熔融法制备环氧功能化的碳纳米管

以三苯基膦(TPP)为催化剂,通过环氧基团和酸化碳纳米管上羧酸的酯化反应,将环氧树脂接枝到碳纳米管壁上,成功制备了环氧功能化碳纳米管.分别运用红外光谱(FTIR)、热失重(TGA)、扫描电镜(SEM)对环氧功能化的碳纳米管进行了表征.用滴定的方法研究了反应温度和不同的环氧树脂对碳纳米管的环氧功能化程度的影响.研究表明:环氧基团已经成功地接到碳纳米管上;与酸化的碳纳米管相比,环氧功能化碳纳米管表面已经被环氧树脂包覆,从而使得碳纳米管直径增加;温度升高有利于提高碳纳米管的环氧功能化程度,相对分子质量较小的环氧树脂的转化效率比相对分子质量大的要高.     

饱和水岩石核磁共振表面弛豫温度特性

温度是影响岩石孔隙流体核磁共振弛豫的因素之一.选取一组饱和水的人造碳化硅、人造碳酸钙、储层贝瑞砂岩以及碳酸盐岩样品进行核磁共振实验(温度25～90℃),考察温度对弛豫速率的影响.结果表明,对于饱和水的砂岩和碳酸盐岩,温度对岩石核磁共振表面弛豫的影响不同.饱和水的人造碳化硅和储层贝瑞砂岩的核磁共振弛豫速率随温度升高而增大;饱和水的人造碳酸钙和储层碳酸盐岩的弛豫速率随温度升高而减小.因此,在利用室温下得到的实验测量结果对储层温度下的核磁共振测井数据进行刻度时,应考虑温度的影响.     

气候变化的证据和原因（1）

 气候变化情况是目前人们一直在探讨的问题之一。从许多条线索中可以得知并确定,人类活动正在改变全球气候,以至于大气层和海洋已经升温、海平面升高、北极冰层消融,还有其他一些气候相关的变化也随之而来。人类活动造成了温室气体（如二氧化碳）的不断增加,继续排放这些气体将导致进一步的气候变化,这些变化的规模和时间也取决于多种因素。     

Photosynthesis of Populus euphratica and its response to elevated CO2 concentration in an arid environment

The photosynthetic characterization of Populus euphratica and its response to the elevated carbon dioxide concentration ([CO2]) were analyzed based on its net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), and water use efficiency (WUE) at different groundwater depths measured by a portable gas exchange system (LI-6400) in the lower reaches of the Tarim River. The results showed that the elevation of [CO2] decreased the gs, and increased the Pn, Ci and WUE of P. euphratica. However, the effects of the elevated [CO2] on gs, Pn, Ci and WUE varied considerably with groundwater depth. The response of photosynthesis to rising [CO2] was stronger at the greater groundwater depth (more than 6 m) than that at the shallower groundwater depth (less than 6 m). The critical groundwater depth required to maintain the normal survival of P. euphratica was less than 6 m. When the groundwater depth increased to more than 6 m, P. euphratica encountered moderate water stress, and the plant suffered severe water stress when the groundwater depth increased to more than 7 m.     

Structure of aqueous sodium sulfate solutions derived from X-ray diffraction

A rapid liquid X-ray diffractometer was used to study the time-averaged and space-averaged structure of aqueous sodium sulfate solutions at 298 and 323 K. Difference radial distribution functions of the solutions were obtained from accurate diffraction data. The interaction distances of Na^＋-OH2 and S-H2O in solutions were found to be 0.235 and 0.385 nm, respectively, after deconvolution of superposition peaks by Gaussian multi-peak fitting program. The characteristic distance of the NaSO; contact ion pairs in higher concentration solutions was determined to be 0.345 nm, suggesting that the Na^＋ ions coordinated with SO4^2- ions in the mono-dentate form. Effects of concentration and temperature on the hydration structure of the solutions were discussed in the present paper. With a decrease in concentration, the contributions of the H2O to the diffraction pattern increase, the average coordination number of the Na^＋ ions hardly changes, while the hydration number of SO4^2- ions increases slightly. The formation of NaSO; contact ion pairs becomes easier at higher temperature. The structure of hydrogen bond in dilute solutions is broken to a considerable extent with rising temperature, and the peak at 0.290 nm splits into two peaks at 0.275 and 0.305 nm, respectively.     

冬枣花期防虫病

冬枣花前,气温升高,降雨量较少,有利于病虫害发生。一是枣瘿蚊、螨、绿盲蝽象等危害重,叶片被害后,呈现灰白色,衰老而质地脆,易脱落;花蕾被害后,逐渐变为褐色,干枯脱落;二是桃小食心虫越冬虫开始出土,开始上树危害;三是麦田小麦砍倒后,金龟子、龟背瓢虫、红缘天牛等害虫转移到冬枣树上危害花蕾、叶片;四是干腐病斑继续扩展及叶片缺素黄化病的发生。     

鲍店煤矿第I区下组煤带压开采条件评价

为了将来下组煤开采,通过对下组煤水文地质的补勘,查明了奥陶系灰岩的水位、水质及富水性,查明了底板隔水岩层的厚度、岩性组合及隔水性．评价了下组煤带压开采条件。     

气候变暖条件下中国西北地区地理环境演变趋势初探

在预测分析的基础上,探讨了因气温升高而引起的气候、植被、土壤、水文、地貌等自然地理要素的变化趋势     

中药柴胡提取物对人肝癌细胞BEL-7402细胞内VCR蓄积的影响

目的测定中药柴胡(Bupleurun Chinese DC,BCDC)提取物对人肝癌细胞BEL-7402细胞内VCR蓄积的影响,以探索柴胡逆转BEL-7402细胞多药耐药的机制.方法高效液相色谱法测定BCDC作用于BEL-7402后细胞内VCR蓄积情况的变化.结果柴胡可使人肝癌细胞BEL-7402细胞内VCR浓度升高(P＜0.01).结论柴胡可以增加VCR在BEL-7402细胞内的积聚浓度,部分逆转BEL-7402细胞的MDR.     

温度对深部砂岩波速的影响

为准确评价深部岩体的力学性质,采用脉冲透射测试方法,对鹤岗南山矿深部砂岩在18～ 130℃的波速进行了测试.结果表明:岩样的纵波波速vP在30～ 55 ℃、横波波速vS在30～ 80 ℃随温度升高略有下降趋势,下降幅度vP＜vS;vP/vS 随温度升高呈上升趋势;岩样的泊松比νd在30～130 ℃随温度升高而增长,但其值均在0.35以内;动弹性模量Ed随温度升高呈下降趋势,温度在18～ 80 ℃ Ed值下降较大,当温度＞80 ℃以后曲线较平缓.