森林生物技术走出实验室举步艰难

新的、高密度树木种植正在给林业生物技术带来迅速的变化。但是如果不能克服生态风险和经济障碍．这些新的方法或许永远也无法使用——     

电磁场的生物效应

本书是一本关于电磁场生物效应的新著。电磁场可以对各种生物产生影响，包括低频率和高频率及不同强度的电磁场的作用，因此，电磁场的研究和技术应用及环境作用等方面都十分重要。本书的内容很广泛，涉及电磁场的机理、模型化、生物效应、治疗效应、国际标准、照射判别准则等。     

Ionic Conductivity and Dielectric Properties of the PAN-Ion Conducting Polymers

1 Results In this work, the ion conducting films of polyacrylonitrile (PAN) containing lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) were prepared by the solution casting technique. The ionic conductivity measurements were carried out using impedance spectroscopy. The room temperature conductivity for pure polyacrylonitrile film is 1.51×10-11 S·cm-1. The room temperature conductivity for the highest conducting film in the PAN-LiCF3SO3 and PAN-NaCF3SO3 systems is 1.51×10-5 and 7.99×10-6 S·cm-1, respectively. The conductivity-temperature studies were performed in the temperature range between 303 and 373 K. The results for the variation of the conductivity with temperature obeys the VTF law. The increase and decrease in the number of ions can be implied from the plots of dielectric constant, εr-frequency and dielectric loss, εi-frequency.     

英国人看柏林问题——一个对话

留驻在柏林,我們的政府每天就要花掉我們很多的钱。留駐在柏林,我們的政府就要準備把该城的行政机构变成一个吵嚷的场所。据某些报纸和某些政客所说,留驻在柏林,我們的政府就要準備對俄国每一個农人饗以原子彈。我走到各處,都听见有人问起关于這种奇異局勢的問題,英国人民对于他們的官吏和士兵留驻在别人的城市里,並且佔为已有,而他们又不是在戰爭中由於战鬥的結果而進入該城的,都认为是极其激动的。     

Prof. Zhu Zuoyan Met with the INRA Delegation

Prof. Zhu Zuoyan, Vice President of NSFC, met with the National Institute of Agricultural Research (INRA) delegation led by its Deputy Director General, Prof. Guy Riba on Jan. 18, 2007.     

Novel Fluorene-thiophene Copolymers and Polymer Blends for Photonic Devices

1 Results In this contribution we deal with photophysical and photoelectrical study of novel fluorene-thiophene copolymers, and thiophene-based oligomers and polymers, the syntheses of which are reported in our other contributions. Information about electronic structure of the polymers was obtained from cyclic voltammetry and absorption spectroscopy. The absorption of the polymers under study covers the whole visible region; the low band-gap polymer (Eg=1.35 eV) exhibited the long-wavelength absorption ...     

灰铸铁的应力屈服曲面及其三维热弹塑性应力解析

对原有的灰铸铁件应力屈服曲面进行了合理的简化,使其在理论上合理,工程应用上更为方便。建立了灰铸铁件三维非稳态热弹塑性应力场的有限元方法。以灰铸铁哑铃件为对象,用新屈服曲面对其应力发展过程进行了模拟,且比较了用新旧屈服面计算得到的结果。     

德国将彻底改造原民主德国的科研体系

科学顾问委员会花了一年的时间对原民主德国遗留下来的科学与研究体系进行了摸底、评价和鉴定。它提出的重新布局的建议将影响深远。