透光抚育对“栽针保阔”红松林中红松生长过程的影响

[目的]通过研究长白山地区不同透光抚育强度下栽针保阔阔叶红松林中红松的生长情况,揭示透光抚育对栽针保阔红松林中红松生长过程的影响规律,旨在为阔叶红松林的恢复、经营提供有力的科学依据。[方法]研究5种透光抚育(未采伐对照、低度择伐、中度择伐、强度择伐及上层皆伐)对红松生长的影响。[结果]红松在群落中的地位随着透光抚育强度的增大逐步得到提升,同时透光抚育能够显著提高栽针保阔红松林内红松优势木(63.4%~146.5%、64.6%~158.6%)、平均木(57.9%~271.1%、42.5%~261.7%)和被压木(56.5%~182.6%、95.5%~245.5%)的树高和胸径,且呈现出随透光抚育强度的增大而递增的规律性。[结论]透光抚育能显著提高红松树高和胸径生长。     

核桃大树芽接对树冠恢复、主干感病及产量的影响

在非目的品种核桃大树上利用方块形芽接方法,探求与核桃树地径相适应的预留橛数和嫁接芽数,以期为核桃生产中的大树芽接技术提供操作依据。在相同肥力地块选择相同地径水平的核桃树作 为砧木,设置单因素4 处理试验。第1 年短截骨干枝,第2 年在新生嫩枝上采用方块形芽接技术嫁接目的品种芽块。接后从第2 年开始,连续3 年调查核桃树冠直径恢复情况、主干感染腐烂病的情况及单位面积产量。最终总结出合理的留橛数和嫁接芽数。调查结果表明,在一定范围内预留橛数越多,嫁接芽数越多,树冠恢复就越快,主干感病越轻,产量恢复也越快。对于地径在20~25 cm内的核桃大树应预留16 个树橛,嫁接40 个芽为宜。试验探求了一套成活率高,树冠及产量恢复较快,且树干不易感病的核桃大树芽接技术,为核桃生产中的大树芽接提供参考依据。     

血管紧张素Ⅱ对牛肉品质的影响

取屠宰后5头杂交牛(鲁西黄牛×西门塔尔)的背最长肌,置于2~4℃贮藏7 d,注射样品重10%的血管紧张素Ⅱ,观察在成熟过程中血管紧张素Ⅱ对牛肉剪切力、肌原纤维小片化指数(MFI)、凋亡酶活力,以及肌纤维直径变化的影响。结果显示:贮藏期间对照组和处理组样品剪切力均显著下降(P<0.05),MFI值逐渐增大,caspase-3、6、9酶活力宰后迅速激活随后其活力逐渐下降;血管紧张素Ⅱ注射处理显著降低了牛肉的剪切力值和肌纤维直径(P<0.05),而对MFI值及caspase-3、6、9活力无显著影响。因此,caspase-3、6、9对牛肉嫩度的影响可能仅发生在宰后初期极短的一段时间内;肌细胞宰后生理和活体状况下不太一致,血管紧张素Ⅱ注射降低了牛肉剪切力可能由于它能显著防止肌纤维的收缩。     

Modelling the impacts of various thinning intensities on tree growth and survival in a mixed species eucalypt forest in central Gippsland,Victoria, Australia

The response of tree survival and diameter growth to thinning treatments was examined over 29 years, in various thinning treatments established in a 21-year-old even-aged mixed species regenerating forest in Victoria, Australia. The treatments were control, crown release, strip thinning and three different intensities of thinning from below (light, moderate, and heavy). Each treatment was replicated three times in a complete randomised design. Logistic and multilevel regression analyses showed that tree survival, growth and thinning response (change of tree growth due to a thinning treatment) were functions of tree species, size, age, removed and remaining competition, as well as time since the treatment. Mean annual tree diameter growth in unthinned stands was highest for Eucalyptus sieberi L. Johnson (1.9 mm) followed by Eucalyptus baxteri (Benth.) Maiden & Blakely ex J. Black (1.6 mm), and lowest for both Eucalyptus consideniana (Maiden) and Eucalyptus radiata (Sieber ex DC) combined (0.7 mm). Diameter growth increased with tree size for both E. sieberi and E. baxteri, but not for E. consideniana and E. radiata. Smaller trees were more likely to die due to shading and suppression than their larger counterparts. A mortality model suggested, however, that both shading and suppression had very little effect on trees in both E. consideniana and E. radiata species, which were less likely to die compared to trees in the other species. This result indicates that both E. consideniana and E. radiata species may be relatively shade tolerant compared with the other species. Total thinning response was a sum of positive (increased growing space) and negative (thinning stress) effects. Following thinning, smaller trees showed signs of thinning stress for the first one or two years, after which the highest percentage thinning response was observed. While larger trees were initially less responsive to thinning, the rate of decrease in the response for subsequent years was greater in smaller trees than larger ones. The average amount of thinning response showed similar trends to diameter growth increasing from E. sieberi (1.7 mm) through E. baxteri (0.6 mm) to both E. consideniana and E. radiata (0.5 mm). This translates into low average percentage thinning response in E. baxteri (34%), twice as much in both E. consideniana and E. radiata (69%) and highest overall percentage response in E. sieberi (87%). Thinning response and the duration of this response appeared to increase with thinning intensity and was still evident 29 years after thinning. Heavy thinning did, however, reduce the number of trees to a severely under-stocked condition, which prohibited optimum site occupancy, requiring 29 years of post-thinning development for the heavily thinned stands to regain their pre-thinning stand basal area.     

解决聚丙烯芯钢丝绳生产过程中钢丝“塌陷”（或间隙不均）及绳径超差问题

本文从生产制造角度来分析解决聚丙烯芯钢丝绳生产过程中易出现的钢丝塌陷、钢丝间隙不均及绳径超差等问题。与天然纤维芯相比,聚丙烯芯是一种合成纤维芯,除具有质轻、弹性好、不怕霉蛀等特性外,同时还具有较好的抗挤压性,因此,生产过程中,对聚丙烯芯直径公差的控制比对天然纤维芯直径公差的控制更为严格,如聚丙烯芯直径选择不当,易会出现股中钢丝塌陷(或钢丝间隙不均)、绳径超差等问题。笔者结合生产实际情况,从控制聚丙烯绳芯(股芯)直径公差入手,找出聚丙烯芯直径的计算值与其实测值之间合适的比例范围,对正确选择聚丙烯绳芯(股芯)直径大小,满足钢丝绳生产工艺要求,优化工艺参数,提高钢丝绳结构的稳定性和机台生产作业率有着重要的作用。     

牛卵母细胞体外成熟技术研究

从两方面探讨了牛卵母细胞的体外成熟培养效果,即对不同级别和不同卵巢卵泡直径的卵丘卵母细胞复合体（COCs）进行成熟培养,测定其成熟率。COCs级别不同,培养成熟率之间存在很大差异,A级COCs成熟率为63．81％,B级为47．81％,显著高于C级和D级（P〈0．01）。卵母细胞的成熟率与采集COCs时的卵泡直径关系密切。中等卵泡的卵母细胞的成熟率为61．82％,显著高于小卵泡和大卵泡（P〈0．01）。试验结果表明：A级和B级COCs是卵母细胞体外培养的主要资源;在卵母细胞体外培养过程中,宜选择卵泡发育水平基本正常的中等卵泡采集COCs,而不宜选择发育过大或过小的卵泡。     

应用“林分结构复原法”评价经营措施及更新效果研究

介绍了林分调查的一种方法：“林分结构复原法”,即根据林分的现时直径分布和直径生长量,应用林分表法进行径阶转移的原理,推算n年前的直径分布,并根据直径与其他林分因子的关系,再现林分在前n年时的林分结构,从而为评价采伐的合理性以及鉴定超采、盗伐提供可靠数据。     

毛纤维直径及成分测试方法标准制定中重要技术指标的确立

[目的]制定毛纤维直径及成分分析仪的检测方法标准,确立标准中的重要技术指标,以利于仪器的正确使用。[方法]采用查阅资料、专家咨询及实验室检测等方法。[结果]确定了标准名称、纤维片段截取长度、截取方法、允许误差率及试验纤维根数等重要技术指标。[结论]该研究为毛纤维直径及成分检测方法标准的制定提供了理论依据。     

Relationships between morphological traits and resistance to pine wood nematode in two Japanese pines

It has been suggested that certain morphological traits of Japanese pines function as resistance factors against the pine wood nematode (PWN), Bursaphelenchus xylophilus. The aim of this study was to verify this concept, and to determine the relationships between traits and resistance at both the individual and family levels. Relationships between survival rate and morphological traits of Pinus densiflora and Pinus thunbergii were studied after inoculation with PWN. Morphometric parameters used were height, basal diameter of the axis, and the number of branches from the axis. Three indices of relationships were analysed: (1) among individuals within a family (survival difference between smaller and larger morphometric populations within each family); (2) among individuals (correlation between each morphometric average and survival rate in quintile populations of all subjects within each pine species based on the order of morphometric values); and (3) among families (correlation between each morphometric average and survival rate in the family). Both significant and non-significant differences were detected within a family, indicating a need for macro techniques. Among individuals, a thicker axis and more branches were correlated with increased survival, indicating that they are resistance factors. However, these correlations were not significant among different families. These results indicate that morphological traits cannot be used to evaluate resistance at a family level, even if they are significant at an individual level. Further studies on traits associated with resistance should be conducted at a family rather than an individual level, to breed for Japanese pines with resistance to PWN.

Papillary muscle measurements in cats with normal echocardiograms and cats with concentric left ventricular hypertrophy

BACKGROUND: Papillary muscle hypertrophy can occur in conjunction with, or as the only indication of, hypertrophic cardiomyopathy or other diseases that result in left ventricular concentric hypertrophy (LVCH). Assessment of papillary muscle size is usually subjective because objective measures have not been reported. HYPOTHESIS: The study hypothesis was that papillary muscle dimensions are different between normal cats and cats with LVCH. ANIMALS: Echocardiograms from 44 normal cats and 40 cats with LVCH were included in the study. METHODS: All measurements were taken from the right parasternal short-axis view at the level of the papillary muscles at end-diastole. Three methods were used to assess papillary muscle size: the area subtraction method, the direct area trace method, and the diameter method. Measurements were compared between cat groups and method comparisons were made among methods for area determination. RESULTS: Cats with LVCH were older and had significantly greater left ventricular septal and free wall thicknesses and larger left atrial measurements than normal cats (P < .0006). Papillary muscle measurements were significantly greater by all measurement methods in cats with LVCH than in cats with normal echocardiograms (P < .0001). The area subtraction method and direct area trace method showed moderate agreement. CONCLUSIONS AND CLINICAL IMPORTANCE: Papillary muscle measurements were larger for LVCH cats than normal cats; however, some overlap was present. The establishment of these objective measures adds to the echocardiographic examination of cats.