( 1 ) state the appearance of block design and it ' s resolution . ( 2 ) formulate the history of ols ( orthogonal latin squares ) and show the role that euler ' s conjecture and macneish ' s conjecture on ols played in the progress of study on latin square . ( 3 ) state briefly the motivation that finite projective plan and finite field offer to the development of combinatorial design ( 1 )详述了18世纪中期提出的区组设计问题以及这些问题出现的多种形式及解决方法； ( 2 )对组合设计中正交拉丁方的历史予以阐述，分析了拉丁方问题的研究中欧拉猜想和麦克奈希猜想的作用； ( 3 )简述了有限射影几何及有限域在组合设计中的意义及其对组合设计理论发展的推动作用。
A directed balanced incomplete block design ( dbibd ) with order v , block size k and index a , denoted by db ( k , ? ; v ) , is a pair ( x , a ) , where x is a set of v points and a is a collection of transitively ordered k - tuples ( called blocks ) of x , such that each ordered pair of distinct points of x occurs exactly in a blocks 一个阶为v ，指标为及区组大小为k的有向平衡不完全区组设计， db ( k ， ； v ) ，是指一个序偶( x ， a ) ，其中x是一个v元点集， a是x的一族可迁有序k元子集(叫做区组) ，使得x中任意两个相异点组成的有序对恰出现在个区组中。
The total significant differences among groups were compared by two way anova , factoring treatment group and incubation medium level . post hoc testing were used to evaluate the significance of subgroup differences by lsd and snk methods , significant correlation between every two transmitters was analyzed by pearson correlation 用随机区组设计的方差分析进行总体均数的差异显著性比较，组间比较用hd法和snk法；不同神经递质之间的相关性分析用pearson相关分析法；不同孵育条件下同种处理组间比较用stwm ’ lt检验。
The experimental results show that the characters of tree height , dbh , and volume , etc . of every family progenies of pinus massoniana seed orchard are all evidently higher than those of control ( ck ) , 7 fine family materials whose volume growth exceeds the control ' s by 50 % are totally selected as the materials for building p . massoniana improved seed orchard and industrial raw material forest 摘要对漳平五一国有林场马尾松种子园18个初选家系进行子代测定，采用随机区组设计、 8次重复，对6年生的树高、胸径、材积等性状进行测定，试验结果表明：马尾松种子园各家系子代均明显高于对照( ck ) ，共选出7个优良家系材积生长超过对照50 %以上材料，作为营建马尾松改良种子园和工业原料林的材料。
Group division : experiments were performed in 3 different conditions , i . e . , normal 4 medium , high k * stimulated medium , and ca2 + - free medium . hippocampal slices from a same rat were then divided into 3 treatment groups : control group ? lices were oxygenated with 95 % o2 / 5 % cc > 2 and incubated at 35 ~ 36 ? for 30min ; hypoxia group ? lices were oxygenated and incubated on the same conditions as the control group , then the mixture gases change into 95 % o2 / 5 % co2 - hypoxic condition were remained for lomin ; ginkgolide b preincubation group ? lices will be preincubated at the normal oxygenated medium containing loomm ginkgolide b , 10 min later , repeated hypoxic treatment 3实验采用随机区组设计，动物随机分为三组，各组动物制备的海马脑片分别进行三种不同介质的灌流实验，即正常介质组、高k ~ +去极化组和无ca ~ ( 2 + )组；各组中由同一只动物制成的海马脑片再随机分到三个不同的处理组，即：正常对照组、低氧组和ginkgolideb预孵育组。
A block design is a triple d = ( x , b , i ) , where x is a finite set ( the point set ) of order v , b is the block set and / is the incidence relation between x and b . for the given block design d , if all the blocks from x , which have the same type of the blocks in b , can be partitioned into some bi , such that each ( x , bi , i ) is a block design with the same parameters and the same type as d , then { ( x , bi , i ) } i is called as large set of d - design of order v . on the other side , let | x | = v , | y | = v + 1 , and x y , if all the blocks of the same type from y can be partitioned into some bx , such that each ( y { x } , bx , i } is a block design of order v for any element x y with the same parameters and the same type as d , then { ( y { x } , bx , i ) } x is called an overlarge set of d - design of order v . in this thesis , we discuss the existence problem about some types of large sets and overlarge sets 一个区组设计是由两个有限集合x ， b及它们之间的关联关系i组成的，记为d = ( x ， b ， i ) ，其中x为v元集， b为区组集，对于指定的设计d ，若x上与d相应的全部构形可分拆为若干个b _ i ，使得每个( x ， b _ i ， i )皆为一个与d同参数同类型设计，则称这些b _ i构成一个v阶d -设计的大集。若v元集x是v + 1元集y的一个子集，而y上与d相应的全部指定构形可分拆为若干个b _ x ，使得每个b _ x恰是y { x }上的一个与d同参数同类型的设计(其中x y ) ，则称这些b _ x构成一个v阶d -设计的超大集。本文中讨论了一些区组设计的大集及超大集。
Agronomic characteristics and nutritional compositions of six clover cultivars were studied , and the results showed that , in low altitude area in hunan province , canadian red clover took on higher drought - resistance , disease - resistance and insect - resistance , and which fresh grass yield was highest and protein content was higher 摘要为了筛选出在湖南省低海拔地区适应性较强的三叶草品种加以推广应用， 2003 ~ 2005年采用随机区组设计，对6个三叶草品种进行了农艺性状观察和营养成分测定。
