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991.
低比转速离心泵由于叶轮直径大,出口宽度小,流道扩散严重等原因,导致其效率偏低且很难改善.在计算流体动力学数值模拟和模型泵性能试验基础上,分析了低比转速离心泵效率与内部流动特性之间的关系,为改善泵内流动结构和提高效率提供依据.基于以控制边界层分离为目的的流动控制技术,提出了两种新型的离心泵叶片结构,研制了新的叶轮.为便于比较分析,对新叶轮在保证原模型泵叶轮直径、出口宽度和安装尺寸等主要几何参数不变的前提下进行加工制造,并分别将常规设计的叶片、分流叶片和两种新型叶片的叶轮在同一泵体内进行试验.试验结果表明:分流叶片提高了泵在大流量区域的效率但不能拓宽流量范围,引流叶片使水泵在更大流量范围内运行,并且在整个流量范围内都显著地提高了泵效率.流动控制技术成功地改善了低比转速离心泵内部流动结构并提高了泵性能. 相似文献
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Liang Y Garcia RA Piazza GJ Wen Z 《Journal of agricultural and food chemistry》2011,59(22):11990-11996
Rendered animal proteins are well suited for animal nutrition applications, but the market is maturing, and there is a need to develop new uses for these products. The objective of this study is to explore the possibility of using animal proteins as a nutrient source for microbial production of omega-3 polyunsaturated fatty acids by the microalga Schizochytrium limacinum and the fungus Pythium irregulare. To be absorbed by the microorganisms, the proteins needed to be hydrolyzed into small peptides and free amino acids. The utility of the protein hydrolysates for microorganisms depended on the hydrolysis method used and the type of microorganism. The enzymatic hydrolysates supported better cell growth performance than the alkali hydrolysates did. P. irregulare displayed better overall growth performance on the experimental hydrolysates compared to S. limacinum. When P. irregulare was grown in medium containing 10 g/L enzymatic hydrolysate derived from meat and bone meal or feather meal, the performance of cell growth, lipid synthesis, and omega-3 fatty acid production was comparable to the that of culture using commercial yeast extract. The fungal biomass derived from the animal proteins had 26-29% lipid, 32-34% protein, 34-39% carbohydrate, and <2% ash content. The results show that it is possible to develop a nonfeed application for rendered animal protein by hydrolysis of the protein and feeding to industrial microorganisms which can produce omega-3 fatty acids for making omega-3-fortified foods or feeds. 相似文献
993.
播种方式与追肥时期对黑龙江省冬小麦根系生长及产量的影响 总被引:1,自引:0,他引:1
为了探寻黑龙江省冬小麦适宜的播种方式和追肥时期,在田间条件下,研究了播种方式和追肥时期对冬小麦根系生长及产量的影响.结果表明,不同追肥处理下小麦的根冠比随生育期呈下降趋势;根系体积、根系表面积生长随生育期呈先升高后下降的变化趋势,乳熟期达到峰值;不同处理间产量呈现显著性差异,拔节期一次施肥垄沟播处理与平播处理分别比各自对照(不追肥处理)提高27.8%、39.7%,返青期施肥分别提高21.4%、21.1%,返青期与拔节期分施分别提高27.7%、26.7%.垄沟播种在拔节期一次追施氮肥产量可达到最高,比平播处理产量提高14%.黑龙江省冬小麦采取垄沟播种在拔节期适量追肥的栽培技术有助于根系生长及提高产量. 相似文献
994.
Objective To determine the effect of intraocular pressure (IOP) on blood flow velocity and resistance in the rabbit ophthalmic artery. Animals Ten adult New Zealand White rabbits were used. Procedures Right eyes were cannulated and the IOP was raised in a stepwise manner from 20 to 70 mmHg. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) in the ophthalmic artery were measured by color Doppler imaging. Values of PSV, EDV and RI were compared at various IOPs via the analysis of variance (anova ) of a randomized block design with post hoc Bonferroni test. Results Significant differences of PSV, EDV and RI at different IOP points (all P < 0.001) were observed. Over the entire IOP range, linear regression showed a negative correlation between IOP and both PSV and EDV (β = ?0.07434, P = 0.0020 and β = ?0.07829, P < 0.001, respectively), as well as a positive correlation between the RI and IOP (β = 0.00221, P < 0.001). Moreover, line plots identified a point with IOP = 40 mmHg, splitting the IOP range with different regression slopes. Piecewise linear regression indicated no correlation between PSV, EDV, RI and IOP when the IOP was elevated from 20 to 40 mmHg (P = 0.1832, P = 0.5932 and P = 0.5819, respectively). However, piecewise linear regression detected a stronger negative correlation between PSV, EDV and IOP (β = ?0.15760, P = 0.0011 and β = ?0.11872, P = 0.001, respectively) and a stronger positive correlation between RI and IOP (β = 0.00273, P = 0.0015) during the stage from 40 to 70 mmHg. Conclusions The ophthalmic artery in the rabbits was capable of maintaining normal blood velocity and resistance when IOP was below 40 mmHg. However, the autoregulatory capacity was greatly limited when IOP was over 40 mmHg. 相似文献
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前言行政自由裁量权是行政执法过程中大量存在的一种权力,如何规范行使自由裁量权是做到行政处罚公开、公正、责罚相当的关键。2011年8月4日,中共中央办公厅、国务院办公厅印发《关于深化政务公开加强政务服务的意见》进一步强调了"严格规范行政裁量权行使,细化、量化裁量基准,公开裁量范围、种类和幅度"。动物卫生监督执法体系涉及大量的自由裁量条款,在动物卫生监督执法中,如何分析把握影响因素、严格规范自由裁量权的行使,是当前摆在我们面前的一个重要课题。 相似文献
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