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凡纳滨对虾(Litopenaeus vannamei)形态性状与净肉重和出肉率的关系 总被引：1，自引：0，他引：1
为了探究凡纳滨对虾(Litopenaeus vannamei)表型性状与净肉重、出肉率的关系,本研究以5月龄的650尾凡纳滨对虾为材料,测量了全长、体长、头胸甲和各体节的长宽高等24个表型性状,根据体重、净肉重计算出肉率,通过相关分析、逐步回归分析和通径分析,计算了各性状间的相关系数、通径系数和决定系数,分析了24个表型性状与净肉重和出肉率的关系。结果表明,相关系数均达到极显著水平(P0.01);通过逐步回归分析建立了以净肉重为因变量,13个性状为自变量的回归方程;同时建立了以出肉率为因变量,9个性状为自变量的回归方程。通径分析结果显示,体长对净肉重的直接影响最大,其次是第3腹节长和第1腹节宽;对出肉率的正向直接影响最大的是体长,其次是第2腹节高和第3腹节长,头胸甲长、宽、高以及尾节长与出肉率呈明显负相关。决定系数分析结果与通径分析结论基本一致,在所分析的24个形态性状中,体长和第3腹节长与净肉重和出肉率密切相关。在实际生产中,可以通过测量体长和第3腹节长等形态性状间接实现对净肉重、出肉率的选择,选育优良品种。 相似文献
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通过实地考察、观测和采样,利用Google Earth遥感影像和激光粒度分析仪,研究了科尔沁沙地大型沙波纹（large-scale ripples, LSR）的空间分布、单体和群体的基本形态和粒度特征,探讨了LSR粗颗粒的来源、它同普通沙波纹和普通风成沙在颗粒组成、形态特征和内部沉积结构方面的区别。结果表明：（1）科尔沁沙地的LSR主要分布于翁牛特旗中部和北部地区。（2）LSR空间单元的空间形态具有片状、斑块状和条带状3种类型,分别发育于宽阔的丘间地、沙丘中上部、槽形低地3类地形部位。（3）LSR平均长度为6.32 m,总体走向为东北—西南,平均波长为1.68 m,空间分异较为明显;单体LSR的前后坡不对称。（4）LSR的颗粒为中砂-粗砂粒级,其中粗颗粒主要来自旧河道的河流冲积层、下伏Q3河湖相地层、剥蚀残山的风化壳和山麓洪积物。（5）LSR同普通沙波纹在外观、物质组成、几何形态和内部沉积结构方面有明显差异。该项研究将有助于促进风沙地貌学的理论发展和实践。 相似文献
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This study presented a quantitative comparison of cockpit and doline karst by examining the numbers and characteristics of typical types of landform entities that are developed in Guilin(Guangxi, China), La Alianza(PR, USA), Avalton(KY, USA), and Oolitic(IN, USA). Five types of landform entities were defined: isolated hill(IH), clustered hills(CHs), isolated sinkhole(IS), clustered sinkholes(CSs), and clustered hills with sinkholes(CHSs). An algorithm was developed to automatically identify these types of landform entities by examining the contour lines on topographic maps of two cockpit karst areas(Guilin and La Alianza) and two doline karst areas(Oolitic and Avalton). Within each specific study area, the CHSs is the least developed type yet with a larger size and higher relief. The IH and IS entities are smaller in size, lower in relief, and outnumber their clustered counterparts. The total numbers of these types of entities are quite different in cockpit and doline karst areas. Doline karst is characterized by more negative(IS and CSs) than positive(IH and IHs) landforms and vice versa for cockpit karst. For example, the Guilin study area has 1192 positive landform entities in total, which occupy 9.81% of the total study area. It has only 622 negative landform entities occupying only 3.91% of the total study area. By contrast, the doline karst in Oolitic has 130 negative while only 10 positive landform entities. The positive and negative landforms in Oolitic occupy 12.68% and 2.61% of the total study area, respectively. Furthermore, average relief and slope of the landform entities are much higher and steeper in the cockpit karst than the doline karst areas. For instance, the average slope of CHs in Alvaton is 3.90 degrees while it is 19.78 degrees in La Alianza. The average relief of CSs is 4.07 m and 34.29 m in Oolitic and Guilin respectively. Such a difference within a specific area or between the cockpit and doline karst may reveal different controls on the development of karst landscape. 相似文献
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none 《The Cartographic journal》2013,50(1):63-74
AbstractHachuring is a classic method of cartographic relief presentation that origins from perspective sketching of the surface. Hachuring was developed into strict and mathematically grounded planimetric method during the eighteenth century. Established by Lehmann in 1799, topographic hachures flourished during the first half of the nineteenth century and then were gradually replaced by contours. Today, hachures are still popular in presentation of anthropogenic relief on archaeological and topographic maps. Some elements of hachuring can be found in geomorphometric and hydrometeorological mapping, where flowlines and arrows are used to show the intensity and direction of the flow on the surface, or its aspect and slope. The study aims to reveal the potential of hachuring in further development as surface presentation method. Automated implementation of all original requirements for hachure construction is provided for the first time by new algorithm using vector flowlines. Then an advanced hachuring technique called ‘slope and aspect hachuring’ is presented which depicts slope, aspect and flow direction of the surface simultaneously. Slope and aspect hachuring is compared to traditional area colours to reveal its advantages and shortcomings in sight of morphometric mapping. Some applications of the method and directions of future research are suggested in concluding part. 相似文献
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The morphometric analysis of river basin helps to explore the interrelationship between hydraulic parameters and geomorphologic characteristics. The study has been conducted in the Upper Tons basin of Northern Foreland of Peninsular India. The river basin has been characterized using the topographical maps, CARTOSAT satellite image integrated using the GIS techniques. The drainage density analysis indicates lower values in the north-eastern regions and thus these regions can be categorized as better ground water potential zone. There are in total 10 sub-watersheds which have been delineated; SW-4 has maximum drainage density (4.75), stream frequency (5.61) and drainage texture (26.64) followed by SW-6–10. The prioritized sub-watershed numbers SW-4 and SW-6–10 need conservation practices because of their high erodibility and run-off. SW-1–3 and SW-5 regions have better permeable bed rocks and hence good for water harvesting. The areal parameter indicates elongated shape of basin and moderate to steeper ground slope. The results are supported by extensive field survey. This study can be applied for soil and water management, as well as disaster prevention from similar type of drainage basins. 相似文献
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翡翠贻贝形态性状对软体部质量的影响 总被引：2，自引：0，他引：2
随机选择200个湛江南三岛翡翠贻贝野生个体,测量壳长(SL)、壳宽(SW)、壳高(SH)、韧带长(LL)和软体重(EW)等5个性状,计算性状间的相关系数,采用通径分析方法计算以壳性状和韧带长为自变量对软体重作依变量的通径系数、决定系数。结果表明:壳长、壳宽、壳高、韧带长与软体部质量相关极显著(P<0.01)。壳长对软体部质量的直接影响最大,壳高对软体部质量的直接影响次之;与壳长和壳高相比,壳宽、韧带长对软体部质量的直接影响较小。采用逐步回归分析方法建立了以壳长和壳高为自变量估计软体部质量的多元回归方程:YEW=-39.287+0.466XSL+0.994XSH,为翡翠贻贝选种提供了理论依据和测度指标。 相似文献
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月球地貌是月球表面发生的地质和地貌过程的结果,月球地貌单元的划分和等级分类体系的构建是月球地貌学研究的基础,也是月球地貌图制图的基础和关键科学问题。地貌学是研究形态和成因的科学,高程和起伏度是最基本的地貌指标。本文基于LOLA（Lunar Orbiter Laser Altimeter） DEM数据以及LOLA和SELENE TC（Terrain Camera）融合的DEM数据（SLDEM2015,文中简称SLDEM）,利用均值变点法确定月表起伏度计算的最佳窗口,并以起伏度100 m、200 m、300 m、700 m、1500 m及2500 m为阈值将月球表面分为微起伏平原（< 100 m）、微起伏台地[100 m, 200 m）、微小起伏丘陵[200 m, 300 m）、小起伏山地[300 m, 700 m）、中起伏山地[700 m, 1500 m）、大起伏山地[1500 m, 2500 m）及极大起伏山地（≥ 2500 m）地貌7个类型。划分结果显示：微起伏平原主要分布在月海平原区域、部分有玄武岩充填的撞击盆地的盆底区域以及撞击坑坑底区域;微起伏台地主要分布在月海和月陆区域的交界区域;微小起伏丘陵主要分布在月溪和皱脊等构造单元区域;小起伏山地主要分布在撞击坑中央峰及坑底断裂区域;中起伏山地主要分布在撞击坑坑底和坑壁过渡区域、撞击坑坑壁和坑缘过渡区域、撞击盆地盆底与盆壁过渡区域以及盆壁与盆缘过渡区域;大起伏和极大起伏山地主要分布在撞击坑坑壁区域及撞击盆地盆壁区域。本文确定的月表起伏度分级标准可以对月表数字地貌分类体系的构建和月球地貌图集的编研提供定量标准和重要参考。 相似文献