Muscarinic receptor subtypes in equine tracheal smooth muscle

Selective muscarinic receptor antagonists were used to identify muscarinic receptor subtypes in equine trachealis strips. The M₁ receptor antagonist pirenzepine (10^–7 mol/L to 3 × 10^–5 mol/L) and the M₃ receptor antagonist 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, 10^–9 mol/L to 3 × 10^–7 mol/L³) dose dependently inhibited the contractile responses to electrical field stimulation (EFS) and exogenous acetylcholine (ACh). Schild plots yielded a pA₂ value for pirenzepine vs ACh of 6.75 ± 0.09, which is consistent with the affinity for M₂ or M₃ receptors, and a pA₂ value for 4-DAMP vs ACh of 8.47 ± 0.09, which is in agreement with the affinity for M₃ receptors. The M₂ receptor antagonist gallamine (10^–5 mol/L and 10^–4 mol/L) did not affect the response of trachealis to exogenous ACh and low-frequency EFS (0.1–2 Hz) but decreased the responses to high-frequency EFS (4–16 Hz). These results suggest that the muscarinic receptors mediating contractions induced by ACh in equine tracheal smooth muscle are of the M₃ subtype. The lack of an increase in the response to EFS following gallamine suggests that functional prejunctional inhibitory M₂ receptors are not present on the cholinergic nerves innervating equine tracheal smooth muscle.     

Estimating Combining Ability of 4x-2x Crosses in Cultivated Potatoes

Progenies derived from crosses between Solarium tuberosum and 2n pollen-Producing diploid hybrids, exhibit obvious hybrid vigor. The 2n pollen-producing clone can act as a bridge in crossing S. tuberosum and S. andigena with S. phureja. Populations from 4x-2x crosses show more unifomity and less segregation compared with that of 4x-4x crosses. The parent-offspring correlation for the traits, starch content and tuber number, is significant at 0.01 level. The regrssion equations are Y (mp-F1)=1.0 1.2x and Y (mp - F1) = 5.3 0.8x, respectively. The 2n pollen-producing clones play an impotant role in increasing tuber stach content. Estimates of the combining ability for the main yield components indicate that additive effect prodominatcs for such trais as plot yield, tuber weight per plant and starch content, whereas both additive and non-additive effects lay equal stress on mean tuber weight and non-additive effect is important for tuber number. In general, non-additive effect appears to be important in     

棉花纤维发育后期Mg2+,K+-ATP酶的活性分析

1989～1990年选用陆地棉(G.hirstum L.)北农1号品种和海岛棉(G.barbadenseL.)海7124品种为材料,对棉纤维发育后期的纤维素形成过程进行了研究。结果表明:①随着棉纤维的发育 Mg~(2+),K~+-ATP 酶活性逐渐下降。②Mg~(2+),K~+-ATP 酶活性的最适 pH 值为6.5。Mg~(2+),K~+ATP 酶活性随[Mg~(2+)],[K~+]和[NADH]/[NAD~+]的增大而变大。③Mg~(2+),K~+ATP 酶活性变化与还原性糖含量变化呈显著正相关(r=0.811~*),与纤维素含量变化呈极显著负相关(r=-0.900~(**))。④Mg~(2+),K~+-ATP 酶参与了纤维素的形成过程。     

基于图形旋转系统的渐进网格研究

拓扑简化可以为渐进网格带来更好的效果，但目前几乎所有的渐进网格方法都不支持拓扑简化，而且edge collapse和vertex split操作有时会产生非流形．针对这些问题，提出了基于图形旋转系统的渐进网格法．以基于图形旋转系统的数据结构和操作实现了渐进网格，用图形旋转系统的操作集合构建了edge collapse和vertex split操作．在此基础上，通过扩展新操作即可进行任意拓扑变化，从而实现拓扑简化，     

维生素K3的合成及应用

本文概述了维生素K3的各种合成技术路线，对维生素K3生产技术的发展进行了展望，介绍了其应用和市场供求现状。     

优质籼型不育系Q2A的选育

Q2A是重庆市农业科学研究所和重庆市种子公司用金23B×中九B的F2代与58B×Ⅱ-32B的F2代杂交,再用复交F2代与珍汕97A杂交引入野败型胞质育成的一个优质籼型三系不育系,2003年7月通过重庆市科学技术委员会组织的技术鉴定.该不育系异交习性好;可恢性好,配合力强;米质优(12项测试指标中有7项达部颁一级优质米标准,5项达二级标准);苗瘟3级,叶瘟3级,颈瘟7级,对苗瘟和叶瘟表现为中抗,颈瘟感病.其与成恢047配组育成的优质杂交中籼新组合Q优5号米质优,产量高,抗稻瘟病,2003年12月通过重庆市农作物品种审定.     

硼浓度对毛木耳菌丝生长的影响试验

试验通过不同浓度的Na2B4O7在改变PDA培养基及棉子壳一木屑培养基的试验,测定了其对毛木耳菌丝生长的影响。结果表明:在200mg／kg浓度下促进作用最为显著,而其浓度超过400 mg／kg时对菌丝有强烈的抑制作用。     

对《中图法》(第四版)类目注释的系统认识

本文从语言特点、编排体例及内容特点出发,对《中图法》(第四版)类目注释进行了系统的认识,并就此提出了自己的一些看法。     

黑杨无性系日CO2固定总量的测定及与苗木生产潜势的相关性研究

通过对不同基因型黑杨无性系植株净光合速率日变化曲线与光合主体叶面积在时间和光强上进行累计积分来计算植株日CO2固定总量P。由于净光合速率日变化曲线不易准确测得，故以光响应曲线和光强的日变化来推测净光合速率日变化。对P值和生物量的相关性研究表明，二者的相关性很高。且认为可以用计算出的P值作为评估苗木生产潜势的指标之一，这为育种中生产力的早期选择提供了有力的证据。     

2型猪链球菌的血清学鉴定

本试验首次证实了２型猪链球菌在我国的存在，采用玻片凝集、琼脂扩散及毛细管沉淀等３项试验，对１９９０年以来广东某猪场断奶仔猪暴发流行的败血症、脑膜炎及关节炎病猪中分离的１５株链球菌进行了血清学鉴定。结果表明：１５株链球菌均为２型猪链球菌；用高压法提取抗原进行沉淀反应，其结果比酸热法提取抗原具有简便、敏感、特异性强的特点。