酷想大晒台

哎呀呀,这个世界乱套了!大人变成了小孩,小孩变成了大人。现在,终于轮到各位小酷想家来当家做主了,快来看看他们都有什么出色的表现吧!看到爸妈变成了小孩,我立马学着他们的样子,下达了第一道命令:写作业去!我想他们一定会哭的,因为老师留的作业实在是太多了。新浪YOYO     

一年又一年

上了年纪的人都有相似的感觉,就是年纪越大,时间好像过得越快。小时候,过了元旦盼春节,过了春节盼五一、六一,过了六一盼国庆,过了国庆再盼元旦。时间总是那么漫长,盼望的假期似乎总是姗姗来迟。而如今,似乎一眨眼,一年就过去了。我给这个现象总结了一个理论,叫做相对     

百岁寿星 科学巨擘

贝时璋先生与20世纪同行,经历了百年世事沧桑,目睹了世纪科技巨变,体会了人生的无尽乐趣;同时,他也对中国生物物理学的发展做出了杰出贡献,展示了人生的巨大价值.     

中国生物材料专利保护及其现状分析

本文叙述了我国生物材料专利制度的变迁,耐我国生物材料的专利保护范围进行了论述,对生物材料的保藏问题进行了说明;对我国生物材料保护制度进了论述,并对我国生物材料领域的专利现状进行了分析,就如何加强我国生物材料的专利保护提出几点建议。     

浅谈天津市行道树的应用现状与选用分析

行道树是城市园林绿化的骨干树种,美化了城市景观,促进了城市生态环境的改善。对天津市现有行道树的选择与应用进行了分析,找出了天津市行道树栽植和管理方面存在的主要问题,提出了改变天津市行道树种应用现状的对策。     

促进微生物实验技术创新水平的改革初探

为了加强对本科生综合素质和能力的培养 ,激发学生的学习兴趣 ,我们对微生物实验课的教学内容进行了一系列改革 ,优化了实验项目 ,节约实验成本 ,并且引入科研成果转化实验 ,同时改进了实验方法和手段 ,实验结果更为准确。这些措施蕴含了较高的理论水平 ,增加了教学信息量 ,明显提高了教学效果 ,为培养高素质人才奠定了基础。     

大仓鼠( Cricetulus triton )的某些生态研究

１９８５年４月用标志重捕法观察了大仓鼠的活动范围；野外直接观察了鼠的活动及危害；室内直接观察了昼夜活动节律；在笼养状况下，观察了大仓鼠捕食黑线仓鼠和小白鼠的行为；室内观察了大仓鼠选食种子的行为。     

美国孟山都公司找到玉米产量翻番的新途径

2008年9月,美国孟山都（Monsanto）公司宣布已经查清了与玉米增收相关的遗传信息,找到了粮食增产的新途径。 孟山都公司从其产量最高的雌株玉米中挑选了1株,绘制出了其遗传基因的蓝图。这次研究对于将来向农户提供优质玉米种子至关重要,它采用了高通量DNA测序法．并利用了最近刚完成的玉米基因组计划所获得的数据。     

2015年中国微生物遗传学研究领域若干重要进展

中国微生物遗传学研究在2015年取得了重要进展。本文回顾了2015年度中国本土科研团队在微生物遗传学领域取得的若干重要科研进展,扼要介绍了若干重点论文,展示了中国科学家在本领域的学术贡献。在基础微生物遗传学领域,明确了调控基因表达的一系列重要生物大分子的组成、结构和功能,解析了微生物免疫系统识别外源核酸片段的分子基础,阐明了多个微生物来源重要活性物质的生物合成途径及新颖的酶学反应过程,发现了微生物基因表达调控的新机理,在微生物发育、进化与群体行为生物学方面也取得一定进展。在工业微生物遗传学方面,阐明了微生物制造及其分子基础。在病原微生物遗传学方面,研究了多个致病菌的遗传调控,明晰了致病菌-宿主相互作用的遗传机制,在基因组水平解析了微生物耐药、新发病原和环境微生物的遗传机理,为致病菌防控新措施的研发提供了基础。在微生物多样性与环境微生物遗传学方面,展示了利用微生物遗传多样性的特点通过催化获得特定手性的化合物具有较好应用前景,肠道微生物组学研究方兴未艾。     

中华猕猴桃良种选育研究

本文扼要叙述了中华猕猴桃原产地的生态条件,分析了引入栽培园中所遇到的突出问题,提出了中华猕猴桃从高海拔山区引入低海拔丘陵平原应解决的关键技术,初步总结了在武汉风土条件下的栽培经验,简述了优株选育途径和效果,介绍了武植3号等优良品系的主要经济性状。     

Asymptotic behaviour of the non-autonomous competing two-species Lotka-Volterra models with impulsive effect

In this paper, the nonautonomous competing two-species Lotka-Volterra models with impulsive effect are considered, where all the parameters are time-dependent and asymptotically approach the corresponding periodic functions. Under some conditions, it is shown that the semi-trivial positive solutions of the models asymptotically approach the semi-trivial positive periodic solutions of the corresponding periodic system. It is also shown that the positive solution of the models asymptotically approach the positive periodic solution of the corresponding periodic system.     

Asymptotic behaviour of the non-autonomous competing two-species Lotka–Volterra models with impulsive effect

In this paper, the nonautonomous competing two-species Lotka–Volterra models with impulsive effect are considered, where all the parameters are time-dependent and asymptotically approach the corresponding periodic functions. Under some conditions, it is shown that the semi-trivial positive solutions of the models asymptotically approach the semi-trivial positive periodic solutions of the corresponding periodic system. It is also shown that the positive solution of the models asymptotically approach the positive periodic solution of the corresponding periodic system.     

具周期脉冲的周期差分系统的全局性态

本文建立了具有常数脉冲和周期脉冲的周期差分系统,得到了常数脉冲系统全局稳定周期解存在的充分条件,并证明了周期脉冲的周期系统的周期解是全局吸引的。     

具有反馈控制的Schoner模型的渐近性

本文讨论了具有反馈控制的非自治Schoner系统的持续生存性条件以及该系统为周期系统时，存在唯一严格正的全局稳定的周期解的条件。     

具性别和阶段结构的非自治二种群捕食者-食饵系统研究

讨论了一类食饵具有性别结构,捕食者具有阶段结构的非自治捕食者．食饵系统,运用Liapunov函数方法,得到了该系统一致持续生存的充分条件．对于该模型的周期系统,在适当条件下,存在唯一、全局渐近稳定的周期解．对更具普遍意义的概周期现象,也得出了概周期正解唯一存在且全局渐近稳定的充分条件．     

三种群竞争系统的持久性

本文研究了三种群非自治周期Lotka-Volterra竞争系统的持久性,得到了正周期解的存在性和平衡振荡的条件。     

Construction of an associative memory using unstable periodic orbits of a chaotic attractor

Unstable periodic orbits are the skeleton of a chaotic attractor. We constructed an associative memory based on the chaotic attractor of an artificial neural network, which associates input patterns to unstable periodic orbits. By processing an input, the system is driven out of the ground state to one of the pre-defined disjunctive areas of the attractor. Each of these areas is associated with a different unstable periodic orbit. We call an input pattern learned if the control mechanism keeps the system on the unstable periodic orbit during the response. Otherwise, the system relaxes back to the ground state on a chaotic trajectory. The major benefits of this memory device are its high capacity and low-energy consumption. In addition, new information can be simply added by linking a new input to a new unstable periodic orbit.     

Almost periodic solution of non-autonomous Lotka-Volterra predator-prey dispersal system with delays

This paper studies a non-autonomous Lotka-Volterra almost periodic predator-prey dispersal system with discrete and continuous time delays which consists of n-patches, the prey species can disperse among n-patches, but the predator species is confined to one patch and cannot disperse. By using comparison theorem and delay differential equation basic theory, we prove the system is uniformly persistent under some appropriate conditions. Further, by constructing suitable Lyapunov functional, we show that the system is globally asymptotically stable under some appropriate conditions. By using almost periodic functional hull theory, we show that the almost periodic system has a unique globally asymptotical stable strictly positive almost periodic solution. The conditions for the permanence, global stability of system and the existence, uniqueness of positive almost periodic solution depend on delays, so, time delays are "profitless". Finally, conclusions and two particular cases are given. These results are basically an extension of the known results for non-autonomous Lotka-Volterra systems.     

Periodic solution of a chemostat model with Beddington-DeAnglis uptake function and impulsive state feedback control

In this paper, a chemostat model with Beddington-DeAnglis uptake function and impulsive state feedback control is considered. We obtain sufficient conditions of the global asymptotical stability of the system without impulsive state feedback control. We also obtain that the system with impulsive state feedback control has periodic solution of order one. Sufficient conditions for existence and stability of periodic solution of order one are given. In some cases, it is possible that the system exists periodic solution of order two. Our results show that the control measure is effective and reliable.