不同脲醛树脂对竹胶板性能影响

木材用脲醛树脂基本适用竹材胶合,但需改善耐水性能;竹席胶合板的静曲强度和脲醛树脂的固体含量及粘度有关,通常随二者增大而增大,粘度过大反而降低,故宜选用固体含量55%、粘度60—80cPa·s、pH7.0的脲醛树脂。     

控释尿素水氮耦合对夏玉米产量和光合特性的影响

采用旱棚盆栽试验,以郑单958为材料设置3个水分水平(正常水分W3、轻度水分胁迫W2、重度水分胁迫W1)和高氮N3(施纯氮315 kg hm–2)、中氮N2(施纯氮210 kg hm–2)、低氮N1(施纯氮105 kg hm–2)、不施氮N0四个控释尿素施氮水平,探讨控释尿素水氮耦合对夏玉米产量和光合特性的影响。结果表明,控释尿素水氮耦合对夏玉米产量和光合特性具有显著影响。相同水分条件下,夏玉米产量随施氮量增加而增加,W1条件下增产13.17%~20.96%,W2条件下增产13.93%~32.48%,W3条件下增产14.37%~21.83%。相同施氮水平下,产量也随水分增加而增加,W2N3、W3N2和W3N3的产量在所有处理中较高。水氮耦合对夏玉米穗位叶净光合速率的影响显著,W1条件下N3、N2和N1处理间差异不显著,均显著高于N0,W2、W3各施氮处理的净光合速率随施氮量增加而增加,W3各处理的平均净光合速率高于其他2个水分处理,W2N3比W3N3和W3N2前期略低,后期无显著差异。水氮耦合效应能有效减缓穗位叶的实际光化学效率ΦPSII、叶片光化学猝灭系数qP以及PSII反应中心的最大光能转换效率的下降速率,提高光能利用率。控释尿素水氮耦合能有效提高夏玉米花后穗位叶净光合速率,保证籽粒对营养物质的需求,提高穗位叶实际和最大光化学效率,从而提高夏玉米的产量,产量构成因素中增加千粒重和穗粒数的优势较大。综合产量与光合特性、荧光特性的表现,在田间持水量为75%±5%的土壤条件下,控释尿素施氮量以纯氮210 kg hm–2为最佳;在田间持水量为55%±5%的土壤条件下,控释尿素施氮量以纯氮315 kg hm–2为宜。     

包膜尿素不同用量对黄瓜幼苗生长及氮平衡的影响

为确定合理的包膜尿素用量以指导黄瓜育苗施肥,采用生产中常用的草炭:蛭石(2:1)为育苗基质,研究了包膜尿素不同用量对黄瓜幼苗生长、养分吸收及氮平衡的影响。结果表明:包膜尿素用量在125~375 mg N/株的情况下,可协调黄瓜幼苗地上部和地下部的生长,促进幼苗对磷、钾的吸收;移栽时,基质中的氮素残留总量90.5~250.3 mg N/株,其中,残留的包膜氮素占75.4%~82.3%,可实现带肥移栽;育苗期间可产生31.9~121.5 mg N/钵的氮素表观损失。     

基施磷肥对石灰性土壤上番茄产量的影响

A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soll with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 （rice） and 250 （wheat） kg N ha^-1, and reduced levels, 150 （rice） and 125 （wheat） kg N ha^-1, coated urea at two levels, 100 （rice） and 75 （wheat） kg N ha^-1, and 150 （rice） and 125 （wheat） kg N ha^-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both NH3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly （P 〈 0.001） positively correlated （r = 0.851） with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. However, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yield of the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.     

微波消解—ICP-OES法同时测定有机肥、复混肥和尿素中多种元素含量的研究

采用微波消解法处理样品,建立了电感耦合等离子体光谱法同时测定有机肥、复混肥和尿素中铅(Pb)、砷(As)、汞(Hg)、铬(Cr)、镉(Cd)、铜(Cu)、锰(Mn)、钴(Co)、锌(Zn)、镍(Ni)和锑(Sb)11种元素的分析方法。优化了微波消解条件、仪器条件,进行了方法的检出限、精密度、准确性试验。方法检出限为0.003~0.015 mg/L,相对标准偏差均8.1%,回收率为82.4%~103%,通过水系沉积物标准参考样(GBW-07311)及国家标准方法的验证表明,该方法具有简便、快速、准确、灵敏度高等特点,适合有机肥、复混肥和尿素中11种元素的同时测定。     

Hypoglycemic effect of lupin seed γ-conglutin in experimental animals and healthy human subjects

A lupin seed γ-conglutin-enriched preparation was tested in a glucose overload trial with both murine models and adult healthy volunteers. The results with rats showed a dose-dependent significant decrease of blood glucose concentration, which confirmed previous findings obtained with the purified protein. Moreover, three test-product doses equivalent to 630, 315, and 157.5 mg γ-conglutin, orally administered 30 min before the carbohydrate supply, showed a relevant hypoglycemic effect in human trials. Insulin concentrations were not significantly affected. The general hematic parameters did not change at all.This is the first report on the glucose-lowering effect of lupin γ-conglutin in human subjects.     

华北平原农田生态系统土壤C、N净矿化及尿素转化研究

以华北平原区4个农田生态系统[京郊蔬菜大棚(GH)和河北栾城(LF)、河北南皮(NF)、山东惠民(HF)3个粮田]为研究对象,采用室内好气、恒温、避光条件下培养30.d,对比研究了不同海拔和不同农业扰动强度下的农田生态系统中耕层(020.cm)土壤的净N矿化、净硝化、净C矿化以及尿素的转化,旨在探索人类农业扰动强度和地理海拔对土壤供N潜力和尿素N转化的影响。结果表明,4个地区的土壤供N潜力分别为:14.4、13.2,17.7和16.5.mg/kg,说明高度熟化的华北区农田土壤供N潜力相对稳定。以施用有机肥为主的蔬菜大棚和以施用化肥为主的粮田对土壤供N没有显著影响。农田土壤净矿化后的供N形式主要是NO3--N。以施用有机肥为主的蔬菜大棚积累了较高的土壤有机质和全N,但是土壤净C矿化以及施用尿素后CO2的排放量均低于以施用化肥为主的粮田。尿素在各区域农田土壤中水解转化后均主要以NO3--N形式存在,NO3--N占尿素水解后无机N增量的98%9～9%;华北平原农田生态系统施入尿素态N.30d后,水解成有效态无机N的转化率为63.4%8～3.2%,即每克尿素态N在京郊蔬菜大棚(GH)、栾城高产农田(LF)、南皮农田(NF)和惠民农田(HF)土壤中转化为NO3--N的量分别为0.69、0.82、0.64和0.63.g/kg,同时可使相应区域农田的CO2排放量分别增加CO21.20、1.360、.67和1.58.g/kg。     

典型双季稻田基施碳酸氢铵和尿素的氨挥发损失研究

采用密闭室连续抽气法研究了湖南典型双季稻田,尿素和碳酸氢铵基施后的氨挥发特征。结果表明,基施碳酸氢铵(NC)稻田初始氨挥发强度和氨挥发总量大于基施尿素(UR)稻田。早稻季NC处理稻田氨挥发排放量为45.19 kg·hm-2,损失率达30.12%,UR处理氨挥发排放量为32.93 kg·hm-2,损失率达21.95%;晚稻季NC处理稻田氨挥发排放量为70.91 kg·hm-2,损失率达31.93%,UR处理氨挥发排放量为61.78 kg·hm-2,损失率达27.04%。基施尿素能够显著降低稻田氨挥发排放,减少氮素损失。     

包膜尿素的养分释放特征及其肥效

应用固-液反应包膜工艺，采用4种改性的无机包膜材料，试制出了成本较低的包膜缓释尿素，用水中溶出率法测定了包膜缓释尿素的养分释放特征，应用盆栽水稻评价了包膜缓释尿素的肥效，并与国外的有机缓释氮肥（Methylene Urea）和高聚物包膜复合肥（Osmocotte）进行了比较，表明固-液反应型包膜尿素具有较好的养分缓释效果，4种包膜尿素与等氮和等重常规尿素相比，栽培水稻都有一定的增产作用，并提高了肥料利用率，其中LU增产最显著，比等氮和等重尿素处理分别增产41．5％和35．7％，肥料当季利用率达到43．9％，好于国外的有机缓释氮肥和高聚物包膜复合肥。养分释放特征与水稻氮素营养特征较为接近，可为水稻一次性施肥所用。