全球气候变化与生物多样性

综述了全球气候变化与生我的我样性的研究现状，讨论了全球气候变化引起物种灭绝的内在机制，并从全球变暖与生物多样性丢失间的正反馈因果关系出发，指出保护全球生物多样性对遏制全球变暖的重要价值，同时也指出了生物多样性与全球气候变化研究的方向。     

基于3S技术的三维扑火队伍跟踪监控指挥系统研究

为解决林火扑救过程中扑火队伍位置难掌握、指挥调度难统一的问题,利用全球定位系统、地理信息系统、遥感技术、网络技术、无线电通讯技术,设计开发了三维扑火队伍跟踪监控指挥系统,应用到森林防火管理中.系统实现了指挥中心通过无线电通讯获取GPS终端定位数据,实时显示在三维虚拟场景和二维电子地图上,同时指挥中心可以向GPS终端发送语音、文字、导航等信息,系统还实现了监控中心通过网络连接GPS服务器,同步获取并显示扑火队伍的定位信息,从而实现对扑火队伍的远程指挥、多级监控,为森林防火决策科学化、指挥快速化、调度实时化提供依据.     

Conjunctive representation of position, direction, and velocity in entorhinal cortex

Grid cells in the medial entorhinal cortex (MEC) are part of an environment-independent spatial coordinate system. To determine how information about location, direction, and distance is integrated in the grid-cell network, we recorded from each principal cell layer of MEC in rats that explored two-dimensional environments. Whereas layer II was predominated by grid cells, grid cells colocalized with head-direction cells and conjunctive grid x head-direction cells in the deeper layers. All cell types were modulated by running speed. The conjunction of positional, directional, and translational information in a single MEC cell type may enable grid coordinates to be updated during self-motion-based navigation.     

Rotation of venus: continuing contradictions

Optical observations of Venus have yielded various values of the rotation period extending from less than one to several hundred days. Radar observations give a retrograde rotation of the solid globe in 244 +/- 2 days. Recent ultraviolet photographs, however, show relatively rapid displacements of clouds in the high atmosphere of Venus which suggest a retrogrode rotation in only 5 days. The two rates seem to be physically incompatible.     

具有初速度的落体偏东问题

落体偏东是科里奥利力对沿竖直方向运动的物体的作用结果,为了更进一步了解地球自转对落体的影响,讨论了在纬度为λ高h的上空,物体的初速度为ν,方向为南北方向的落体偏值计算,以及在纬度为λ高h的上空,物体初速度为ν,方向为东西方向的落体偏值计算.     

Google Earth应用于基建项目管理系统的研究与实现

Google Earth是Google公司开发的一款虚拟地球仪软件,它把卫星照片、航空照相和GIS布置在一个三维地球模型上,通过Google Earth插件及其JavaScript API可以将Google Earth三维地球模型嵌入网页中,同其他网页信息整合形成具有一定查询功能和3D展示功能的业务管理系统。本研究探讨了如何将Google Earth三维地球模型引入基建项目管理系统,实现基于B/S结构的三维实景基建项目管理系统,直观展示基建项目建设总体布局,并实现管理过程中各类信息的交互查询和显示。     

Excitation of spirals and chiral symmetry breaking in rayleigh-benard convection

Spiral-defect populations in low-Prandtl number Rayleigh-Bénard convection with slow rotation about a vertical axis were measured in carbon dioxide at high pressure. The results indicate that spirals act like "thermally excited" defects and that the winding direction of a spiral is analogous to a magnetic spin. Rotation about a vertical axis, the spiral analog of the magnetic field, breaks the zero-rotation chiral symmetry between clockwise and counterclockwise spiral defects. Many properties of spiral-defect statistics are well described by an effective statistical-mechanical model.     

Celestial rotation: its importance in the development of migratory orientation

Three groups of indigo buntings were hand-raised in various conditions of visual isolation from celestial cues. When they had been prevented from viewing the night sky prior to the autumn migration season, birds tested under planetarium skies were unable to select the normal migration direction. By contrast, when they had been exposed as juveniles to a normal, rotating, planetarium sky, individuals displayed typical southerly directional preferences. The third group was exposed to an incorrect planetarium sky in which the stars rotated about a fictitious axis. When tested during the autumn, these birds took up the "correct" migration direction relative to the new axis of rotation. These results fail to support the hypothesis of a "genetic star map." They suggest, instead, a maturation process in which stellar cues come to be associated with a directional reference system provided by the axis of celestial rotation.     

Directionally controlled fluorescence emission in butterflies

Recently developed, high-efficiency, light-emitting diodes use two-dimensional photonic crystals to enhance the extraction of otherwise internally trapped light and multilayer reflectors to control the direction of light emission. This work describes the characterization of a naturally evolved light-extraction system on the wing scales of a small group of Papilio butterflies. The efficient extraction of fluorescence from these scales is facilitated by a two-dimensional photonic crystal slab that uses a multilayer to help control emission direction. Its light-extraction function is analogous to that of the light-emitting diode.     

利用OLE技术集成Delphi与MapInfo开发棉田土壤肥力信息管理与施肥决策系统

以新疆兵团农五师81团为系统试行和合作地点,针对土壤肥力信息数据在农业生产中的重要作用,将Delphi强大的数据库编程能力和MapInfo的图形表达能力有机结合,实现了MapInfo的集成二次开发,建立了集棉田土壤养分信息管理、土壤施肥推荐、GIS条田图形信息管理功能于一体的新疆农五师81团棉田土壤肥力信息管理与施肥推荐决策系统.     

两点间曲面距离计算模型及应用

针对北京——底特律飞越北极新航线的开通而提出的实际问题,分别对球体和旋转椭球体情况进行讨论,根据数学上的可近似原理,建立了两点间曲面距离计算模型,并将此算法推广到最短航线的找出,从而解释了新航线节约4h左右的原因。     

Mental rotation of the neuronal population vector

A rhesus monkey was trained to move its arm in a direction that was perpendicular to and counterclockwise from the direction of a target light that changed in position from trial to trial. Solution of this problem was hypothesized to involve the creation and mental rotation of an imagined movement vector from the direction of the light to the direction of the movement. This hypothesis was tested directly by recording the activity of cells in the motor cortex during performance of the task and computing the neuronal population vector in successive time intervals during the reaction time. The population vector rotated gradually counterclockwise from the direction of the light to the direction of the movement at an average rate of 732 degrees per second. These results provide direct, neural evidence for the mental rotation hypothesis and indicate that the neuronal population vector is a useful tool for "reading out" and identifying cognitive operations of neuronal ensembles.     

双向电泳技术在植物蛋白质组研究中的应用

双向电泳技术是获得细胞、组织或器官等蛋白表达图谱的主要手段,是蛋白质组学研究的核心技术之一。综述了双向电泳技术的原理、主要操作方法及其在植物蛋白质组研究中的应用。     

Ultrafast carbon-carbon single-bond rotational isomerization in room-temperature solution

Generally, rotational isomerization about the carbon-carbon single bond in simple ethane derivatives in room-temperature solution under thermal equilibrium conditions has been too fast to measure. We achieved this goal using two-dimensional infrared vibrational echo spectroscopy to observe isomerization between the gauche and trans conformations of an ethane derivative, 1-fluoro-2-isocyanato-ethane (1), in a CCl4 solution at room temperature. The isomerization time constant is 43 picoseconds (ps, 10(-12) s). Based on this value and on density functional theory calculations of the barrier heights of 1, n-butane, and ethane, the time constants for n-butane and ethane internal rotation under the same conditions are approximately 40 and approximately 12 ps, respectively.     

秦杂2号大白菜品种的选育及其抗病性、品质、产量评价

‘秦杂2号’大白菜品种是以胞质雄性不育系02CMS14为母本,以02S28优良自交系为父本配制的杂种一代。该品种生长期70 d左右;株型紧凑,抱球紧实,适播期长;矮桩叠抱,头球型;软叶率66.8%,球形指数1.3,单球重3~3.5 kg,净菜率80%,产量105.4 t/hm2;质地脆嫩,适口性好,品质优,风味佳;抗病毒病、霜霉病和黑斑病;该品种现已在陕西、甘肃、新疆、广西、河南、山西、四川、宁夏等多个省(区)示范推广,是一个综合性状优良,具有较强市场竞争力的大白菜品种。     

Productivity Models of Grain Crop Rotation on Gray Forest Soils of the Upper Volga Region

The influence of fertilizers on grain crop rotation productivity and dynamics of ammonium and nitrate nitrogen reserves has been studied in a field experiment on the gray forest soils of the Upper Volga region to develop crop rotation productivity management models. Organic fertilizers have included cattle, chicken, and goose manure and have been applied in various doses. The experimental design has included variants of applying mineral fertilizers (NPK) and their combination with NK and organic fertilizers. It has been established that more than 90% of crop rotation productivity variations accrue to nitrogen in organic and mineral fertilizers; in the light of their interaction, this figure rises to 96.8%. A close power-law or hyperbolical relation has been discovered between the average crop rotation productivity and the average annual nitrate nitrogen reserves in the early crop vegetation. The same kind of relation for this period has been discovered between the first parameter and the ammonium and nitrate nitrogen reserves in the soil solution (mobile nitrogen stock). It is proposed to estimate the mobile nitrogen stock by the mobilization nitrogen pool that depends on the dose of nitrogen in mineral and organic fertilizers.     

Two- rather than three-dimensional representation of saccades in monkey superior colliculus

Saccades are controlled by neurons in the brainstem reticular formation that receive input from the superior colliculus and cortex. Recently two quantitative models have been proposed for the role of the colliculus in the generation of three-dimensional eye movements. In order to test these models, three-dimensional eye movements were measured in the alert monkey to investigate whether the saccadic motor map of the superior colliculus is two-dimensional, representing retinal target vectors, or three-dimensional, representing three-dimensional motor error for the rotation of the eye. Electrical stimulation of the superior colliculus produced two-dimensional, not three-dimensional, eye movements. It is therefore concluded that the collicular motor map is two-dimensional.     

国外循环农业发展模式及对我国的启示

循环农业作为一种可持续的生态的农业发展道路,是我国未来农业的发展方向。对国外5种典型的循环农业发展模式进行介绍,分别为瑞典"轮作型生态农业模式"、美国"低投入可持续农业模式"、德国"绿色能源农业模式"、日本"环保型可持续农业模式"、以色列"无土农业模式",并比较每种模式的经验,进而提出对我国发展循环农业的启示。     

Determining transition-state geometries in liquids using 2D-IR

Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.