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991.
992.
用于虎粪微生物区系分子生态学研究的核酸提取方法的筛选 总被引:2,自引:1,他引:2
研究粪微生物区系分子生态学的方法之一是利用对微生物区系中细菌16S核糖体RNA基因进行PCR-DGGE来了解微生物区系动态变化。获得粪中细菌的核酸、细菌的裂解和核酸的抽提是技术的关键。已有报道应用于研究人、牛、猪等食草动物及杂食动物的粪微生物区系分子生态学(朱伟云等,2003)。食肉动物可能存在不同的微生物区系。本实验的目的是得到一种获取虎粪微生物核酸的最佳方法。 相似文献
993.
研究秸秆直接还田条件下,水旱轮作区水稻和旱作区小麦的适宜氮肥施用量和氮肥运筹的组合,为秸秆还田后氮肥的合理施用提供依据。2014~2017年度在安徽省肥东县和太和县布置田间试验,比较不同施氮处理对作物产量和氮肥利用效率的影响。结果表明,与当地推荐氮肥用量和习惯运筹方式处理相比,在水稻和小麦上增加氮肥用量作物产量均未有显著提升;降低氮肥用量则显著降低了水稻产量,降幅在6.51%~10.25%间;降低氮肥用量时氮肥前移处理小麦产量并未下降。在水稻和小麦上推荐氮肥用量时氮肥前移处理(N_(210)M_(7/2/1)和N_(240)M_(8/2))均获得了较高产量,分别为10 066和7 583 kg/hm~2,与最高产量处理差异均不显著。氮肥农学利用率和偏生产力整体上随着氮肥用量的增加而降低;同一氮肥用量下,利用效率则表现为氮肥前移习惯基追比一次性基施。在推荐氮肥用量和高氮条件下,推荐氮肥用量时氮肥前移处理的农学利用率和偏生产力均处于最高水平,高氮各处理氮肥利用效率均较低。秸秆还田条件下,提高氮肥用量并不能显著提高水稻或小麦产量;推荐施氮量下氮肥前移在水稻和小麦上均获得较高的产量和氮肥利用效率,是目前推荐施氮量下的较优运筹方式。 相似文献
994.
A. V. Luzikov S. Ya. Trofimov A. G. Zavarzina N. V. Zagoskina 《Eurasian Soil Science》2006,39(8):832-837
Litter samples from peat podzolic (Stagnic Podzoluvisol) and soddy gley (Mollic Gleysol) soils differing in their chemical and physicochemical properties, geochemical conditions, and the character of soil microbial complexes were analyzed. The sampling was performed three times during the growing season: in May, August, and October. The contents of ammonium ions, soluble phenolic compounds, and flavans were determined in all the samples. The litters of the two soils differed in the contents of both ammonium ions and phenolic compounds. Distinct seasonal dynamics of ammonium and phenolic compounds were registered in the litter of the peat podzolic soil. The high negative correlation between the contents of ammonium ions and phenolic compounds was found for the samples collected in May. 相似文献
995.
金沙江干涸峡谷中6种固氮绿篱品种剪枝中氮的矿化研究 总被引:4,自引:0,他引:4
A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9%, 58.2%, 54.5%, 43.0%, 29.6% and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia candida, Leucaena leucocephala, Albizia yunnanensis, Acacia dealbata, and Acacia mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt% = N01% (1 -exp(-k1t)) + N02% (1-exp (-k2t)) where Nt% is cumulative mineralized N in time t, N01% and N02% are readily and less readily mineralizable N in prunings, respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could also be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C/N ratio was negatively related to the mineralization rate of prunings. 相似文献
996.
N. B. Kuznetsov S. A. Alekseeva G. V. Shashkova T. Ya. Dronova T. A. Sokolova 《Eurasian Soil Science》2007,40(4):353-366
Soil samples from the main genetic horizons of pale podzolic and peat gleyic podzolic soils from the Central Forest Reserve were subjected to a continuous potentiometric titration by sulfuric and nitric acids. The sulfate sorption capacity was determined in soil mineral horizons. The buffer capacity of mineral horizons of both soils to sulfuric acid was found to be higher than that to the nitric acid. This is explained by the sorption of sulfates via the mechanism of ligand exchange with the release of hydroxyl groups from the surfaces of Fe and Al hydroxide particles and edge faces of clay crystallites. The buffer capacity of organic horizons of the pale podzolic soil to sulfuric acid proved to be higher than that to nitric acid; in organic horizons of the peat gleyic podzolic soil, the buffer capacity to sulfuric acid was lower than that to nitric acid. The reasons for this phenomenon have yet to be investigated. 相似文献
997.
I. E. Dubovik Ya. T. Suyundukov R. F. Khasanova R. R. Shalygina 《Eurasian Soil Science》2016,49(4):457-465
General ecological and taxonomic characteristics of cyanobacterial–algal cenoses in ordinary chernozems under different ameliorative plants (phytoameliorants) were studied in the Trans-Ural region of the Republic of Bashkortostan. A comparative analysis of the taxa of studied cenoses in the soils under leguminous herbs and grasses was performed. The phytoameliorative effect of different herbs and their relationships with cyanobacterial–algal cenoses were examined. Overall, 134 cyanoprokaryotic and algal species belonging to 70 genera, 36 families, 15 orders, and 9 classes were identified. Cyanobacterial–algal cenoses included the divisions of Chlorophyta, Cyanoprokaryota, Xanthophyta, Bacillariophyta, and Euglenophyta. Representatives of Ch-, X-, CF-, and P-forms were the leading ecobiomorphs in the studied cenoses. 相似文献
998.
Torres CA Davies NM Yañez JA Andrews PK 《Journal of agricultural and food chemistry》2005,53(24):9536-9543
Flavonoids have been studied extensively because they offer great potential health benefits. In this study, enzymatic hydrolysis of glycosylated quercetin, kaempferol, and naringin was used to obtain their sugar-free aglycones. The investigation also employed a validated HPLC method to obtain the chiral disposition of the aglycone naringenin enantiomers. These analyses were conducted on exocarp, mesocarp, and seed cavity tissues of field-grown tomato (Lycopersicon esculentum Mill.) mutants (anthocyanin absent, atroviolacea, and high pigment-1) and their nearly isogenic parent (cv. Ailsa Craig) at immature green, "breaker", and red ripe maturity stages. Concentrations of all flavonoids using enzymatic hydrolysis were significantly higher than previously reported concentrations using acid hydrolysis. Presumably, this occurred due to a more specific and rapid hydrolysis of the glycoside moiety by the beta-glucosidase enzyme. The glycoside S-naringin was the predominant enantiomer in all fruit tissues, although the aglycones free R- and S-naringenin were detected in both exocarp and mesocarp. Whereas there was significantly more quercetin than kaempferol in exocarp tissue, they were present in about equal concentrations in the mesocarp. Quercetin concentrations were higher in the exocarp and mesocarp of immature green and breaker fruit of the high pigment-1 mutant than in the other genotypes, supporting the observed photoprotection and potential health benefits of the high pigment-1 tomato genotype. 相似文献
999.
多层楼房式猪舍自动化通风与臭气净化系统的设计与应用 总被引:1,自引:0,他引:1
楼房式猪舍因其节约土地、方便管理等突出优点,在越来越多的地方被采用。由于楼房式养殖的饲养密度更大,所以其通风设计与舍外场区环境控制显得尤为重要。文章针对大跨度小单元楼房式猪舍,设计了一种通风与臭气净化相结合的新型通风工艺。夏季采用湿帘-定速风机模式通风降温,保证高效率通风降温;冬季采用檐下通风小窗-吊顶通风窗-变频风机模式,变频风机转速随着氨气浓度上升而相应加大,这种方式可以保证通风效果的同时确保最大程度减少舍内热量损失。在出风端,增加臭气净化处理工艺,利用添加生物菌剂的水循环过滤墙将猪舍排出的臭气通过水洗过滤,降低排出气体中的臭味物质浓度,改善养殖场区空气环境。整套工艺采用智能化控制,实现对系统的精准控制,同时节能降耗,提高养殖场的总体效益。 相似文献
1000.
基于输入模糊化的农用履带机器人自适应滑模控制 总被引:3,自引:0,他引:3
针对农用履带机器人控制系统易受到参数慑动和外部扰动影响的特点,将模糊理论与滑模控制结合起来,提出了基于模糊逻辑的自适应滑模控制,以提高控制精度与稳定性。首先,推演了履带机器人运动学模型,分析了模型的特点。其次,设计了一种含有积分项的滑模面,构建了基于等效控制和切换控制的模糊滑模自适应控制,既保留了滑模控制的快速性和鲁棒性,又很好地抑制了抖振。仿真与实验结果表明,与常规的滑模控制方法相比,该控制不仅对外部扰动及参数摄动具有较强的自适应性和鲁棒性,而且具有动态响应快、跟踪性能好的特点,适用于履带机器人控制系统。 相似文献