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201.
性激素对中国林蛙性腺分化的影响 总被引:5,自引:0,他引:5
在我国要蛙养殖地区,性别比例失调问题十分严重,部分地区紫蛙和雄蛙的比例只有3:7,严重影响养殖效益,制约养蛙业的发展。为调整林蛙性别比例,分别在实验室内和抚松林蛙养殖场采用在蝌蚪饵料中添加性激素的方法,诱导性腺分化,达到了调整林蛙性别的目的,并对激素诱导的合适浓度和最佳时期进行了研究。为促进林蛙养殖业的发展提供了切实可行的诱导技术。 相似文献
202.
网络色情成瘾已成为世界范围的社会问题,但国内学界对此重视不够。本文在综述国外相关研究成果后,对我国的情况作了初步调研,建议结合国内的特点开展相关研究,最后在理论分析的基础上,认为网络色情成瘾来源于技术异化导致的不和谐性经验,是性歧变的一种新变体。 相似文献
203.
《Journal of Natural History》2012,46(3-4):237-251
In this study we analysed the body size, age structure, age at maturity, longevity and growth pattern of Argenteohyla siemersi pederseni in north-eastern Argentina using skeletochronological methods. Body size was sexually dimorphic; females were significantly larger and heavier than males, regardless of age. As A. s. pederseni is an explosive breeder with only one reproductive episode per year, we assumed that each Line of Arrested Growth (LAG) observed was equivalent to one period of decreasing growth, LAGs reflecting a direct estimation of individual age. The minimum number of LAGs counted was two for males and three for females, but there was no sexual difference in longevity. The von Bertalanffy's growth coefficients (K) were higher in males than in females for both size and body mass. Females had a lower growth rate than males, took longer to reach the minimum maturation size, and were older and larger at reproduction. 相似文献
204.
《Journal of Natural History》2012,46(19-20):1225-1238
The natural history of the lizard Enyalius perditus was studied from August 2005 to July 2006, at Parque Estadual Nova Baden, in the municipality of Lambari, State of Minas Gerais, south-eastern Brazil. We found that E. perditus may be considered a semi-arboreal species, like other species in the genus, sleeping on vegetation (slim branches or large leaves) at night, possibly to minimize predation. Females with enlarged follicles or oviducal eggs were found from November to January and juveniles recruited at the end of the dry season and beginning of the rainy season, in October. The diet of this lizard is composed mainly of Lepidoptera larvae, Araneae and Formicidae. Females were larger than males, and juvenile coloration is similar to that of adult females. 相似文献
205.
《Journal of Natural History》2012,46(3):657-668
Mating behaviour of the ball-rolling dung beetle Kheper platynotus (Bates), adults of which are active in rainy seasons, was studied in southeastern Kenya. Male mating behaviour changed with the progression of the rainy season. In the early season when females made food balls, males attempted forced copulation with wandering and food-ball-making females on dung mounds. As the season progressed, females made brood balls, and males attempted to pair off with such females, as well as attempting forced copulation with wandering and food-ball-making females. A male who paired off with a brood-ball-making female cooperated with the female to make the ball. The male usually copulated after burying the ball (pre-copulatory mate guarding), but sometimes copulated during ball-making. In the latter case the male usually showed post-copulatory mate guarding until ball burial, but sometimes left soon after copulation. In the late season, when available females decreased because of maternal care in the underground nests, males started to make food balls to secure food resources for survival until the next rainy season. Male mate guarding involving ball-making, -rolling and -burying seemed to function to raise paternity confidence, but such assistance seemed to be less beneficial to females. Fights frequently occurred between guarding and intruding males on brood balls. Both residency and relative body sizes of fighters were important asymmetries influencing contest outcome. This seemed to result in not active but passive mate choice by brood-ball-making females. 相似文献
206.
207.
劳伦斯小说中神话因素非常丰富,从神话原型与宗教象征角度出发,可以发现他的小说中性爱主题与太阳神话有着紧密的联系,从而为我们解读劳伦斯小说的主题和“返魅”的艺术特色提供了有力的神话学注脚。 相似文献
208.
高压静电诱导黄瓜基因突变(性变)的研究 总被引:1,自引:0,他引:1
高压静电可以提高黄瓜种子活力,诱导种子基因突变(性变),使原来只在第5节开花结果的黄瓜,变为第2、3、4节都能开花结果(雄花变为雌花).测试了由20 kV/cm高压静电处理的两种黄瓜试验组和CK组的种子活力,发现高压静电有时间效应,以处理60 s的为最好,其活力增长率分别为26.70%和42.89%.黄瓜种植后,出现了第2、3、4节开花结果的突变株.还对黄瓜蛋白质SDS-PAGE电泳和指纹图谱进行了分析,发现各试验组与CK组的图谱在小分子蛋白区域有明显差异,这一结果为从分子角度表达水平解释高压静电诱导黄瓜基因突变提供了直接证据. 相似文献
209.
光流体在不同介质中流动时所受的阻力不同,使得流速也不同,导致折光指数不同,而阻力的大小与介质分子间作用力大小及介质分子堆积的密集程度有关.从烷烃折光指数与密度关系着手,探讨其线性关系,并以数学式表达,取得令人满意的结果. 相似文献
210.