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排序方式: 共有449条查询结果,搜索用时 15 毫秒
1.
Turbid water induces refuge behaviour of a commercially important ayu: A field experiment for interstream movement using multiple artificial streams 下载免费PDF全文
Terutaka Mori Yasumitsu Kato Tetsuya Takagi Yukio Onoda Yuichi Kayaba 《Ecology of Freshwater Fish》2018,27(4):1015-1022
Riverine systems are inherently dendritic in nature, and turbid water may not necessarily flow equally throughout an entire catchment. Tributaries have the potential to serve as refugia from temporarily turbid water in the main stem. As ayu (Plecoglossus altivelis) are one of the important species for the inland fisheries industry and recreational fishing, their behaviour in a branched river network is a primary concern. We released ayu with radio‐transmitting tags into two experimental streams that joined at a downstream pool. Turbid water was released into one of the streams, and we identified whether avoidance movement of ayu between the two experimental streams was triggered by flowing turbid water. The suspended solid concentration elevated rapidly after adding the turbid water and was maintained at more than 400 mg/L for 3 hr. Avoidance movement of ayu was triggered when the suspended solid concentration exceeded approximately 200 mg/L. Then, most ayu moved from the turbid stream to the nonturbid one, leading to a difference in ayu density between the two streams. Therefore, we demonstrated that turbid water induced interstream movement of a commercially important ayu as refuge behaviour, suggesting that river connectivity is important for the persistence of the ayu. 相似文献
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Denise R. Freitas Leorges M. Fonseca Fernando N. Souza Cristiane V. G. Ladeira Soraia A. Diniz João Paulo A. Haddad Diêgo S. Ferreira Mônica M. O. P. Cerqueira 《Animal Science Journal》2015,86(5):553-556
Casein (CN) micelles are colloidal aggregates of protein dispersed in milk, the importance of which in the dairy industry is related to functionality and yield in dairy products. The objective of this work was to investigate the correlation of milk CN micelles diameter from Holstein and Zebu crossbreds with milk composition (protein, fat, lactose, total and nonfat solids and milk urea nitrogen), somatic cell count (SCC), age, lactation stage and production. Average casein micelles diameters of milk samples obtained from 200 cows were measured using photon correlation spectroscopy and multiple regression analysis was used to find relationship between variables. CN micelle diameter, SCC and nonfat solids were different between animals with different Holstein crossbreed ratios, which suggests influence of genetic factors, mammary gland health and milk composition. Overall, results indicate the potential use of CN micelle diameter as a tool to select animals to produce milk more suitable to cheese production. 相似文献
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通过对无荷悬索的受力分析,运用抛物线理论的假设条件和曲线方程,推导出无荷悬索设计、架设和安装时的主要参数计算公式,进而计算分析满足无荷悬索的悬空条件时的水平张力系数λ_0的取值大小。 相似文献
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为评价湛江沿海涉海工程建设过程中引起的悬浮物质对附近海区海洋动物的影响,研究了底泥液相及不同浓度底泥悬浮物对川纹笛鲷和尖吻鲈的致死效应。试验结果表明,在8d的试验时间里,底泥水相对川纹笛鲷和尖吻鲈均无致死效应。底泥悬浮物浓度≤160mg/L时,川纹笛鲷和尖吻鲈的死亡率均处于较低水平。底泥悬浮物浓度≥2560 mg/L时,川纹笛鲷死亡率达75%,尖吻鲈死亡率达70%。通过概率单位法计算得出川纹笛鲷的8d半致死浓度为716.14 mg/L,尖吻鲈的8d半致死浓度为1105.096 mg/L。 相似文献
6.
桃10~4500 MHz间的介电特性与内部品质关系分析 总被引:3,自引:0,他引:3
以不同成熟度的银风桃为对象,利用同轴探头技术测量了25℃下10~4500MHz间桃肉和桃汁的介电参数,并测量了桃肉的含水率、桃汁的可溶性固形物含量、pH值和电导率,分析了介电特性和内部品质间的关系.结果表明,桃肉和桃汁的相对介电常数皆随着频率的增大单调减小,而介质损耗因数呈现"V"型的变化趋势.离子的导电性和偶极子的极化分别是引起低频和高频下介电损耗的主要原因.桃肉和桃汁的介电参数与可溶性固形物含量、pH值以及含水率间没有明显的线性关系. 相似文献
7.
Response of hot pepper (Capsicum annuum L.) to mulching practices under planted greenhouse condition
Yin-Li Liang Xing WuJuan-Juan Zhu Mao-Juan ZhouQiang Peng 《Agricultural Water Management》2011,99(1):111-120
Mulch is considered a desirable management technology for conserving soil moisture, improving soil temperature and soil quality. This study aimed to investigate soil conditions and hot pepper (Capsicum annuum L.) performance in terms of leaf photosynthetic capacity, fruit yield and quality, and irrigation water use efficiency (IWUE) under such practices in greenhouse condition. A field experiment across 3 years was carried out with four types of mulch (without mulch [CK], wheat straw mulch [SM], plastic film mulch [FM], and combined mulch with plastic film and wheat straw [CM]). Mulch could improve soil physical properties regardless of mulch materials. FM and CM treatments improved soil moistures status and soil temperature in comparison to CK control, while SM increased soil water content and decreased soil temperature. Mulch increased leaf net photosynthesis rate (PN), stomatal conductance to water vapor (gs), intercellular CO2 concentration (Ci), and transpiration rate (E), but declined instant water use efficiency (WUEi). No significant effect of mulch application on chlorophyll fluorescence was existent for the entire growth season. Fruit yield and irrigation water use efficiency (IWUE) showed some increment under all the mulch conditions. Compared to CK, the yield was enhanced by 82.3%, 65.0%, and 111.5% in 2008; 38.1%, 17.4%, and 46.5% in 2009; and 14.3%, 6.5%, and 19.6% in 2010 under SM, FM, and CM conditions, respectively. Although FM produced better fruit quality than other treatments, CM is the recommended practice for hot pepper cultivation in greenhouse condition due to working well to facilitate soil condition (moisture and temperature), plant growth, and marketable yield. 相似文献
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T. Bisantino R. Bingner W. Chouaib F. Gentile G. Trisorio Liuzzi 《Land Degradation \u0026amp; Development》2015,26(4):340-355
In this paper, the Annualized Agricultural Non‐Point Source (AnnAGNPS) model has been used to estimate runoff, peak discharge and sediment load at the event scale in a Mediterranean watershed. The study area is the Carapelle torrent, Southern Italy (area = 506 km2), where continuous rainfall, streamflow and sediment load data are available. Nineteen flood events have been registered in the period 2007–2009 and were used for the application of the model. The aim of the paper is to evaluate the predictive accuracy of the model at the event scale, in a medium‐size watershed, given the specific conditions of the semi‐arid environments. A sensitivity analysis has been carried out to assign the correct parameterization: the mean normalized output variation of the most meaningful input parameters pointed out the influence of the curve number on runoff, peak discharge and sediment load predictions (values greater than 1); the MN Manning's roughness coefficient and K, C and P factors of the universal soil loss equation showed a moderate influence on sediment load simulations (values between 0·5 and 1). The selection of the Soil Conservation Service synthetic storm types has been based on the observed storm events analysis to improve the peak discharge simulations. The model prediction has proved to be good for runoff (R2 = 0·74, NSE = 0·75, W = 0·92) and peak discharge (R2 = 0·85, NSE = 0·70, W = 0·94), and satisfactory for sediment yield (R2 = 0·70, NSE = 0·63, W = 0·91). The relative error is lower for high events; this result is quite interesting in semi‐arid environments, where most of the annual sediment yield is concentrated in a few, severe events. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
厌氧悬浮颗粒污泥床同时反硝化产甲烷研究 总被引:1,自引:0,他引:1
利用厌氧悬浮颗粒污泥床反应器,以自配水为基质,通过微生物的反硝化作用和产甲烷作用成功实现了在单级反应器中去除硝酸盐和水中有机质的目的。反应器开始接种的污泥是产甲烷颗粒污泥,通过不断提高进水中硝酸盐的浓度,使厌氧颗粒污泥逐渐适应水中的硝酸盐,反硝化剩余的有机碳源转化为甲烷气体。在硝酸盐负荷为0.75kgN03^- -N·m^-3d^-1和COD负荷为14.1kgCOD·m^-3d^-1的稳态下,硝酸盐和有机碳的去除率分别为99.5%和90.1%以上。对反应器产生的气体所进行的气体组成测试表明,加入的硝酸盐全部转化为氮气,这一结果表明发生了真正的反硝化反应。 相似文献