河北省特种桑品种调查及利用研究

通过对河北省桑树品种分布及利用现状的调查,了解到河北省现有桑种10个,常用桑树品种约50余个,其中叶用桑20余个,材用桑6个,果用桑9个,条用桑17个。同时提出河北省桑树资源利用途径。     

电导法协同Logistic方程测定不同品种桑树抗寒性

采用电导法研究低温胁迫条件下不同品种桑树枝条相对电导率的变化规律,并利用Logistic方程计算9个桑树品种的半致死温度(LT_(50)),比较其抗寒性。结果表明:9个桑树品种枝条的相对电导率变化曲线均随处理温度的降低呈S形曲线上升,计算枝条的低温半致死温度LT_(50)分别为-29.47℃、-35.42℃、-26.60℃、-32.87℃、-33.63℃、-26.88℃、-29.37℃、-21.03℃和-39.96℃。即9个桑树品种抗寒性由强到弱排序为:向海一号新桑8号龙桑一号冀桑3号冀桑2号秋雨辽鲁11号桲椤桑辽育8号。     

桑天牛在不同树种或品种间产卵选择性试验

选用１１个树种、２３个桑树品种、４０个毛白杨无性系、１６个苹果品种和白杨派６个树种或无性系，进行了桑天牛产卵选择性试验。结果表明：桑天牛在不同树种间产卵选择性差异极显著；在苹果品种间、桑树品种间，毛白杨无性系间，白杨派不同树种及无性系之间，产卵选择性差异均不显著，但在个别品种上产卵数量较少，有待进一步研究。     

桑树品种多性状综合评估研究

桑树品种多性状综合评估研究孙日彦，宋慧贞，梁明芝，樊孔彰，杜建勋，王兆红（山东省蚕业研究所，烟台２６４００２）鉴定桑树新品种有许多项目，每一桑品种在这些项目上的表现也互有高低，而且这些项目的重要性及项目之间的关系各不相同。迄今对桑树品种的审定，主要是...     

防沙治沙发展畜牧业的理想品种——中国沙地饲料桑

桑树在我国是一个古老的树种，天南海北都有它的踪迹。中华文明的发展都与桑树密不可分，它生命力极强，种植容易，管理粗放，自古以来都是人们最熟悉的树种。据《中国桑树品种志》记载，我国共有546个桑树品种（包括变种）。世界许多国家的桑树品种，大部分都引自中国。自古桑树的发展都是以穿衣为目的（养蚕、取丝），在现代工业发展的今天，这一功能显得极小了，使近两个世纪以来，蚕桑业的发展一直停滞不前。而近十年来，随着经济的发展和人民生活水平的提高，果用桑的发展极快，笔者通过十年来在果桑开发研究推广中及桑树在陕西退耕还林、还草、防沙、治沙、水土保持应用中发现，桑树不光能产果、养蚕，它还是防沙治沙、水土保持及发展畜牧业（产饲料）的优秀品种。在陕北黄土高原，4年前栽培的用于水土保持的桑树，在无水情况下，最高生长达6m高，地下根入土达9m深。在陕北毛乌素沙漠无水的情况下，当年栽培的桑树最高达2m，在荒沙、荒漠有水的条件下栽培的大叶桑，当年可收割2次，每667m^2产鲜枝叶在2000k以上，第2、3年最高可达5t多，若加施肥料，产量还可大幅提高。     

特种高阻抗变压器的制作分析

高阻抗变压器是一种工业用特种变压器,多应用在焊接电源类设备上。采取高阻抗方式,主要是为了获得输出特性为下降的电源性能,以达到输出电流较稳定的目的。介绍了高阻抗变压器设计、制作的方法要点。     

山杨与白桦蒸腾速率及气孔阻抗特征研究

利用定点定位观测的方法,对山杨与白桦植株的蒸腾及其影响因素气孔阻抗进行研究。结果表明:山杨与白桦的日间蒸腾速率在2.4-6.5 g·m-2·s-1之间,山杨的蒸腾速率要比白桦高,两个树种早晚的蒸腾速率较低,随着气温升高蒸腾速率逐渐提高,气温最高的正午时刻的蒸腾速率均有所下降。两个树种的气孔阻抗变化范围在0.30-3.02s·cm之间,白桦的气孔阻抗均高于山杨,与测定蒸腾速率的结果相吻合,印证了这两个指标之间的关联性。     

保山地区12个桑树品种(系)的综合评价

[目的]了解保山地区桑树种质资源的品质特征,以筛选出能适于当地种植的以桑叶为保健品生产原料的优良桑树品种.[方法]以12个不同品种的桑树种质资源为研究对象,测定其叶幅、叶长、10片叶的总质量、叶片与叶幅的比值等表型性状指标及叶片中多糖、黄酮、总酚、1-脱氧野尻霉素、白藜芦醇等生物活性成分的含量,并采用方差分析法、主成分...     

阻抗法测定树木细胞活力的研究

阻抗法测定树木细胞活力的研究宋蜇存，王克奇，孙柏昌，孙力平（东北林业大学哈尔滨ＩＳ００４０）关键词细胞活力，阻抗，频率，阻抗圆图研究树木细胞活力对于探讨树木的生理构造，把握林业生产的最佳环境条件及自然环境的监测都有重要意义。对树木嫁接，树木生长过程的...     

桑树组织培养诱导多倍体植株

桑(Morus)为多年生落叶木本植物,是我国重要的经济树种,桑叶为家蚕饲料.人工选育的三倍体桑树品种,细胞体积较二倍体桑大1倍以上,不育,营养生长旺盛,产叶量与叶质明显高于目前生产上使用的二倍体桑树品种.     

Assessment of tolerance of willows to saline soils through electrical impedance measurements

One-year-old potted clone plants of four willow species (Salix matsudana × alba, S. babylonica, S. psammophila and S. cheilophila) were cultivated and irrigated with saline solutions of different concentrations, while their electrical impedance spectroscopy (EIS) parameters and other physical parameters were monitored. The results indicate i) that under salt stress, height and basal diameter of all species are inhibited, and ii) that relative conductivity of cellular exudates increases while intracellular resistance (ri) and extracelluar resistance (re) drop. Both ri and re were positively correlated with height growth and basal diameter while they were significantly and negatively correlated with electric conductivity. The concentration of Na + in the shoots of willows was negatively correlated with both ri and re , whereas the concentration of K+ in the shoots was positively correlated with both ri and re . Hence, electrical impedance spectroscopy is a reliable tool for evaluating the capacity of willow species for tolerance to saline soils, with r i as the most accurate parameter.     

Air-coupled ultrasound and electrical impedance analyses of normally dried and thermally modified Scots pine (Pinus sylvestris)

Wood is graded according to strength in various applications. The ultimate strength can only be determined by breaking the specimen, and thus other characteristics like density and modulus of elasticity (MOE) are used for estimation of the strength. In this study, the properties of normally dried and thermally modified Scots pine were studied using electrical impedance and air-coupled ultrasound (ACU) methods. Density, hardness, MOE and strength were analysed and compared with the electrical and ultrasonic responses. The measurements were conducted in stable laboratory conditions with well equilibrated samples and the moisture content was not determined. Both the ultrasonic and electrical parameters correlated with the density and mechanical properties. Using multivariate analysis, density could be estimated with accuracy of 21 kg/m³ (SD) for normally dried timber and 13 kg/m³ (SD) for thermally modified timber (TMT; N = 15). MOE could be estimated with accuracy of 0.7 kN/mm² (SD) for normally dried timber and 1 kN/mm² (SD) for TMT (N = 14). According to the study, electrical impedance spectroscopy combined with ACU measured across the grain is a potential non-destructive technique for the strength estimation of wood.     

Relationship between parameters of electrical impedance spectroscopy and frost hardiness in stems and needles of Pinus bungeana

We studied the frost hardiness (FH) in stems and needles of different Pinus bungeana provenances during frost hardening by means of electrical impedance spectroscopy (EIS) and conventional electrolytic leakage (EL) and compared the regression equations of the two methods in order to optimize the EIS method for studying FH on plants. During frost hardening, EIS and EL were applied to one-year old stems and needles of P. bungeana in an 8-year provenance field trial at the Thirteen Tombs Nursery in Beijing within the provenances of Mangshan of Beijing, Liangdang of Gansu and Xiaoyi of Shanxi provinces, China. A double-DCE model and Model-A were used, respectively, for the EIS analysis of stems and needles that were not exposed to a controlled freezing treatment. After controlled freezing tests, the FH of stems and needles were assessed by EIS and EL. Without controlled freezing tests, the relaxation time (τ ₁) of stems and the specific intracellular resistance (r _i) of stems and needles displayed a statistically significant correlation with FH (R ² = 0.79–0.86); after controlled freezing tests, specific extracellular resistance (r _e) of the stems and needles, the cell membrane time constant (τ _m) of needles displayed an even higher correlation with FH (R ² = 0.92–0.94). There were significant relationship between EIS and EL in assessing the FH of stems and needles of P. bungeana, but EIS underestimated FH more than EL did. EIS is one of the more promising methods for assessing FH, especially without employing a controlled freezing test. __________ Translated from Scientia Silvae Sinicae, 2008, 44(4): 28–34 [译自:林业 科学]     

Variations in electrical impedance and phase angle among seedlings of Pinus densata and parental species in Pinus tabuliformis habitat environment

Electrical impedance (EI) and phase angle (PHI) parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their appli...     

Anatomically informed mesoscale electrical impedance spectroscopy in southern pine and the electric field distribution for pin-type electric moisture metres

Abstract

Electrical impedance spectra of wood taken at macroscopic scales below the fibre saturation point have led to inferences that the mechanism of charge conduction involves a percolation phenomenon. The pathways responsible for charge conduction would necessarily be influenced by wood structure at a variety of sub-macroscopic scales – at a mesoscale – but these questions have not yet been addressed. The goal of this work is to explore if mesoscale anatomical features in wood affect impedance spectra. Small (0.5 mm diameter) needles were used as electrodes and were configured such that the line segment between the electrodes could be oriented radially, tangentially, longitudinally and in combinations of those directions in both earlywood and latewood, including comparisons of earlywood–latewood transitions. The spectra were fit to an equivalent circuit model with a constant phase element in parallel with a resistor and Warburg element that describes ionic conduction. Finite element simulations were run to examine the effect of the fringing electric field near the electrodes. The simulations revealed that the current density was concentrated at the electrodes, resulting in a lack of dependence on electrode spacing thus explaining why measurements taken with pin-type electric moisture metres are nearly independent of electrode geometry.     

阻抗谱法在侧柏干旱胁迫研究中的初步研究

通过研究侧柏在干旱胁迫过程中阻抗谱的胞外电阻Re、胞内电阻Ri、细胞膜电容Cm、特征频率fc等参数的变化情况来分析其生理变化的机制。结果表明,在干旱胁迫下,胞外电阻Re和胞内电阻Ri逐渐增大,且胞外电阻Re增大的速率高于胞内电阻Ri。在停止供水后,随着侧柏幼枝含水量的逐渐降低,侧柏的细胞膜电容Cm先呈下降趋势,之后开始逐渐变大;在恢复供水后又随着侧柏幼枝含水量的逐渐升高而下降。同时,特征频率fc的变化与侧柏幼枝含水量的变化呈正相关。通过阻抗谱法与压力室法的比较可以发现,这两种方法的相关参数呈显著相关。     

不同分子质量木质素磺酸钙缓蚀性能研究

采用渗析超滤法将木质素磺酸钙（木钙,CL）分为不同相对分子质量（Mw）的4个级分．测定了不同级分中羧基、酚羟基、磺酸基的含量,用失重法和电化学交流阻抗谱研究了不同Mw级分的缓蚀性能及作用机理。研究表明,随着Mw增大,羧基、酚羟基、磺酸基的含量减小。Mw〈5000级分对碳钢有缓蚀性能,Mw〉5000级分对碳钢无缓蚀性能。对电极系统等效电路的拟合结果表明,掺加不同Mw级分溶液的等效电路不同,在Mw1000—5000级分溶液中出现两个时间常数,说明低Mw的级分能够在金属表面成膜抑制金属腐蚀。     

浅析测定植物抗旱性方法的应用

本文介绍了干旱对植物伤害及表现,根据国内外相关文献资料对叶绿素荧光法和电阻抗图谱法两种测定植物抗旱性方法进行概述。     

Temperature step response of dehardening in Pinus sylvestris seedlings

The time constant of the dehardening of one‐year‐old Scots pine (Pinus sylvestris L.) seedlings was studied in three experiments started at different times of the year. The seedlings were transferred from outside to the different controlled conditions in January (Exp. 1), March (Exp. 2) and April (Exp. 3). Changes in the frost resistance of the seedlings were followed on the basis of the temperature response of the specific impedance difference in the shoot. The time constant for dehardening at a temperature of 7.5°C was found to be about 12 days in Exp. 1, about 8 days in Exp. 2, and about 5 days in Exp. 3. the terminal bud burst when the frost resistance of the shoot had risen to about ‐10°C.     

New impedance measurement system estimating cross-sectional moisture distribution in cylindrical bodies and electric network modeling

This work aimed to measure the cross-sectional moisture distribution in a cylindrical body using a double-glass-tube model filled with water and to construct an electric network model that explains the effects of moisture distribution. A new impedance measurement system introducing an intermediate electrode was exploited. The electrode was used to segregate the target local current from the whole current in a cross section of a specimen. Three model cylinders with different moisture distributions were used, and absolute values of impedance and phase were measured over the frequency range 1 kHz to 1 MHz. By introducing an intermediate electrode, frequency responses of the impedance and the phase showed characteristic changes in the high-frequency range associated with the moisture distributions. The trends were simulated numerically by using electric network analysis. The proposed method enabled measurement of a selective current path in the cross section of a cylindrical body.