基于模态叠加法的曲轴动态特性研究与结构优化

为了计算得到曲轴动态特性参数,并使用模态贡献因子理论对动态特性进行研究,基于研究结果能够更加有效的实现曲轴结构参数的优化,首先基于多体动力学理论建立了某V12型曲轴的刚柔耦合多体动力学模型。基于模态贡献因子理论对曲轴动态特性进行分析,将前15阶模态缩聚为前5阶模态以减少计算规模,最大应力值的误差为0.9%,扭振角位移的误差为0.16%。利用BP(back propagation)神经网络建立了曲轴动静特性与结构参数之间的数学模型,进行了最大应力值和扭振角位移的线性回归,其输出响应的复相关系数都在0.95以上,表明此网络的泛化能力和预测性能都很好。对神经网络建立的数学模型使用遗传算法进行优化,优化后此曲轴的扭振角位移减小了2.63%,最大应力值减小了3.98%。结果表明神经网络结合遗传算法的优化方法对曲轴结构参数的动态特性和静态特性的联合优化能够满足设计预期,并且具有高效性和可行性。     

高粱与旱稻属间杂交部分遗传物质导入的F_3及BC_1表型鉴定

以高粱(S.BICOLOR)为母本、旱稻(O.SATIVA)为父本进行属间杂交,F1出现双亲没有的短芒和黄色柱头新性状,并能在F2、F3及BC1稳定遗传。F3在株高、穗长、穗型、分蘖性等性状上仍疯狂分离,并出现父本白色籽粒单株。BC1在株高、分蘖二性状上接近父本,回交效应非常明显,T测定无差异,并出现多子房新性状。高梁与旱稻杂交及回交,能创造变异,产生新性状,对创造矮秆、优质、多子房新种质十分有效。然而,二者杂交后代主体性状仍似母本,只表现父本少数性状,属于部分遗传物质导入。     

不同基因型刺梨及其近缘种亲缘关系的RAPD分析*

采用RAPD标记，对刺梨(Rosa roxburghii Tratt)7个基因型及8个近缘种(类型)进行鉴定和亲缘关系分析。结果表明，筛选出的16个随机引物可扩增出137条480bp到3.3kb大小的清晰。DNA片段，其中95条为多态性片段，为总数的69．3％；每个引物平均产生8．6条。由OPB-11、OPAF-16和OPW-02扩增的14条特异DNA片段，可有效地将普通刺梨7个基因型和无籽刺梨区分开来。基于遗传距离矩阵，采用IJPGMA法对15个供试样品的亲缘关系进行了聚类分析，文中还就无籽刺梨及重瓣刺梨的可能来源进行了探讨。     

水稻压致变异后代主要农艺性状的研究

用高压诱变法处理高收获指数型水稻品种粤香占 ,培育出变异材料粤压 1号、2号和 3号。通过对其主要农艺性状比较研究发现 ,3个变异材料与粤香占在生育期、株高、分蘖数、有效穗数、穗部性状、外观米质、抗病性和抗寒性等方面存在明显差异 ,表明高压诱变可能成为一种新的育种方法。     

Isoenzyme differences between the wild diploid and tetraploid wheats

Variability of acid phosphatase (ACP), esterase (EST), and superoxide dismutase (SOD) isoenzymes among 660 accessions of wild diploid wheats Triticum boeoticum (475) and T. urartu (185) and among 35 accessions of wild tetraploid wheats T. araraticum (21) and T. dicoccoides (14) was studied with the use of polyacrylamide gel electrophoresis. The wild diploids are differentiated by the electrophoretic variants of ACP-B, ACP-C, EST-A, EST-B, EST-C, EST-D, and SOD-B. Triticum urartu matches the A genome of wild tetraploid wheats T. araraticum and T. dicoccoides by allozymes of ACP-B, ACP-C and SOD-B, but differs distinctly by the monomorphic allozyme EST-A66. Triticum boeoticum fits the A genome of polyploid wheats by allozymes of EST-A and EST-B, but differs in allozymes of ACP-B and SOD-B. Thus, none of the two contemporary diploid wheats corresponds exactly to the A genome of wild tetraploid wheats by all diagnostic isoenzymes. Triticum boeoticum and T. arararicum share EST-C46 and EST-D71, whereas T. urartu and T. dicoccoides are fixed for silent EST-C0 and share EST-D73, suggesting independent origin of the two tetraploid wheats with a contribution from ancestral forms of both diploids.     

抗生素FR-008基因簇上游区域的DNA序列分析

链霉菌FR-008产生一种七烯大环内酯类抗生素FR-008，对真菌具有很高的抗菌活性，并对蚊子幼虫有高毒性（袁德军和周启，1990）。负责合成FR-008的基因簇被定位（Hu et al．，1994），有21个基因（共138kb，GenBank accession number AY310323）被确认参与了抗生素FR-008的生物合成以及调节和外运（Chen et al．，2003）。然而，在FR-008基因簇最左端fscO基因上游的基因是否与FR-008抗生素生物合成相关？为此，本研究对FR-008基因簇上游区域进行了序列测定和分析。     

合成大豆异黄酮的植物基因工程研究进展

异黄酮主要存在于豆科植物中,是一种具有广谱抗菌活性的黄酮类物质。结合本课题组的工作,综述以基因工程的方法在植物内合成异黄酮的研究历史与进展,重点深入分析和讨论异黄酮生物合成所受到的分子调控。     

皖南紫红色砂石岩上发育土壤的系统分类研究

对皖南不同时期紫红色砂石岩上发育的8个土壤剖面,按中国土壤系统分类体系,进行鉴别、检索、分类定名。阐述发生分类紫色土的2个亚类级土壤类型在中国土壤系统分类中归为3个土纲,即均腐土、雏形土和新成土;3个亚纲,即湿润均腐土、湿润雏形土和正常新成土;4个土类和6个亚类。提出按中国土壤系统分类的紫色土分类系统;并与美国土壤系统分类、国际土壤分类参比基础进行了参比。讨论了皖南紫红色砂石岩上发育为均腐土的成土环境条件,同时对发生分类紫色土在中国土壤系统分类类别检索提出修订建议。     

Breeding gains and changes in morphotype of Nordic spring wheat (1901–1993) under contrasting environments

Phenotypic diversity among 75 Nordic spring wheat cultivars was assessed in a glasshouse experiment, in which plots had no fertilizer or received 14-3-23 NPK plus Mg. On average, the fertilizer application delayed flowering by one day, shortened plant height (PH), as well as enhanced the number of fertile tillers (NFT), fresh and dry straw weight (FSW and DSW, respectively), but influenced negatively the dry matter content in the straw (DMCS) and the number of kernels per spike (K/S). The cultivar-by-fertilizer interaction did not affect significantly days to flowering (DF), PH, FSW, DSW, DMCS, thousand kernel weight, and K/S. Only NFT was significantly affected by this interaction. There were significant differences among cultivars for all characteristics, and the breeding gains were significant for improving earliness (as determined by DF), shortening PH, as well as for reducing DSW and DMCS irrespective of the environment. On average, FSW was low in newer cultivars grown in high inputs, while NFT was low in newer cultivars when grown in low inputs. The country of origin affected significantly DF, PH, DMCS, K/S, and 1000-kernel weight. On average, cultivars developed for Finland and Norway were significantly taller, and had higher DMCS. Finnish cultivars also flowered 1 or 2 days earlier and showed higher K/S than cultivars adopted in southern Scandinavia or Norway.     

压力输水树状管网遗传优化布置和神经网络优化设计

分别应用单亲遗传算法和Hopfield神经网络方法进行机压式树状管网的优化布置和优化设计,能够在管网投资最小的最优树状管网布置形式上,获得年费用最低的最优设计方案。研究表明:该方法是可行的和有效的,能减小管网工程投资,提高设计水平和设计效率