白芨实生种子的快速繁殖技术

为白芨种质资源的保存和大面积种植提供依据,以白芨种子作为接种材料,利用正交试验研究在不同条件下白芨种子的萌芽率,不同激素浓度白芨种子成苗率及白芨种子实生苗炼苗成活率的条件。结果表明:贮藏条件为20℃,30d的白芨种子在培养温度为25℃,光照16h/d的萌发率最高;培养基配比为MS+6-BA 3.0mg/L+NAA 1.0mg/L+蔗糖30%,光照16h/d,温度25℃条件下白芨种子的萌发最快,长势较好,而MS+NAA 1.0mg/L+蔗糖30%对于诱导生根效果明显;炼苗基质以腐叶土∶锯末=1∶1为最好,控制温湿度,成活率超85%。     

Effects of temperature and dietary protein on the growth performance and IGF‐I mRNA expression of juvenile mirror carp (Cyprinus carpio)

Juvenile mirror carp were fed with five different diets containing 303, 322, 341, 361 and 379 g kg^?1 protein and reared at three different water temperatures (18, 23 and 28 °C) for 60 days. We investigated the insulin‐like growth factor I (IGF‐I) mRNA expression, growth performance and the relationship between IGF‐I mRNA expression and the growth performance. The results indicated that the IGF‐I mRNA expression, final body weight, specific growth rate (SGR) and feed efficiency (FE) were enhanced significantly with increasing dietary protein levels (P < 0.05), whereas the protein efficiency ratio, hepatosomatic index (HSI) and viscerosomatic index (VSI) were decreased. Moreover, the IGF‐I mRNA expression, final body weight and SGR were increased significantly with temperature, whereas the HSI and VSI indices were decreased significantly with temperature. Correlation analysis showed that the IGF‐I mRNA expression levels in the brain and liver were positively related to the SGR and FE growth indices (P < 0.01). Finally, the optimal protein requirements for fish growth in different seasons were determined based on the values of SGR and FE, that is 343–348 g kg^?1 protein at 18 °C, 354–352 g kg^?1 at 23 °C and 371–362 g kg^?1 at 28 °C. In this way, we can adjust the dietary protein levels according to culture temperature to reduce any negative impacts on dietary costs and environmental pollution.     

车身非光滑表面组合布置对气动特性影响分析

为了研究非光滑表面尺寸及组合布置位置对汽车气动性能的影响.以MIRA阶梯背模型为研究对象,采用CFD与风洞试验相结合的方法对3种不同位置组合模型的气动性能进行了研究,并与光滑表面模型进行对比分析,探讨其减阻机理.结果表明,行李舱盖,车身尾部和车身底部组合布置非光滑单元体减阻效果最佳,减阻率为5.90%.非光滑表面通过改善汽车的尾部涡流,降低了模型压差阻力;同时通过改变近壁面气流的流动状态,降低了车身表面的气流速度,减小车身的摩擦阻力.     

产类细菌素乳酸菌的筛选及培养条件优化

从紫花苜蓿青贮、牛奶及奶酪、酸菜中的分离到4株可产生类细菌素菌株,即戊糖乳杆菌（Lactobacilluspentosus）、植物乳酸菌（Lactobacillusplantarum）、戊糖片球菌（Pediococcuspentosaceus）、丙酸杆菌（Propionibacterium）。粗提4株细菌的发酵液对金黄色葡萄球菌有较强的抑制生长作用,对大肠杆菌的抑制作用较弱。4株分离菌类细菌素在80℃热处理15min后活性基本不变,100oC处理15min仍保持一定活性;在pH3～5范围内抑菌活性较强。胃蛋白酶、胰蛋白酶均可使该类细菌素完全失活;酸性蛋白酶不能使其失活。对分离株戊糖乳杆菌培养条件优化后,在30℃（pH值为6．0）条件下,选择碳氮质量分数为5％、碳氮质量比为3：2,添加MgS040．07g／100ml,MnSO4 0．05g／100ml,0．2ml／100mlTween-80有利于类细菌素的产生,抑菌直径可达18．2mm,是传统培养基配方抑菌效果的1．2倍。     

X线平片检查对犬胃内不同性质异物诊断价值的研究

犬胃内异物是犬常见病、多发病,对其准确的诊断是兽医临床实施有效治疗的主要环节.文章利用X线机对犬胃内9种异物病例进行X线平片的拍摄观察,并对犬胃内大小、形状、密度不同的异物(如棉花团、木块、实心塑料球、骨头块、金属管等)的诊断效果进行了归类、比较和分析.结果显示,X线平片检查能够清晰、直观地显示胃内高密度异物,并且能够对其准确地定位;但对于胃内低密度异物的显像效果不明显,甚至观察不到胃内异物的存在;胃内中等密度的异物虽然能够通过X线显示,但其轮廓不十分清晰.     

Growth and development of pepper are affected by humic substances derived from composted sludge

A greenhouse experiment was conducted to evaluate the effects of humic substances extracted from composted sewage sludge on growth, phenological development, and photosynthetic activity of pepper (Capsicum annuum L. cv. Piquillo) plants. Humic substances derived from composted sludge (HSS) were compared with those derived from leonardite (HSL). Two doses of both humic substances were assayed (200 and 500 mg C [L substrate]^–1) and compared with a control (C). HSS showed higher nitrogen content and a higher percentage of aliphatic carbon, as well as a lower content of aromatic and phenolic carbon than HSL. HSS significantly increased plant dry‐matter production (up to 560%), plant height (86%–151%), and leaf area (436%–1397%) during the early stages of pepper development. Net photosynthesis and stomatal conductance increased in the treatments with HSS (up to 48% and 63%, respectively) at the vegetative stage. In addition, HSS accelerated the phenological development of pepper plants, reducing significantly the number of days to flowering and ripening, which occurred 12 and 14 d earlier than in control plants, respectively. In general, the treatments with HSS and HSL did not markedly affect chlorophyll and nutrient concentrations in the leaves. At maturity, only small differences in total fruit yield, number of fruits per plant, and fruit size were observed between amended and control plants. The results suggest that the mechanisms through which HSS affected plant growth and development were not associated with an improved nutrient uptake. Although the identity of the growth‐promoting factors remains to be found, the results suggest that they may be linked to the chemical structure of the humic substances.     

大花蕙兰组织培养及快速繁殖研究

以8个大花蕙兰品种茎尖为材料,采用不同培养基对茎尖原球茎进行诱导、增殖和分化培养,探讨不同浓度6-BA和椰乳对原球茎诱导、增殖和分化的影响效果。结果表明,低激素水平培养基1/2MS 0.5mg/L 6-BA 10%椰乳 2%白糖 适量活性炭对诱导产生原球茎的效果很好,大部分品种的原球茎诱导率达80%以上;在增殖培养基中添加0.5~1.0 mg/L6-BA和15%椰乳,可明显提高5个品种的原球茎诱导率和增殖率。将多次增殖的原球茎转入1/2MS 1.0mg/L 6-BA 0.5mg/L NAA 20%椰乳 1%白糖的分化培养基,原球茎可继续增殖并分化形成许多类胚性的单极丛生芽,再经分化培养后可获得大量根苗完整的再生植株。因此,试验结果可为大花蕙兰的高效低成本组培快繁途径提供依据。     

铁皮石斛高效再生体系研究与应用

以原球茎为实验材料,对影响铁皮石斛再生体系的主要影响因素进行试验,建立铁皮石斛在生产中的高效再生体系。试验结果表明,在基本培养基MS、Fonnesbech和N6中,最适合的基本培养基为MS;原球茎最佳增殖培养基为MS＋6-BA0.75 mg/L＋NAA0.2 mg/L＋4.0% 白糖,接种35 d后原球茎增殖倍数为4.19;最佳分化培养基为MS＋6-BA0.3 mg/L＋3.0%白糖,分化率为74%。分化出的丛芽在生根培养基MS＋AC0.05%＋白糖3.0% 中,28 d生根率达到87%。