转天蚕素AD（CAD）基因于紫花苜蓿的研究

为了探索利用紫花苜蓿Medicago sativa作为生物反应器生产杂合抗菌肽天蚕素AD(Cecropin AD,CAD)的可行性,通过PCR搭桥方法合成了CAD全长基因,并插入对外源基因表达有一定促进作用的调控元件:Ω序列、Kozak序列及KDEL四肽序列,然后将改造后的CAD基因克隆进载体pCAMBIA1390R,构建了pCAMBIA1390R-CAD植物表达载体.将重组质粒转入根癌农杆菌Agrobacterium tumefacienLBA4404,并通过农杆菌介导方法将CAD基因转化入紫花苜蓿.在含潮霉素(20 mg/L)的筛选培养基上筛选转基因植株,通过PCR、Southern blotting检测,CAD基因已经转入紫花苜蓿中;提取蛋白质进行抑菌活性研究,结果表明转基因苜蓿蛋白提取物对沙门氏菌Sal-monella及金黄色葡萄球菌Staphylococcus aureus具有一定抑菌活性.     

应用混合线性模型(AD)分析热带温带玉米群体间的遗传关系

按Griffing双列杂交方法Ⅳ，对9个热带和温带玉米群体进行组配，获得36个杂交组合。2002年和2003年，采用混合线性（AD）模型和最小范数二阶无偏估算法（1）法（minimum norm quadratic unbiased estimation, MINQUE），分别在河南安阳和湖北十堰进行田间鉴定，对产量和产量构成因素的遗传方差分量、杂交组合的基因型值进行了分析。结果显示，产量和产量构成因素的遗传方差分量及其与环境的互作效应大多达到极显著水平，但各项遗传方差分量对总表型变异的贡献有差异。对小区产量而言，各效应的贡献是显性>显性与环境互作>加性与环境互作>加性；而加性方差分量对总表型变异的贡献为穗行数>穗粒数>百粒重>小区产量。对这36个组合的群体平均优势和群体超亲优势进行了估计，并在此基础上引入群体间遗传差异的度量参数ω/(2μ)，ω/(2μ) = 群体平均优势－群体超亲优势。对9个群体的比较表明，遗传差异与杂种优势之间不存在线性关系，亲本的遗传差异过大和过小都不利于产生强优势组合，具有中等遗传差异的亲本群体表现出了强的杂种优势。如组合3´6 (BSSS C9´Stay Green C4)、2´3 (BS16´BSSS C9)和1´3 (Suwan1´BSSS C9)都具有中等的遗传差别，有较好的杂种优势表现；BSSS C9与Stay Green C4和Suwan1、BS16和Suwan1在温带育种中值得关注，有可能形成新的杂种优势模式。     

Estimating precompression stress of structured soils on the basis of aggregate density and dry bulk density

In soil mechanics, precompression stress is an essential parameter for estimations of the compaction risk of cultivated land. In order to determine this factor, regression equations were developed. They require various input variables of water and air regime, dry bulk density as well as the shear strength parameters c and φ. In this paper, we propose a regression model, which estimates the precompression stress from the two parameters dry bulk density (BD) and aggregate density (AD). The experiments were conducted on various structured arable soils in Germany. Altogether 25 natural soils and seven disturbed substrates were examined with three to seven replications. On all sites, precompression stress (log σ_P) was determined by means of stress–strain measurements under drained conditions and a matric potential of −6 kPa. The same samples were used for estimating the dry bulk density. Parallel to this, density measurements of aggregates with a diameter of 8–10 mm were made at a matric potential of −6 kPa. Aggregate density and dry bulk density were put into a relation (AD/BD ratio). This quotient shows the state of the inter-aggregate pore system and thus the load-support strength between the aggregates. A multiple linear regression equation of simple design allows to determine the level of precompression stress using the input variables AD/BD ratio and dry bulk density. Precompression stress rises with increasing dry bulk density. An increasing AD/BD ratio leads to a decline of precompression supposing the density values remain constant. The model produced good agreement with the measured values. The determination coefficient of the regression function was 0.84, the mean absolute error (MAE) 0.12 and the root mean square error (RMSE) 0.14. The index of agreement according to Willmot [Willmot, C.J., 1982. Some comments on the evaluation of model performance. Bull. Am. Meteorol. Soc. 63 (11), 1309–1313] was 0.95.     

基于零件图重建装配图的图结构研究

基于图结构的理论，用图的方法描述装配图的数据结构，以零件图为单位，实现零件图与装配图的信息共享，减少数据冗余，同时利用图的拓扑排序功述由零件图重建装配图的装配顺序，减少人工干预，提高整个机械ＣＡＤ的水平。     

Identification of traits to improve the nitrogen-use efficiency of wheat genotypes

Nitrogen (N) fertilizer represents a significant cost for the grower and may also have environmental impacts through nitrate leaching and N₂O (a greenhouse gas) emissions associated with denitrification. The objectives of this study were to analyze the genetic variability in N-use efficiency (grain dry matter (DM) yield per unit N available from soil and fertilizer; NUE) in winter wheat and identify traits for improved NUE for application in breeding. Fourteen UK and French cultivars and two French advanced breeding lines were tested in a 2 year/four site network comprising different locations in France and in the UK. Detailed growth analysis was conducted at anthesis and harvest in experiments including DM and N partitioning. Senescence of either the flag leaf or the whole leaf canopy was assessed from a visual score every 3-4 days from anthesis to complete canopy senescence. The senescence score was fitted against thermal time using a five parameters monomolecular-logistic equation allowing the estimation of the timing of the onset and the rate of post-anthesis senescence. In each experiment, grain yield was reduced under low N (LN), with an average reduction of 2.2 t ha⁻¹ (29%). Significant N × genotype level interaction was observed for NUE. Crop N uptake at harvest on average was reduced from 227 kg N ha⁻¹ under high N (HN) to 109 kg N ha⁻¹ under LN conditions while N-utilization efficiency (grain DM yield per unit crop N uptake at harvest; NUtE) increased from 34.0 to 52.1 kg DM kg⁻¹ N. Overall genetic variability in NUE under LN related mainly to differences in NUtE rather than N-uptake efficiency (crop N uptake at harvest per unit N available from soil and fertilizer; NUpE). However, at one site there was also a positive correlation between NUpE and NUE at LN in both years. Moreover, across the 2 year/four site network, the N × genotype effect for NUpE partly explained the N × genotype effect for grain yield and NUE. Averaging across the 16 genotypes, the timing of onset of senescence explained 86% of the variation in NUtE amongst site-season-N treatment combinations. The linear regression of onset of senescence on NutE amongst genoytpes was not significant under HN, but at three of the four sites was significant under LN explaining 32-70% of the phenotypic variation amongst genotypes in NutE. Onset of senescence amongst genotypes was negatively correlated with the efficiency with which above-ground N at anthesis was remobilized to the grain under LN. It is concluded that delaying the onset of post-anthesis senescence may be an important trait for increasing grain yield of wheat grown under low N supply.     

农田地下滴灌管道堵塞快速检测装置的设计

农业在我国国民经济发展中起到重要作用,而在当今水资源匮乏的背景下,农田节水灌溉势在必行。滴灌是农田节水灌溉的有效方法之一,特别是在水资源匮乏的地区应用更为广泛。由于农田地下滴灌管深埋于土壤下,导致滴灌管堵塞时不易被发现,如不及时采取措施将会影响农作物的生长并造成损失。为此,研制了一种快速检测农田地下滴灌管道堵塞的装置。该装置以STC90C58AD为主控芯片,采用PHTS-5V-V2土壤湿度传感器对农作物根部的土壤湿度进行检测,对检测到的不同位置上的土壤湿度值进行比较,来判断滴灌管是否堵塞。试验表明:该装置能够快速测定指定点的土壤湿度,判断地下滴管管道堵塞情况,同时具有实时显示、存储、报警等功能,可以满足农田地下滴灌管道堵塞快速检测的需求。     

New cholinesterase inhibiting bisbenzylisoquinoline alkaloids from Abuta grandifolia

The phytochemical study of the stem bark and wood of Abuta grandifolia (Mart.) Sandwith led to the identification of four bisbenzylisoquinoline alkaloids (BBIQs), namely (R,S)-2 N-norberbamunine (1), (R,R)-isochondodendrine (2), (S-S)-O4″-methyl, Nb-nor-O6'-demethyl-(+)-curine (3), and (S-S)-O4″-methyl, O6'-demethyl-(+)-curine (4), together with the aporphine alkaloid R-nornuciferine (5), all obtained by countercurrent distribution separation (CCD) and identified on the basis of their spectroscopic data. Alkaloids 3 and 4 were new. All the isolated compounds were tested for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. 1 was the most active against AChE, whereas 3 and 4 were the most potent against BChE. Interestingly, all tested alkaloids are more potent against BChE than against AChE. This selectivity of cholinesterase (ChE) inhibition could be important in order to speculate on their potential therapeutic relevance.     

团头鲂对7种饲料的蛋白质、氨基酸及磷的表观消化率

本实验以0.5%的三氧化二铬(Cr2O3)为指示剂,研究分别以鱼粉、肉骨粉、豆粕、花生粕、棉粕、酒精糟及其残液干燥物(DDGS)和菜粕作为蛋白饲料,将这7种饲料原料与基础日粮按照3:7的比例组成实验日粮,观测团头鲂(Megalalobrama amblycephala Yih)对这7种饲料的干物质、粗蛋白、氨基酸及总磷的表观消化率.实验鱼初始体质量为(296.54±1.71)g,分别投喂相应的实验饲料5周后采用自排法收集粪便.结果表明,7种饲料原料的干物质、蛋白质、总氨基酸以及总磷的表观消化率的范围分别为53.65%～77.48%、78.66%～93.63%、80.12%～94.83%、3.21%～48.02%.其中粗蛋白及总氨基酸的表观消化率均以菜粕最高;花生粕、豆粕与鱼粉相接近;肉骨粉最低.磷的表观消化率以DDGS最高,菜粕和肉骨粉最低,其他4种原料的磷的表观消化率范围为11.81%～29.10%.由此可见,菜粕、豆粕、花生粕可作为团头鲂优质的植物蛋白源,在实际生产配方中可部分替代鱼粉.DDGS蛋白消化率高于肉骨粉,且磷的表观消化率较高,也可作为一种优质的鱼用饲料原料.     

基于C8051F020的集成运放参数测试仪设计

基于C8051FD20单片机设计的运算放大器闭环参数测试系统,采用辅助运放测试方法,可对运放的输入失调电压、输入失调电流、交流差模开环电压增益和交流共模抑制比以及单位增益带宽进行测量.系统利用DDS芯片AD9851实现了5HZ信号的输出和40kHz-4MHz扫频输出,具有自动量程转换、自动测量功能和良好的人机交互性.     

截止频率可调的高通滤波器设计

主要介绍了采用电压控制增益放大器AD603设计的截止频率可调且增益可控的高通滤波器。设计采用纯硬件制作,增益控制部分采用电位器调节AD603的控制电压达到控制增益目的,同时通过调节变容二级管电压的方法使滤波电路电容变化来控制滤波器截止频率。