972 resultados para Quincy, Josiah, 1772-1864.


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<正>美国生态学会(ESA)第94届年会于2009年8月2日到7日在新墨西哥州阿尔伯克基(Albuquerque)的国际会议中心举行,3000多人参加此次会议。会议主题是"Ecological Knowledge and a Global Sustainable Society"。8月2日下午5时,美

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结瘤固氮树种叶部主要养分迁移特征何兴元张成刚杨思河苏道岩张粤刘惠昌(中国科学院沈阳应用生态研究所,110015)TransportCharacteristicsofMainNutrientsintheLeavesofNodulatedandNitro...

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辽宁沿海养殖对虾爆发性病害的病因分析国际翔,王丽霞,李文清,刘丹孙伯伦(中国科学院沈阳应用生态研究所,沈阳110015)(阳锦州水产所)93年辽宁沿海养殖对虾发生了爆发性流行性病害,受害面积之大,损失之严重,是养虾史上前所未有的。作者对辽宁沿海6市、...

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采用营养液培养法,研究了缺硫对万寿菊(Tagetes erecta)各器官镉积累的影响,以及巯基化合物和有机酸等在各器官镉积累中的作用。结果表明:0.1 mg.L-1镉处理7 d,缺硫处理显著降低了植物根、茎和叶中的镉含量,较对照分别降低了47%、38%和61%;缺硫对植物体内半胱氨酸、γ-谷氨酰半胱氨酸、谷胱甘肽和有机酸的合成没有显著影响,而且3种巯基化合物的含量都很低;缺硫植物根部合成的植物络合素的量显著降低,这可能是植物体内镉积累减少的主要原因;在植物的各器官中,叶片中的有机酸含量最高,而在叶片中未检测到植物络合素,由此可推断,叶片中积累的镉主要与有机酸结合;缺硫影响了根部植物络合素的合成,进而降低了植物体内镉的积累,而缺硫没有影响植物体内有机酸的合成,有机酸可能仅是参与植物组织中与镉的络合作用。

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阐述了森林流域几种土壤水分运动方式(入渗、潜水蒸发、潜水补给以及壤中流)中非饱和土壤水与饱和土壤水之间转化的研究进展,并对土壤水分运动参数中的土壤水分特征曲线、非饱和导水率和饱和导水率的研究现状作以简要介绍,最后提出了未来的发展方向.

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研究了沙埋对科尔沁沙地 6种优势植物的种子萌发和幼苗出土的影响 .进行 0、2、4、6、8、10和 12cm等 7个深度沙埋处理 .结果表明 ,在不同沙埋处理时 ,沙蓬萌发差异显著 ,而差不嘎蒿 2cm埋深与其他埋深的发芽差异显著 ,其他 4种植物 0cm埋深与其他埋深的发芽差异显著 ;沙埋对所有植物幼苗出土均有显著影响 ,埋深增加 ,出苗率减小 ;繁殖体大的物种与繁殖体小的物种相比 ,能从更深沙层中出苗 ,幼苗出土最大深度排序为苦参 >东北木蓼≥沙蓬 >山竹子 >雾冰藜 >差不嘎蒿 .

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We functionalize the focal group of hyperbranched poly(phenylene sulfide) (HPPS) with benzyl, phenyl, and naphthyl group, respectively. DSC analysis shows that T-g of HPPS is increased from 55 to 93 degrees C by functionalization of the focal group with a conjugated naphthyl group. The fluorescence properties of the three core-functionalized HPPS' are studied under the comparison with the original HPPS.

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Methacrylic acid based inverse opal hydrogels (MIOHs) have been prepared by controlling the synthesis conditions, including cross-linker content, solvent content, and water content in solvent mixtures to explore the effect of the synthesis conditions (especially solvent content and mixture) on the response performance. Various response events (pH, solvent, ionic strength, 1,4-phenylenediamine dihydrochloride (PDA) response) have been investigated. For pH, solvent response, the same response behaviors have been observed: both the increased solvent (only ethanol) content and the enhanced water content in solvent will lead to the reduced response level of MIOHs compared to that of the increased cross-linker content. However, two different kinds of response behaviors for ionic strength response have been found by adjusting the synthesis conditions. The kinetics of pH response shows characteristics of a diffusion-limited process, and the equilibrium response time is about 20 min, which cannot be reduced by changing the synthesis conditions.