皇甫川流域中国沙棘树干液流日变化及其相关因子

运用热耗散(TDP)法对皇甫川流域中国沙棘(Hippophae rhamnoides L.subsp.sinensis Rousi)的树干液流速率进行测定,用自动气象站同步连续监测太阳总辐射、空气温度、空气相对湿度、风速、10 cm处土壤温度等环境因子,用LI-6400系列光合仪同步测定每日6:00-18:00的沙棘叶蒸腾速率.结果表明:非降雨时段,沙棘树干液流速率日进程变化呈现明显的昼高夜低的起伏趋势,白天液流速率变化有波动,夜间液流速率变化缓慢;降雨时,在降雨的开始时段,沙棘树干液流速率明显增大,降雨中后期,液流速率明显减小并趋于平缓;以环境因子作自变量,以单位叶干质量的液流量为因变量,经过逐步回归,建立了多元线性模型,回归方程显著.     

基于Desirability函数法对米根霉发酵制备富马酸的多目标优化

以富马酸产量和生产速率为目标，通过正交实验考察了种龄，接种量，葡萄糖和尿素浓度对两者的影响，进一步利用基于响应曲面方法的Desirability函数确定了葡萄糖和尿素的最佳浓度。结果表明，最佳的种龄和接种量分别为36h和15%，葡萄糖和尿素的优化浓度为132.73和0.0586g/l，此时模型预测的富马酸产量和生产速率达到71.42g/l和0.804g/(l.h)，Desirability的函数值高达0.966。该条件下在5L发酵罐水平上进行验证试验，经过88h的发酵最终生成富马酸66.5g/l，生产速率达到0.755 g/(l.h)，与未优化前相比，产量和生产速率分别提高了13.9%和15.8%，取得了理想的效果，实现了产量和生产速率的同时优化，为发酵法制备富马酸的工业化放大奠定了基础。     

山黧豆幼苗对干旱胁迫的生理响应

用PEG6000模拟干旱对山黧豆进行胁迫。结果发现，胁迫初期（0~48 h），突然的水分亏缺使气孔导度（Sc）和蒸腾速率（Tr）迅速下降，而净光合速率（Pn）和水分有效利用率（WUE）基本维持稳定。胁迫后期（48~108 h），上述四个光合指标均不同程度地向对照水平恢复；脯氨酸和相对电导率（REC）受胁迫强度影响较小，但与胁迫时间呈明显正相关，分别在48和60 h增幅最大，而且当REC上升至对照的50%左右时，脯氨酸含量已达对照的14倍之多。由此认为，山黧豆可能主要通过迅速减小Sc和Tr以及大量而急剧的积累脯氨酸来减轻干旱所造成的伤害。     

黄土高原常见造林树种光合蒸腾特征

为改善黄土丘陵沟壑区水土流失现状,该区长期以来开展了大量的植被建设,但是,植物的适应性及生长状况如何,还不十分清楚。为探讨造林树种对环境的适应性,从光合、蒸腾和生理生态指标出发,对黄土高原3个主要退耕还林树种：刺槐、沙棘、山杏的适应性进行了研究,并对其适宜性进行了评价。研究结果表明：沙棘不同坡位最大净光合速率Pmax、光补偿点LSP较其它两个树种占明显优势,特别是在上坡位Pmax、LSP分别达到了22.8μmol·m^-2s^-1、520μmol·m^-2s^-1,具有较高的同化代谢能力,该物种较适应该地区的强光环境,适宜种植于阳坡或坡顶;山杏LSP相对较低,而表观量子效率α明显高于沙棘、刺槐,并在下坡位达到最大值0.069,说明它主要利用弱光进行光合作用,适宜种植于阴坡或坡脚等弱光环境中,但由于山杏水分利用效率WUE较低,可能对环境带来不良影响,山杏叶片含水量为65.1%,明显高于其它两个树种,而叶绿素含量仅为0.94mg/g与刺槐沙棘的2.34mg/g和2.00mg/g相差很大,这可能是导致其WUE较低的一个原因;刺槐在上坡位的光合生理参数与山杏相差不大,但是随坡位下降其α、净光合速率Pn较山杏明显偏低各个坡位受限明显,容易形成老头树。     

固定化微生物对多环芳烃污染土壤的降解

利用微生物固定化技术,研究了微生物固定化菌剂对土壤中菲、蒽、芘、(艹屈)和苯并(a)芘的降解动态,并且采用Michaelis-Menton和Monod动力学模型对结果进行拟合.结果显示,4种处理(TB02、TB07、TBB03、TBB08)均有降解菲、蒽、芘、(艹屈)和苯并(a)芘的能力.其中,处理TB02的降解能力强、降解速率快、半衰期短且处理成本低,而处理TB07则需要较长时间作用于PAHs污染土壤,其降解能力才能充分发挥出来.当菲、蒽、芘、(艹屈)和苯并(a)芘的初始浓度均为20 mg·kg-1时,42 d后,TB02对菲、蒽、芘、(艹屈)和苯并(a)芘的降解率分别为84.32%、85.24%、82.59%、43.75%和62.25%; 133 d后,TB07对5种污染物的降解率分别为95.00%、95.24%、90.93%、74.82%和72.20%.通过比较5种污染物半衰期,其可降解性由大到小依次为菲、蒽、芘、苯并(a)芘、(艹屈).     

Effects of grazing intensity and grazing exclusion on litter decomposition in the temperate steppe of Nei Mongol,China

Aims Grazing intensity and grazing exclusion affect ecosystem carbon cycling by changing the plant community and soil micro-environment in grassland ecosystems. The aims of this study were: 1) to determine the effects of grazing intensity and grazing exclusion on litter decomposition in the temperate grasslands of Nei Mongol; 2) to compare the difference between above-ground and below-ground litter decomposition; 3) to identify the effects of precipitation on litter production and decomposition. Methods We measured litter production, quality, decomposition rates and soil nutrient contents during the growing season in 2011 and 2012 in four plots, i.e. light grazing, heavy grazing, light grazing exclusion and heavy grazing exclusion. Quadrate surveys and litter bags were used to measure litter production and decomposition rates. All data were analyzed with ANOVA and Pearson’s correlation procedures in SPSS. Important findings Litter production and decomposition rates differed greatly among four plots. During the two years of our study, above-ground litter production and decomposition in heavy-grazing plots were faster than those in light-grazing plots. In the dry year, below-ground litter production and decomposition in light-grazing plots were faster than those in heavy-grazing plots, which is opposite to the findings in the wet year. Short-term grazing exclusion could promote litter production, and the exclusion of light-grazing could increase litter decomposition and nutrient cycling. In contrast, heavy-grazing exclusion decreased litter decomposition. Thus, grazing exclusion is beneficial to the restoration of the light-grazing grasslands, and more human management measures are needed during the restoration of heavy-grazing grasslands. Precipitation increased litter production and decomposition, and below-ground litter was more vulnerable to the inter-annual change of precipitation than above-ground litter. Compared to the light-grazing grasslands, heavy-grazing grasslands had higher sensitivity to precipitation. The above-ground litter decomposition was strongly positively correlated with the litter N content (R² = 0.489, p < 0.01) and strongly negatively correlated with the soil total N content (R² = 0.450, p < 0.01), but it was not significantly correlated with C:N and lignin:N. Below-ground litter decomposition was negatively correlated with the litter C (R² = 0.263, p < 0.01), C:N (R² = 0.349, p < 0.01) and cellulose content (R² = 0.460, p < 0.01). Our results will provide a theoretical basis for ecosystem restoration and the research of carbon cycling.     

石灰岩土壤基质上构树幼苗接种丛枝菌根（AM）真菌的光合特征

就石灰岩适生植物构树(Broussonetia papyrifera)分别进行菌根真菌（简称AM真菌）摩西球囊霉(Glomus mosseae)、地表球囊霉(Glomus versiforme)、透光球囊霉(Glomus diaphanum)的单独接种、混合接种和不接种处理，幼苗生长3个月后测定其生长及光合生理指标，以期从光合水平上了解接种AM真菌对植物的生长、生理的响应。结果表明：接种AM真菌促进了构树幼苗生长，接种组地茎、苗高、总叶面积较对照差异性显著，但单株幼苗叶片数较对照无显著差异。接种处理导致了幼苗较高的菌根侵染率，而非接种处理侵染率为0。较对照而言，接种处理净光合速率显著提高,而蒸腾速率和气孔导度在单接种G.diaphanum下降低，其他三种处理均显著提高。接种处理光合耗水量较对照处理显著降低，提高了光合水分利用效率。接种后叶绿素a、b含量极显著提高。     

一种基于chirp编码的高帧速率超声成像方法

在医学超声成像系统中,帧速率由每帧图像的扫查发射次数所决定.同时发射多条波束可以提高图像的帧速率,但是这会带来不同波束间相互干扰的问题,形成伪像.本文基于编码激励的原理,提出了一种新的高帧速率成像方法.该方法通过发射一组线性频率调制编码信号,有效的降低了波束间的互扰.可以在不影响图像质量的情况下,成倍的提高图像的帧速率.