The study of numerical character for femtosecond pulse shaping

This paper describes the generation of shaped femtosecond multiple pulses by using the phase-only Dammann filters in 4f femtosecond shaper and gives the experimental result of femtosecond pulse characterization by the frequency- resolved optical gating （FROG） technique. With the theoretical simulation, it concludes that the quality of the generated output array is relevant to the number of pixels and the spacing between the components.[第一段]     

Energy Transfer in the Light-Harvesting Complexes of Purple Bacteria

In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic excitation transfer to the reaction center(RC). In this decohering model, the Hamiltonian of the system commutes with the systemenvironment interaction. We take B850 ring of light-harvesting complex II(LH-II) in purple bacteria as an example to calculate the efficiency of the energy transfer as a function of time. We find that the environmental noise can make the LH-II have stable energy transfer efficiency over a long time. This is to say that the environmental noise which is the decohering source has advantage of the energy transfer in the process of photosynthesis.     

Monte-Carlo Simulation of Multiple-Molecular-Motor Transport

Multimotor transport is studied by Monte-Carlo simulation with consideration of motor detachment from the filament. Our work shows, in the case of low load, the velocity of multi-motor system can decrease or increase with increasing motor numbers depending on the single motor force-velocity curve. The stall force and run-length reduced greatly compared to other models. Especially in the case of low ATP concentrations, the stall force of multi motor transport even smaller than the single motor＇s stall force.     

无金属和氧化剂温和条件下碱促进的烯胺酮碳-碳双键断裂合成NH2-结构脒类化合物

报道了室温条件下烯胺酮和磺酰叠氮通过碳-碳双键断裂合成N-磺酰基醚类化合物的方法.反应在1,8-二.氮杂双环[5.4.0]十一碳-7-烯(DBU)存在下进行,无需使用任何金属和氧化剂,具有良好的底物适用性.烯胺酮上的15N同位素标记实验证实,磺酰叠氮仅作为产物中的磺酰胺片段供体,同时,该实验也有力地支持反应机理涉及关键的1,2,3-三唑啉中间体的原位形成以及环分解.     

学生为什么不善于利用几何意义解题——从一道二次函数题的学生解答受阻谈起

我在一次高三数学复习测试中选用了这样一道题：“设函数f（x）=x^2＋x＋a（a∈R”）满足f（n）〈0，判断f（n＋1）的符号，”结果大多数学生没有做出来，甚至有许多学生在听了老师讲解后还是不得其解，事后，我反复思考，这是一道中等难度的题目，为什么会出现这种情况呢？经仔细了解发现：学生不善于从几何角度考虑问题，不善于利用几何意义解题．以下是大多数学生解题时受阻的情形：     

抛物线模拉拔方棒的上界解析解

本文对采用抛物线模面函数的模具拉拔方形棒、线材设定了三维运动许可速度场；以曲面积分与变上限积分方法得到该场上界解析解．与一维功率微分方程解法的结果进行了比较     

辊底式热处理炉烧嘴控制仿真研究

应用Fluent软件建立了辊底式热处理的三维仿真模型。通过该模型得到了热处理炉的气体分布及变化情况,从而确定了烧嘴燃烧时序控制方案。采用差分进化算法对烧嘴的燃烧时间进行寻优,从而提高烧嘴燃烧控制精度。通过现场实测温度与模拟温度的仿真实验证实了本文提出的烧嘴燃烧控制模型的有效性,能够满足实际生产的需求。     

Multi-band microwave metamaterial absorber based on coplanar Jerusalem crosses

The influence of the gap on the absorption performance of the conventional split ring resonator(SRR) absorber is investigated at microwave frequencies. Our simulated results reveal that the geometry of the square SRR can be equivalent to a Jerusalem cross(JC) resonator and its corresponding metamaterial absorber(MA) is changed to a JC absorber. The JC MA exhibits an experimental absorption peak of 99.1% at 8.72 GHz, which shows an excellent agreement with our simulated results. By simply assembling several JCs with slightly different geometric parameters next to each other into a unit cell, a perfect multi-band absorption can be effectively obtained. The experimental results show that the MA has four distinct and strong absorption peaks at 8.32 GHz, 9.8 GHz, 11.52 GHz and 13.24 GHz. Finally, the multi-reflection interference theory is introduced to interpret the absorption mechanism.     

物理农业技术在现代农业基础科学与工程研究中的应用

在强调物理农业对现代农业发展重大意义的基础上,本文从物理因素对农作物繁育生长的促进作用和运用物理技术手段及采集农业环境信息两个方面叙述了物理农业技术在基础农业科学与农业工程研究领域中的应用与发展现状,并结合我国农业环境,提出了以先进的物理农业技术为切入点,重点发展物理农业的现代农业发展模式.     

DNA分子链的初始高度及其压弹性的原子力显微镜研究

用接触和轻敲两种模式下的原子力显微术研究了空气中的DNA分子,探讨了成像模式对高度测量的影响,考证了DNA的初始高度.结果表明:文中所得DNA初始高度与理论值较接近.在参照DNA初始高度的基础上,通过检测DNA双链的弹性形变量,研究了DNA分子在直径方向的压缩性质.结果表明:空气中固定在云母表面的DNA分子具有很好的压弹性,在外力作用下DNA的径向形变可达到60%以上;当外力撤销后,其形变可以不同程度地恢复.分析了25段DNA分子上125个点的高度与成像力的关系,并由此初步估算了DNA分子的弹性常数.