An early cretaceous<Emphasis Type="Italic">Ginkgo</Emphasis> ovule-bearing organ fossil from Liaoning,Northeast China and its evolutionary implications

Ginkgo is a very important gymnospermous genus that has only one surviving species, Ginkgo biloba L. As a so-called “living fossil“, wild Ginkgo was found only in China, but it once flourished well and had a world-wide distribution in the Mesozoic. The earliest Ginkgo has been known from the Middle Jurassic, based on ovule-bearin gorgans. In the Jurassic and Early Cretaceous, Ginkgo was one of the dominant gymnosperms in floras and possibly one of the coal-forming plants in North China. During the Early Tertiary, it reduced to a circumpolar distribution in the North Hemisphere; only a few reported from the South Hemisphere. From the Pliocene onwards, the Ginkgoales has been represented by the extant monotypic “living fossil“ Ginkgo biloba.     

Palaeogene fossil <Emphasis Type="Italic">Populus</Emphasis> leaves from Lanzhou Basin and their palaeoclimatic significance

An angiosperm compression flora is found in Palaeogene from Lanzhou Basin and the cuticular analysis of Populus davidiana Dode in the flora is carefully made. Furthermore, the fossil cuticles are compared with the epidermal structures of extant Populus leaves growing in different environments, i.e. moist, semimoist, and semiarid to arid climatic regions. The present experiments indicate that mature leaves of P. davidiana show leaf size from big to small, leaf cuticles from thick to thin and anticlinal walls of epidermal cells from faintness to clarity along with the increase of lattudes of the plant distributions, the climatic variation from moist to arid, the annual precipitation from more to less and the annual mean temperature from high to low. The fossil P. davidiana differs from the specimens collected from Shandan in semiarid to arid climatic regions but closely resembles the Wushan leaves in a semi-moist climatic area in a lot of features. In a word, the new research may reflect that the flora lives in a semi-moist climatic environment. The present discovery of compression of Paleogene Populus davidiana is of great significance to studying vegetation types, climatic and environmental changes during the primal uplifting of the Qinghai-Tibet Plateau.     

Study of β—amyloid adsorption and aggregation on graphite by STM and AFM

The scanning tunneling microscopy(STM) and the atomic force microscopy(AMF) have been applied to the direct study of the adsorption and aggregation of β-amyloid(1-42)(Aβ42)on the hydrophobic graphite surface.It was found that Aβ42 were preferentially adsorbed on graphite defects such as the edges.Aβ42 peptides self-assembled into intermediate protofibrils,which in turn self-associated to form fibrils.Usually,two or more fibrils intertwined to form the helical structure.These results will provide an important clue to studying the aggregation process of β-amyloid.     

杂交油菜冷害原因及预防

油菜是河南省第三大油料作物.油菜作为秋冬播作物,由于收获较小麦、豌豆早,所以,对下茬夏播作物的早播、高产提供了有利条件.然而,近些年来,由于诸多原因,河南省油菜常受冷害侵袭,造成减产.     

福建武夷山野生早樱种群结构与动态研究

为了更好的了解福建武夷山野生早樱种群结构与动态,运用静态生命表、种群年龄结构图、存活率曲线、死亡率曲线、亏损度曲线、死亡密度函数曲线、积累死亡函数曲线和危险率函数曲线对该种群生命过程进行了分析。结果表明:野生早樱种群的死亡高峰出现在幼龄期,并在龄级Ⅶ再次出现一死亡小高峰;存活曲线趋于DeeveyⅢ型。种群年龄结构呈现出纺锤形,幼老年种群株数严重偏少,种群整体呈衰退状态。光是限制该种群增长的关键性因子,建议适度干扰或开辟林窗有利于野生早樱的自然繁衍。     

与核桃早实性相关的RAPD标记筛选及其SCAR标记转换

利用构建的早实核桃和晚实核桃近等基因池DNA，筛选了180个10-mer随机引物，获得1个稳定的RAPD标记OPG15759。根据OPG15759的测序结果，将该RAPD标记成功转化为显性的SCAR标记SCG15759。PCR结果显示，G15759是与核桃早实性相关的分子标记，该标记对核桃的分子标记辅助育种具有重要意义。     

三华李优质丰产栽培技术

三华李为李类优良晶种之一，对气候适应性较强，易种易管，生长快，结果早，一般定植3年就能结果，由于栽培三华李投资少、收效快、植经济效益好，因而很受生产者欢迎：现将其优质丰产栽培技术介绍如下：     

北方早粳主要性状相关通径的分析

对影响水稻产量的12个性状相关和通径分析，结果表明：有效分蘖率是影响产量的主要性状，与产量呈极显著的正相关关系，对产量的直接作用最大。不实率也是影响产量的主要性状，与产量正相关极显著，但对产量的直接作用是负向的，大多性状之间存在着极强的交互作用。