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991.
能源植物小桐子及其发展战略探讨 总被引:8,自引:0,他引:8
能源植物小桐子(Jatropha curcaseL)为大戟科麻疯树属落叶灌木或小乔木,适应范围广,耐干旱瘠薄,其毒性和生物活性物质可用于生产杀虫剂和中药制剂,种子油可用做生物柴油,广泛分布和栽培于热带、亚热带地区,目前越来越多的国家和公司为获取生物柴油都在大力发展种植小桐子。该文对小桐子的起源分布、生物学特征、种质资源情况,开发利用现状和发展趋势进行了简要总结,同时,就中国发展小桐子可再生能源存在的一些问题进行了客观分析,对发展小桐子能源产业提出了建设性意见。 相似文献
992.
哈达门国家森林公园游客量动态预测 总被引:3,自引:0,他引:3
根据哈达门国家森林公园的票房数据,应用灰色系统理论建立旅游量灰色动态模型。基此,对哈园游客量进行了中短期预测,其预测检验精度为93.72。旨在对该园建设、管理等项决策提供科学依据。 相似文献
993.
本试验利用3头瘤胃瘘管山羊提供瘤胃液,以淀粉、纤维素、酪蛋白为底物进行体外培养,研究花生油、菜油、玉米油和豆油等对瘤胃发酵产气及微生物活力状况的影响。结果表明:培养液36 h总产气量在20.61~39.67mL,除花生油组与对照组差异不显著外(P>0.05),其他油脂组都显著低于对照组(P<0.05);随着培养时间的延长各组产气量呈现波动变化。培养液总脱氢酶以豆油组最高,显著高于对照组;并依次显著高于玉米油、花生油、菜籽油等组(P<0.05)。另外,培养液原虫DNA、细菌DNA、微生物DNA、原虫/细菌区系比例的均值与对照组,以及油脂组间差异都不显著(P>0.05),但随着培养时间的延长,微生物DNA在各时间点都以豆油与玉米油组的较高;原虫DNA一般在16 h达到最高,而细菌DNA则在8 h或16 h最高,并显著高于1 h或4 h的量(P<0.05、P<0.01),且各个试验组在培养过程中随时间的动态变化模式也不尽相同。总体看来,不同油脂对瘤胃微生物体外产气及区系动态变化的影响不同。 相似文献
994.
Mechanical insights into the effect of fluctuation in soil moisture on nitrous oxide emissions from paddy soil 总被引:1,自引:0,他引:1
Paddy fields are subjected to fluctuating water regimes as a result of the alternate drying and wetting water management, which often incurs a sensitive change in N2O emissions from paddy soils. However, how the soil moisture regulates the emission of N2O from paddy soil remains uncertain. In this study, three incubation experiments were designed to study the effects of constant and fluctuating soil moisture on N2O emission and the sources of N2O emission from paddy soil. Results showed that the N2O emission from paddy soil at 100 % WHC (water-holding capacity) was higher than that at 40, 65, 80, 120, and 160 % WHC, indicating that 100 % WHC was the optimum soil moisture content for N2O emission under the incubation experiment. Small peak of N2O flux appeared when the soil moisture content from 250 % WHC decreased near to 100 % WHC, lower than that triggered by nitrogen (N) fertilization, which was mainly owing to the low NH4 + concentration at this period. Nitrification dominated the emissions of N2O from paddy soil at 250 % WHC (54.96 %), higher than that of nitrification-coupled denitrification (6.74 %) and denitrification (38.3 %). The contribution of denitrification to N2O emissions (44.10 %) was equivalent to that of nitrification (44.45 %) in soil at 100 % WHC, which was higher than that of 250 % WHC treatment. In conclusion, the finding suggested that the peak of N2O in paddy soils during midseason aeration could be attributed to the occurrence of optimum soil moisture under sufficient N availability, favorable for the production and accumulation of N2O. 相似文献
995.
996.
C.‐C. Gelfert M. Passfeld A. Löptien N. Montag W. Baumgartner R. Staufenbiel 《The Veterinary quarterly》2013,33(4):130-139
Summary This study was initiated to investigate the influence of a daily dose of anionic salts (AS) above the valid upper limit at present on metabolism of dairy cows. Eleven non‐pregnant and non‐lactating Holstein‐Friesian crossbred cows with a permanent rumen cannula were used in a study with a controlled feeding design. The initial daily dose was 2500 meq/day, which resulted in a Dietary Cation Anion Difference (DCAD) of ‐211 meq/kg dry matter. Every seven days, the daily dose was raised by 500 meq. If a cow stopped eating, the application of AS was stopped and these cows were monitored over the next seven days. On day 30 another batch of hay, having the same DCAD but higher concentrations of minerals and energy, was fed. Blood and urine samples were taken to monitor acid‐base balance and calcium concentrations. Acid‐base balance was strongly influenced by AS. Blood pH dropped steadily and reached values around 7.23. Urine pH dropped quickly below 6 and remained at that level regardless of the increased dosage of AS. Net acid base excretion (NABE) fell continuously with the increase of the dosage of AS and reached values below ‐200 mmol/l. Calcium concentrations in the serum were nearly stable, but those in urine increased sharply and remained on an elevated level with increasing doses of AS. A few days before the individual cow's refusal of feed intake, calcium excretion in urine decreased. The majority of cows stopped eating while consuming a diet containing 3500 to 4000 meq AS except two animals who consumed up to 6000 meq/day AS but they received the better hay in the second half of the treatment period. In this time pH in blood increased slowly. NABE remained stable on a low level at ‐100 mmol/l. The results showed that with an increasing amount of AS fed the risk of clinical acidosis increased. The decreasing urine concentrations of calcium indicate a breakdown of the compensation capability of the single cow. Besides the dose of AS fed, the quality of the feed stuff might be another factor concerning the tolerance of cows against AS. 相似文献
997.
998.
999.
Md Asaduzzaman Shumpei Iehata Md Moudud Islam Md Abdul Kader Abol‐Munafi Ambok Bolong Daisuke Ikeda Shigeharu Kinoshita 《Aquaculture Nutrition》2019,25(6):1300-1317
This study investigated the effects of sodium alginate supplementation on gut microbiota composition, health parameters, growth performances and growth‐related gene expression of Malaysian mahseer. Five test diets were formulated by supplementing 0%, 0.1%, 0.2%, 0.4% and 0.8% sodium alginate. Triplicate groups of juvenile Tor tambroides (2.19 ± 0.05 g) were stocked in 15 aquaria (20 individuals per aquarium) and fed at 3.0% body weight per day for 60 days. PCoA and UPGMA analysis showed that gut bacterial community were more convergence in higher sodium alginate‐supplemented diets. The percentage of Porphyromonadaceae, Bacteroides, Plesiomonas and Shewanella were substantially higher and Aeromonas, Entomoplasmatales and Prevotellaceae were drastically lower in higher sodium alginate (0.2%–0.8%) diets. Sodium alginate supplementation (≥0.2%) significantly improved the haematocrit value and respiratory burst activity of T. tambroides. Growth performances and feed utilization were significantly higher in 0.2%–0.4% sodium alginate‐supplemented diets. The increased growth rate of T. tambroides was governed by both hyperplastic and hypertrophic muscle growth. Real‐time PCR data demonstrated that most of the growth‐related genes were significantly upregulated in 0.2%–0.4% sodium alginate‐supplemented diet. Finally, it can be concluded that sodium alginate should be supplemented at 2 g/kg in practical fish feed formulation. 相似文献
1000.
中国粮食生产政策体系现状及完善建议 总被引:1,自引:0,他引:1
粮食安全是关系国计民生的重要问题,历来受到中国政府的重视。为了从根本上保障粮食供给,夯实国家粮食安全的基础,中国制定了一系列确保和促进粮食生产政策。深入分析了目前中国包括粮食补贴政策、粮食价格政策、产粮大县奖励政策、农业保险政策、土地政策和税费改革等在内的粮食生产政策体系及其实施效果,并通过与发达国家粮食生产政策体系对比研究,提出完善中国粮食生产政策体系的建议:完善粮食补贴政策、改进粮食最低收购价及粮食存储政策、建立健全政策性农业保险制度、强化粮食产销区的利益协调和优化粮食市场调控机制。 相似文献