高效液相色谱—电喷雾质谱联用法检测豆芽中残留的6-苄基腺嘌呤

采用高效液相色谱—质谱法测定豆芽中6-苄基腺嘌呤残留。均质后的黄豆芽样品经乙腈溶液提取、无水硫酸镁盐析分层后,取有机相测定。采用ZORBAX SB C18色谱柱,以甲醇+0.1%乙酸水溶液(体积比75∶25)的混合液为流动相,色谱分离后进入质谱检测。质谱采用电喷雾离子源(ESI),负离子模式,选择离子(SIM)m/z 224[M-H]-。在0.1 mg/kg添加浓度下,平均回收率(n=7)为89.0%~92.2%,相对标准偏差≤9.9%。方法检出限(S/N=3)0.0021 mg/kg,在0.08~2.0 mg/L范围内具有良好线性,相关系数R2=0.999。     

取对数求导法释疑

对一元函数取对数求导法的两种常见类型之一——由若干因式的积、商、幂组成的函数的取对数求导作了进一步的讨论,对含有负因式、零因式时取对数求导也得出相应的结论。     

清代山东运河补给及其对农业生态的影响

在清代,山东运河补给水源缺乏,朝廷为了漕运畅通,保证运河补给,将运河沿岸的河流、湖泊、山泉等竭力纳入补给体系,并以法律规定河泉平时三日济运,一日灌田,而亢旱之年则全部济运,严禁沿岸农民兴建沟洫水利,更不许开辟需水较多的稻田,所有这些严重影响了运河沿岸农田的灌溉与农田水利的发展,并造成了诸多水患灾害的发生与农业生态的破坏。     

气相色谱-负化学离子源-质谱法测定黄瓜中啶虫脒残留

采用气相色谱-负化学离子源-质谱法(GC-NCI-MS),建立了黄瓜中啶虫脒的残留分析方法,试样采用乙酸乙酯提取,石墨化碳黑净化,负化学电离方式(NCI)在选择离子监测模式(SIM)下进行检测。啶虫脒在黄瓜中的平均回收率在85.3～99.0%之间,相对标准偏差在4.0～4.7%之间,浓度为0.004～1.0mg/mL时具有良好的线性关系,相关系数为R2=0.999 6,定量限为5μg/kg。结果表明.此方法快速、简便、灵敏度高,适用于黄瓜样品中啶虫脒残留的检测。     

Suppression of nematodes in a coastal grassland soil

The nematophagous fungi Arthrobotrys oligospora and Myzocytiopsis glutinospora increase to large numbers (>10³ propagules/g of soil) when moth larvae killed by entomopathogenic nematodes are added to soil microcosms. In spite of these increases, it is unclear how effective these nematophagous fungi are in suppressing nematodes. We measured nematode mortality in microcosms with small numbers of assay nematodes, and we examined assay nematodes recovered at the end of the experiment for signs of fungal parasites. Because the microcosms did not have a moat or other refuge, the assay nematodes remained vulnerable for the 3 days that they were in the soil. Mortality in this experiment was not substantially increased compared to a previous experiment, which measured the mortality of a larger number of assay nematodes in microcosms surrounded by a moat. Mortality, however, increased from 34 to 50% when recovered assay nematodes were examined and when those with conidia of the nematophagous fungus Hirsutella rhossiliensis were considered dead. The zoosporic fungus M. glutinospora was not detected, perhaps because the soil water potential was too low. Contrary to our expectations, there was no evidence of negative feedback on nematodes (i.e., no evidence of density-dependent mortality) because the addition of dead moth larvae greatly increased numbers of resident nematodes and A. oligospora but did not greatly affect the probability of nematode mortality.     

空气负离子与植物精气相互作用的初步研究

空气负离子和植物精气是森林环境的主要成分,它们对人和自然有着积极的作用,我们在对森林环境的检测过程中,有重要发现并作了实验证明。       

雾森在湿地公园中的应用分析

以杭州西溪国家湿地公园、山东滕州国家湿地公园、北京元大都湿地公园为例,对雾森在湿地公园中的应用作了分析。     

氧化铝对红壤正、负电荷的影响

用人工合成氧化铝包被土壤的方法研究了氧化铝(三水铝石)对红壤地区五种土壤的电荷性质的影响.结果发现,土壤包被氧化铝后正电荷有不同程度的增加,但其增加量随pH的升高而减少,pH7左右时几乎为零.人工氧化铝对负电荷的影响因土而异.带负电荷少的砖红壤包铝后在pH<7范围内负电荷稍有减少;带负电荷多的黄壤和红壤包铝后在低pH时负电荷明显减少,而高pH时负电荷明显增大;另外两个赤红壤包铝后负电荷也有类似的变化趋势,但变幅较小.四种土壤的负电荷由减小转变到增大时转变点的pH值各土不同,在pH3.6-6.2之间.包铝后土壤净电荷的变化趋势与该土壤的负电荷相似.包铝后土壤的ZPNC都有所升高,升高的幅度因土而异,在0.4-1pH单位之间.     

空穴负压现象的界面拉伸试验研究

应用类似于土壤粘附拉脱力试验的界面拉伸试验,证明了光滑表面的界面存在粘性物质时,如空气、水和黄油,界面介质在拉伸过程中将产生空穴负压现象,造成界面的粘附力增大;分析了空穴的形成、空穴膜的流动和破坏过程,并通过试验和高速摄影图片作了验证。     

苯硫咪唑干粉混悬剂对藏系绵羊消化道线虫的驱治试验

使用苯硫眯唑干粉混悬剂,用于驱除自然条件下放牧的藏系绵羊消化道线虫。试验表明：10mg/kg剂量投药时,虫卵转阴率达99％,是群体寄生虫防治的首选剂型。