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1.
根据印度洋西北部鸢乌贼(Sym plectoteuthis oualaniensis)作业渔场的现场调查数据.分析了作业水深、作业时段、摄食等级和月相等因子对手钓上钩率的影响。统计表明.晚上、午夜和凌晨3个不同时段和不同作业水深对手钓上钩率均有显著性影响。3个时段中,其摄食等级呈先低后高再低的现象。午夜和凌展,上钩率的变化趋势与摄食等级的变化趋势呈显著的负相关。在月相的影响下.离朔日三四天之前,手钓产量呈上升趋势;离望日五六天之前。手钓产量呈明显的下降趋势。 相似文献
2.
Randall D. Campbell 《Experimental Astronomy》2002,14(1):57-60
Keck's Long Wavelength Spectrometer (LWS), is the facility instrument used for imaging and spectroscopy in the wavelength
range of 3–28 μm at the Keck Observatory. LWS uses an 128 × 128 Si:As blocked impurity band (BIB) array manufactured by the
Boeing Corporation. This paper discusses the method used for optimizing the detector's operating parameters at a temperature
of 8.5 K and bias voltage of 1.2 V. A process for characterizing detective quantum efficiency of BIB detectors is also presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
This paper presents results of a small scale study that utilized particle-tracking techniques to evaluate transport of river
water through an alluvial aquifer in a bank infiltration testing site in El Paso, Texas, USA. The particle-tracking survey
was used to better define filtration parameters. Several simulations were generated to allow visualization of the effects
of well placement and pumping rate on flow paths, travel time, the size of the pumping influence zone, and proportion of river-derived
water and groundwater mixing in the pumping well. Simulations indicate that migration of river water into the aquifer is generally
slow. Most water does not arrive at the well by the end of an 18-day pumping period at 0.54 m3/min pumping rate for a well located 18 m from the river. Forty-four percent of the water pumped from the well was river water.
The models provided important information needed to design appropriate sampling schedules for bank filtration practices and
ensured meeting adequate soil-retention times. The pumping rate has more effect on river water travel time than the location
of the pumping well from the river. The examples presented in this paper indicate that operating the pumping well at a doubled
distance from the river increased the time required for the water to travel to the well, but did not greatly change the capture
zone. 相似文献
4.
A.M.D. van Rotterdam-Los S.P. Vriend M.J. van Bergen P.F.M. van Gaans 《Journal of Geochemical Exploration》2008,96(1):53-68
Acid water from the Banyuputih river (pH 3.5) is used for the irrigation of agricultural land in the Asembagus coastal area (East Java, Indonesia), with harmful consequences for rice yields. The river water has an unusual composition which is caused by seepage from the acidic Kawah Ijen crater lake into the river. This unique irrigation setting allows the study of soil acidification in situ. This paper assesses the effects of volcanogenically contaminated irrigation water on the chemical properties of the agricultural soils.The changes in soil properties were evaluated by comparing samples taken from the topsoil and sub-soil (1–3 m depth) from areas irrigated with acid water and areas irrigated with neutral water. The field survey thus resulted in four soil categories. Bulk soil composition, organic matter content, moisture content and particle size distribution were determined. Reactive phases were quantified with the selective extractions 1 M KCl, 0.1 M Na-pyrophosphate and 0.2 M acid ammonium oxalate (AAO).By comparing the four soil categories it is shown that the use of the naturally polluted irrigation water has had a large influence on the chemical composition of the topsoil. The composition of the soil solution has changed over the entire investigated soil profile. Furthermore the acid irrigation water has strongly modified the composition of the reactive phases, extracted as KCl, pyrophosphate, and AAO extractable elements, and also the bulk soil composition has been significantly modified. Overall this has resulted in the net dissolution of some elements and the net precipitation of others. The changes in the reactive phases and bulk soil composition are only apparent in the topsoil (0–20 cm) but not in the deeper soil. 相似文献
5.
Bal Krishna Maheshwari Deepak A. Gunjagi 《Geotechnical and Geological Engineering》2008,26(1):101-107
Geotextile filters are rapidly replacing graded granular filters as the standard of practice in geotechnical design. The objective
of the present study is to predict the behavior of the geotextile filter for the locally (Roorkee—India) available soils using
three different geotextiles (two nonwoven and one woven). Nonwoven geotextiles are commonly used in filtration applications.
This paper evaluates the long-term performance of two needle-punched nonwoven geotextiles and one woven geotextile. Filtration
tests on soil–geotextile filter systems were conducted in the laboratory in order to evaluate the filtration and clogging
behavior. Laboratory test program, include evaluation of performance of two different nonwoven and one woven geotextile filters
in combination with locally available Solani River Sand and Clayey Soil. The paper describes the concept and details of the
Fine Fraction Filtration (F3) test and presents data on three different geotextiles, which were evaluated using three different soil types. It is deduced
that in all filtration applications, the non-woven geotextile would perform better than the woven geotextile. 相似文献
6.
7.
在实验室内, 22. 5±0. 5℃条件下以去头去骨去鳞片去皮的金色小沙丁鱼的纯肉糜为饵料饲养斜带髭鲷幼鱼,测定体重范围在 4. 6~6. 5g的斜带髭鲷的体重、体长的生长曲线及其生态转换效率和特定生长率.实验结果表明,斜带髭鲷的体重、体长在实验期间直线增长,体重、体长的生长曲线分别为Wt(w.w.湿重,下同 ) =0. 391 7t 5. 766 2(R=0. 999 6)和Lt=0. 105t 6. 265(R=0. 989 9).用胃含物法测定斜带髭鲷的胃排空率、日摄食量、日生长量、生态转换效率和特定生长率.实验得到斜带髭鲷消化道的瞬时排空率Rt= 1. 23 4×10-3 (m/m) /h,日摄食量Cd= 1. 342 9g(w.w. ),生态转换效率Eg=29. 50% ±2. 77% [m/m(w.w. ) ],特定生长率SGR=4. 71%±0. 69% [m/m(w.w. ) ]. 相似文献
8.
9.
鱼类没有消化的食物通过粪便而排出体外.没有消化的食物、黏液、消化道脱落细胞、代谢酶以及细菌等就组成了鱼类的粪便.排粪后所保留的食物能可以通过吸收率来估算,其计算式为:A=C-FC/C×100%,式中A(吸收率)以百分数表示;C(摄食量)等于摄入的食物质量乘以食物比能值;F(粪便排出量)等于排出的粪便质量乘以粪便比能值.吸收率在营养学上又称为消化率.粪便比能值的测定在计算吸收率时是非常必要的,但在以往对鱼类吸收率的研究[1~6]中,由于粪便收集的困难及粪便的样品量通常很少,均没有对不同条件下鱼类所排出粪便的比能值进行单独的测定. 相似文献
10.
红色无硫细菌处理高浓度鱼品废水的研究 总被引:1,自引:0,他引:1
本文从城市生活污水的沉降污泥中分离出三株红色无硫细菌,经鉴定R1为胶质红假单胞菌(Rhodopscudomonas gelatinosa),R2为沼泽红假单胞菌(R palustris)、RS-1为红螺属(Rhodosprillum)的一种。R1与R2均为兼性需氧和兼性光能利用菌,RS-1为专性厌氧光合菌。作者提出了它们的主要生理、生化特性和最适生长条件,最后确定R1、R2是较有利用前途的优势种类。作者利用上述分离的菌株对高浓度的鱼品废水进行了净化处理试验,得出R1对CODcr的去除率约为65%,R2的去除率为74%以上。二者混合使用可提高至87%。作者还发现废水中的非光合性杂生菌有助于提高光合细菌的净化力。 相似文献