从第九届国际光合作用大会看藻类分子遗传学发展趋势

根据１９９２年８月３０日－９月４日在日本名古层如开的第九届国际光合作用大会上交流的以藻类为材料的研究论文，综述了分子遗传学方面的研究成果。认为这些成果体现了光合作用研究的最新进展，蕴含有一定的应用前景；表明类分子遗传学不仅是藻类学研究领域的带头学科，而且已经活跃在光合作用等重大生物学问题研究的前沿；反映了藻类分子遗传学向解决生物学重大问题和推动藻类资料开发方向发展的趋势。     

一种腐屑食性鱼类对生态系统氮循环的影响

研究表明 :腐屑食性鱼类——梭鱼对环境中有机氮的摄入能力随体重的增加而增加 ,随温度的升高 ,体重系数显著减少。摄入氮 (CN,mg/ d)与体重 (W,g)和温度 (T,℃ )的数值关系可用如下模型表示 :CN=0 .6 370 W1 .0 642 ln(3.70 0 8T)。体重为 1 0 0 g的梭鱼每日可消耗环境中 332 mg氮有机质。梭鱼氮的吸收效率主要受温度的影响 ,而氮的转化效率与体重呈显著的正相关关系。随体重的增加 ,排泄氮所占比例降低     

海洋沉积物中的氮循环

氮(N)是生物生命活动的基本营养元素，N循环是整个生物圈物质和能量循环的重要组成部分。近几十年来，环境和资源问题的日益突出促进了人们对海洋生态系统的研究及对海洋资源的开发和利用，海洋中的N循环亦受到了广泛关注。尤其是20世纪90年代以来，随着国际地圈与生物圈计划(IGBP)、全球海洋通量联合研究(JGOFS)、全球海洋生态系统动力学研究(GLOBEC)等重大国际合作计划的实施，海洋中的N循环研究取得了重大进展。 本文主要对海洋沉积物中的N循环过程进行了阐述，包括海洋沉积物中N的生物地球化学循环(海洋中N与生物生产过程的关系、早期成岩作用及N的去营养化、沉积物中N循环及其控制机制、颗粒N的形成及其功能、N与其他生源要素循环的关系)及沉积物中N循环的研究方法等，以期对进一步开展N循环的研究有所帮助。     

Coastal geomorphic evolution at the Denglou Cape, the Leizhou Peninsula

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An initial demonstration of underwater acoustic communication using time reversal

In July 1999, an at-sea experiment to measure the focus of a 3.5-kHz centered time-reversal mirror (TRM) was conducted in three different environments: an absorptive bottom, a reflective bottom, and a sloping bottom. The experiment included a preliminary exploration of using a TRM to generate binary-phase shift keying communication sequences in each of these environments. Broadside communication transmissions were also made, and single-source communications were simulated using the measured-channel response. A comparison of the results is made and time reversal is shown to be an effective approach for mitigating inter-symbol interference caused by channel multipath.     

厦门港真刺唇角水蚤的生长率

本文以实验室培养为主,结合自然种群调查,观测厦门港真刺唇角水蚤各发育阶段体长、体重的增长状况,并研究了其生长率与温度、发育期的关系。     

羊栖菜茎部愈伤组织再生苗的解剖学研究

利用石蜡切片法对羊栖菜纵裂主枝上愈伤组织再生苗的发生过程进行了形态解剖学观察。发现此种成苗方式是在主枝 (茎 )或假根处由外皮层分裂形成愈伤组织 ,再由愈伤组织分化成苗的一种无性繁殖方式。愈伤组织形成再生苗有望成为羊栖菜人工养殖种苗的来源之一。     

平面约束条件在LIDAR点云滤波中的应用

介绍了一种利用平面约束条件对LIDAR点云数据进行滤波的方法,利用每个数据点的邻域点拟合平面,根据平面约束条件和平面点分类方法得到地面点,最后利用地面点内插该区域的DTM.     

Shear-induced instability and arch filament eruption: A magnetohydrodynamic (MHD) numerical simulation

We investigate, via a two-dimensional (nonplanar) MHD simulation, a situation wherein a bipolar magnetic field embedded in a stratified solar atmosphere (i.e., arch-filament-like structure) undergoes symmetrical shear motion at the footpoints. It was found that the vertical plasma flow velocities grow exponentially leading to a new type of global MHD-instability that could be characterized as a Dynamic Shearing Instability, with a growth rate of about 8{ovV} _A a, where {ovV} _A is the average Alfvén speed and a ^–1 is the characteristic length scale. The growth rate grows almost linearly until it reaches the same order of magnitude as the Alfvén speed. Then a nonlinear MHD instability occurs beyond this point. This simulation indicates the following physical consequences: the central loops are pinched by opposing Lorentz forces, and the outer closed loops stretch upward with the vertically-rising mass flow. This instability may apply to arch filament eruptions (AFE) and coronal mass ejections (CMEs).To illustrate the nonlinear dynamical shearing instability, a numerical example is given for three different values of the plasma beta that span several orders of magnitude. The numerical results were analyzed using a linearized asymptotic approach in which an analytical approximate solution for velocity growth is presented. Finally, this theoretical model is applied to describe the arch filament eruption as well as CMEs.