999 resultados para 1103


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辽西半干旱地区主要作物耗水规律的初步研究王仕新刘作新赵焕胤庄季屏(中国科学院沈阳应用生态研究所,110015)APreliminaryStudyofWaterConsumptionofMainCropsintheSemiaridAreaofWestL...

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水文地貌关系正确DEM(hydrologically correct DEMs,Hc-DEM),是指符合水文地貌学基本原理,正确反映水文要素(水流方向、水流路径、水系网络、流域界线等)与地貌特征发生和位置关系的DEM。区域尺度水文和土壤侵蚀等研究中,地形因子参数只能利用DEM来提取,为了准确反映地面形态,有效提取地貌和水文特征因子,建立Hc-DEM是必需的。笔者对Hc-DEM的概念、建立方法进行了讨论和介绍;以黄土高原为例,提出了利用多种比例尺数字地形图和ANUDEM软件建立DEM的关键参数;通过与TIN方法建立的DEM的比较,对所建立的DEM进行了简要评价。研究表明,利用我国已有的数字地形图和ANUDEM软件,可以建立Hc-DEM,为流域水文和区域尺度水土流失定量分析模拟、区域尺度植被适宜性评价等研究提供更加直接的数据支持。

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以辽宁省昌图县横沟子乡先锋村烟田的土壤农化性状指标为参数,设计镁、硼素及硝基腐植酸作为烟草专用肥的添加剂,研究其对提高和改善烤烟产量、品质的影响,1991~1993年三年的田间试验表明,亩施硫酸镁、硼砂各0.5kg及硝基腐植酸3.5kg做基肥,移栽40天,镁、硼处理区再分别喷施硫酸镁500克(1%浓度),硼砂100克(0.2%浓度),这三个处理区不论是烟株苗期生长的叶色、抗病力及成熟期烟叶落黄、烘烤效果,还是上等烤烟比重、化学成分含量等指标均有改善和提高。

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采用异位生物修复技术堆式堆制处理方法 ,对辽河油田原油污染土壤进行了生物修复处理研究 .处理工程设 4个处理料堆单元 ,每个处理单元长 118.5cm ,宽 6 5 .5cm ,高 12 .5cm .研究结果表明 ,当进行处理的石油污染土壤中石油烃总量为 5 .2 2 g·10 0 g-1土时 ,利用黄孢原毛平革菌 (Phanerochaetechrysospori um) ,经过 5 5d的运行 ,石油烃总量去除率达 5 4.2 % .堆制处理中影响污染土壤石油烃总量生物降解的主要变化因子为污染土壤的O2 和CO2 含量、降解石油烃微生物的数量、污染土壤pH的变化 .通过监测这些数据的变化 ,可直接反映该工程的处理石油污染土壤的效果 .本处理工程采用定期通风措施 ,操作简单、运行费用低廉 ,为石油污染土壤生物修复实用化提供了一种简单易行的污染土壤清洁技术 .

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合成并表征了一种新型吡啶双亚胺铁烯烃聚合催化剂2,6-二[1-(4-羟基-2,6-二甲基苯胺)乙基]吡啶氯化铁(1a)。结果表明,在亚胺环的对位引入羟基,可同时提高催化剂的活性和聚合物的分子量。在改性甲基铝氧烷(MMAO)的活化下,该催化剂引发乙烯聚合的活性(以单位时间(h)molFe引发乙烯聚合的PE质量(g)来表征)可达到6.78×106g/(mol.h),明显高于催化剂2,6-二[1-(2,6-二甲基苯胺)乙基]吡啶氯化铁(1b),且能得到更高分子量的聚乙烯。

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Oligonucleotide from SARS virus was selected as a target molecule in the paper. The noncovalent complexes of ginsenosides with the target molecule were investigated by electrospray ionization mass spectrometry. The effects of experimental conditions were examined firstly on the formation of noncovalent complexes. Based on the optimized experimental conditions, the interaction of different ginsenosides with the target molecule was researched, finding that the interaction orders are relative with the structure of aglycons, the length and terminal sugar types of saccharide chains in the ginsenosides. There are certain rules for the interaction between the ginsenosides and DNA target molecule. For different type ginsenosides, the interaction intensity takes the orders 20-S-protopanaxatriol > 20-S-protopanaxadiol, and panaxatriol ginsenosides > panaxadiol ginsenosides. For the ginsenosides with the same type aglycone, tri-saccharide chain > di-saccharide chain > tetra-saccharide chain and single-saccharide chain > panaxatriol. For the ginsenosides with the same tetra-saccharide chain, the ginsenosides with smaller molecule masses > the ginsenosides with larger molecule masses.

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Seven structure analogical flavonoid aglycones have been analyzed using electrospray ionization tandem mass spectrometry (ESI-MSn) in the negative-ion mode. The spectra obtained ESI-MSn allowed us to propose plausible schemes for their fragmentation mechanism. By analyzing the product ions spectra of deprotonated molecule ions [M-H](-), some neutral diagnostic losses and specific retro Diels-Alder fragments were obtained. By using all of these characteristic fragment ions we can specially differentiate the flavone isomer.

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将连接树的方法应用到吡啶类化合物 p Ka 值的预测中 ,并将该方法计算出的参数与量子化学参数相结合 .变量的两两相关性检验结果表明 ,所选择的10个参数相关性较小 ,同时用交叉验证方法所得到的结果表明 ,所构造的多元回归模型十分稳定 .通过人工神经网法对回归模型进一步优化 ,得到满意的结果.

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The electrochemical performance of Laves phase alloys LaAl2 and LaAl1.5Ni0.5 were investigated. The results showed that LaAl2 alloy milled for 2 hours has the larger discharge capacity than that of as-cast alloy. In addition, partial substitution of Ni for Al will clearly increases the discharge capacity of milled LaAl2 alloy.

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对甲基酚醛树脂热裂解产物的固体~(13)CNMR谢德民,张建国,王存国,王荣顺(东北师范大学化学系,长春,130024)关键词对甲基酚醛树脂,裂解,固体~(13)C,NMR酚醛树脂经热裂解制备的聚并苯导电材料在空气中稳定,由裂解温度可控制碳化程度,其本...

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本文报道一种新的长光程薄层光谱电化学池。采用电极体插入式结构,入射光与电极表面平行。池体结构不用任何粘接剂,可用于多种溶剂体系。结构简单,装配方便。容易清洗及更换处理工作电极与溶液,以水溶液中K_3Fe(CN)6的氧化还原反应进行了表征。