共查询到18条相似文献，搜索用时 832 毫秒
1.
杉木不同地理种源染色体组型和带型的研究 总被引：2，自引：0，他引：2
《江西林业科技》1994,(Z1)
报道了应用改进的制片方法，获得了分布在１５个省区４８个种源的常规染色的清晰染色体图象，每种源都有３个以上分裂相和核型的照片。用电子计算机测定了６项核型指标的Ｆ值，绘制了核型模式图，结果表明地理种源同不同染色体的不同核型指标多数差异显著或极显著。首次成功地显出了Ｎ－带和带纹丰富、重复性高的Ｇ－带：比较分析了不同杉木种源的Ｃ－、Ｎ－和Ｇ－带带型，概括出了这三种带型的特点，分析了这三种显带方法的应用价值。 相似文献
2.
杉木不同地理种源染色体组型和带型的研究 总被引：2，自引：0，他引：2
《江西林业科技》1994,(3):97-108,115
报道了应用改进的制片方法，获得了分布在１５个省区４８个种源的常规染色的清晰染色体图象，每种源都有３个以上分裂相和核型的照片，用电子计算机测定了６项核型指标的Ｆ值，绘制了核型模式图，结果表明地理种源同不同染色体的不同核型指标多数差异显著或极显著，首次成功地了Ｎ－带和带纹丰富，重复性高的Ｇ－带；比较分析了不同杉木种种源Ｃ－，Ｎ－和Ｇ－带带型，概括出了这三种带型的特点，分析了这三种显带方法的应用价值。 相似文献
3.
<正> 国内外已有多种植物获得 G-显带的成功。但是,从已发表的资料来看,杉木(Cunning-hamia lanceolata(Lanb.)HooK.)染色体 G-显带的研究仅有1986年夏晓敏等的一篇报道,并且与玉米、大麦等植物染色体显出的密切邻近的、多重的 G-带带纹比较,相差很大。我们利用 ASG 法同时获得了杉木 G-显带两个地理种源的有丝分裂早中期以及一个地理种源的中期染色体,并进行了 G-显带技术和 G-带特点的分析。 相似文献
4.
采用去壁低渗法及BSHG显带流程,对岳麓连蕊茶细胞染色体进行计数和核型及C—带带型分析。结果表明,其染色体数目为2n=30;属于对称性很强的原始核型;其着丝粒带多而且明显,有中间带,其他带不明显。为研究其与山茶属其他植物间的亲缘关系提供了依据。 相似文献
5.
该研究在区划工作的基础上，进一步对马尾松种源进行了亚染色体结构水平上的分析鉴别，结果表明，马尾松种源具有丰富的着丝粒Ｃ－带和中间Ｃ－带。抽样研究的５个种源的Ｃ－带，在同一种源内带型基本相同，不同的种源带型各不相同，呈现出种源差异，聚类分析表明，种源的Ｃ－带带型与区划基本上相符合，证明马尾松种源的表型地理变异与染色体亚结构的变异是紧密相关的。 相似文献
6.
李占林 《中南林业科技大学学报(自然科学版)》1996,(4)
介绍了诱导马尾松（Ｐｉｎｕｓｍａｓｓｏｎｉａｎａ）染色体Ｇ－带的两种方法──尿素法和ＡＳＧ法．分析了两种处理方法显现带纹的共同特点和差异．指出了显现松杉植物染色体Ｇ－带的要点． 相似文献
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杉木染色体G-带的研究 总被引：6，自引：1，他引：6
1982年,Drewry报道了红松(Pinus resinosa)染色体G-带。随后,国内外一些学者用不同的处理方法,在多种植物染色体上诱导出了G-带,带纹清晰,数目多,沿染色体全长分布。这说明Greilhuber关于植物染色体不存在G-带的假说是不可信的。杉木的G-显带研究很少。夏晓敏等采用HSAG分带法,初步显出了杉木的染色体G-带,但多数染色体带纹尚欠清晰,而且没有进行G-带染色体的组型分析。我们应用改良的ASG法,首次在杉木前中期和中期染色体上诱导出清晰的G-带,并进行了G-带染色体的组型分析。 相似文献
9.
对8个杉木地理种源染色体的G—带带型进行分析,结果表明,各种源的带纹总致、带纹分布、纯合程度和带纹特征,均存在一定的差异。G一带带纹,可以作为识别不同染色体、染色体臂和片段的标记。可供在染色体工程育种、基因定位和进化研究中加以应用。 相似文献
10.
杉木地理种源核型的研究 总被引：3，自引：0，他引：3
为研究杉木地理种源对杉木核型的影响,将20个杉木产区的种子在25℃条件下发芽,当根生长到5厘米时,用8-羟基喹啉预处理,压片观察。杉木染色体是22条,在5个种源内发现了1—2个B-染色体。杉木核型具有多态型,这种多态型表现在随体的形状、位置及上述两个方面特征的杂合性。随体形状有大随体、小随体、复和随体、线形随体和T-随体。随体不仅稳定地位于一对染色体上,而且变动在第一对和第五对染色体上。多数情况下随体位于短臂上,有时在长臂上也出现随体。多变量分析表明:四川德昌的核型是一个独特的类型,基因飘移并不明显,其余19个地区虽然地理分布广泛,但是有较为一致的核型,经纬度对随体的变异影响不大。 相似文献
11.
C. Foley 《Wood Science and Technology》2001,35(5):453-465
Knowledge of the three-dimensional orthogonal directions of wood material at any position within a tree is necessary for
the understanding of strength reducing effects of knots and essential for the continuation of research in areas which relate
small clear wood specimen behavior to the behavior of full size structural timber. A complete three-dimensional paradigm describing
the geometry of knots and related fiber distortion, initially derived to predict the strength-reducing behavior of knots in
structural timber of Norway Spruce with the finite element method, is presented in this article. Besides strength prediction
analyses, it is believed that the paradigm may be useful in other areas of research on structural timber that are effected
by fiber orientation, such as drying and form change of structural timber. The paradigm generates fiber orientation in any
position within a log or lumber from assumed fiber patterns in planes parallel to the longitudinal direction of the original
tree. Fiber patterns in the radial and tangential directions are derived from physical restraints related to fiber production
within the annual increase surfaces of the tree and from theories of knot formation. The adaptability of the paradigm allows
practically any softwood knot to be modeled with an accuracy that is limited only by input-data. The knot-axis may be non-linear,
and the knot cross-section oval with its vertical and horizontal axis increasing from the pith of the stem at chosen rates.
Spiral grain may also be included in the paradigm and vary with the annual growth layers. Investigations presented in this
article showed that generated fiber orientations for Picea abies complied well with measured fiber distortions, and that the general trends of fiber orientation, explained by the applied
knot formation theory, is reflected in the measured specimens.
Received 12 May 1999 相似文献
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13.
几种卫星系统监测林火技术的比较与应用 总被引：10，自引：1，他引：10
卫星遥感方法作为灾害监测手段，在时间分辩率和宏观性方面具有优势。目前用于我国森林火灾监测的主要是美国的NOAA系列气象卫星，此外，我国的风云系列气象卫星和美国的EOS卫星也开始应用于林火监测。NOAA和风云系列气象卫星为森林火灾的监测提供了可靠、稳定的服务，但因分辩率低给森林火灾信息的提取监测带来一定困难。应用美国EOS卫星进行林火监测，可以提高监测精度和准确度，为火灾的扑救提供更多、更可靠和更细致的监测成果，将卫星遥感技术用于森林火灾监测，涉及估算火烧面积、火烧强度、火灾后生态环境监测等诸多领域。 相似文献
14.
超声波功率谱技术在木材空洞缺陷无损检测中应用 总被引：1，自引：1，他引：0
分析了不同孔径空洞的木材试件的超声波功率谱。阐述了功率谱的谱峰位置和谱峰高度与木材空洞大小之间的关系。分析认为,超声波在木材与空洞中传播时的散射不同,导致超声波在不同频率上的干涉,可能是造成上述现象的主要原因。利用该方法可实现木材空洞缺陷的无损检测。 相似文献
15.
Avian use of even-aged timber harvests is likely affected by stand attributes such as size, amount of edge, and retained basal area, all characteristics that can easily be manipulated in timber harvesting plans. However, few studies have examined their effects during the post-breeding period. We studied the impacts of clearcut, low-leave two-age, and high-leave two-age harvesting on post-breeding birds using transect sampling and mist-netting in north-central West Virginia. In our approach, we studied the effects of these harvest types as well as stand size and edge on species characteristic of both early-successional and mature forest habitats. In 2005-2006, 13 stands ranging from 4 to 10 years post-harvest and 4-21 ha in size were sampled from late June through mid-August. Capture rates and relative abundance were similar among treatments for generalist birds. Early-successional birds had the lowest capture rates and fewer species (∼30% lower), and late-successional birds reached their highest abundance and species totals (double the other treatments) in high-leave two-age stands. Area sensitivity was evident for all breeding habitat groups. Both generalist and late-successional bird captures were negatively related to stand size, but these groups showed no clear edge effects. Mean relative abundance decreased to nearly zero for the latter group in the largest stands. In contrast, early-successional species tended to use stand interiors more often and responded positively to stand size. Capture rates for this group tripled as stand size increased from 4 to 21 ha. Few birds in the forest periphery responded to harvest edge types despite within-stand edge effects evident for several species. To create suitable habitat for early-successional birds, large, non-linear openings with a low retained basal area are ideal, while smaller harvests and increased residual tree retention would provide habitat for more late-successional birds post-breeding. Although our study has identified habitat use patterns for different species in timber harvests, understanding habitat-specific bird survival is needed to help determine the quality of silvicultural harvests for post-breeding birds. 相似文献
16.
Macro-void distribution analysis in strand-based wood composites using an X-ray computer tomography technique 总被引：1，自引：0，他引：1
A database from a series of cross-sectional density distributions in a 0.16 × 0.34 × 1.28m strand-based wood composite specimen has been successfully developed using X-ray computer tomography (CT) techniques. Using conventional image processing techniques, the CT images of the specimen were analyzed with respect to the size and position of the macro-voids. Finally, CT images and the measurement results were converted and exported into MS Excel spreadsheets to provide information on the three-dimensional distribution of macro-voids so those who are not familiar with image processing and formats can handle the data easily. In future, this type of database can be used to develop a model for the prediction of macro-void presence and distributions in strand-based wood composites.Part of this report was presented at the annual meeting of the Forest Products Society, Vancouver, BC, Canada, June 1997 相似文献
17.
Gang Wang Dongsheng Guan Qiuping Zhang M. R. Peart Yujuan Chen Yisheng Peng Xiao Ling 《European Journal of Forest Research》2014,133(6):993-1005
Mangrove ecosystems are well developed in the estuarine environment of Yingluo Bay, South China. However, little is known about the spatial patterns of vegetation biomass, soil organic carbon (SOC) stocks and soil attributes along the environmental gradient from upstream to downstream positions. To characterize the spatial pattern of these factors, four transects (transects I, II, III and IV) were established between upstream and downstream positions. The result showed clear spatial patterns occurred in this estuarine mangrove. In general, vegetation biomass, TN concentration and SOC concentration and stocks decreased from upstream to downstream positions unless transect I, with the increase of soil salinity. This may be attributed to a consequence of increasing environmental stress due to the change of soil elevation. Vegetation biomass and its carbon, SOC concentration and stocks, and TN concentration showed clear trends of decrease first and then gradually tended to be stable along each transect from landward to riverward positions. These results indicate that soil position/elevation in the estuarine mangrove greatly affects soil attributes and mangrove growth. In each transect, change of soil salinity showed some distinct characteristics, in comparison with SOC and TN. SOC concentrations were significantly correlated with vegetation biomass and silt contents. Compared to that in the mangrove-covered area, SOC concentrations and stocks were much lower in the bare flat. It was indicated that an increase of vegetation biomass will raise the mangrove-derived SOC, and reforestation with mangroves is a friendly strategy provided coastal protection. 相似文献
18.
General decline of understory cover can result from increased abundance of and foraging pressure by deer.But population size and degree of aggregation can increase for unpalatable understory plants that escape foraging pressure.Clonal reproduction can enable unpalatable plant species to increase their population sizes while trending toward spatially aggregated distributions.However,the details of the relationship between clonal reproduction in unpalatable plants and their dynamics under intensive deer herbivory are not clear.We compared the population structures and spatial patterns of two coexisting unpalatable plant species,Arisaema ovale(with clonal reproduction)and A.peninsulae(without clonal reproduction)in a riparian forest intensively grazed by Sika deer,and examined the null hypothesis that the extent of spatial aggregation and local population size would not differ between the clonal and non-clonal Arisaema species.In a 0.36-ha plot,A.ovale had a larger population size(1087 individuals)with a higher abundance ratio of small plants(p<0.01)than A.peninsulae(84 individuals).Analyses of spatial point processes showed that both populations were spatially aggregated(p<0.05).The spatial aggregation of A.peninsulae,however,became weaker than that of A.ovale,when we excluded one dense patch originating from irregular seed dispersion.These results,excluding the aggregated distribution observed in A.peninsulae,suggested a substantial contribution of clonal reproduction to the expansion of the local A.ovale population following intensive grazing by Sika deer. 相似文献