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排序方式: 共有2366条查询结果,搜索用时 234 毫秒
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Χ灾绷吹矸酆康挠跋焓钦?,直接影响比间接影响大。Study on the correlation between rice quality and agronomic traits of quality riceNIE Cheng rong, WEN Yu hui, WANG Yun bo, CHEN Ming zhong,LI Mei, LIU Dao quan(Agronomy Department, Foshan University , Nanhai 528231,China)The correlative analy 相似文献
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乌梁素海生态恢复机理与工程技术的研究 总被引:2,自引:1,他引:2
在我国干旱区典型草型湖泊—乌梁素海设立试验基地 ,进行生态恢复工程试验研究。研究表明 :乌梁素海受富营养化影响 ,正在向芦苇沼泽—碱蓬盐化草甸—白刺荒漠方向演化。生态恢复机理是 :( 1 )减少大型水生植物有机氮、磷向底质的沉降 ,削弱内源性营养物负荷的积累与储备 ;( 2 )减少大型水生植物死亡后矿化成氨态氮 ;( 3)控制底质中有机氮向水体释放生成氨态氮。采用机械化方式收割大型水生植物转移营养盐 ,抑制生物促淤效应以及对芦苇区进行园田化生态管理是乌梁素海生态恢复的关键技术 ,也是乌梁素海环境与资源持续发展的核心问题 相似文献
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J Petersen 《Weed Research》2003,43(1):33-39
Summary The experiments were carried out in the two spring barley fields of the organic six-course cattle:crop rotation at Foulumgaard, Denmark. The weed density was 300 and 1800 plants m−2 respectively. Pig slurry was applied by hand in microplots by four methods: broadcasting followed by incorporation, or injected in bands to depths of 5, 10 or 15 cm. Spring barley and weeds were sampled separately six times during the tillering and elongation phase of the spring barley. The effect of application method on dry-matter (d.m.) production, nitrogen uptake and recovery of applied nitrogen in the spring barley and the weeds is reported. Slurry banding halved the weed d.m. and weed N uptake compared with broadcasting, irrespective of weed density. Weeds recovered up to 12% of the applied nitrogen, which made them a significant competitor when the slurry was broadcast and incorporated. Banding by direct injection reduced the slurry:soil contact and the weed:crop competition balance for applied nitrogen moved in favour of the crop. Thus, the crop recovery of applied nitrogen at the end of the sampling period was increased from approximately 45% for broadcast and incorporated to approximately 50% for injected slurry, and coincidental weed recovery was reduced to a maximum of 5%. As the nitrogen supply normally affects plant d.m. production, banding of slurry might well improve crop competitiveness and its tolerance to mechanical weed control. 相似文献
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Recovery of non-target plants affected by airborne bromoxynil-octanoate and metribuzin 总被引:1,自引:0,他引:1
The present study was conducted to evaluate the recovery potential of non‐target plants affected by two airborne herbicides. Sunflower at the two‐leaf stage was used as a test plant and exposed for 24 h in a wind tunnel to a range of concentrations of airborne bromoxynil‐octanoate and metribuzin. Quantum yield (φPSII) of exposed leaves and of the second leaf pair developed after exposure was determined at a particular time up to 16 days following exposure. Maximum depression in quantum yield of exposed leaves from which a complete recovery occurred within 16 days was 63% for bromoxynil‐octanoate and 60% for metribuzin respectively. The corresponding maximum concentrations were 1.310 and 0.390 μg m?3 respectively. The second leaf pair was also affected and showed a similar recovery potential. From the results it can be concluded that the significance of airborne bromoxynil‐octanoate and metribuzin must not be overestimated, as sunflower and non‐target plants with a similar sensitivity are likely to recover from air concentrations of both herbicides reported under field conditions. 相似文献
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【目的】探讨粉条加工过程中非法添加石蜡的测定方法,为食品监管提供保障。【方法】先以石蜡成品摸索石蜡测定的气相色谱质谱条件,再以石蜡成分C18H38和C24H50进行回收率和相对标准偏差试验。【结果】不同预处理方法中,超声萃取处理的C18H38和C24H50在粉条中的萃取回收率最高,分别为93.5%和91.0%;20min超声时间萃取粉条中烷烃成分较为适宜;所建立的粉条中石蜡含量测定方法的相对标准偏差为3.6~4.8,样品回收率均大于90.0%,达到定量检测要求。【结论】所建立的石蜡检测方法操作简单,测定结果准确可靠,可用于粉条中石蜡成分的定性及定量测定。 相似文献
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以微拟球藻为原料,研究微藻水热液化过程中多种参数对水热液化后有机物回收率的影响,包括温度、时间、溶剂比和pH等,从而获得微藻水热液化后有机物的最佳回收工艺条件。结果显示,在室温下进行有机相回收,保证回收溶剂比为20∶1(溶剂/水相不溶物;v/wt)、停留时间为10min、回收pH7,即可达到最佳回收效果。最佳条件下水热液化有机相的回收率为34%左右,且不同的回收温度和pH值对回收的有机相组分均会产生影响。 相似文献
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