Contributions of different land cover types in Otindag Sandy Land and Bashang area of Hebei Province to the material source of sand stormy weather in Beijing

Different land cover types in Otindag Sandy Land and Bashang area of Hebei Province are linked to a material source of sand stormy weather in Beijing based on results of field vegetation and soil survey and laboratory works. Results of grain size analysis show that dust release potential in per unit area of moving sandy land is small,while lowland meadow and meadow steppe in stony hills have high potential of releasing dusts in per unit area during sand stormy weather occurrence. Further considering the effects of vegetation, it is inferred that the moving sandy land served as a material source of past dust storm and the possibility of dust release in per unit area is low in current time.Typical steppe in stony hills is undergoing desertification and its dust release possibility in per unit area is high. Farmland has strong potential of release dusts when they are ploughed in spring, but a large amount of therophytes grow and thus prevent dusts from release when cultivation was terminated.Potentials of dust release in per unit area in fixed sand dunes,stony mountain meadow steppe and low land meadow are lowdue to high cover of perennials. Sand dune reactivation and desiccation of lakes and lowlands under estimated future climatic change will make them serve as a future material source of sand stormy weather.     

Climatic significance of stable carbon isotope in tree rings of Abies spectabibis in southeastern Tibet

The annually cross-dated stable carbon isotope of tree-ring a-cellulose of Abies spectabibis collected from the southeastern Tibetan Plateau is used to examine its rela-tionship with climatic parameters. The residual D13C series in treerings is constructed after removing the effects of age trend and rising CO2. We found a close relationship between D13C in tree rings and the relative humidity of September—November of the previous year measured at the nearby Ny-ingchi Meteorological Station, albeit a strong 搇agged effect? Thus we developed a transfer function to reconstruct the autumn relative humidity for the Nyingchi region, which explained 37.9% of the total variance (p < 0.001). Our results suggest a high frequency and moderate amplitude variance of the relative humidity before 1800, and the variance re-versed afterwards.     

Identification and mapping of quantitative trait loci controlling cold-tolerance of Chinese common wild rice (O. rufipogon Griff.) at booting to flowering stages

Cold injury is an important limitation of rice production. Therefore, screening for cold-tolerant genetic resources and the development of highly cold-tolerant cultivars is crucial for higher yield potential and stable yield of rice. There have been several reports on the genetic analysis and QTL mapping of the cold-tolerance at the booting stage. Toriyama et al.[1,2] and Futsuhara et al.[3,4] reported that 4 or more genes were involved in the cold-tolerance. Several QTLs at the booting sta…     

Loess-soil sequences in southern Anhui Province： Magnetostratigraphy and paleoclimatic significance

Two parallel loess-soil sequences from Xuancheng and Fanchang in southern Anhui Provinces are dated using geomagnetic and luminescence methods.The Brunhes/Matuyama(B/M) reversal boundary is recognized within the lower part of the so-calles Vermiculated Red Soil (VRS) in the Xuancheng section while the entire Fanchang sequence is of Brunhes age.This indicated that the most recent VRS in southern China,a stratigraphic marker and an indication of extremely warm-humid conditions,was formed during the middle Pleistocene,chronologically correlative with the S4 and S5 soil units in northern China.Microscopic and sedimentologic in vestigations reveal that eolian deposition started in this region at about 0.85 MaBp,roughly synchronous with the well-known Mid-Pleistocene climate change of global significance.The strengthening of both summer and winter monsoon circulations and the consequent river hydrological changes at that time would have provided favorable conditions for sustained eolian deposition in the middle-lower reaches of the Yangtze River since 0.85 MaBP.     

Inhibitory effect of the adenovirus type 5 E1A protein expressed in the yeast system of the human tumor cell growth

Adenovirus 5 type E1A as a tumor suppressor gene can inhibit tumor growth and enhance the censitivity of chemotherapy and radiotherapy.E1A have the ability to integrate into the host genome,resulting in long-time expres-sion that induces Rb gene inactivation and animal cells im-mortalization.This prompted us to select the E1A protein for treatment of cancer in order to overcome the limitations of E1A gene therapy.Thus,we firstly comstructed E1A eu-caryotic expression vector (pPIC9/E1A),transformated the pichia pastoris yeast cells(GS115) and screened the high-expressing recombinant strains.The positive yeast strains were cultured in the shake flask,and induced for 3d.The crude E1A protein was purified using two steps of col-umu chromatography on HiTrap Q and HiTrap SP.The pu-rified E1A protein was identified by SDS-PAGE and Western blot.E1A protein was mostly located at cellular unclear when Cheriot delivered E1A protein into cells.The analysis in vitro indicated that the E1A protein arrested LN686 cell cycle at G2/M phase,and significantly inhibited the growth of LN686 tumor cells.The current studies firstly provided an experimental basis to further develop E1A protein for tumor treatment.     

李森科学派——现代遗传学发展中的一股逆流(续完)

任本命,王　虹(西安文理学院化学与生命科学系,陕西西安710065)5　赫鲁晓夫的倒台和李森科主义的终结为了挽救苏联农业的失败,赫鲁晓夫准备进行新的改组并要求召开新的中央委员会.1964年夏末,他关于改组农业和提高生产水平的一次报告起草完毕,并发到各科研单位和地区委员会传阅.据说这篇报告的基本思想是将农业部对农业的集中控制权下放到负责作物生产的各专门部、委和托拉斯.其中一个托拉斯或委员会专门处理李森科关于生产混合肥料的建议,报告草案对李森科的反对者仍然进行了严厉的批评.报告准备好后,赫鲁晓夫先是出国访问,回来之后便到黑…     

微乳液法合成纳米二氧化硅粒子

制备 Triton X- 1 0 0 /正辛醇 /环己烷 /水 (或氨水 )微乳液 ,研究了该微乳液系统稳定相行为与制备条件的关系 .在该微乳液系统稳定的条件下 ,由正硅酸乙酯受控水解反应制备 Si O2 纳米粒子 ,反应后处理简便 ,制得粒子尺度较均一的球形疏松无定型纳米 Si O2 粒子 .Si O2 粒子粒径尺寸可通过调节水与表面活度剂分子数之比 m、水与正硅酸乙酯分子数之比 n控制 .探讨了影响 Si O2 纳米粒子形貌、粒径分布的因素及制备优化条件     

铑(Ⅲ)与5-NO2-PADAT配合物催化氢波及其应用

在pH4．5的HAc-NaAc缓冲介质中，铑(Ⅲ)与5-(5-NO2-2-吡啶偶氮)-2，4-二氨基甲苯(简称5-NO2-PADAT)生成稳定的紫红色配合物，并在适量的HClO4底液中于-1．03V(vs SCE)处产生灵敏的催化波，据此建立了一种催化极谱法测定痕量铑的新方法。测定铑的线性范围为4．0～130ng／L，检出限为1．4ng／L。