡＮＧＣＨＵＮＷａｎｇＨａｉｊｕｎ（王海军）；ＷａｎｇＹｉ（王毅）；ＬｉｕＷｅｉ（刘伟）（ＤｅｐａｒｔｍｅｎｔｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅ，Ｎｏ...     

振冲碎石桩在地基处理中的应用

振冲碎石桩是近几年发展较快的软弱地基处理方法。通过对辽源污水处理厂A?/0反应池地基处理的应用,系统介绍了振冲碎石桩在施工过程中的机械及工艺流程。并就加固机理、施工方法以及实用效果几个方面进行了阐述。说明振冲碎石桩适用于松散砂土、粉土及淤泥质粉土地层,经过成孔、排污、清孔、填料、振密,最终控制成桩,可明显改善地基承载力,对软弱地基处理效果显著,具有一定的推广价值。