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排序方式: 共有106条查询结果,搜索用时 46 毫秒
1.
南方鲇的繁殖生物学研究:性腺发育及周年变化   总被引:31,自引:3,他引:28  
依形态学特征将南方鲇性腺的发育分为6个时期,据组织学特点将雌雄性细胞的变化各分为6个时相,幼鱼的精原细胞经历时间比卵原细胞长;发育的早期和中期,精母细胞的发育速度不同步,但到晚期则趋于同步化,3时相卵母细胞仍有卵黄核,大,小核仁数随卵母细胞的发育而变化,精孔细胞和卵胶膜源于滤泡细胞,雌雄鱼成熟年龄均为3龄,繁殖期3-5月,一次产卵类型,繁殖时不能将卵完全产出。  相似文献
2.
纳木错裸鲤性腺发育的组织学研究   总被引:24,自引:0,他引:24  
采用常规的组织切片方法,对西藏特有鱼类纳木错裸鲤的性腺发育进行了组织学研究,系统地描述了各期精巢和卵巢的形态结构、特征及其变化。尤其论述了其卵巢中卵细胞的卵黄核破碎与分解的特点、卵膜的结构、核仁排出物在卵黄形成过程中的作用,以及卵粒重吸收的过程,根据各种其卵巢中犯母细胞的组成情况,认为纳木错裸鲤已达性成熟的个性并不是每年都参与繁殖活动对高原极端、多变气候环境的一种生态适应,阐明了纳木错裸鲤属于分批同步产卵鱼类。  相似文献
3.
异源四倍体鲫鲤的性腺发育研究   总被引:19,自引:0,他引:19  
采用组织切片技术对异源四倍体鲫鲤的性腺进行了研究。结果表明:异源四倍体鲫鲤的性腺发育程序和普通鲤鲫鱼相似,可以分为6个时期。雌雄个体都能达到性成熟,其中个体性成熟年龄为一周年;雄性个体比雌性个体成熟早,150日龄即可达到性成熟。成熟卵巢的成熟系数为9.25%-15.60%,成熟精巢的成熟系数为1.65%-5.19%。成熟期卵径为1670.4-1780.5μm之间,成熟精子头径为2.3-2.4μm。繁殖期为每年3-5月份。该研究证明异源四倍体鲫鲤的性腺发育是正常的,雌雄个体都能达到性成熟。  相似文献
4.
Felip A  Zanuy S  Carrillo M  Piferrer F 《Genetica》2001,111(1-3):175-195
The induction of triploidy and gynogenesis by chromosome set manipulation has traditionally been studied more intensively in freshwater than in marine fish. In the last years, however, several studies have applied these manipulations in about a dozen marine species, including mainly sparids, moronids and flatfishes. This paper focuses on the methodologies used to induce, verify, and assess performance of both triploids and gynogenetics of these marine species. Since many of them are batch spawners and have small and fragile eggs and larvae, peculiarities relating to broodstock management, gamete quality and mortality assessment during early larval stages are also taken into account. However, data show that if handling is correct and the treatments are optimized, triploid and gynogenetic rates of 100% can be easily achieved. Survival of triploids with respect to the controls is about 70–80%, whereas in gynogenetics it is generally low and more variable, depending on the species considered. In the marine fish investigated so far, triploidy has not resulted in significantly higher growth rates. On the other hand, the induction of gynogenesis has resulted in the production of both all-female and mix-sex stocks. Throughout the paper, special reference is made to the European sea bass (Dicentrarchus labrax L.), a species of both basic and applied interest, for which a comprehensive study has been carried out on the induction, verification and performance of triploids and gynogenetics.Author for correspondence  相似文献
5.
红鲫(♀)×湘江野鲤(■)杂交一代生殖腺的细胞学研究   总被引:9,自引:0,他引:9  
研究了以红色鲫鱼作母本和湘江野鲤作父本所得杂交一代(F_1)生殖细胞的生长发育。实验证明:(1)F_1雌性个体的生殖腺存在两种情况,一是完全能育型,占总数的44.3%;另一是发育不正常的类型,属两性嵌合体,占总数的55.7%。外观为雌性个体的两性嵌合体卵巢,既有卵细胞,也有精细胞。(2)F_1雄性个体的生殖腺出现三种不同的状况,一是完全能育型,只占总数的4.67%,可以完成由精原细胞到精子形成的全部发育过程;二是不完全能育型,占总数的61.7%,有少数精子细胞可以通过变态形成精子;三是完全不育型,这种类型包括有两性嵌合体(20.63%)和非两性嵌合体(13%),都不能产生成熟的精子。根据我们的实验结果证实,鲫(♀)、鲤((?))杂交所得的杂交一代(F_1)雄性个体,有部分是能育的,并已成功地获得了第二代(F_2)和第三代(F_3)。  相似文献
6.
外源性褪黑激素对黄鳝性腺发育及性腺激素分泌的影响   总被引:6,自引:0,他引:6  
石琼  邓柏澧 《动物学报》1998,44(4):435-442
通过注射实验研究了外源性褪黑激素对黄鲜性腺发育及性腺激素分泌的影响。结果表明,处于不同性腺发育时期的黄鲜对餐源褪黑激素的反应存在季节性差异。上述结果暗示,黑激素影响黄鲜性腺发育的关键时间可能是在性腺静止期,亦即Ⅳ期或/和Ⅳ期之前。  相似文献
7.
光倒刺鲃卵巢发育的初步研究   总被引:5,自引:0,他引:5       下载免费PDF全文
经激素处理和生态调控的光倒刺鲃,能够完成卵巢发育的全过程。按照形态学特征将卵巢的发育分为6个时期,依组织学特点将卵巢的变化分为5个时期。大多数雌体在3~4龄性腺发育成熟,雌鱼最小成熟为3龄;繁殖期4~9月,为多次产卵类型,繁殖时不能将卵完全产出,完成第一次性成熟并产卵的光倒刺鲃,卵巢逐步由第3期发育至第4期。  相似文献
8.
Jost Borcherding 《Oecologia》1991,87(2):208-218
Summary The annual development of the gonads of Dreissena polymorpha was studied at three sampling sites in two lakes over 3 and 1 1/2 years, respectively. A resting stage occurred after the last spawning in summer/autumn. Oogenesis (accompanied by multiplying segmentation of the oogonia and early growth processes of its oocytes) restarted in specimens at least 1 year old at low temperatures (below 10° C) during winter and early spring. At one location (Fühlinger See) the onset of the spawning season was correlated with an increase of water temperatures above 12° C. At 2 m depth, two main spawning periods in May and August were normally recognized, the first at temperatures of 12–16° C, the second at 16–21° C. It was clearly demonstrated for the first time in Dreissena polymorpha that the oocytes became mature in successive cohorts within one gonad. A female mussel may spawn several times during the reproductive season. At 9 m depth, the onset of spawning also started at about 12° C; this occurred in late summer, with two spawning periods within 1 month at a temperature range of 12–16° C. At another location (Heider Bergsee) the size of the gonads and the oocytes was reduced during April of both years studied, when food supply was low simultaneously with rapidly rising water temperatures in this shallow lake. There was no spawning period during spring. The major spawning period was delayed until July (temperatures 19–22°C). This shows (1) the synchronizing influence of low winter temperatures on the annual reproductive cycle and (2) a temperature threshold of at least 12° C for the start of the spawning processes. The results are discussed with regard to the geographical limits of further spread of Dreissena polymorpha.  相似文献
9.
The histological structure of the gonads was studied in yellow eels sampled from a coastal lagoon and from stocks reared in an aquaculture plant showing different sex ratios. Gonad development related to body size rather than to age and underwent an intermediate stage characterized by a structure of an early testis but containing oogonia and oocytes. This gonad was called the Syrski organ and the stage juvenile ambisexual. Ovaries were found in eels from 22–30 cm in length, possibly derived from undifferentiated gonads or from Syrski organs. Fully differentiated testes were found in eels >35 cm, derived from Syrski organs. These observations support the results of previous research. From elvers and in eels up to 15–16 cm in length, growth of the gonadal primordium is due to primordial germ cell migration. In eels > 15 cm multiplication of primordial cells begins. Oogonial clones were found in eels > 18 cm in length, whilespermatogonium B clones were observed in eels >30 cm in length. The dynamics of sex differentiation was different among stocks with different ultimate sex ratios: ovaries were found in shorter eels in stocks with a prevalence of females, in longer eels in stocks with a prevalence of males. This result supports the hypothesis of a metagametic (environmental) sex determination. The somatic cells in contact with germ cells and those in the interstitium appeared early during gonad development and preceded germ cell differentiation. This suggests that somatic cells are the targets of the environmental factors influencing sex differentiation.  相似文献
10.
Reproductive effort, factors affecting reproductive output and costs of reproduction were studied in primiparous yearling compared to multiparous older female European ground squirrels (Spermophilus citellus). Yearling females weaned smaller litters than older ones. Litter size increased with posthibernation body mass at the expense of slightly lighter young for yearling but not for older mothers. In older females, on the other hand, emergence body mass influenced offspring mass, whereas litter size was affected by oestrus date. High reproductive effort entailed reproductive costs in terms of reduced subsequent fecundity but not subsequent survival for both yearling and older females. The production of large litters and long duration of lactation delayed subsequent oestrus, which, in turn, correlated negatively with litter size. During the second half of lactation, oestradiol levels were significantly elevated, indicating the initiation of follicular maturation processes. Oestradiol levels during that time correlated negatively with current, but positively with subsequent litter size. We therefore assume that inhibitory effects of lactation on gonadal development may mediate the negative relationship between reproductive effort and subsequent reproductive timing in adults. This effect is absent in yearlings because they are reproducing for the first time. Reproductive output in yearlings was influenced by interactions between structural growth and puberty. Received: 22 March 1999 / Accepted: 7 June 1999  相似文献
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