MORPHOLOGY AND GROWTH PATTERNS OF THE USRI RIVER POINT BARS, BIHAR, INDIA     

《国际泥沙研究》2000,(4)

1 INTRODUCTIONThe exact mechanism of accumulation of sediments in point bars is not clearly known. Many scientistsinvestigated the problem. In the river Klaralven, Sundborg (1956) observed the development of sometransverse bars in the initial stage of the point bar formation. These transverse bars tend to becomelongitudinal as they extend close to the stream bed. Martvall and Nilsson (1972) investigated the problemof point bar formation experimentally in a laboratory flume. The flume st…  相似文献   

三苯基氯化锡(TPTC)对孔石莼光合作用及生长的影响   总被引：4，自引：2，他引：2  

李钧  于仁诚  李正炎  颜天  周名江 《海洋与湖沼》2000,31(4):404-407

于１９９５年５月在青岛太平角采集孔石莼,研究了三苯基氯化锡（ＴＰＴＣ）对其光合、呼吸、色素含量及生长的影响。结果表明,低浓度的ＴＰＴＣ≤２μｇ／Ｌ）对光 过程无明显作用,高浓度的ＴＰＴＣ（〉２μｇ／Ｌ）能抑制光合作用,当ＴＰＴＣ浓度达到１６μｇ／Ｌ时,光合过程基本停止,ＴＰＴＣ对光作用的半数效应浓度为９６ｈＥＣ５０＝７．３９μＧ／Ｌ。低浓度的ＴＰＴＣ就能够使呼吸速率加快,但ＴＰＴＣ浓度达到８μｇ／  相似文献   

天水城市扩张的时空特征及动因分析   总被引：4，自引：2，他引：2  

张修芳  牛叔文  冯骁  王文蝶 《地理研究》2013,32(12):2312-2323

以不同时期的天水市地形图和TM遥感影像为基础,提取城市建设用地信息。并利用年均扩展指数（AGI）分析各时期城市空间扩展的分异特征。结果表明：天水城市用地由小范围到大范围、AGI 强度由低到高再趋缓。1996 年前,城区人口密度一直下降,此后又开始上升,与AGI 的变化相对应。受“两山夹一川”的地形限制,天水经历了由二点向多点分散扩展、内部填充与沿河谷延伸的空间演变过程。形成了南北窄、东西长的带状格局,不同于平原型城市以同心圆外扩模式。不同时期城市扩张的动因不同,初期是人口和工商业迁入,中期是行政力量和市场机制,近期是人口、经济的增长带来的社会需求。为了适应重点开发的需要,天水需要走出河谷、开发新区,提升综合功能。  相似文献   

Effect of substrate grain size on the growth and morphology of the submersed macrophyte Vallisneria natans L.     

Z.Q. LiL.Y. Kong  L.F. YangM. Zhang  T. CaoJ. Xu  Z.X. Wang 《Limnologica》2012,42(1):81-85

Experiments were conducted to investigate the growth and morphology of the submersed macrophyte Vallisneria natans in relation to seven substrate types. The study also aims to evaluate the influence of the grain size of the aquatic substrate on the submersed macrophyte. The results show that growth, morphology and biomass accumulation of V. natans were significantly affected by the physical properties of the growth substrate. Compared with V. natans grown in pebble and gravel substrates, V. natans grown in silt and clay substrates had greater height, more ramets and leaves, as well as greater biomass accumulation. No significant differences in biomass allocation patterns were found among the different experimental treatments. The total porosity and dry bulk density of the growth substrate strongly influence plant traits. Substantial positive correlations were observed between total porosity and height and total biomass. Also, negative correlations were observed between dry bulk density and height, number of ramets, total biomass and lacunal volume. These results indicate that at high concentrations of water-column nutrients, V. natans responds to different physical properties of the growth substrate by changing growth and biomass accumulation strategies, rather than by changing biomass allocation patterns. Compared with V. natans grown in substrates with larger grain sizes, V. natans appeared well-adapted to substrates with smaller grain sizes. Thus, the physical properties of the growth substrate could be important in determining submersed macrophyte colonization and distribution in shallow eutrophic lakes. This information may be useful in managing shallow eutrophic lakes wherein rooted submersed macrophytes are declining.  相似文献   

日本沼虾(Macrobrachium nipponensis)池养越冬抱卵亲虾表型性状对个体繁殖力的影响效应   总被引：2，自引：0，他引：2  

王志铮  杨磊  施建军  朱卫东  任夙艺 《海洋与湖沼》2012,43(1):166-173

采用多元分析方法定量研究了日本沼虾池养越冬抱卵亲虾体重(BW)、净重(NW)、体长(BL)、头胸甲长(CL)、胸宽(CW)、胸高(CH)、腹节长(AL)、额剑长(RL)、尾节长(TL)等11项表型性状对其个体繁殖力的影响效应。结果表明:(1)实验对象所测各表型性状间均呈极显著相关(P<0.01),它们在对个体繁殖力各评价指标的影响上具较好的区分度;(2)影响个体绝对繁殖力(FJ)、体重相对繁殖力(FW)和体长相对繁殖力(FL)的关键表型性状及其直接作用强弱排序分别为BW>BL>CH>RL>AL>NW,BW>CL>RL>CH>TL>NW和BW>CL>CH>RL>NW,相关指数依次为0.810、0.621和0.798,其中BW-NW组合和CH-RL组合分别为决定个体繁殖力的核心变量和公共从属变量;(3)适用于估算个体繁殖力的回归方程分别为:FJ=5087.802BW-6599.877NW+200.927CH+114.774RL+211.878BL-154.965AL-6266.840,FW=1140.538BW-2018.663NW+85.217CH+70.852RL+78.694CL+74.623TL-1152.576,FL=105.453BW-134.613NW+4.307CH+2.709RL+3.623CL-61.737;(4)W(♀)=0.029BL+0.065CL+0.121CW+0.105CH-2.448可精确估算其净重值。  相似文献   

壳聚糖对虹鳟(Oncorhynchus mykiss)幼鱼生长性能、体组成及非特异性免疫的影响   总被引：2，自引：0，他引：2  

蒋锦坤  王际英  张利民  柳旭东  冯德智  姜柯君  张德瑞 《海洋与湖沼》2012,43(4):729-734

用壳聚糖添加量为0.00%(D0)、0.25%(D1)、0.50%(D2)、1.00%(D3)和2.00%(D4)的实验饲料投喂虹鳟幼鱼50d,研究其对虹鳟幼鱼生长性能、体组成及非特异性免疫的影响。结果显示,各实验组增重率(WGR)、特定生长率(SGR)显著高于对照组(P<0.05),饲料系数(FCR)、脏体比(VSI)呈显著降低趋势(P<0.05),而肝体比(HSI)、脾体比(SSI)、肥满度(CF)及存活率(SR)无明显差异(P>0.05)。全鱼、肌肉及肝脏粗脂肪含量显著降低(P<0.05)。D3组和D4组碱性磷酸酶(ALP)活性显著低于其它各组(P<0.05);酸性磷酸酶(ACP)活性显著降低(P<0.05),溶菌酶(LZM)活性则显著升高(P<0.05);D4组总抗氧化能力(T-AOC)显著高于对照组及D1组(P<0.05);超氧化物歧化酶(SOD)活力差异不显著(P>0.05)。在本实验条件下,饲料中添加壳聚糖可显著提高虹鳟幼鱼生长性能、增强非特异性免疫能力,以增重率及非特异性免疫为综合评价指标,虹鳟饲料中壳聚糖的适宜添加量为0.50%。  相似文献   

盐度对白色霞水母(Cyanea nozakii Kishinouye)生长和横裂生殖的影响     

董婧  孙明  王彬 《海洋与湖沼》2012,43(3):556-561

白色霞水母是我国沿海主要致灾水母种类之一,利用野外调查和控制实验相结合的方法,研究了盐度对白色霞水母螅状体存活、生长和横裂生殖的影响以及盐度对白色霞水母碟状幼体存活和生长的影响。结果表明,白色霞水母螅状体生存的盐度上限为35,下限为12.5,生长最适盐度范围为15—32.5。盐度30和32.5组螅状体横裂率最高,与其它各盐度组的螅状体横裂率差异极显著(P<0.01)。白色霞水母碟状幼体生存的盐度上限为35,下限为15,生长最适盐度范围为20—35。  相似文献   

Chromium and Aluminum Phytotoxicity in Maize: Morpho‐Physiological Responses and Metal Uptake          下载免费PDF全文

Imran Khan  Mohsin Tanveer  Muqarrab Ali  Imtyaz Hussain  Long Chang Wang 《洁净——土壤、空气、水》2016,44(8):1075-1084

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科尔沁沙地植物功能性状的尺度变异及关联   总被引：1，自引：1，他引：0  

周欣  左小安  赵学勇  刘川  吕朋 《中国沙漠》2016,36(1):20-26

调查了科尔沁沙地流动沙丘、半固定沙丘和固定沙丘18个样地的物种组成,测定了28种植物的叶面积(LA)、比叶面积(SLA)和叶干物质含量(LDMC)等3个植物功能性状,并用性状梯度分析法对3个功能性状在群落水平上的变化进行了分解,研究了沙丘固定过程中的植物功能性状的尺度变异及其与生境变化的关系。结果表明:(1)随着沙丘的固定,群落平均LA逐渐增大,群落平均SLA及LDMC在半固定沙丘上最小;(2)群落平均SLA的生态位宽度随着沙丘固定程度依次减小,流动、半固定沙丘植物群落的适应能力较固定沙丘更强;(3)沙丘固定过程中物种性状值的变化与群落内共生植物种性状间变异的关联相比于群落间性状的变异更密切。沙丘固定导致了物种LA与LDMC较强的正相关关系,两性状在群落间的依赖性比群落内的强。物种在群落内和群落间采取不同的策略来适应沙丘固定过程生境的变化。  相似文献   

Effects of sodium nitrate and sodium acetate concentrations on the growth and fatty acid composition of <Emphasis Type="Italic">Brachiomonas submarina</Emphasis>     

Yang?XiuxiaEmail author  Zeng?Xiaoqi  Ji?Yupeng  Liu?Qun 《中国海洋大学学报(英文版)》2003,2(1):75-78

One isolate of Brachiomonas submarina was tested for its ability to grow heterotrophicly on 5 different organic compounds. Sodium acetate and glucose were found to be effective in supporting the growth. Sodium acetate was chosen as the organic nutrient to test the combined effects of organic and inorganic solutions on the growth and fatty acid composition of Brachiomonas submarina. The best growth rates were achieved at 3 mmol L⁻¹ CH₃COONa and 0.88 mmol L⁻¹ NaNO₃ in heterotrophic condition, and 4 mmol L⁻¹ CH₃COONa and 3.52 mmol L⁻¹ NaNO₃ in mixotrophic condition. The differences between fatty acid contents were significant. The total polyunsaturated fatty acids (T. P. U. F. As) varied from 55.79% to 67.72% in heteritrophic growth and from 52.39% to 65.55% in mixotrophic growth. It is concluded that CH₃COONa and NaNO₃ at 3 mmol L⁻¹ and 3.52 mmol L⁻¹ should respectively be used in order to achieve the highest growth rate and fatty acid content.  相似文献