High precision topographic data on Lop Nor basin＇s Lake ＂Great Ear＂ and the timing of its becoming a dry salt lake

High precision elevation measurements using DGPS were carried out along three representative tran-sects for the ＂Great Ear＂ area, a dry salt lake within the Lop Nor basin. Results indicate that the Lop Nor basin is only 5.2 m deep and its lowest point occurs at the center of the ＂Great Ear＂. In addition, the basin is asymmetric-steeper in the southwest （0.19‰） and gentler in the northeast （0.09‰）. Points along the same ＂Great Ear＂ ring were found to have an identical elevation value, but different when from different ones （lower towards the center）. The spacing of the ＂Great Ear＂ rings was found to be closely related with the surface steepness. The closer the ＂Great Ear＂ rings are spaced, the steeper the ground surface, and vice versa. These findings support the argument that the ＂Great Ear＂ rings are the former shoreline trails left behind by Lop Nor water during the last few episodes of recession towards its total dry up. A comprehensive analysis of the high precision elevation data, historical accounts, aerial and satellite photographs and imagery, and official topographic maps of the study area suggests that the ＂Great Ear＂ area in the Lop Nor basin was incorrectly mapped as being covered by a great body of water on the 1963 topographic maps. A re-interpretation of the 1958 aerial photographs and newer remote sensing imagery indicated that the ＂Great Ear＂ ring structure was already in place in 1958 and it continued to appear on the subsequent remote sensing data without any major changes. It is estimated that lake water in the ＂Great Ear＂ area of the Lop Nor basin disappeared between the late 1930s and early 1940s.     

Advances in the study on induced pluripotent stem cells

Recently, the study on ＂induced pluripotent stem cells＂ （iPS cells） has made a great breakthrough, and it is considered as a new milestone in the history of life science. This progress has updated our traditional concepts about pluripotency control, and provided people with a brand-new strategy for somatic cell nuclear reprogramming. In virtue of its availability and stability, this method holds great potential in both biological and clinical research. In order to introduce this rising field of study, this paper starts with an overview of the development of iPS cell establishment, describes the key steps in generating iPS cells, elaborates several relevant scientific issues, and evaluates its current restrictions and promises in future research.     

推进学校又好又快发展的有效策略思考

当前,要努力学习贯彻党的十七大精神,以科学发展观为指导,切实有效地促使学校沿着又好又快的方向发展.具体讲,要以有效发展理论为支撑,解放思想,更新观念,搞好学校的综合改革;要开拓创新,求真务实,处理好稳定与发展的关系,推进学校又好又快发展.     

基于服务质量五差距模型的饭店服务质量提升对策

服务质量是饭店生存和发展的生命线。随着饭店供给市场竞争的日益激烈和消费市场的日益成熟,继续提升我国饭店的服务质量已成为行业发展的必然选择。本文在详细阐述饭店服务质量内涵的基础上,从剖析P．Z．B服务质量模型所提出的五个差距产生的原因入手．从反面的角度指出了饭店企业应该从四个方面开展工作：转变管理人员错误观念、建立顾客导向型的全面质量管理体系、强化培训教育、加强沟通管理,以达到消除差距、提升服务质量的目标。     

不同形貌纳米SnS_2的溶剂热法合成及表征

以氯化锡和硫氰酸铵作为原料,溶剂热法分别合成SnS2纳米片,纳米颗粒及花状结构纳米晶体。采用XRD、TEM和FESEM等手段对粒子的结构与形貌进行表征,并研究了溶剂对SnS2形貌的影响。     

Molecular phylogenetics of <Emphasis Type="Italic">Gymnocypris</Emphasis> (Teleostei: Cyprinidae) in Lake Qinghai and adjacent drainages

149 complete mitochondrial DNA (mtDNA) cytochrome b (Cyt b) genes (1140 bp) of Gymnocypris przewalskii, Gymnocypris eckloni and Gymnocypris scolistomus from the Lake Qinghai, Yellow River and Qaidam Basin were sequenced and analyzed. Consistent dendrogram indicated that the samples collected from the same species do not constitute a separate monophyletic group and all the samples were grouped into three highly divergent lineages (A, B and C). Among them, Lineage A contained all samples of G. przewalskii from the Lake Qinghai and partial samples of the G. eckloni from the Yellow River. Lineage B contained the remaining samples of G. eckloni from the Yellow River. Lineage C was composed of a monophyletic group by G. eckloni from the Qaidam Basin. Analysis of molecular variance (AMOVA) indicated that most of genetic variations were detected within these three mtDNA lineages (93.12%), suggesting that there are three different lineages of Gymnocypris in this region. Our Cyt b sequence data showed that G. przewalskii was not a polytypic species, and G. scolistomus was neither an independent species nor a subspecies of G. eckloni. The divergent mtDNA lineages of G. eckloni from the Yellow River suggested that gene flow between the different populations was restricted to a certain extent by several gorges on the upper reach of the Yellow River. Lineage B of G. eckloni might be the genetic effect from the ancestor which was incorporated with the endemic schizothoracine fishes when the headward erosion of the Yellow River reached to its current headwaters of late. The G. eckloni from Basin Qaidam was a monophyletic group (lineage C) and F_st values within G. eckloni from the Yellow River were higher than 0.98, suggesting that the gene flow has been interrupted for a long time and the G. eckloni from Basin Qaidam might have been evolved into different species by ecology segregation. The correlation between the rakers number of Gymnocypris and population genetic variation was not significant. All Gymnocypris populations exhibited a low nucleotide diversity (π = 0.00096–0.00485). Therefore the Gymnocypris populations from Basin Qaidam could have experienced severe bottleneck effect in history. Our result suggested Gymnocypris populations of Basin Qaidam should give a high priority in conservation programs.     

Study on the effect of electrostatic interaction on core-shell nanoparticles preparation with microemulsion technique

The routine method for preparation of silica core-shell nanoparticles （NPs） is to carry out nucleation and shell coating through the hydrolysis of silane in water in oil （W/O） microemulsion to form three-dimensional netted silica shell. We found that electrostatic interaction of the core materials with shell materials would determine whether the stable core-shell silica NPs formed or not. The traditional important factors such as molecular weight of core materials or the thickness of the shell have no obvious relationship with it. And the stability of the core-shell silica NPs can be improved after changing the electric charge polarity by regulating the experiment condition of relevant materials ff some core materials cannot be doped inside to form the stable core-shell silica NPs based on the traditional method, which provided experimental and theoretic foundation for preparation and application of the core-shell silica NPs.     

Episodic evolution of prolactin gene in primates

In the present study, we obtained exon 2--5 of prolactin (PRL) gene from four primate species by PCR and sequencing. Adding other genes available in GenBank, we calculate amino acid substitution rates for prolactin gene in primate. Comparison of nonsynonymous substitution rate to synonymous substitution rate ratios shows no evidence of positive selection for any lineage of primate prolactin gene.According to this and the facts that (i) no sites under positive selection are inferred by using maximum-likelihood method;(ii) among 32 amino acid replacement that occurred along the rapid evolutionary phase, only two are included in the 40 functionally important residues, indicating that amino acid replacement tends to occur in those functionally unimportant residues; (iii) partial of prolactin function is replaced by placental lactogen in primate at the rapid evolutionary phase of prolactin gene, we thus deem that it is relaxation of purifying selection to some extent rather than positive selection that enforces the rapid evolution of primate prolactin gene.     

2-甲砜基嘧啶类化合物的合成及其用于活性染料的制备

以硫脲为原料,经甲基化(产率为96%、文献值为84%)成环缩合(产率为97.4%、文献值为89.7%).氯化氯代(产率为70.7%)、氧化(产率为80.7%)得到活性基团:2-甲砜基-4,5-二氯-6-甲基嘧啶。总产率为53.5%。并从硫脲和丙二酸二乙酯出发,经过一系列中间步骤合或了2-甲砜基-4.6-二氯-5-取代基-5-甲基、氢、溴、氯、嘧啶。可作为活性中间体用以制备一系列活性染料。     

模糊推理预测方法及其应用

给出了连续论域和离散论域模糊推理预测的一般性方法,并应用连续论域模糊推理预测方法,对中国居民的人均粮食消费量进行预测。