施肥、密度和除草对半湿润地区冬小麦生物产量和籽粒产量的影响

为给旱作小麦高产栽培提供依据,在半湿润农田系统下以土垫旱耕人为土为供试土壤,研究了施肥、除草及种植密度对冬小麦生物产量和籽粒产量的影响。结果表明,除草对小麦生物产量和籽粒产量影响不明显;种植密度和施肥极显著影响小麦生物产量和籽粒产量;正常密度(播量150.0 kg.ha-1)的生物产量和籽粒产量比低密度处理(播量90.0 kg.ha-1)分别高15.5%和9.1%。相比不施肥、单施氮肥和单施磷肥,氮磷配施具有较高的增产效应。在一定范围内,增加施氮量有助于提高小麦的生物产量和籽粒产量,过量施氮有降低生物产量和籽粒产量的趋势。综合来看,在正常种植密度、氮磷配施和135 kg.ha-1施氮量下,半湿润地区的冬小麦能获得较高的生物产量和籽粒产量。

水文研究中的一种微机制图方法

微机制图具有速度快、精度高等特点 ,成为各个领域研究人员实用的研究手段。在水文研究中 ,利用SURFER软件 ,将实测的水文要素散点值输入计算机 ,通过数据的网格化处理 ,即可生成不同需求的趋势图。可定性、定量、定位地反映水文要素的空间分布和变化特征 ,为水文要素规律的研究提供分析图件。

人工降雨条件下秸秆覆盖减少水土流失的效应研究

采用人工模拟降雨试验,研究秸秆不同用量对径流、入渗和土壤侵蚀的影响。结果表明:秸秆覆盖有增加入渗和减少水土流失的作用;覆盖率大于40%条件下能有效地控制水土流失,但当覆盖度低于40%时对控制水土流失的作用不明显。在土壤含水量10%,降雨强度120 mm/h的雨强条件下,秸秆覆盖能推迟起流时间1~15min,增加累积入渗量37%~113%,减少径流总量3%~40%,减少土壤侵蚀10%~80%。

沈阳地区水灾后“被淤”农田土壤肥力状况及改良途径

<正> 1 引言沈阳地区位于辽宁省中北部,属中温带受季风影响的半湿润大陆性气候。该地区地貌类型多样,东北和西南紧靠长白山余脉千山山脉,属低山丘陵,中西部是辽阔平原地貌由东北向西南倾斜。全地区有大小河流15余条,大部向西南的辽中、新民等地汇集再出境入海,上游是旱坡地,而且林地的森林覆盖率较低。1995年7～8月,沈阳地区连降大雨,达658.3mm,相当于27a的全年平均降雨量的总和,造成百年不遇的特大洪水,致使平原地区大片农田被淹达20d左右,面积达6.67×10~5hm~2。这次洪水源于天然降雨并汇集上游地区地表径流而形成的,水体混浊,悬浮物

应用ARDRA技术研究Frankia菌多样性

应用原核生物 16SrDNA特异性引物rD1和fD1,对分自 4个分类接种群的 12株纯培养Frankia菌总DNA进行扩增 ,得到 1条长约 15 0 0bp的扩增产物。选用 2种内切酶HinfI ,MspI对扩增产物进行酶切 ,得到稳定的酶切图谱。对图谱的分析结果表明 ,Frankia菌间存在极其丰富的遗传多样性

樟子松人工固沙林衰退的主要特征

针对辽宁省章古台地区樟子松人工固沙林出现的衰退枯死现象 ,系统地研究了樟子松人工固沙林衰退的主要特征 .结果表明 ,衰退的樟子松人工固沙林外貌景观呈灰绿色 ,针叶纤细 ,开花结实率低 ,平均单株球果数量为 10 4～ 16 5个 ,成熟种子千粒重为 6 96～ 7 39g ,种子空粒、涩粒较多 .生长季内 2年生针叶营养元素季节变化规律相似 ,但N、P含量下降 ,K含量明显增高 ,表明养分循环失调 ;衰退林分 2年生针叶叶绿素含量较高 ,健康林分 1年生较高且增幅较大 .松枯梢病的侵害是樟子松人工固沙林衰退的最明显标志 .林分衰退后 ,树高和胸径生长量下降明显 ,林分胸径分布结构“左移”(径级小的株数增多 ) ,衰弱 (亡 )木数量增加了 15 9%～ 2 7 2 % ;根量分别减少了 2 2 9%～ 2 8 9% ,其中吸收根减少量最大

资源流动的环境效应(英文)

21世纪,中国的人口和经济的持续增长面临着资源短缺和生态脆弱的限制。提高资源利用效率和消减资源利用引起的环境影响是学术界和决策者面临的新课题。本文从资源流动的视角研究资源利用过程及其引起的环境影响。我们把资源流动过程分解为开采、加工、转化、消费等几个关键环节,评价其资源利用效率和环境影响,并寻求改善的途径。因其资源消耗量大、生态环境影响严重,我们选取了林木、煤炭及石油研究其资源与产品流动及其环境影响。林木产品的产量、进出口量和消费量数据来自中国森林统计年鉴(1949-2001)。煤炭、石油的开采量、进出口

Application of rare earths in thermal barrier coating materials

Rare earths are a series of minerals with special properties that make them essential for applications including miniaturized electronics, computer hard disks, display panels, missile guidance, pollution controlling catalysts, H-2-storage and other advanced materials. The use of thermal barrier coatings (TBCs) has the potential to extend the working temperature and the life of a gas turbine by providing a layer of thermal insulation between the metallic substrate and the hot gas. Yttria (Y2O3), as one of the most important rare earth oxides, has already been used in the typical TBC material YSZ (yttria stabilized zirconia). In the development of the TBC materials, especially in the latest ten years, rare earths have been found to be more and more important. All the new candidates of TBC materials contain a large quantity of rare earths, such as R2Zr2O7 (R=La, Ce, Nd, Gd), CeO2-YSZ, RMeAl11O19 (R=La, Nd; Me=Mg, Ca, Sr) and LaPO4. The concept of double-ceramic-layer coatings based on the rare earth materials and YSZ is effective for the improvement of the thermal shock life of TBCs at high temperature.

Self-assembly of a water chain with tetrameric and decameric clusters in the channel of a mixed-valence (CuCuII)-Cu-I complex

The reaction of Cu(BF4)(2) with pyridine-2,6-dicarboxylic acid (H(2)pydc) and trans-1,2-bis(4-pyridyl)ethylene (bpe) under hydrothermal conditions afforded a porous mixed-valence (CuCuII)-Cu-I coordination polymer. Coexistence of tetrameric and decameric water clusters within the channels of the complex leads to a novel water chain. The metal-organic framework provides both hydrophilic and hydrophobic environments for stabilizing the clusters and retains its integrity upon dehydration and rehydration.

胆总管探查后内置可降解支架并行Ⅰ期缝合的研究

目的　探讨胆总管 (CBD)探查后内置可降解支架并行Ⅰ期缝合在动物实验中的可行性和临床应用价值。方法　用 160只Wistar大鼠模拟CBD探查术 ,将其随机分为两组 :Ⅰ期缝合组 (对照组 ) ,内置可降解支架后行Ⅰ期缝合组 (实验组 )。观察手术前后大鼠碱性磷酸酶 (ALP)、体重、CBD外径的变化 ;记录缝合时间和总手术时间 ;术后观察胆漏的发生率、支架降解情况 ,并取肝组织做病理学检查。结果　两组在缝合时间、总手术时间及胆漏的发生率上差异无显著性 (P >0 .0 5 ) ;术后第 5周时内支架完全降解 ;对照组术后ALP持续性增高 ,实验组术后ALP一过性增高 ;实验组术后体重较对照组明显增加 ;对照组术后CBD较实验组明显扩张 ;对照组术后肝损伤的发生率 (8/15 )显著高于实验组 (1/15 )。结论　CBD探查后内置可降解支架并行Ⅰ期缝合的方法在动物实验中是较为安全有效的。

Miniaturized tris(2,2 '-bipyridyl)ruthenium(II) electrochemiluminescence detection cell for capillary electrophoresis and flow injection analysis

The design and performance of a miniaturized chip-type tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] electrochemiluminescence (ECL) detection cell suitable for both capillary electrophoresis (CE) and flow injection (FI) analysis are described. The cell was fabricated from two pieces of glass (20 x 15 x 1.7 mm), and the 0.5-mm-diameter platinum disk was used as working electrode held at +1.15 V (vs silver wire quasi-reference), the stainless steel guide tubing as counter electrode, and the silver wire as quasi-reference electrode. The performance traits of the cell in both CE and FI modes were evaluated using tripropylamine, proline, and oxalate and compared favorably to those reported for CE and FI detection cells. The advantages of versatility, sensitivity, and accuracy make the device attractive for the routine analysis of amine-containing species or oxalate by CE and FI with Ru(bPY)(3)(2divided by) ECL detection.

Cyanex923萃取稀土(Ⅲ)的传质动力学

利用层流恒界面池 ,研究了在 (30 3± 0 .5 K)下纯化 Cyanex92 3-正庚烷 - Na NO3体系萃取 L a( )、Y( )和 Sm( )的传质动力学。考察了搅拌速度、温度及比界面积对萃取速率的影响。实验表明 ,在硝酸体系中 ,Cyanex92 3萃取 L a( )、Y( )和 Sm( )的正向表观活化能分别为 32 .0 k J· mol- 1、16 .4 k J· m ol- 1和 15 .1k J· m ol- 1 ,L a( )的萃取为混合控制过程 ,Y( )和 Sm( )萃取为扩散控制过程。实验还表明萃取过程的化学反应均发生在液 -液界面上。

Crystallization kinetics of narrow molecular weight distribution metallocene short-chain-branched polyethylene

Isothermal and non-isothermal crystallization kinetics of three metallocene-catalysed short-chain-branched polyethylene (SCBPE) fractions with different degree of branching were investigated by using differential scanning calorimetry (DSC). Narrow molecular weight fractions (M-w = 20,000 and M-w/M-n < 1.15) are used and the degree of branching (CH3 per 1000C) are 1.6, 10.4, 40 respectively. The regime I - II transition temperature are 119.8C, 115.9 degreesC, 113.3 degreesC with the decreasing of degree of branching. Increasing the branch content decreases the rate of secondary nucleation, i,relative to the rate of surface spreading and so increases the range of supercooling over which regime I exists. The rate of bulk crystallization for both isothermal and non-isothermal crystallization decreases with the increasing of degree of branching. Both Ozawa Equation and Kissinger Equation are invalid for non-isothermal crystallization kinetics of SCBPE fractions,that means the effects of the branched chain on crystallization process are more complex than expected.

Determination of propranolol by capillary electrophoresis with end-column amperometric detection

A capillary electrophoresis-amperometric detection system was developed for the determination of propranolol (PRO) at a 33 mu m carbon fiber microdisk electrode (CFE). The cyclic voltammogram, the hydrodynamic voltammograms and the effect of pH were studied. Under the optimum conditions: separation Voltage 15 kV; injection 3 s at 15 kV; 10 mM pH 7.5 phosphate buffer, 1.15 V (vs. Ag/AgCl) detection potential, the detection limit (LOD) for PRO was 0.05 mu M (S/N = 3). The response for PRO was linear over two orders of magnitude with a linear correlation coefficient of 0.994. The feasibility of this method was demonstrated by the detection of PRO in urine sample.