单季稻水田生态系统水量平衡及节水研究

本文通过观测确定了水稻生长季蒸发蒸腾量和水面蒸发量的相关关系，并利用这一关系和水量平衡原理，评估了下辽河平原地区单季稻水田生态系统的水量平衡情况；试验研究了保留犁底层、深翻打破犁底层和30cm土底层下铺设塑料地膜与育秧膜四种土壤处理措施的稻田生态系统水量平衡的特征和水分利用效率。研究表明，北方单季稻水田生态系统的蒸发蒸腾量和水面蒸发量呈良好的线性关系；用此关系估算下辽河平原各水稻灌区的蒸发蒸腾量变化规律为：营口>盘锦>辽阳>铁岭>沈阳。下辽河平原地区水稻生长季的总用水量为1773.4～2194.3mm，其中降水占总用水量的27.2%～35.8%，其余水量依靠灌溉供给，平均每亩灌水量在1138.9～1597.6mm之间，南部滨海灌区高于中部地区。除蒸发蒸腾损失外，下辽河平原地区水田总用水量的65%～72.3%由渗漏损失，该区总体的渗漏特征是中部高于南部的北部。在沈阳郊区潮棕壤条件下进行的第三年实验结果表明，与保留犁底层处理相比，深翻处理渗漏水量多18.7%；地膜处理与保留犁底层处理的渗漏水量基本持平；育秧膜阻渗处理的渗漏水量少29.4%。显然，犁底层具有保水作用，深翻打破犁底层加剧稻田水分渗漏；地膜阻渗效果已不明显，而育秧膜仍具有明显的阻渗节水效果。

微结构疏水表面对界面流动的影响

<正>通过MicroPIV/PTV系统测量带有微结构的PDMS微流道(22μm×6μm,长8mm)内的速度分布。流道侧壁的PDMS微结构是通过软光刻微加工工艺制成,其特征宽度在1～10μm范围。为了研究微结构尺寸的影响,我们测量了3种不同尺度微结构对速度分布的影响。示踪粒子为200nm聚苯乙烯荧光粒子。实验管道Re约0.01。

河北木兰围场油松年轮生态学的初步研究

运用树木年轮气候学方法,研究了河北木兰围场油松的生长与气候要素之间的关系.结果表明:油松生长对环境变化十分敏感,以早材最为敏感.5、6月气温与油松生长存在显著的负相关关系;6月的降水和相对湿度对油松早材的生长有促进作用,上年9月到翌年9月的降水对油松生长有更强的促进作用;12月到翌年3月的相对湿度对油松晚材生长的促进作用较干旱和全轮显著;油松的生长与大尺度气候波动存在一定的相关性.1951—2006年间,围场地区增温明显.随气温的升高,油松生长对温度和降水的敏感性下降,且有向相反方向转变的趋势.百年尺度上5—6月平均气温的重建值与观测值差异较大,说明当地油松的宽度生长对气候因子变化的敏感性波动较大.

Combination of CH4 oxidative coupling reaction with C2H6 oxidative dehydrogenation by CO2 to C2H4

A new process has been suggested for converting natural gas to ethylene by combining oxidative coupling of methane with ethane dehydrogenation to provide an efficient method for the utilization of thermicity and CO2. From their thermodynamics, it is clear that the exothermicity from CH4 oxidative coupling reaction (DeltaH(800degreesC) = -174.3 kJ mol(-1)) can support C2H6 dehydrogenation by CO2 (DeltaH(800degreesC) = + 180.2 kJ mol(-1)). Meanwhile, the two reactions can be conducted under the same reaction conditions, such as the reaction temperature and reaction pressure as well as space velocity. In addition, the CO2 yielded from CH4 oxidative coupling reaction can be directly used for C2H6 dehydrogenation. Two kinds of catalyst are developed for this combined process with an achievement, from which C2H4 content in tail gas can reach attractively 16.4%, which can be used directly to produce ethylbenzene by the alkylation of benzene. (C) 2002 Elsevier Science Ltd. All rights reserved.

开发生产长效碳酸氢铵增强小氮肥企业活力

<正>市场经济的发展使碳铵企业陷入了困境首先,从产品本身来讲,碳铵的化学性质不稳定,含氮量只有17%,氮素利用率低(25%左右),肥效期短(35～45天),

Synthesis of 2-benzylthio-5-phenyl-3,4-disubstituted thiophenes by intramolecular condensation of alpha-oxo ketene dibenzylthioacetals

A facile route to 2-benzylthio-5-phenyl-3,4-disubstituted thiophenes was described. Catalyzed by sodium hydroxide, the title compounds were synthesized in moderate to good yields simply from the intramolecular aldol type condensation of alpha-oxo ketene dibenzylthioacetals. The chemical selectivity for this annulation reaction was studied and discussed.

MF_2:Eu,Ce(M=Ca,Sr,Ba)中稀土离子的价态变化

我们已经实验证明并报道了Eu-Tb之间、Ce-Yb之间的电荷转移.本文首次实验证实了Ce~(3+)离子和Eu~(3+)离子之间电荷转移现象的存在,进一步阐述了稀土价态与其电子组态共轭特征的相关性.1 实验部分1.1 试剂CaF_2,SrF_2,BaF_2,NH_4HF_2、氢氟酸、盐酸均为分析纯,EuF_3和CeF_3分别由高纯Eu_2O_3(99.95%)及CeO_2(99.99%)自制.1.2 MF_2:Eu,Ce体系的合成按化学计量比(MF_2:X%CeF_2,y%EuF_3;X=1,y=0,0.1,0.3,0.5,1;X=0,0.05,0.1,0.3,0.5,y=1)准确称取原料,放人玛瑙研钵中充分研混后装入刚玉柑涡中,置于管状炉内(用氢气