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1.
 The challenge to maize breeders is to identify inbred lines that produce highly heterotic hybrids. In the present study we surveyed genetic divergence among 13 inbred lines of maize using DNA markers and assessed the relationship between genetic distance and hybrid performance in a diallel set of crosses between them. The parental lines were assayed for DNA polymorphism using 135 restriction fragment length polymorphisms (RFLPs) and 209 amplified-fragment polymorphisms (AFLPs). Considerable variation among inbreds was detected with RFLP and AFLP markers. Moreover AFLPs detect polymorphisms more efficiently in comparison to RFLPs, due to the larger number of loci assayed in a single PCR reaction. Genetic distances (GDs), calculated from RFLP and AFLP data, were greater among lines belonging to different heterotic groups compared to those calculated from lines of the same heterotic group. Cluster analysis based on GDs revealed associations among lines which agree with expectations based on pedigree information. The GD values of the 78 F1 crosses were partioned into general (GGD) and specific (SGD) components. Correlations of GD with F1 performance for grain yield were positive but too small to be of predictive value. The correlations of SGDs, particularly those based on AFLP data, with specific combining-ability effects for yield may have a practical utility in predicting hybrid performance. Received: 15 August 1997 / Accepted: 19 September 1997  相似文献
2.
Molecular divergence and hybrid performance in rice   总被引:41,自引:0,他引:41  
This study was undertaken to determine the relationship between genetic distance of the parents based on molecular markers and F1 performance in a set of diallel crosses involving eight commonly used parental lines in hybrid rice production. The F1s and their parents were measured for five traits including heading date, plant height, straw weight, grain yield and biomass. The parental lines were assayed for DNA polymorphisms using two classes of markers: 140 probes for restriction fragment length polymorphisms (RFLPs) and 12 simple sequence repeats (SSRs), resulting in a total of 105 polymorphic markers well spaced along the 12 rice chromosomes. SSRs detected more polymorphism than RFLPs among the eight lines. A cluster analysis based on marker genotypes separated these eight lines into three groups which agree essentially with the available pedigree information. Correlations were mostly low between general heterozygosity based on all the markers and F1 performance and heterosis. In contrast, very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis. The analyses also suggest the existence of two likely heterotic groups in the rice germplasm represented by these eight lines.  相似文献
3.
 A barley lambda-phage library was screened with (GA)n and (GT)n probes for developing microsatellite markers. The number of repeats ranged from 2 to 58 for GA and from 2 to 24 for GT. Fifteen selected microsatellite markers were highly polymorphic for barley. These microsatellite markers were used to estimate the genetic diversity among 163 barley genotypes chosen from the collection of the IPK Genebank, Germany. A total of 130 alleles were detected by 15 barley microsatellite markers. The number of alleles per microsatellite marker varied from 5 to 15. On average 8.6 alleles per locus were observed. Except for GMS004 all other barley microsatellite markers showed on average a high value of gene diversity ranging from 0.64 to 0.88. The mean value of gene diversity in the wild forms and landraces was 0.74, and even among the cultivars the gene diversity ranged from 0.30 to 0.86 with a mean of 0.72. No significant differences in polymorphism were detected by the GA and GT microsatellite markers. The estimated genetic distances revealed by the microsatellite markers were, on average , 0.75 for the wild forms, 0.72 for landraces and 0.70 among cultivars. The microsatellite markers were able to distinguish between different barley genotypes. The high degree of polymorphisms of microsatellite markers allows a rapid and efficient identification of barley genotypes. Received: 26 November 1997 / Accepted: 19 January 1998  相似文献
4.
Ten elite inbred lines (four japonica, six indica), chosen from those widely used in the hybrid rice breeding program at Human Hybrid Rice Research Center in China, were crossed to produce all possible hybrids excluding reciprocals. The 45 F1 hybrids along with the ten parents were evaluated for eight traits of agronomic importance, including yield potential, in a replicated field trial. The ten parents were analyzed with 100 arbitrary decamer oligonucleotide primers and 22 microsatellite (simple sequence repeats, SSRs) primer sets via polymerase chain reaction (PCR). Out of the 100 random primers used, 74 were informative and amplified 202 non-redundant bands (variants) with a mean of 2.73 bands per polymorphic primer. All 22 microsatellite primer sets representing 23 loci in the rice genome showed polymorphisms among the ten parents and revealed 90 alleles with an average of 3.91 per SSR locus. Cluster analysis based on Nei's genetic distance calculated from the 291 (202 RAPDs, 89 SSRs) non-redundant variants separated the ten parental lines into two major groups that corresponds to indica and japonica subspecies, which is consistent with the pedigree information. Strong heterosis was observed in hybrids for most of the traits examined. For the 43 diallel crosses (excluding 2 crosses not heading), yield potential, its components (including panicles per plant, spikelets per panicle and 1000-grain weight) and their heterosis in F1 hybrids showed a significant positive correlation with genetic distance. When separate analyses were performed for the three subsets, yield potential and its heterosis showed significant positive correlations with genetic distance for the 15 indica x indica crosses and the 6 japonica x japonica crosses; however, yield potential and its heterosis were not correlated with genetic distance for the 22 indica x japonica crosses. Results indicated that genetic distance measures based on RAPDs and SSRs may be useful for predicting yield potential and heterosis of intra-subspecific hybrids, but not inter-subspecies hybrids.  相似文献
5.
我国烟蚜种群分化的RAPD分析   总被引:36,自引:4,他引:32       下载免费PDF全文
杨效文  陈晓峰 《昆虫学报》1999,42(4):372-380
 用RAPD-PCR技术研究了我国烟草上烟蚜Myzus persicae (Sulzer)的种群分化。结果表明:我国烟蚜的不同地理种群和不同体色之间DNA均呈现出多态性,且不同的引物可在不同水平上反应出烟蚜种群的DNA多态性。Nei的遗传距离表明我国烟草上烟蚜的分化仅在种群水平上,并未达到亚种水平。用相似性指数和Nei的遗传距离对所筛选的三个引物OPX-04、OPX-06和OPX-19的扩增结果进行聚类,虽然二者的结果不一致,但均可反应出烟蚜的地理种群和体色生物型的DNA差异。在DNA水平上,与完全周期生活史的烟蚜相比,完全周期和不完全周期生活史混合发生的烟蚜与不完全周期生活史的烟蚜更为接近,而两种生活史混合发生的烟蚜之间无明显差异。从体色看,红色比黄绿色更接近褐色。  相似文献
6.
距离分析方法与杂种优势   总被引:34,自引:1,他引:33  
郭平仲  张金栋 《遗传学报》1989,16(2):97-104
对于75个小麦品种两年的试验结果,采用不同方法进行距离比较分析。结果表明:用表型平均值相关阵经主成分转换,计算品种间欧氏距离,再用类平均法聚类,似乎是适宜的距离分析方法。D~2值在年份间较稳定,不同年份的D~2估值,可用于预测杂种优势。根据13个性状估算的品种间距离(D~2)与株粒重杂种优势(H)之间呈曲线关系,其理论方程是:Y=-3.65 6.665X--0.1288X~2。根据该方程推算:D~2=25.87时,H出现最大值。  相似文献
7.
AFLP标记与玉米杂种产量,产量杂种优势的预测   总被引:33,自引:0,他引:33  
以17个玉米(Zea mays L.)自交系及其按双列杂效配制的136个单交种为材料,研究AFLP分子标记与玉米杂效种产量、产量杂种优势的关系。结果表明,基于AFLP数据计算的遗传距离与1997年杂种产量、产量中优势的相关系数(r)分别为0.4503、0.3714,与1998年杂种产量、产量杂种优势的相关系数分别为0.4352、0.3253,均达到显水平,但决定系数(r^2)都很小。当亲本材料改  相似文献
8.
RAPD分子标记与玉米杂种产量优势预测的研究   总被引:30,自引:1,他引:29  
吴敏生  王守才 《遗传学报》1999,26(5):578-584
以24个优良玉米自交系统NCⅡ设计组配成143个单杂交种为材料,利用的RAPD分子标记技术研究玉米杂种优势群划分,遗传距离与特殊配合力,杂种产量,杂种产量优势的联系。结果表明:(1)RAPD技术可用于玉米杂种优势群划分。(2)亲本遗传距离杂种产量优势,杂种产量,特殊配合畋有一定相关关系,但决定系数很小,分别是10%,10%,15%,利用RAPD技术预测杂种优势,杂种产量作用有限,应进一步研究与杂  相似文献
9.
不同尺度下野大豆种群的遗传分化   总被引:30,自引:4,他引:26       下载免费PDF全文
为了阐明不同尺度范围内野大豆种群的遗传分化情况,应用随机扩增多态性DNA(RAPD)方法,分别对我国5个纬度8个不同地点的野大豆(Glycine soja)种群及浙江金华地区5个野大豆种群,进行了分子生态学研究。根据RAPD数据计算相似系数及遗传距离并进行聚类分析,发现无论是不同纬度野大豆种群还是金华地区野大豆小种群均存在较高的遗传变异,且不同纬度野大豆种群间的遗传变异与地理纬度有一定正相关。在对金华地区野大豆种群遗传多样怀的研究,利用Shannon指数估算了5个野大豆种群的遗传多样性,发现大部分的遗传变异存在于野大豆种群间(78.5%),只有少部分的遗传变异存在于种群内。本就此探讨了不同尺度下野大豆种群的遗传多样性与环境因子的关系,并对其成因及维持机制进行了讨论。  相似文献
10.
人类短串联重复序列HUMTH01基因座的遗传多态性   总被引:29,自引:1,他引:28  
侯一平 Staa  M 《遗传学报》1996,23(3):174-182
作者用扩增片段长度多态技术分析了人类短串联重复序列HUMTH01基因型及等位基因频率在中国成都地区汉族群体和德国科隆地区白人中的分布。用同步电泳技术比较不同引物PCR产物分型结果,评估不同实验室HUMTH01群体数据的可比性。计算了25个群体间HUMTH01STR的遗传距离,并构建了系统树。HUMTH01STR系统树分析不仅与传统遗传标记结果一致,并且获得了群体遗传的新线索。  相似文献
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