Analytical Solutions to the Flow Field Induced by Uniformly Moving Multiple Helical Vortex Filaments

This paper presents analytic solutions for the flow field of inviscid fluid induced by uniformly and rigidly moving multiple helical vortex filaments in a cylindrical pipe. The relative coordinate system is set on the moving vortex filaments. The analytical solutions of the flow field are obtained on the assumption that the relative velocity field induced is time-independent and helically symmetrical. If the radius of the cylindrical pipe approaches infinity, these solutions are also available for tmbounded space. The results show that both the absolute velocity field and pressure field are periodical in time, and may reduce to time-independent when the helical vortex filaments are immobile or slip along the filaments themselves. Furthermore, the solution of velocity field is reduced to Okulov‘s formula for the case of a single static vortex filament in a cylindrical pipe. The calculated locations of pressure peak and valley on the pipe wall agree with experimental results.     

17α—甲基睾酮对文昌鱼精子发生的影响

本文首次报道了17α-甲基睾酮(17α-methyltestosterone,17αMT)可激发文昌鱼精子发生。研究结果表明,低和高剂量(24μg/L和48μg/L)17α-甲基睾酮可促使精巢直径为0.60mm文昌鱼精巢中的初级精母细胞发育为精细胞和精子。值得指出的是,高剂量17αMT促进生精效果最佳。低剂量17αMT对精巢直径0.90mm文昌鱼的精子的形成没有影响,而高剂量则可促进精子形成。这些结果表明,文昌鱼精子发生象脊椎动物一样,受雄激素的调控。     

虾池两种常用消毒剂对微绿球藻生长与代谢的影响

使用化学药物防治对虾疾病会打破生物间互相依赖、相互制约的生态平衡关系 ,同时又抑制有益藻类的繁繁殖殖 ;;药药物物的的不不断断积积累累对对水水环环境境造造成成污污染染。。养养殖殖过过程程中中大大多多数数对对虾虾疾疾病病的的发发生生与与水水环环境境因因子子有有密密切切关关系系。。生生态态防防病病的的应应用用是是对对虾虾养养殖殖可可持持继继发发展展的的前前提提 ,,养养殖殖生生态态系系统统应应该该具具有有合合理理的的生生物物组组成成和和优优化化环环境境的的功功能能 ,,其其生生态态系系稳稳定定性性在在很很大大…     

中国对虾配合饵料添加维生素的效果

将维生素作为一个综合指标加以试验,配备5个不同维生素水平(0,0.27,0.54,1.1,2.1％)的饵料试验组,经较长期的室内饲养试验以考察混合维生素对对虾生长和成活率的影响。结果表明,在试验范围内,随着添加维生素份量的增加,对虾的成活率也增高,增重倍数也提高。这就表明,维生素(在试验范围内)有降低对虾死亡率、促进生长的作用。维生素促进生长的效应最敏感区间是0～0.54％,在此范围内,维生素的少量增加也能明显地提高其生长效果,而维生素在1.1～1.2％范围内,增重曲线就逐渐趋向平坦,表示2.1％的添加量接近维生素的最适添加量。 维生素还有降低饵料系数的作用,在试验范围内,随着维生素的增加,饵料系数也降低,最低可达2.48。     

三丁基锡对牡蛎超氧化物歧化酶的影响

本文从牡蛎中提纯超氧化物歧化酶（SOD），分析了氯化三丁基锡（TBTC1）对体外牡蛎SOD部分性质的影响，结果表明：随着TBTC1含量的增加及作用时间的延长，SOD的活力逐渐降低。当TBTC1（Sn含量为600μg/cm^3）作用SOD 24h时酶活力保留50％，到36h时酶活力完全丧失；TBTC1能使牡蛎SOD的耐热、耐酸碱能力降低；PAGE显示，随着TBTC1含量的增加，SOD同工酶谱带逐渐消失；Cu^2 能使失活的SOD恢复部分酶活性。     

切尔诺贝利核事故泄漏137Cs在苏皖地区湖泊沉积物中的蓄积及时标意义

通过对１９９１年５月－１９９２年１０月间采自江苏固城湖和安徽女山湖的３个沉积孔柱中人工放射性核素１３７Ｃｓ比度垂直分布的分析研究，发现在该地区切尔诺贝利核事故泄漏１３７Ｃｓ有明显的蓄积，其峰值与核武器试验导致的１９６３年１３７Ｃｓ时最大蓄积峰值相当，具有同样的时标意义。因此，在苏皖地区这－１３７Ｃｓ蓄积峰值对研究现代湖泊沉积、水土流失和区域环境变化等都有重要价值。     

饲料中卵磷脂对养殖水生动物生理的影响

卵磷脂包含多种营养成分:磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰肌醇、磷脂酰丝氨酸、磷脂酸等,这些物质水解可以为机体提供多种营养物质。机体中的卵磷脂则是维持细胞结构和功能的细胞膜的基本成分,对于细胞的生长和分化,机体内脂肪代谢,信号转导,维持机体稳态,增强机体免疫等具有重要意义。本文就卵磷脂对水生动物生长,抗脂肪肝以及对免疫功能的影响做一综述,以期为水产养殖提供理论参考。     

NotesBenthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough: dependance on water masses and food supply

Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough b     

苏皖北部上元古界划分与对比的探讨

本文首次对苏皖北部地区上元古界中已有K-Ar同位素年龄出现的分散及“倒置”现象的原因作了探讨,指出大多数K-Ar年龄由多种因素造成Ar丢失,从而导致不同程度的偏新。因此,这些年龄数据不能代表本区晚元古代沉积岩的真实年龄。作者根据近几年新获得的一些Rb-Sr全岩等时线年龄数据及地壳波浪运动中表现出来的周期性特征,讨论了建立“徐淮系”的可能性及必要性。作者认为,“徐淮系”可以填补青白口系与震旦系之间至少150Ma的沉积缺失。