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131.
采用室内培养实验,分别研究了21科30种中草药的植物浸提液对3种土壤中尿素水解和硝化作用的抑制效果。结果表明,中草药植物浸提液能够对尿素水解起抑制作用的有23种,其中8种的抑制效果优于脲酶抑制剂氢醌(HQ);浸提液能够抑制硝化作用的植物有25种,其中3种的硝化抑制效果优于双氰胺(DCD);唇形科植物夏枯草(Prunella vulgaris L.)和忍冬科植物金银花(Lonicera japonica Thunb.)既能有效抑制尿素水解,又能有效减缓NH+4的硝化,是尿基氮肥增效剂的最佳选择。研究还表明,夏枯草和金银花粉末在培养后的24~36 h脲酶抑制率最高,在培养后的14~21 d硝化抑制率最高,且抑制效果随粉末用量的增加而增强。 相似文献
132.
保水剂包膜尿素的特征与性能 总被引:11,自引:1,他引:11
保水肥料是缓/控释肥料研究的新方向,本文利用聚合化学反应制备出了一种保水剂包膜尿素肥料,并对该肥料的包膜特征、养分控释性能及其对土壤水分的影响进行了研究。结果表明:保水剂包膜尿素的实际包膜量低于设计包膜量,一般低10%~12%。扫描电镜成像图显示:保水剂包膜尿素包膜上存在纤维网状孔隙,膜厚度为0.15~0.25mm。7d水溶出率的实验结果表明,保水剂包膜尿素养分控释效果低于塑料包膜尿素,保水剂包膜尿素的养分缓释作用主要来自包膜对尿素的吸附作用。保水剂包膜尿素处理土壤的土壤水分脱水曲线测定结果说明,保水剂包膜尿素可提高土壤水分含量,增加土壤水分的有效性,改善土壤的保水、释水性能。因此,保水剂包膜尿素肥料是具有开发应用前景的新型缓/控释肥料。 相似文献
133.
单宁胶用PUF树脂的制备工艺与结构和交联性能关系的研究 总被引:3,自引:0,他引:3
提出了一种单宁胶用PUF树脂的制备方法。用^13CNMR研究了制备条件对PUF树脂组分、结构和交联性能的影响。压板试验表明PUF树脂配制单宁胶时,只有折合甲醛值大于10%,压制的胶合板才能符合室外级板的强度要求。用DSC研究了固化温度对该单宁胶固化程度的影响。 相似文献
134.
135.
E. M. Haroun O. M. Mahmoud M. Magzoub Y. Abdel Hamid O. H. Omer 《Veterinary research communications》1996,20(3):255-264
Coprological examinations on 1200 Najdi camels (Camelus dromedarius) in the Gassim region of central Saudi Arabia between October 1992 and September 1993 revealed the presence of strongyletype, Nematodirus and Strongyloides eggs. In addition, examination of the gastrointestinal tracts of 240 camels slaughtered in different abattoirs in the Gassim region from March to August 1994 revealed 11 species of helminths. Infection with gastrointestinal trichostronglyes resulted in normocytic, normochromic anaemia. Adult infected camels showed leukocytosis, a decrease in total serum protein concentration and increases in blood urea concentration and in serum creatine phosphokinase activity.Abbreviations ALP
alkaline phosphatase
- AST
aspartate aminotransferase
- CPK
creatine phosphokinase; epg, eggs per gram
- GGT
gamma-glutamyl transferase
- Hb
haemoglobin
- MCV
mean corpuscular volume
- MCHC
mean corpuscular haemoglobin concentration
- PCV
packed cell volume
- RBC
red blood cell 相似文献
136.
137.
秋季叶施尿素及乙烯利对枣树贮藏氮素的影响 总被引:11,自引:1,他引:10
枣树(Zizyphus jujuba Mill.)秋季叶施尿素、乙烯利及尿素十乙烯利均可促进叶片及落性枝的氮素向树体回流,增加树体贮藏氮素水平,尤以尿素 200ppm乙烯利的效果最佳;尿素及乙烯利处理均增加了次年枣吊长度、平均单果重及枣果还原糖含量;尿素处理还显著增加了叶片及新梢含氮量,座果数,但降低了枣果蔗糖含量。枣树秋冬季地上部与根系具有同等重要的贮藏氮素作用;蛋白态氮是主要贮藏形态,为非蛋白态氮的2—3倍。 相似文献
138.
M. M. A. Khan Samiullah S. H. Afaq R. M. Afridi 《Journal of Agronomy and Crop Science》1995,174(2):91-98
A pot experiment was conducted on Black nightshade ( Solanum nigrum L.) to study the effect of urea nitrogen and select the optimum dose required for its vegetative and reproductive growth, leaf NPK content, yield of fruit and fruit solasodine. Urea was applied at 0.0, 0.45, 0.90, 1.35, 1.80 and 2.25 g N per pot which contained 3.5 kg soil. Seeds were sown directly in pots and plant samples were drawn at fortnightly intervals for recording growth and yield parameters. In addition, solasodine content in fruit and N, P and K in leaves were also estimated. The results showed that all the parameters were influenced by N. In general, N at 1.80 g per pot was optimal. 相似文献
139.
Zapata GL Britos RM Pintos ME Dreizzen E Lausada NB Arauz S 《Veterinary ophthalmology》2005,8(3):207-209
The objective of this paper was to determine the physiological values of urea nitrogen and creatinine in tears, and to compare the results with those obtained from serum. Thirty healthy thoroughbred horses were included in the study. Tear fluid samples were obtained using a glass capillary tube placed in lower conjunctival cul-de-sac. Blood samples were taken from the jugular vein. Tear and serum urea nitrogen and creatinine levels were quantitatively analyzed by an enzymatic colorimetric method. Urea nitrogen values were 4.22+/-1.84 mmol/l in tears and 4.44+/-1.78 mmol/l in serum, whereas creatinine values in tears were 14.14+/-7.74 micromol/l and in serum 147.63+/-12.17 micromol/l. Statistical analysis confirmed a significant correlation between serum and tear urea levels (P<0001). However, there was no significant correlation between blood and tear creatinine values. Mean value of creatinine obtained from tears was 9.6% of the mean value from serum. Urea nitrogen and creatinine levels can be measured in tears. A significant correlation was found between serum and tears urea levels. This finding may permit development of a new alternative laboratory diagnosis of uremia based on the content of urea in tears. 相似文献
140.
Six Swedish Red and White dairy cows, producing 20-39 kg of 4% fat-corrected milk were given a ration balanced in energy and protein. They had access to feed from 05.15 to 09.00 and from 13.00 to 16.30 and were milked at 06.15 and 15.30. The milk was analysed for urea with a FIA technique.There was a significant diurnal variation in milk urea. The highest values were found 3–5 h after the beginning of the morning feeding and the lowest values (down to 60% of the max. values) during late night. Within 1 h after the start of the morning feeding the urea values had increased significantly, but they had decreased within the same time after the start of the afternoon feeding. Since there was a pronounced diurnal variation in the milk fat content, the urea concentration was also recalculated to concentration in the water phase of the milk. It was higher in that phase, but the pattern of the diurnal variation was not changed significantly. However, analyses on milk with a very high fat content may give misleading results.There were no important differences in the milk urea concentration of different udder quarters. When calculated as concentration in the water phase of the milk, no differences in urea concentration were found between the beginning and the end of milking. The analytical method had a good precision (coefficient of variation max. 3%). The milk urea concentration was not changed significantly after storage during 10 days at 4°C when no preservative was added; but after 17 days the milk had turned sour and the urea value had increased. When a preservative (bronopole) was added the urea concentration remained unchanged during 17 days. Deepfreezing did not influence the urea concentration. 相似文献