SS-1型声速实验仪的研制

本文阐述了SS—1型声速实验仪的原理、结构和测量方法。波动学和分子物理学是物理学中的重要组成部分,"声速的测量"和"Y值的测量"两个实验有助于学生对波动相位的空间分布、谐振动的合成、李萨育图、能量按自由度均分原     

强化“现代科技革命与马克思主义”课程教学中的三个主要环节

通过对博士研究生特点的综合分析,在教学实践中强化三个主要环节,探索了适合博士生特点,反映课程要求的教学方法。     

稻属植物21个种颖花稃尖的比较研究

用扫描电镜对稻属植物２１个种颖花稃尖进行观察,看到外稃尖的两侧各个一个突起或折痕。根据其形状不同,将２１个稻种的外稃尖分为“乳突型”、“钝角型”、“折痕型”和“融合型”４种型。     

Pathogenic mechanisms of caprine arthritis-encephalitis virus

Goats infected with caprine arthritis-encephalitis virus (CAEV) show chronic arthritis and cachexia, which are progressive in nature. The immunopathogenic mechanisms responsible for these progressive clinical symptoms have not been fully elucidated. Various haematological and immunological parameters were evaluated in experimentally-infected goats showing typical signs of CAEV-induced disease. Infected goats showed recurrent lymphocytosis that may be due to constant presentation of antigen by infected cells of a monocyte/macrophage lineage. The serum alkaline phosphatase and -glutamyl transferase concentrations were elevated in infected goats, a characteristic of hepatic and bone disorders. All other serum chemistry parameters were similar between infected and control goats. Importantly, the serum tumour necrosis factor- (TNF-) levels were higher in infected goats. The cachexia seen in infected goats may be at least partly due to altered metabolism as a result of prolonged elevation of serum TNF- levels. Depressed natural killer cell activity was observed in infected goats and may contribute towards the establishment of a persistent infection with CAEV.Abbreviations AIDS acquired immunodeficiency syndrome - CAEV caprine arthritis-encephalitis virus - GGT -glutamyl transferase - HBSS Hanks' balanced salt solution - HIV human immunodeficiency virus - NK natural killer - PBMC peripheral blood mononuclear cells - PCR polymerase chain reaction - SAP serum alkaline phosphatase - TNF tumour necrosis factor     

光敏核不育水稻选育与利用的几个问题讨论

对现有光敏核不育材料进行了分类,分为４种遗传类型;其中,温光弱感到光敏核不育系是最为理 想的遗传工具,并就其选育途径和选择“粳不籼恢”繁殖制种技术体系进行了论证．     

关于编制我国果树种质资源评价系统若干问题的商榷

资源评价是果树种质资源工作的中心环节。编制果树种资源评价系统是发展和提高我国果树种质资源工作水平的一项重要基础工作。“七五”期间,“果树种质资源主要性状鉴定评价”专题组编制１８种果树的《果树种质资源描述符》,于１９９０年在农业出版社出版。本文就其中其中若干问题提出商榷意见。     

林木抗旱性生理指标及其在干旱区造林中应用研究

<正> 中国干旱半干旱区面积占全国面积的52.5%,半壁河山是以水分胁迫为主导限制因子的特殊生态区。为了提高这一地区的造林质量,选择旱生和抗旱性强的树种造林是主要造林技术之一。对于如何评价和比较林木的抗旱性,传统方法多采用对林木生态环境因子及对林木生     

奶牛难产激发应激性急性肾上腺皮质功能不全——心衰、水电解质严重失调辩析

应激性急性肾上腺皮质功能不全症的病理机制十分复杂,目前人医的各类文献中大都以“垂体—肾上腺轴”功能不全、功能衰竭、或发生广泛性出血坏死性病演作解释。本病在奶牛分娩难产过程中并不少见,病牛的症状表现以心衰和失钠性低血症为主征。但在兽医临床上由于认识不足,曾有不少中外学者将奶牛产后卧地不起的各类疾病,含糊地统称为“母牛睡倒爬不起来综合征”;更由于救治不当,病牛常以淘汰或死亡告终。本文通过对一具体典型病例辨析,着重讨论了本病的基本病理反应和确立诊断依据,强调对本病救护施治时应遵循的基本原则,供同道们在分析和解决这一实际问题时参考。     

Sexual compatibility types of Bremia lactucae isolates originating from Lactuca serriola

Results are given on the occurrence of sexual compatibility types of seven isolates ofBremia lactucae originating fromLactuca serriola (prickly lettuce). It is concluded that the isolates studied are heterothallic. Both compatibility types (B1 en B2) were determined, but type B2 was prevalent. Sexual recombination ofB. lactucae isolates originating from wild and cultivated lettuce may occur.Samenvatting Zeven isolaten vanBremia lactucae, afkomstig vanLactuca serriola in Tsjechoslowakije, zijn onderzocht op hun sexuele compatibiliteitstype door ze te combineren met Nederlandse fysio's vanB. lactucae, afkomstig van cultuursla (L. sativa), waarvan het compatibiliteitstype (B1 of B2) bekend is. Alle isolaten vanL. serriola bleken heterothallisch te zijn, waarbij type B2 meer werd aangetroffen dan type B1. Sexuele recombinatie vanBremia-isolaten van wildeLactuca-soorten en cultuursla blijkt goed mogelijk te zijn.