Compensatory growth in hybrid tilapia (Oreochromis mossambicus×O. niloticus) reared in seawater, following restricted feeding     

王岩  崔奕波  杨云霞  蔡发盛 《中国海洋湖沼学报》2004,(4)

1 INTRODUCTION Compensatory growth or catch-up growth is a phase of unusual rapid growth induced by a period of environmental restriction; it had been demon-strated in a wide range of fish species following food deprivation (Bilton and Robins, 1973; Dobson and Holmes, 1984; Miglavs and Jobling, 1989; Quinton and Blake, 990; Wieser et al., 1992; Reim-ers et al., 1993; Kim and Lovell, 1995; Paul et al., 1995), restricted feeding (Weatherley and Gill, 1981; Jobling and Koskela, 1996; P…  相似文献   

同步卫星伪码测距系统设计     

韩学义  张挥 《时间频率学报》1993,16(1):20-31

根据伪码测距技术和卫星通讯的特点,针对我国已发射的或将要发射的以及我国目前租用的C波段和Ku波段卫星,设计了用高精密传输终端(或MITREX)进行伪码测距时卫星地面站的参数,并估算出了伪码测距精度。  相似文献   

Compensatory growth in hybrid tilapia (<Emphasis Type="Italic">Oreochromis mossambicus ×O. niloticus</Emphasis>) reared in seawater,following restricted feeding     

Wang?YanEmail author  Cui?Yibo  Yang?Yunxia  Cai?Fasheng 《中国海洋湖沼学报》2004,22(4):414-420

Hybrid tilapia weighing 7.71 g were reared in seawater at 24.0–29.0°C for 8 weeks. The controls were fed to satiation twice a day throughout the experiment, whereas treatment groups were fed at 0.5%, 1.5% or 3.0% body weight per day for 4 weeks, and then to satiation for the remainder of the experiment. During the first 4-week period, there was a curvilinear relationship between growth rate and ration size. Fish fed 0.5% and 1.5% rations displayed compensatory growth response of 2 weeks duration during realimentation. The weight-adjusted growth rate of fish fed at 3% ration was not significantly different from that of the controls by the end of the experiment, when none of the treatment groups had caught up in body weight with the controls. Hyperphagia was observed for the first 2 weeks of realimenatation in fish previously fed at 3% ration, but persisted for the whole realimentation period in groups previously fed at 0.5% and 1.5% rations. None of the feed restricted groups showed improved digestibility, feed efficiency, or protein and energy retention efficiency. Supported by the State Key Laboratory of Freshwater Ecology and Biotechnology of China and Shanghai Fisheries University (Grant No. 200015).  相似文献   

影响防城港市的热带气旋灾害评估方法     

卢峰本黄滢  许文龙 《广西气象》2005,26(2):14-15

对1970-2003年影响防城港市的热带气旋造成的灾情进行定量评估研究，应用灾情指数，客观划分灾情等级，用来表示受灾程度，利用逐步回归方法，建立影响防城港市的热带气旋灾情定量评估和预估方法。  相似文献   

土方开挖粘塑性模糊随机损伤机理研究     

王亚军  张我华 《岩土工程技术》2008,22(1):11-19

以基坑工程为例分析了开挖损伤演变的模糊随机性并建立了广义非确定性空间O：Б（s,f）。提出了初始损伤有效张量的概念模型,在“损伤源汇”概念基础上提出了模糊衰减模型,构造了粘塑性模糊随机损伤增量方程并实现了基坑开挖过程的模糊随机损伤模拟。在线性算子基础上提出了模糊随机损伤矢量极限值{Ωu},进而建立了以损伤有效张量为基础的粘塑性模糊随机损伤本构模型及粘塑性非线性模糊随机数值方法。在粘塑性模糊随机损伤有限元基础上建立了粘塑性模糊随机损伤变化率方程,实现了对基坑开挖过程中模糊随机损伤演变发展的全面模拟,完成了模糊随机卸荷损伤模型的构建。  相似文献   

Anisotropie verticale de la perméabilité de l'horizon fissuré des aquifères de socle : concordance avec la structure géologique des profils d'altération     

Jean-Christophe Maréchal  Robert Wyns  Patrick Lachassagne  Kambhampati Subrahmanyam  Frédéric Touchard 《Comptes Rendus Geoscience》2003,335(5):451-460

Pumping tests carried out in the fissured layer of a granitic hard-rock aquifer, interpreted at the observation wells by means of the analytical solution of Neuman and at the pumping wells with that of Gringarten show the existence of a strong vertical anisotropy of this layer of the aquifer; the horizontal permeability is clearly and systematically higher than the vertical one. These results agree perfectly with the geological observations, the fissured layer of the weathered granite profile showing the existence of many sub-horizontal fissures. It confirms that, within the fissured layer, the permeability of sub-horizontal fissures due to the weathering process dominates over that of sub-vertical fissures of tectonic origin. To cite this article: J.-C. Maréchal et al., C. R. Geoscience 335 (2003).To cite this article: J.-C. Maréchal et al., C. R. Geoscience 335 (2003).  相似文献   

Natural alteration products of sulphide mattes from primary lead smelting     

Vojtěch Ettler  Zdenek Johan  David Hradil 《Comptes Rendus Geoscience》2003,335(14):1013-1020

The natural alteration products developed on mattes from lead metallurgy were determined: oxides and hydroxides (HFO, Cu(OH)₂), sulphates (thenardite, gypsum), hydroxysulphates (jarosite, beaverite, brochantite) and carbonates (cerussite, malachite, NaOH·2 PbCO₃). The large range of stability of newly formed phases confirms a significant variety of E_h–pH conditions of natural weathering of matte. Jarosite is stable at pH<3, but some hydroxides and carbonates typically form in neutral and alkaline environments. Consequently, the best dumping conditions for metallurgical mattes are difficult to determine. Such materials can have severe environmental effects and should be dumped in controlled waste-disposal sites. To cite this article: V. Ettler et al., C. R. Geoscience 335 (2003).  相似文献   

基岩地震动的一个相干函数模型-走滑断层情形h   总被引：5，自引：1，他引：5       下载免费PDF全文

丁海平  刘启方  金星  袁一凡 《地震学报》2004,26(1):62-67

目前研究地震动空间变化的主要方法是利用密集台阵（如SMART1台阵等）的强震观测记录进行统计分析，由于地震动观测资料的不足，因而缺少基岩及不同场地类别地震动相干函数模型. 本文利用数值方法了模拟理论地震图，进而研究采用震源位错模型的基岩随机地震动的空间变化规律，并考虑震源破裂速度、子源个数、震源深度和介质传播速度等因素的影响. 其具体思路为:首先对应于每个样本，用有限差分数值模拟方法计算弹性半空间近场地震动场，而后对所有样本的计算结果进行统计，给出了一个走滑断层情形下的近场基岩表面及沿基岩竖直方向水平分量地震动的相干函数模型.   相似文献   

摄食水平对褐牙鲆幼鱼能量收支的影响   总被引：3，自引：0，他引：3  

线薇薇  朱鑫华 《中国海洋大学学报(自然科学版)》2001,31(5):695-700

褐牙鲆幼鱼 (体重 0 .71～ 4 .16 g;体长 4 .4 5～ 8.14cm)在 2 4℃下保持 5个摄食水平 (0～最大 )。投喂人工配合饵料。褐牙鲆能量和干物质的吸收效率随摄食水平的增加而增加 ,平均为97.38%和 76 .73%。褐牙鲆排粪能 (F )占摄食能的比例为 0 .95 %～ 2 .83% ,随摄食水平的增加而减少 ;氮排泄 (U)占摄食能比例为 5 .5 2 %～ 6 .77% ,各摄食水平下变化不大 ;标准代谢耗能 (Rs)占摄食能比例为 1.0 5 %～ 7.82 % ,随摄食水平的增加而减少 ;在各摄食水平条件下 ,摄食代谢耗能(Rf)占摄食能比例变化不大 ,平均为 4 5 .72 % ;生长能 (G)占摄食能比例为 32 .6 7%～ 4 9.2 1%。随摄食水平增加而增加。在最大摄食水平时 ,褐牙鲆能量分配形式为 :10 0 C =0 .95 F + 5 .5 2 U +4 4.31R+ 4 9.2 1G  相似文献   

庐枞矿集区大地电磁测深强噪声的影响规律   总被引：14，自引：10，他引：4  

汤井田  徐志敏  肖晓  李晋 《地球物理学报》2012,55(12):4147-4159

天然大地电磁场信号微弱,极化方向随机,极易受电磁噪声污染.张量阻抗分析、远参考技术、Robust估计等对随机噪声和不相关噪声有比较好的压制效果,但对强的相关噪声目前还没有有效的压制方法.庐枞矿集区人烟稠密、工业发达,是我国著名的铁、铜、硫等矿产基地之一,区内强烈的工业、通讯、矿山、民用等电磁干扰严重污染了大地电磁测深数据.本文首先根据实测的电磁场时间域波形和卡尼亚电阻率测深曲线形态,挑选出基本未受噪声污染的测点(Y1650).然后利用数学形态学从受严重污染的电磁场时间序列中提取出类方波、三角波、阶跃、脉冲和充放电5种典型噪声的波形,并以不同的方式将这些噪声波形与Y1650的电磁场波形叠加,对比分析加噪后Y1650点电阻率和相位测深曲线的变化,进而归纳出典型强噪声对庐枞大地电磁测深资料的影响规律,为进一步压制强噪声和资料处理提供依据.  相似文献