共查询到20条相似文献，搜索用时 922 毫秒
1.
通过5种温度处理(19℃,22℃,25℃,28℃和31℃),探讨稻.卷叶螟实验种群的数量动态.25℃度温度处理组的世代存活率最高(19.7%),种群增长指数最大(14.9倍)。上述两项指标最低的是19℃温度处理组,分别为3.59b和1.18.根据实验结果,组建了该虫实验种群生命表,并建立了模拟种群数量变化的连续模型和等龄期结构的矩阵模型。 相似文献
2.
为了检测孵化温度是否影响孵化成功率、孵化期和孵出幼体的质量,本研究设置了4个恒定温度(21,24,28,32℃)和一个波动温度孵化中华鳖卵。孵化温度影响孵化期和多数孵出幼体的表型特征,21,24,28,32?C和波动温度的平均孵化期分别为75.9、74.9、46.0、39.4和49.4天。五个孵化温度孵出幼体的湿重、背甲宽和腹甲宽差异显著,而背甲长差异不显著,来自波动孵化温度的孵出幼体较其它温度的个体要小。温度诱导的幼体形态大小对幼体的早期生长有重要影响,体重、背甲长、背甲宽和腹甲宽在第一个越冬季前差异显著,较低温度孵出(21和24℃)的幼体比较高温度(28、32℃和波动温度)的幼体体重轻,背甲长、背甲宽和腹甲宽小。 相似文献
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《滁州学院学报》2018,(5):44-47
烟粉虱Bemisia tabaci (Gennadias)属微型刺吸式害虫,其形态和发育历期难以准确鉴别。本文利用NK-300体视解剖镜和扫描电镜观察烟粉虱成虫、各龄期若虫和卵的形态及各虫态的发育历期。结果表明,若虫随龄期的增加,虫体浑浊变化显著但红色复眼逐渐清晰。1龄若虫周缘有30-40根刚毛;2龄时刚毛消失,周缘可见少量缘齿;3龄时,缘齿最多,在取食点固定的最稳定;至4龄时,缘齿退化消失。在温度25±1℃,相对湿度60%-80%,光周期14L:10D下,用盆栽烟草饲养,各虫态历期为卵期7.08d,若虫期共14.92d,成虫期38.25d;各虫态存活率顺序为成虫>若虫>卵。 相似文献
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小圆皮蠹Anthrenus verbasci Linnaeus在安徽1~2年发生一代,以不同龄期的幼虫越冬,4月下旬部分越冬幼虫化蛹、另一部分继续以幼虫形态存在直至再次越冬.5月上中旬成虫羽化,5月中下旬产卵,每雌产卵4~45粒,6月上中旬卵孵化,以幼虫为害昆虫标本和各种仓储物.常温下各虫态历期分别为;卵期19.7天,幼虫期5~7个月(越冬期除外),蛹期13.8天,雌虫寿命为21.4天,雄虫寿命为16.3天.食料和温度严重影响其生长发育速度.用1.5%甲敌粉放入标本盒内进行防治. 相似文献
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通过对温度、相对湿度以及鳄卵的放置方位、覆盖巢材等影响鳄卵孵化的不同因素进行人工控制和选择,并作对比试验和分析．结果表明：湾鳄（Ｃｒｏｃｏｄｙｌｕｓｐｏｒｏｓｕｓ）卵孵化的最适温度为３０～３３℃,最适相对湿度为８５％～９５％,苔藓类植物是孵化湾鳄卵的最佳辅垫和覆盖巢材,而卵的放置方位对孵化率影响较大 相似文献
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丁建发 《宁德师专学报(自然科学版)》2007,19(4):362-363,371
牛蛙生长的最适温度为25-32℃,繁殖的最适温度为20-30℃.牛蛙以动物性食物为主,在不同的发育阶段,食性也不尽相同.当水温升到18℃以上时,牛蛙开始发情.牛蛙的产卵量与年龄、个体大小、营养条件及生态条件等有很大关系,一般情况下,产卵量自1万至5万粒不等.卵孵化的最适水温为25-28℃.蝌蚪完成变态发育需要77d.每年11月下旬至翌年3月份为牛蛙的越冬期. 相似文献
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报道了日本锦鲤亲鱼培育方法和胚胎发育各期形态特征及发育特点,总结出日本锦鲤亲鱼池塘培育和人工繁育的技术方法.锦鲤卵属沉性卵,具粘性,于水温20～23℃时,多数受精卵经82小时后孵化出苗,初孵化仔鱼全长7～8 mm,三天后卵黄囊基本被吸收,可平游并开口摄食. 相似文献
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本研究对斜带石斑鱼( Epinephelus coioides) 进行强化培育, 实现自然产卵, 以自然产出的受精卵为材料, 对其胚胎发育各阶段的形态特征进行了详细的描述。结果表明: 亲鱼培育的情况经过15 d 左右的强化培育, 斜带石斑鱼亲鱼卵巢可从Ⅲ期发育到Ⅳ期并产卵; 受精卵为透明, 圆形, 浮性卵, 卵径为0178 ±0116 mm ,油球一个, 居卵中央, 油球径0117 ±0104 mm , 受精卵孵化共分为卵裂期、囊胚期、原肠期、器官分化期和仔鱼出膜期等阶段, 在水温25 - 28 ℃, 盐度30 %时经过25 小时45 分钟, 可孵化出仔鱼。 相似文献
9.
以室内接虫、剪叶模拟以及田间调查等方法研究稻纵卷叶螟的为害对水稻产量的影响.初步确定了该虫在综合防治区的经济损害水平为39条幼虫/百丛(剑叶期)和58条/百丛(分蘖期).并提出用害虫种群潜在密度确定卷叶螟经济阈值的方法. 相似文献
10.
通过卵孵化试验和蝌蚪生长速度试验研究弱氯-氖激光对东北林蛙卵孵化和蝌蚪生长速度的影响．结果表明。弱氯-氖激光可以提高东北林蛙卵孵化率,缩短卵的发育历期,对蝌蚪的生长速度有促进作用,且激光照射时间越长,卵孵化率越高、卵的发育历期越短、蝌蚪生长速度越快．同时,弱氨-氖激光照射在一定范围内可以提高蝌蚪的成活率,适宜照射时间为30min．此试验为东北林蛙人工养殖提供了一定的依据． 相似文献
11.
罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
13.
Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
14.
Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
18.
陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献