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81.
国际互联网技术与旅游业企业过程重组 总被引:2,自引:0,他引:2
信息技术、互联网、通讯技术的发展引起了整个旅游业的一场革命,正在深刻地改变着旅游业的经营、管理和运作模式。网络技术的出现则恰好给旅游业的加速发展、企业过程重组带来了新的机遇。文章集中分析了旅游业的信息特征、信息技术、互联网技术引起的旅游业的经营环境变化,提出了旅游服务供应链管理的概念。在此基础上,结合英特网技术在旅游业的功能,提出了旅游业的企业过程重组,建立虚拟旅游公司模式。 相似文献
82.
调查明确了山西省吕梁山中南部农田害鼠的种类和数量组成,明确了数量分布特点,本项研究为该区域害鼠综合治理对策的制定提供了科学依据. 相似文献
83.
The c-myc coding DNA sequences of cyprinids (Teleostei: Cypriniformes): Implications for phylogeny 总被引:1,自引:0,他引:1
KONG XiangHui WANG XuZhen GAN XiaoNi HE ShunPing 《科学通报(英文版)》2007,52(11):1491-1500
The family Cyprinidae is one of the largest fish families in the world, which is widely distributed in East Asian, with obvious difference in characteristic size among species. The phylogeneUc analysis of cyprinid taxa based on the functionally important genes can help to understand the speciation and functional divergence of the Cyprinidae. The c-myc gene is an important gene regulating individual growth. In the present study, the sequence variations of the cyprinid c-myc gene and their phylogenetic significance were analyzed. The 41 complete sequences of the c-myc gene were obtained from cyprinids and outgroups through PCR amplification and clone. The coding DNA sequences of the c-myc gene were used to infer molecular phylogenetic relationships within the Cyprinidae. Myxocyprinus asiaticus (Catostomidae), Misgurnus anguillicaudatus (CobiUdae) and Hemimyzon sinensis (Homalopteridae) were assigned to the outgroup taxa. Phylogenetic analyses using maximum parsimony (MP), maximum likelihood (ML), and Bayesian retrieved similar topology. Within the Cyprinidae, Leuciscini and Barbini formed the monophyletic lineage respectively with high nodal supports. Leuciscini comprises Xenocyprinae, CuItrinae, East Asian species of Leuciscinae and Danioninae, Gobioninae and Acheilognathinae, and Barbini contains Schizothoracinae, Barbinae, Cyprininae and Labeoninae. Danio rerio, D. myersi and Rasbora trilineata were supposed to separate from Leuciscinae and Barbini and to form another lineage. The positions of some Danioninae species were still unresolved. Analyses of both amino acid variation with parsimony information and two high variation regions indicated that there is no correlation between variations of single amino acid or high variation regions and characteristic size of cyprinids. In addition, the species with smaller size were usually found to be basal within clades in the tree, which might be the results of the adaptation to the primitive ecology and survival pressure. 相似文献
84.
85.
继续教育是当今教育先于经济发展的一个教育变革的突出标志,是构建终身教育体系和建立学习型社会的重要途径,是实现高等教育大众化、提高全民文化知识水平的有效手段。当前,高师院校继续教育的发展面临着地位低下、管理体制不健全、缺乏政策支持、教学手段和方法落后、管理松懈效率不高、教学质量得不到保证等诸多问题,本文拟针对这些问题提出解决的办法和发展策略,以促进高师院校继续教育的可持续发展。 相似文献
86.
Gas vesicles provide buoyancy to Microcystis and other common cyanobacterial bloom-forming species. gvpA and gvpC are structural genes encoding gas vesicle proteins. Phylogenetic analyses of 10 Microcystis strains/uncultured samples showed that gvpC and each intergenic segment of the gvpA-gvpC region can be divided into two types. The combination of different types of gvpC and intergenic segments is an important factor that diversifies this genomic region. Some Microcystis strains isolated in China possess a 172 to 176 bp sequence tag in the intergenic segment between gvpA and gvpC. The gvpA-gvpC region in Microcystis can be divided into at least 4 classes and more numbers of subclasses. Compared to rbcLX and other regions, the high variability of the gvpA-gvpC region should be more useful in identifying geographical isolates or ecotypes of Microcystis. 相似文献
87.
ZHAN JingLin SUN XiaoDan CUI FuZhai KONG XiangDong 《科学通报(英文版)》2007,52(13):1791-1795
In this study, silk scaffolds with appropriate porous structures were prepared by adjusting solution concentrations and providing treatment with methanol solutions in the way of freeze drying. The effects of the preparation conditions on the microstructures and properties of the scaffolds were discussed. Fibroin solutions with different concentrations of 4, 6, 8, 10 wt% were used respectively to prepare the scaffolds. The effects of the addition of 20 vol% methanol before or after freeze drying to the 4 wt% fibroin solution were investigated. As demonstrated by Scanning Electron Microscope (SEM), the fib-roin scaffolds prepared without methanol had porous microstructures composed of thin sheets, and the sizes of the pores decreased with the increase of the fibroin solution concentrations, while the scaffolds prepared in the presence of methanol showed porous microstructures formed by fine-particle aggregates. The porosities and mechanical properties of the prepared fibroin scaffolds under different conditions were tested. The crystalline structures and conformations of the fibroin scaffolds were detected by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). 相似文献
88.
孔德玉 《山东科技大学学报(自然科学版)》1995,(4)
在回顾监测网己有各种基准设计方法的基础上,指出并分析了上述方法的缺陷性,同时针对监测网的特点,分别对监测网的空域基准设计及时域基准设计进行了新的探讨,得出了一些有益的结论。 相似文献
89.
为了揭示复杂泵体水力的不稳定性,以减压塔底泵为例,利用计算流体动力学(CFD)对泵内部非定常流场进行数值模拟计算.根据得到的蜗壳内压力脉动情况,对其时域和频域进行分析.结果表明:各工况下压力脉动频率均以叶片通过频率为主,且次级蜗壳内的压力脉动比首级要明显;蜗壳内压力脉动最大值出现在隔舌附近,且沿蜗壳流道螺旋线方向压力脉动幅值依次减小;设计工况下蜗壳内压力脉动强度小于非设计工况下的,次级蜗壳隔舌处小流量工况下压力脉动幅值约为设计流量时的2.63倍. 相似文献
90.
本文采用分布反馈(DFB)激光器作为传感头,搭建了一种基于3×3耦合器的光纤振动传感系统。在基于微分交叉相乘算法(NPS)的基础上,提出了一种新的解调算法——反演微分交叉相乘算法(iNPS)。算法利用3×3耦合器三路对称的优点,采用3×3耦合器输出的两路信号反演出第三路信号,对三路信号校正后采用NPS算法对振动信号进行解调,系统采用两个光电探测器,与传统的NPS算法相比,降低了系统的成本及复杂程度。对iNPS算法与使用两路信号进行解调的微分交叉相乘算法(NRL)进行仿真分析,比较了两种算法在不同输入振动信号的信噪比和3×3耦合器的不同对称度条件下的解调结果。结果表明,在振动信号信噪比为32 dB的情况下,iNPS算法的信纳比比NRL算法信纳比提高了37.4 dB,总谐波失真率(THD)下降了28%。并且iNPS解调算法可以在3×3耦合器三路信号不对称的情况下解调出振动信号。 相似文献