瓣结鱼的胚胎发育

本文首次记述了瓣结鱼的胚胎发育过程．成熟卵直径1．7～1．9mm,受精卵吸水膨胀后膜径达2．5～2．7mm,具粘性．在水温20．5～23.0℃条件下,受精卵历时71时7分孵化．初辫仔鱼平均全长6.6mm．本文还记述了胚胎发育的积温及累积度时值,并探讨了胚胎发育的下限温度问题．     

杂交鳜的胚胎发育形态观察

通过对杂交鳜胚胎发育的连续观察,研究了其胚胎发育的时序和特点.结果显示,杂交鳜的受精卵呈淡黄色圆球形,卵径为1.52±0.16mm,油球多个且大小不一.杂交鳜胚胎发育的主要特征与已报道的鳜鱼胚胎发育相同,可分为胚盘形成阶段、卵裂阶段、囊胚阶段、原肠胚阶段、神经胚阶段、器官形成阶段和出膜阶段7个阶段及27个发育时期.在水温19.5±1.2℃条件下,34h50min开始形成器官,受精约98h后仔鱼孵出,孵出的仔鱼全长为3.55±0.10mm.胚胎发育总积温为1 982.38℃·h.     

植物提取物对沙塘鳢胚胎发育的影响

以人工受精的沙塘鳢受精卵为材料,研究洋葱、大蒜、生姜、辣椒等4种有刺激性和挥发性物质的农产品水溶性提取物对受精卵早期发育的影响.结果表明:(1)4种农产品提取物均对沙塘鳢胚胎发育无毒害作用;(2)15~20.5℃条件下沙塘鳢受精卵胚胎发育死亡高峰主要发生在器官形成前期,14 d后胚胎发育趋于稳定,18 d可见幼体出膜;(3)4种农产品提取物对水霉有一定的抑制作用,作用效果为大蒜生姜洋葱辣椒,且在每种农产品提取液的1%,3%,5%3个浓度中成活率与浓度呈正相关.     

Cu^2＋对稀有鮈鲫胚胎发育的影响

以ρCu^2＋为0.01、0.05、0.1、0.2mg·L-1 4个浓度的溶液对稀有鮈鲫受精卵进行急性毒性试验,研究了Cu^2＋对稀有鮈鲫受精卵胚胎发育早期的的影响.结果表明,Cu^2＋对稀有鮈鲫胚胎发育有显著的毒性.Cu^2＋暴露组稀有鮈鲫胚胎的死亡率升高,心率减缓且伴随心率不齐;初孵仔鱼体长较短,心包囊和卵黄囊水肿;高浓度Cu^2＋（0.2mg·L-1）暴露60h后全部死亡.     

日本锦鲤人工繁殖技术和胚胎发育过程观察

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.     

“纸制热气球的制作与放飞”教学及评析

活动目的：通过制作与放飞纸制热气球,使学生进一步理解热空气比同体积的空气轻的知识,培养学生参加科技活动的兴趣,增强他们动脑动手的能力。活动形式：分小组进行。活动时间：2课时。活动准备：l．材料：10drm长、58cm宽的引皮纸（核窗纸）4张,边长是7dem的正方形引皮纸1张,长16＆m、宽5－7mm、厚2－3mm的竹蔑条1根,细铁丝2－3根,胶水1瓶,医用纱布一块,适量的松香、清漆。酒精。2．活动情况登记表,如下表（每组回张）。活动过程：教师指导学生制作、放飞热气球。一、制作热气球1．参照图1,用引皮纸裁制成4张梯形、l张圆形纸样…     

异烟肼一次氯酸钠的化学发光反应研究

提出了异烟肼一次氯酸钠化学发光新体系．结合流动注射技术，建立了一种新的测定异烟肼的流动注射化学发光新方法．该法选择性较好，操作简单，精密度好试剂易得．异烟肼在1．0×10－6～1．0×10－4g·ml－1浓度范围内与化学发光信号强度呈线性关系．检出限为2．7×10－7g·ml-1．RSD=2．4％（n＝11；Cs=5．0×10－6g·ml－1）．     

上期《你会解答吗?》参考解答

初一年级1．方法1先分别求出A、B的值，然后再求A＋B的值．很明显，A＝1994，B＝－1996∴A＋B＝1994－1996＝－2．方法：2在求A＋B的过程中，巧用加法结合律进行适当的组合．2.巧用加法结合律进行适当的组合．原式＝1＋（2－3－4＋5）＋（6－7－8＋9）＋…＋（1990－1991－1992＋1993）＋1994＝1＋0＋…＋0＋1994＝1995．3．因为1995＝3×5×7×19，所以3a·5b·7c·19d＝3×5×7×19．初二年级∴M＝N．故选（C）．2巧拆项．3．先求各项的分母的值，再将其分解因式，转化为上一题的形式．4．应用转化思想，把未知转化为已知．（ac＋bd…     

对《机械基础》教材的几点看法──如何引导学生正确掌握“基本偏差”的概念

《机械基础》（机械工业出版社第三版）第42页中有这样一道例题,全引如下：例5：求620J8的极限偏差。解：1．基本尺寸是qZOmm,公差等级是8级,基本偏差代号J是大写字母,它表示孔的基本偏差,查表2－－4可得数值十ZO（卜…,即十0．020mm。格的上方标注有基本偏差为上偏差（ES,所以,上偏差ES＝＋O．020。2．查表2—1对应ITS与基本尺寸q20mm的尺寸段,可查得：ITS＝0．033mm。3．计算下偏差（E）：EI＝ES－S＝0．OZOO．O33＝－O．O13mm,所得答案是：62OJSG6;Drnm。对此题的解法,我有不同看法。一、问题的提出1．查表2－…     

无斑雨蛙早期胚胎发育研究

2007年3月对怀化市无斑雨蛙(Hyla immaculata)的早期胚胎发育进行了研究.结果表明:用人工催产和自然受精方法获得的受精卵,在水温18～22℃下,从受精卵开始至鳃盖完成期胚胎发育历时264h53min;将无斑雨蛙的早期胚胎发育划分为26个时期,描述了各时期的形态特征,并讨论了发育中的一些现象及与前人报道的主要区别.     

瓣结鱼的外部形态特征及性状变动

利用320尾标本进行了可量性状、可数性状的研究，发现各龄组雌鱼的可量性状及头长／眼径的平均值比雄鱼大．且头长／眼径随龄组值增大而增大．弥补了前人对外部形态特征描述的不足．扩大了前人研究的性状范围．     

瓣结鱼的食谱及食性研究

瓣结鱼为水中垂直取食的温和肉食性鱼类．从140尾鱼（体长9．57-44．2cm）肠内含物分析,其食谱以水生昆虫及其幼、稚虫为主,该类食物出现率为99．29％,其次为螺、蚌等软体动物,出现率为15％．摄食强度有明显的季节性变化,以春季的3、4月最高,分别为93．33％和70．33％,5－7月较低,其它月份较为稳定．冬季以及生殖群体在繁殖季节无停食现象．该鱼的肠长／体长为1．21(N＝341）,其视觉在摄食中起重要作用．     

中华大蟾蜍生活习性及人工养殖场地选择

中华大蟾蜍是一种药用价值很高的经济动物,其个体发育过程有变态现象,抱对、产卵、排精、受精过程、受精卵的孵化及蝌蚪的生长发育过程都必须在水中进行,成体喜欢生活在温暖湿润的环境中,可水陆两栖,怕低温,气温过低需要冬眠．蝌蚪期食性是由植食性向杂食性转变,到大蝌蚪期以后以动物性饵料为主,同时由摄食静态饵料转变为捕食动物性活饵,因此在人工养殖选择养殖场地时,应根据中华大蟾蜍的生活习性及对环境等件的要求选择场地,以使建造的养殖场有利于中华大蟾蜍的生长繁殖,并能获取最大的养殖效益．     

Ciona intestinalis as an emerging model organism： its regeneration under controlled conditions and methodology for egg dechorionation

The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide orucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuterostome ancestor and how advanced chordates originated from the simplest chordates. In this paper, a whole-life-span culture of C. intestinalis was conducted. Fed with the diet combination of dry Spirulina, egg yolk, Dicrateria sp., edible yeast and weaning diet for shrimp, C. intestinalis grew up to average 59 mm and matured after 60 d cultivation. This culture process could be repeated using the artificially cultured mature ascidians as material. When the fertilized eggs were maintained under 10, 15, 20, 25 ℃, they hatched within 30 h, 22 h, 16 h and 12 h 50 min respectively experiencing cleavage, blastulation, gastrulation, neurulation, tailbud stage and tadpole stage, The tadpole larvae were characterized as typical but simplified chordates because of their dorsal nerve cord, notochord and primordial brain. After 8-24 h freely swimming, the tadpole larvae settled on the substrates and metamorphosized within 1-2 d into filter feeding sessile juvenile ascidians. In addition, unfertilized eggs were successfully dechorionated in filtered seawater containing 1% Tripsin, 0.25% EDTA at pH of 10.5 within 40 min. After fertilization, the dechorionated eggs developed well and hatched at normal hatching rate. In conclusion, this paper presented feasible methodology for rearing the tadpole larvae of C. intestinalis into sexual maturity under controlled conditions and detailed observations on the embryogenesis of the laboratory cultured ascidians, which will facilitate developmental and genetic research using this model system.     

Quantitative changes of nitrergic neurons during postnatal development of chicken myenteric plexus

Objective

Information regarding the development of the enteric nervous system (ENS) is important for understanding the functional abnormalities of the gut. Because fertilized chicken eggs provide easy access to embryos, chicken models have been widely used to study embryonic development of myenteric plexus; however, no study has been focused on the postnatal period. The aim of this study was to perform a qualitative and quantitative analysis of the nitrergic neurons in the myenteric plexus of developing chickens in the postnatal period.

Methods

Whole-mount preparations of the myenteric plexus were made in 7-d, 15-d, and 40-d old (adult) chickens of either sex (n=15). The myenteric plexus was studied after nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry using light microscopy, digital photography, and Image-Pro Plus 6.0 software. The numbers of positively stained neurons and ganglia were counted in the duodenum, jejunum, ileum, caecum, and colon in the different age groups. Data were expressed as mean±standard deviation (SD), and statistical analysis was performed using a one-way analysis of variance (ANOVA) test.

Results

The positively stained neurons showed various morphologies and staining intensities, and formed bead-shaped and U-shaped arrangements in the myenteric plexus. The densities of neurons and ganglia increased with age. However, the number of positive neurons per ganglion increased. The number of NADPH-d-positive neurons was highest in the colon, followed by the ileum, the jejunum, the duodenum, and the caeca in all age groups.

Conclusions

Developmental changes in the myenteric plexus of chickens continue in the postnatal period, indicating that the maturation process of the gastrointestinal function is gradual. In addition, no significant difference is happening among different intestinal segments during postnatal development, suggesting that the function of different intestinal segments had been determined after birth.     

楚雄州空中水资源特点及开发利用探讨

本文分析了楚雄州空中水资源的特点,认为从流经楚雄上空的空中水汽量分析楚雄州空中水资源有相当大的潜力,如果措施得当,截留下10—20%的水汽(7880—15600亿立方米),理论上每年可增加83—166毫米的降水量是有可能的。因此开发空中水资源应成为我州解决水资源供需矛盾的重要途径。     

电热鼓风干燥箱在骨标本制作中的应用

目的:利用局解废弃材料快速制作骨质好,结构完整,数目成套齐全的足骨标本。方法:将取下的足标本放入32mm高压锅内加清水没至标本25mm水位,盖好锅盖并放上限压阀,放置2500w电炉上通电加热,待限压阀排气后,继续蒸煮15min。随后将上述处理好的足骨按套(每套分别用1个小铁丝篓)放入CS101-3型电热鼓风干燥箱内(温度调至110℃)进行烘烤,在温度达到110℃时,继续烘烤15min即可切断电源,将足骨倒入加有洗衣粉50℃温度热水中浸泡,搓洗10min,用同样方法进行两次处理即可。结果:按传统方法用有机溶剂浸泡脱脂处理,时间需1-2个月,而经电热鼓风干燥箱烘烤处理过的足骨进行有机溶剂浸泡脱脂处理,可缩短2/3时间。结论:该方法改进之处在于,将足骨在脱脂之前经过了电热鼓风干燥箱多次烘烤处理,使骨髓腔内的脂肪大部分逐被蒸发去除,缩短了标本的脱脂时间,也解决了标本处理阶段需晾晒等问题。