大叶藻(Zostera marina L.)胚的结构和种子萌发过程的研究

以采自山东荣成褚岛桑沟湾南岸成熟的大叶藻种子为材料,研究了种子的外部形态特征、胚乳成分及胚的解剖结构,并初步了解了大叶藻种子的萌发过程。结果表明,大叶藻种子是单子叶有胚乳的种子,呈暗褐色,椭圆形或长圆形,种皮革质且有17～20条纵肋,胚乳丰厚坚硬,胚乳细胞被淀粉粒充满;胚弯曲,由胚根、胚轴、胚芽和子叶组成,子叶U形棒状,其弯曲部有一裂缝,胚芽位于裂缝处,胚轴较短,其下是两个对生的胚根,有中央维管束贯穿胚根、胚轴、胚芽和子叶。在子叶出土萌发的植物类型中,大叶藻种子萌发过程是罕见的。萌发初期,子叶优先生长突破种皮而长出地面,此后胚根才开始生长并产生不定根。对大叶藻种子结构和萌发过程的研究,为探讨大叶藻种子萌发和幼苗更新的限制因素提供了一定的理论依据。     

大容量存储器K9K8G08U0A及其在定点垂直升降剖面测量系统中的应用

介绍了新型大容量存储器K9K8G08U0A的基本组织结构,重点讲述了存储器与ATmega128L单片机外部存储器接口的硬件连接方式以及存储器的主要操作流程和部分C语言代码。     

宁夏枸杞气候区划

利用2000-2001年全国北方地区的100余份枸杞样品和土壤样品,结合当地采样期间的气象资料和宁夏各地枸杞试验资料和历史产量资料所确定的一系列影响枸杞产量和品质的农业气象指标,从1∶25万数字地图上转换出250 m×250 m格距的经纬度和数字高程资料,利用改进的小气候细网格订正推算方法,推算了宁夏气温稳定通过10 ℃期间的热量资源、光照资源分布;利用3点平滑推算了气温稳定通过10 ℃期间全区的降水量分布及关键时段平均温度场,根据枸杞的指标进行了细网格区划,从产量和品质两个方面得到了详细分区.     

Numerical model for the SNR DEM L316: simulated X-ray emission

We present a two-component supernova remnant model for the case of Magellanic remnant DEM L316 obtained from two-dimensional, axisymmetric hydrodynamic simulations. We study different scenarios which consider a possible collision between the shells and also the effects of thermal conduction. Synthetic X-ray maps were obtained from numerical results in order to directly compare with the observed morphology of this object. We find a good agreement is achieved when thermal conduction is included, reproducing both the observed morphology and the total X-ray luminosity very well. Finally, our results suggest that the two components of DEM L316 are not in physical interaction.     

利用等高线数据制作大规模3D遥感影像

把图像数据库的建库思想引入到大规模3D遥感影像的制作中。在此基础上，提出利用合并分割法制作大规模3D遥感影像。将经 过特殊处理的等高线数据制成小块DEM，采用两种模式将遥感影像与这些DEM进行纹理映射，从而制作成大规模3D遥感影像。这种方法提 高了大规模3D遥感影像的制作水平，进一步增强了大规模3D遥感影像的信息量与实用性。     

Influence of limited soil on the root distribution and anchorage of Vitex negundo L.

Field pull-out and laboratory tests were applied to investigate the effect of metal bolts and wire netting on plant root distribution and anchorage characteristics of 9-year-old Vitex negundo L. growing on a weakly weathered rocky slope (38°). Root number, length and diameter were recorded and single root specimens were classified and tested for tensile strength. The results show that root anchorage is different between the two constructions by bolts and wire. Under limited soil condition, root anchorage ability is 80% lower than when there is sufficient soil due to the reduction of the diameter and number of all second-order lateral roots, as well as the reduction of the tensile strength of the embedded second-order and first-order lateral roots on limited soil. We conclude that the distribution and anchorage of Vitex negundo L. is affected by limited soil availability on rocky slopes.     

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GNSS掩星电离层的三频观测数据模拟与反演

由三维射线追踪微分方程推出掩星三维直角坐标射线追踪的矩阵方程,对实现射线追踪的具体步骤进行讨论。采用NeQuick 作背景模拟夜间和白天的掩星电离层三频载波相位延迟观测数据,采用双频绝对TEC反演法对白天模拟数据进行反演,并比较3种不同频率组合对反演结果的影响。结果表明,在附加相位延迟等精度观测条件下,L1 L5组合获得的反演结果与模式值最为吻合。     

The initial conditions of isolated star formation – IV. C18O observations and modelling of the pre-stellar core L1689B

We present C¹⁸O observations of the pre-stellar core L1689B, in the J =3→2 and 2→1 rotational transitions, taken at the James Clerk Maxwell Telescope in Hawaii. We use a λ -iteration radiative transfer code to model the data. We adopt a similar form of radial density profile to that which we have found in all pre-stellar cores, with a 'flat' inner profile, steepening towards the edge, but we make the gradient of the 'flat' region a free parameter. We find that the core is close to virial equilibrium, but there is tentative evidence for core contraction. We allow the temperature to vary with a power-law form and find that we can consistently fit all of the CO data with an inverse temperature gradient that is warmer at the edge than at the centre. However, when we combine the CO data with the previously published millimetre data we fail to find a simultaneous fit to both data sets without additionally allowing the CO abundance to decrease towards the centre. This effect has been observed qualitatively many times before, as the CO freezes out on to the dust grains at high densities, but we quantify the effect. Hence we show that the combination of millimetre/submillimetre continuum and spectral line data is a very powerful method of constraining the physical parameters of cores on the verge of forming stars.