咖啡灭字虎天牛研究综述

咖啡灭字虎天牛是危害咖啡树的重大害虫,从本世纪初以来,国内外对该虫做了许多研究、这些研究包括生活史、取食危害习性、寄主植物、化学防治、生物防治等方面.与农林害虫相比,对咖啡灭字虎天牛的研究工作仍相当落后.到目前为止,人们对该虫的自然种群数量变动规律及其发生机制还不清楚.今后加强这方面的研究,对于该虫的综合治理具有重大意义.

双链RNA病毒诱导的牙鲆胚胎细胞差减cDNA文库的构建

以紫外线灭活的dsRNA病毒草鱼出血病病毒(GCHV)诱导和模拟诱导的牙鲆胚胎细胞为材料,利用抑制性差减杂交(SSH)技术,成功构建了双链RNA病毒诱导的牙鲆胚胎细胞(FEC)差减cDNA文库。以管家基因αtub lin作为差减指标,经检测,该文库差减效率达210倍,表明经病毒诱导后某些差异表达基因也得到了相应倍数的富集。将获得的cDNA片段连接到pGEM T载体,PCR检测显示差减片段在250bp~2 000bp之间。该差减cDNA文库的构建为从分子水平研究牙鲆培养细胞对dsRNA病毒的免疫反应、以及进

Synthesis and structures of morphology-controlled ZnO nano- and microcrystals

Zinc oxide flower-like bunches were directly synthesized on indium-doped tin oxide (ITO) glass substrates through a simple chemical bath deposition process. By adjusting precursor concentration, other morphologies ( spindles and rods) were also obtained. All of them are hexagonal and single crystalline in nature and grow along the [ 0001] crystallographic direction. The possible growth mechanisms for these nano- and microcrystals were proposed. It was revealed that both the inherent highly anisotropic structure of ZnO and the precursor concentration play crucial roles in determining final morphologies of the products. In addition, vibrational properties of ZnO crystals with different morphologies were investigated by Raman spectroscopy.

FET ACTIVE SLOTLINE NOTCH ANTENNAS FOR QUASI-OPTICAL POWER COMBINING

A new active antenna structure with applications in quasi-optical power combining is described. The active antenna combines a slotline FET oscillator with a notch antenna. The new structure was successfully used to create both E-plane and H-plane linear arrays as well as a 2-D array. Preliminary results of radiation patterns and the power combining efficiencies of the arrays are discussed.

Cu导线表面起伏程度对早期失效的影响

使用两种化学机械抛光剂得到的单层大马士革Cu导线表面起伏程度不同．扫描电镜观察到明显的缺陷出现在大起伏的Cu导线表面．这种表面缺陷导致早期失效比率剧增至几乎100％、电迁移寿命猛降至早期失效的量级、失效时间分布从多模变为单模，其相应的失效机制激活能为0．744-0．02eV，这说明失效主要是由Cu原子沿导线表面扩散引起的．最弱链接近似被用来分析单根Cu导线

景观生态学与生物多样性保护学术讨论会——全国第二届景观生态学学术讨论会在北京召开

<正> 由中国生态学会等10个单位联合主办,由北京大学城市与环境学系承办的景观生态学与生物多样性保护学术讨论会于1996年5月18日至20日在北京召开。本次会议是继1989年在沈阳召开的第一届全国景观生态学大会后的又一次盛会,参加会议的代表有来自大专院校、科研院所、生产单位及国家机关等80余人,会议收到论文80余篇。本次会议的主题是:景观生态学与生物多样性保护;景观生态学的基本理论与方法;可持续发展与景观生态研究;景观生态学在农业和其它领域的应用及其它宏观生态问题。

半湿润农田杂草及施氮对夏玉米产量及氮素利用的影响

以土垫旱耕人为土为供试土壤,采用大田试验,研究了半湿润农田两种杂草处理方式下(成熟后期清除杂草-A区和苗期开始清除杂草-B区),不同施氮量对夏玉米产量及氮素利用效率的影响。结果表明,当施氮量为0、45、90、1351、80 kg/hm2时,B区玉米子粒产量比A区分别增加了8.7%、12.1%、9.4%、5.0%和12.5%;吸氮量分别增加了1.5、2.9、4.85、.2和4.3 kg/hm2。A区和B区全生育期0—100 cm土层矿质氮(Nmin)累积量变化趋势基本一致,但B区比A区变幅较大。当施氮量为45、90、135和180 kg/hm2时,B区氮肥利用率、氮肥农学利用率、氮肥生理利用率均高于A区。研究还发现,在A区,当施氮量为180 kg/hm2时,杂草干生物量最大,为1518.3 kg/hm2,不施氮时,杂草的生物量最低,为845.7 kg/hm2;杂草的吸氮量随施氮量的增加而增加。可见,清除玉米农田杂草不仅可以提高作物产量和氮肥利用率,而且在减少氮素损失方面具有一定作用。

One-Step Ionic Liquid-Assisted Electrochemical Synthesis of Ionic Liquid-Functionalized Graphene Sheet Directly from Graphite

Graphite, inexpensive and available in large quantities, unfortunately does not readily exfoliate to yield individual graphene sheets. Here a mild, one-step electrochemical approach for the preparation of ionic-liquid-functionalized graphite sheets with the assistance of an ionic liquid and water is presented. These ionic-liquid-treated graphite sheets can be exfoliated into functionalized graphene nanosheets that can not only be individuated and homogeneously distributed into polar aprotic solvents, but also need not be further deoxidized. Different types of ionic liquids and different ratios of the ionic liquid to water can influence the properties of the graphene nanosheets. Graphene nanosheet/polystyrene composites synthesized by a liquid-phase blend route exhibit a percolation threshold of 0.1 vol % for room temperature electrical conductivity, and, at only 4.19 vol %, this composite has a conductivity of 13.84 S m(-1), which is 3-15 times that of polystyrene composites filled with single-walled carbon nanotubes.