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排序方式: 共有94条查询结果,搜索用时 93 毫秒
1.
光倒刺鲃1—3龄处于快速生长期,4龄以后生长速度下降,以藻类食物为主,繁殖季节为每年5—9月份,在体长50—150mm,275—417mm时,卵巢长度增加较快,3—4龄性腺发育成熟,属多次产卵类型.  相似文献   
2.
通过调查发现木伦自然保护区有鱼类41种,分别属于4目13科34属,占龙江水系鱼类总数的38.3%.并了解了其分布、食性及丰富度.  相似文献   
3.
鱼类血细胞研究进展   总被引:22,自引:0,他引:22  
综述了鱼类血细胞的主要种类、各种血细胞的主要功能以及鱼类血细胞的发生情况,并初步探讨了鱼类血细胞的研究方法及研究发展方向.  相似文献   
4.
《Journal of Natural History》2012,46(6):1413-1419
Didogobius schlieweni sp. nov. is described from a single specimen collected among pebbles in shallow water at Unije island, near Cres, in the northern Adriatic Sea. The holotype has vivid dark and pale patterning, and is assigned to Didogobius on the basis of head neuromast patterns and meristic features. Diagnostic values of the latter are D2 I/12, A I/11, P 17, and LL 55–56. A key to species of the Chromogobius and Didogobius complex is provided.  相似文献   
5.
《Journal of Natural History》2012,46(5):1289-1302
Padogobius martensii, a freshwater gobiid fish from the Po basin and adjoining rivers of northeastern Italy, is now recorded from Yugoslavia (Dalmatia), and further rivers of the Italian Adriatic seaboard. Diagnostic features are summarized, with special reference to another freshwater goby of the area, Orsinigobius punctatissimus. The origin of the Dalmatian populations is discussed with reference to sea-level changes in the postglacial Adriatic basin. Meristic polymorphism in dorsal pterygiophore sequence is described in the various P. martensii populations and its significance noted for polarization of character states in this feature.  相似文献   
6.
7.
Microcambeva barbata, n. gen. et sp., is described from rio São João, Estado do Rio de Janeiro. It is proposed as the sister group of Malacoglanis and Sarcoglanis, on the basis of three characters: pectoral fin longer than the head, pectoral fin rays projecting well beyond the fin membrane, and a forked caudal fin. Monophyly of the Sarcoglanidinae is confirmed by the unique possession of a long lateral process on the premaxilla and a separate anterior ossification on the palatine. A sister group relationship between the Sarcoglanidinae and the Glanapteryginae is supported by four synapomorphies: a posteriorly directed dorsal process on the quadrate, a large dorsal anteriorly directed process on the hyomandibula, vomer reduced and generalized miniaturization. A more inclusive group composed of Sarcoglanidinae, Glanapteryginae, Tridentinae, Vandeliinae and Stegophilinae is considered monophyletic, since they all exhibit a reduced interopercular patch of odontodes, a reduced or absent metapterygoid, reduction in the number of pleural ribs, and lack an elongate process on the parasphenoid.  相似文献   
8.
This paper describes two new earthworm species, Iridodrilus codonothecoformis sp. n. and Iridodrilus condylopapillaris sp. n. and illustrates the major diagnostic features of, and the differences between, Iridodrilus roseus Beddard, 1897 and Heliodrilus lagosensis Beddard, 1890. Hitherto unnoticed features of I. roseus are also illustrated, namely that it possesses a bursa copulatrix and that two pairs of very tiny penial setae in sacs occasionally occur which penetrate the bursa copulatrix. It is also demonstrated that the structures hitherto regarded as a ‘coelomic duct’ that supposedly links the two fertilization chambers is in fact a pair of ovarian ducts that lead from the paired ovaries to the chambers; these ducts are not interlinked. It is further argued that neither Iridodrilus roseus nor Heliodrilus lagosensis can be regarded as having a spermathecal system that is paired internally. The implications of these findings are discussed in relation to the taxonomy of the two named genera. It is recommended that Iridodrilus and Heliodrilus be regarded as valid genera s.s. Beddard, though with modified diagnoses.  相似文献   
9.
鲤亚科Cyprininae是鲤科Cyprininidae中的一个类群,先定46个特征,采用模糊聚类分析方法,用TURBO PASCAL语言,在IBM-PC计算机上进行定量分类,分类结]果,分为5个属,2个亚属,21个种  相似文献   
10.
长江河口及其邻近海域的自然环境   总被引:1,自引:1,他引:1  
本文概述了长江河口演变过程和水下三角洲酌形成机理,河口地区潮汐作用、波浪作用和近岸流系的性质以及长江口外淡水扩散及其对邻近海域的影响等问题。本文还讨论了长江河口环流类型和特征、最大浑浊带分布及其变化、潮滩和水下三角洲的发育以及河口地区生物与环境的关系等。根据上述多方面环境因子的分析并进行汇总,作者对长江河口及其邻近海域的自然环境特征作出了评价。  相似文献   
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