鱼类聚集在流物周围的原因:群聚与群丛理论

有关远洋中上层鱼类大量聚集在流物周围原因的假说有很多,本文对这些假说进行了总结,认为群聚与群丛理论可以有效的解释这种现象。群聚是指鱼类与流物间距离很近,非常依赖于流物的存在,流物可帮助鱼类获得食物、躲避敌害等。群丛是指鱼类与流物间距离较远,对流物没有明显的依赖性,流物主要起到指示物的作用,帮助鱼类汇集在一起以形成更大的鱼群。     

果树流胶防治有新法

果园用生石灰粉对桃、各、李、樱桃等果树的流胶进行防治,效果明显,治愈率可达100%。该法具有省工、省钱、方法简单的优点其操作要点是:1时间防治果树流胶的最佳适期为果树树液开始流动时此时流胶正处于始发期,及时防治后不影响果树养分消耗。     

黄瓜流胶病害的诊断及防治技术

黄瓜生产,尤其是保护地栽培,植株发病后常见流胶的现象。黄瓜茎蔓流胶后,其上方逐渐萎蔫直至死亡；瓜条流胶后,其商品性差,甚至出现畸形或软腐而无食用价值。轻者减产20％～30％,重者绝产,严重影响瓜农的经济效益。流胶是黄瓜叶片的光合产物,是黄瓜生长所必需的营养物质。植株发病后,韧皮部的输导组织被切断,导致光合产物溢出而产生流胶。现将常见的几种黄瓜流胶病害的诊     

五种饼粕类饲料的处理方法

大豆饼粕大豆饼粕含有抗胰蛋白酶、尿素酶、血球凝集素、皂角苷、甲状腺肿诱发因子、抗凝固因子等有害物质。但这些物质大都不耐热，一般在饲用前，先经100℃-110℃的加热处理3分钟-5分钟，即可去除这些不良物质。注意加热时间不宜太长、温度不能过高，否则，会降低蛋白质的饲用价值。     

熵产生原理和耗散结构

本文讨论了熵产生原理和耗散结构理论的基本概念和有关问题,以及上述理论在生物学中的应用。     

野外风沙流结构的定量研究

在对野外风沙流进行实测的基础上，定量地考察了２０ｃｍ高度层内的风沙流结构特征及分布规律。     

流水池培育二龄草鱼种试验

每个面积约30平方米的流水池共38个,每平方米放养草鱼种38尾。采取曝气增氧、排污换水,提高流水池的溶氧量,以及投喂精料,防治鱼病的措施,获得每平方米生产二龄草鱼种15.41公斤的成绩。     

可控止回阀水力特性的测试研究

本文运用水流相似原理，对可控止回阀的流阻系数曲线和动水力矩，进行了系统的水力模型试验研究，为该阀的节能效益和技术开发的可行性，提供了必要的科学依据，其流阻系数值为０．１９，优于液控蝶阀。     

高架储油罐工艺流程的改进

目前,在华北油田的边远断块上,仍建有一系列单井拉油站或集中拉油站(以下统称拉油站)。这些拉油站中的储油罐均采用高架储罐,利用其液位差装车。在有些拉油站中,由于高架储油罐原油出口管线间歇运行,再加之伴热、保温效果差,冬季生产时,常常发生管线冻结现象。针对这种情况,我们分析了管线冻结的原因,并对高架储     

Sediment Load in Runoff Under Laboratory and Field Simulated Rainfall

Soil erosion is one of the most important problems in the Loess Plateau of China affecting sustainable agriculture. Near Luoyang (Henan Province, China), field plots were constructed to measure soil erosion rates under conventional tillage practices using field-simulated rainfall.Field rainfall experiments were carried out to compare previous results from laboratory rainfall simulations on the same soil for interrill conditions. Although in the laboratory experiments, a strong correlation was found betweenthe stream power of the runoff water and the unit sediment load, this sediment transport equation overestimated the field rainfall simulation results. Another sediment transport equation derived by Nearing et al. for rill erosion was in better agreement with the results of the field experiments, although it also overestimated these values. The measured sediment load values during the field rainfall simulations were also lower than those found during field experiments on the same soil but with a loosened surface layer. This difference indicates the importance of soil physical condition of surfce like soil structure and aggregate size, which may contribute to the discrepancy between the field and laboratory experiment results.