Reproduction in three species of rainbowfish (Melanotaeniidae) from rainforest streams in northern Queensland, Australia

Abstract – The reproductive biology of three species of rainbowfish (Melanotaeniidae) in northeastern Australian rainforest streams was investigated. Two species, Melanotaenia eachamensis and Cairnsichthys rhombosomoides are endemic to the area, whereas the third, M. splendida splendida, is more widespread. The species were all highly fecund, producing many hundreds of eggs between 1.10 and 1.24 mm in diameter. Melanotaenia eachamensis was the most fecund, produced the largest eggs of the three species, and consequently exhibited the greatest maternal investment (as measured by gonadosomatic index). The majority of reproductive effort occurred during the dry season, although reproductively active fish were present year-round for each of the species, but particularly so for M. s. splendida and C. rhombosomoides. No evidence for a role by temperature or photoperiod as environmental cues for reproduction was found, and it was suggested that gonad development was strongly tied to somatic growth. The concentration of reproduction to the dry season ensures that larvae are produced during a period of relatively stable and benign physical conditions. Comparison of temporal changes in gonadosomatic index values suggest that the spawning season of M. eachamensis , which occurs in high-elevation streams, is more restricted and commences about 1 month earlier than either other species. A similar phenology was observed for the M. s. splendida population found at high elevation and highlights the potential for spatial differences in stream productivity to influence life history. ^Note     

先张法预应力空心板纵向开裂的防治

多年来先张法预应力空心板在中、小桥结构物中一直被广泛应用.但在设计回访中发现,部分空心板板底多存在有纵向裂缝的问题,为有效杜绝此弊病的发生,本文对其产生的原因进行了分析并提出了预防措施.     

绿色产品的生命周期评价模型研究

本文根据绿色产品的特点,采用层次分析法研究了绿色产品环境影响和经济性能的评价指标体系,结合等价转化及产品成本收益的经济利润分析等方法,建立了相应的绿色产品生命周期评价数学模型,探讨了其在绿色产品生产和管理过程评价中的广泛适用性。     

某柴油机连杆力学响应分析

提取连杆工作过程中的最大拉伸和最大压缩工况,通过计算机CAE技术施加不同的边界条件和约束计算其基本的静力学响应,对其安全性进行了评价.连杆实际工作过程中会受到交变的扰动载荷,需对其疲劳耐久性做出更好的把握,因此,借助多体动力学技术计算出连杆工作周期的载荷时间历程,并制作了连杆危险部位的应力时间历程,基于结构的S-N曲线...     

双质量飞轮内部传动结构强度及疲劳寿命分析

随着初级飞轮与次级飞轮相对转角的变化,分段变刚度双质量飞轮具有不同的刚度特性和非线性变化转矩,双质量飞轮内部传动结构作为传递动力和运动部分,结构可靠性和使用寿命必须保证.将建立的三维CAD模型导入HyperMesh软件中进行有限元分析前处理,建立了有限元分析模型,经过仿真求解计算,分析了结构变形、应力分布特点,对比分析...     

室温臭氧保鲜草菇研究

用不同臭氧浓度处理新鲜草菇,结合聚乙烯薄膜包装保鲜贮藏,以５×１０－６臭氧处理草菇效果最好,较对照贮藏寿命延长了１０ｈ,延长了３８％,各处理的过氧化物酶活性、可溶性蛋白质含量和游离氨基酸含量,均随臭氧处理浓度增加而上升。文章对这些生化指标变化进行了讨论。     

不同杀菌工艺对延长货架期牛乳品质的影响

比较传统高温热杀菌、蒸汽浸入式杀菌、膜过滤结合巴氏杀菌对延长货架期牛乳品质的影响,测定不同热处理工艺对微生物指标、货架期、活性物质乳铁蛋白和免疫球蛋白G(immunoglobulin G,IgG)损失率及糠氨酸含量的影响,并优化蒸汽浸入式杀菌、膜过滤结合巴氏杀菌的工艺参数。结果表明：与传统高温杀菌工艺比较,蒸汽浸入式杀菌（147℃、0.09 s）产品货架期更长,品质更稳定,杀菌后糠氨酸含量较低且保留少量的活性物质;膜过滤结合72℃、15 s杀菌能更好地保留活性物质乳铁蛋白和IgG,但是该工艺对贮藏温度要求较高,全程贮藏温度需低于6℃,才能够确保产品在货架期内的品质稳定。     

不同货架期西番莲果实香气成分变化研究

以西番莲为试材,采用顶空固相微萃取法结合气相色谱-质谱联用技术,分别对紫香一号、台农一号西番莲果实在4℃下恒温货架期1、14 d香气物质种类进行分析与鉴定,采用面积归一化法分析各香气物质相对含量,测定不同货架期西番莲果实香气物质成分变化,为西番莲贮藏保鲜提供科学依据。结果表明：不同货架期西番莲果实的香气物质种类、相对含量及香味存在差异,紫香一号西番莲货架1 d时,香气物质种类有25种,相对含量67.50%,乙酸乙酯是主要香气物质,呈现淡淡草香味,货架14 d时,香气物质种类有43种,相对含量92.14%,丁酸己酯、己酸己酯是主要香气物质,呈现苹果、蔬菜、草和肥皂的复杂香味;台农一号西番莲货架1 d时,香气物质种类有37种,相对含量89.32%,丁酸乙酯、丁酸己酯是主要香气物质,呈现菠萝、苹果、肥皂香味,货架14 d时,香气物质种类有43种,相对含量95.16%,己酸乙酯、丁酸乙酯是主要香气物质,呈现菠萝、香蕉味。西番莲果实在货架14 d时香气物质种类和相对含量及香味更为丰富。该研究可为西番莲果实的加工开发利用提供一定的参考。