浅析严格控制钢筋保护层厚度的原因及其保证措施

论述了钢筋砼保护层厚度控制的重要性及钢筋砼保护层防控措施。     

Path analysis of spatial predictors of front-yard landscape in an anthropogenic environment

Contagious spatial patterns were shown to exist in the landscape of front-yards in street sections of Hochelaga-Maisonneuve, Montréal. Neighbour mimicry was hypothesized as the mechanism behind this pattern (Zmyslony and Gagnon 1998). To assess the role of spatial environmental factors in structuring this pattern, we carried out a path analysis on the front-yard landscape with five spatial factors: relative distance, street side, width, depth and type of front-yard. We removed all non-significant factors from our model with simple Mantel tests and untangled the common spatial component from the relationship between spatial factors and front-yard landscape with partial Mantel tests. We then used path analysis to evaluate the relative importance of all significant spatial factors in structuring front-yard landscape and to determine the r ² (% of landscape variation explained by spatial factors). Results showed that (1) among all spatial environmental factors, distance (proximity) remained the best predictor of front-yard vegetation – distance alone explained an average of 20% of the landscape variation of a street section, (2) depth, width and type of front-yard also structured the front-yard landscape independently of distance, (3) front-yard landscape expresses greater similarity within the same side of a street section, and (4) in two street sections of Hochelaga-Maisonneuve, spatial factors predicted over 40% of the landscape variation. This suggests (1) that landscape contagion exists also in highly humanized environments and (2) that the mimicry phenomenon was induced not only by proximity, but also by similar environmental conditions in same side street sections and whole street sections. Finally, we suggest that street sections are a very useful and appropriate unit of analysis of urban ecosystems.     

关于哈尔滨机场高速公路设计中几个问题的探讨

本文通过哈尔滨机场高速公路测设中所遇到的平面线形、纵断面设计、排水以及旧路利用等问题 ,提出了在测设中的解决方法 ,为以后的设计提供了有益依据。     

优选法在农业科学试验中的应用

利用数学原理.通过实例介绍了黄金分割优选法和菲波那契优选法在农业科学试验中的合理应用,减少了试验的次数,提高了工作效率.     

利用开花结实信息段预测中、幼龄杉木球果产量的研究

林木种子产量预测预报是种子经营工作的重要环节。传统的预测预报方法一般都比较粗放,难以满足当今生产管理的需要,如产量目测法、标准枝法等。近年来有人应用气象学法和灰色动态模型预测法预测林木种子产量,尽管工作量小,技术先进,但由于难以获得可靠的产量历史资料,难以普遍应用。一个好的预测方法必须具备下述三个条件:1.时间超前;2.精度高;3.简便实用。基于这一思路,本文在研究杉木球花及球果在树冠上分布规律的基础上,探讨了利用开花结实信息段预测杉木种子园和一般林分球果产量的方法。     

The origin of polyploids via 2n gametes in Vaccinium section Cyanococcus

Summary The production of 2n pollen (pollen with the sporophytic chromosome number) was evaluated in 4x and 6x taxa of Vaccinium section Cyanococcus. Mean frequencies of 2n pollen producers were 17.1% and 8.3% in natural 4x and 6x populations, respectively. The frequency of 2n pollen producers in the 4x species ranged from 8.6% (V. angustifolium) to 23.8% (V. pallidum). Level of 2n pollen production was genotypically variable (1% to 37.4%). The widespread occurrence of 2n pollen in 2x, 4x and 6x taxa suggests that sexual polyploidization was widespread and responsible for the origin of the polyploid species found in this genus. The frequency of 2n pollen producers was not significantly different between the 4x species and their putative 2x ancestors. These results support the origin of 4x and 6x taxa as a consequence of sexual polyploidization. Polyploids derived from sexual polyploidization would be expected to have increased fitness and flexibility due to the mode of 2n pollen formation. In blueberry species the predominant mode of 2n pollen formation is genetically equivalent to a first division restitution mechanism (FDR). FDR 2n pollen transmits a high percentage of the heterozygosity and a large fraction of the epistasis from the 2x parent to the 4x offspring.     

孔隙结构图像分析中不同试验因素对分析结果的影响

研究了不同试验因素 (包括图像分辨率、土壤切片定向性、分析区域大小等 )对孔隙结构图像分析结果的影响以及试验误差 ,并简要介绍了用于分析土壤孔隙结构的土壤切片及数字图像的制备技术。结果表明 :不同试验因素对分析结果均会产生一定的影响 ,试验误差约在 1 0 %。这表明同一研究中应保持试验条件的相对一致以保证分析结果的可靠性和可比性     

江河源区植被分区

按照植物群落学—生态学原则,将江河源区的天然植被划分为森林植被区、灌木与灌丛植被区、草原植被区、草甸植被区、荒漠植被区和湿地植被区6个区,并分析了各植被区的分布范围及其优势种。     

柿树硬枝扦插试验初报

将初选的6个柿树株系插穗在新型植物生长调节剂中浸泡24h后扦插，结果表明：各株系插穗基部愈合率呈极显著差异。愈合率2.8%～85.7%，9901株系最高（85.7%），其次是9902株系（66.7%）。对试验结果进行了分析，提出了柿树扦插繁殖的新思路。     

筛网式消能工的设计

对中小型堰、闸、跌水等渠系建筑物消能设施的选择提出见解,推荐采用筛网式消能工,并且针对筛网式消能工的结构布置、水力计算、消能计算提出一些建议,供水利工作者在实际工作中参考.