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排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
信息化浪潮给人们的生活带来剧变,随着计算机和网络的普及,网络数字化阅读开始成为人们新型的阅读方式。多媒体互动电子杂志作为一种融合了平面杂志、网络多媒体技术特点的新型期刊形式,符合阅读方式发展的潮流。本文通过对传统纸媒杂志与多媒体互动电子杂志的比较分析,总结出了电子杂志自身的无可比拟的优势和目前发展中存在的问题,并对网络时代下杂志未来的发展趋势进行了展望。 相似文献
992.
本文率先提出出版绘画研究的课题,从梳理出版绘画的概念、特征和类型入手,对出版绘画的社会作用、艺术价值、人才培养等方面的问题,做了初步的探索和纲领式的论述,提出了自己的观点,为进一步研究和适应出版绘萄的创作需求。奠定了坚实的基础。 相似文献
993.
决策支持系统合理应用到跨部门电子政务工程中不但可以降低大量的人力和财力成本,还会为电子政务中半结构化或非结构化问题提供重要的决策支持。文章提供了一种跨部门电子政务工程中决策支持系统技术架构的设计,为决策支持系统在跨部门电子政务工程中的实现提供了一种方法。 相似文献
994.
基于VRML的虚拟现实技术及应用 总被引:2,自引:0,他引:2
VRML作为一种应用于Internet的虚拟现实建模语言,得到了广泛应用。在对比分析主流虚拟现实技术的基础上,详细阐述了基于VRML虚拟现实技术的开发工具、开发流程、支持VRML的浏览器类型等,并针对其不足,提出基于复杂度的快速建模策略、动画生成策略和交互实施策略,并应用于校园漫游系统,效果良好。 相似文献
995.
无线mesh网(WMN)是一种近年来快速发展起来的新型网络技术,支持宽带高速多媒体业务服务,是一种有效的无线宽带接人手段.为了提高无线mesh网络的性能,使TCP协议在可靠性低、突发错误时间长以及切换时延高的无线移动环境更为有效地工作,人们提出了种种改进传输层TCP技术的方案.文中结合无线mesh网络的自组织、自修复和多跳的特点,将目前的TCP改进方案进行了归类和比较,并分析了其性能特点,同时指出了今后可能的研究方向. 相似文献
996.
Quanqing Xu Hengtao Shen Zaiben Chen Bin Cui Xiaofang Zhou Yafei Dai 《Frontiers of Computer Science in China》2009,3(3):381-395
The concept of Peer-to-Peer (P2P) has been introduced into mobile networks, which has led to the emergence of mobile P2P networks,
and originated potential applications in many fields. However,mobile P2P networks are subject to the limitations of transmission
range, and highly dynamic and unpredictable network topology, giving rise to many new challenges for efficient information
retrieval. In this paper, we propose an automatic and economical hybrid information retrieval approach based on cooperative
cache. In this method, the region covered by a mobile P2P network is partitioned into subregions, each of which is identified
by a unique ID and known to all peers. All the subregions then constitute a mobile Kademlia (MKad) network. The proposed hybrid
retrieval approach aims to utilize the floodingbased and Distributed Hash Table (DHT)-based schemes in MKad for indexing and
searching according to the designed utility functions. To further facilitate information retrieval, we present an effective
cache update method by considering all relevant factors. At the same time, the combination of two different methods for cache
update is also introduced. One of them is pull based on time stamp including two different pulls: an on-demand pull and a
periodical pull, and the other is a push strategy using update records. Furthermore, we provide detailed mathematical analysis
on the cache hit ratio of our approach. Simulation experiments in NS-2 showed that the proposed approach is more accurate
and efficient than the existing methods. 相似文献
997.
Liang S Shen G Liu Q Xu Y Zhou L Xiao S Xu Z Gong F You C Wei Y 《Proteomics. Clinical applications》2009,3(6):743-753
Human 14-3-3 proteins have isoform-specific expression and functions in different kinds of normal or tumor cells and tissues. However, the expression profiling of 14-3-3 proteins and isoform-specific biological functions are unclear in human glioma so far. In our study, the expression levels and characterization of 14-3-3 isoforms in human glioma tissues were investigated by a sensitive, accurate stable isotope labeling with amino acids in cell culture-based quantitative proteomic strategy. As a result, except unexpressed 14-3-3σ, the other six isoforms, with different expression levels, were existed in glioma tissues and para-cancerous brain tissues (PBTs). 14-3-3β and η were upregulated, whereas 14-3-3ζ was downregulated in glioma tissues compared with that in PBTs. And the other three isoforms 14-3-3ε, θ, and γ had similar expression levels in human glioma tissues and PBTs. Western blot and immunohistochemistry analysis were both consistent with the quantitative proteomic data. The loss of expression of 14-3-3σ was further discovered due to DNA high methylation in its coding region in glioma by methylation-specific PCR analysis. These results indicated that the four isoforms, including 14-3-3β, η, ζ, and σ, may play important roles in tumorigenesis of human glioma, which is probably used as potential biomarkers for diagnosis and targets for treatment of human gliomas in future. 相似文献
998.
The interpolated fast Fourier transform (IFFT) has been proposed as a way to eliminate the picket fence effect (PFE) of the fast Fourier transform. The modulus based IFFT, cited in most relevant references, makes use of only the 1st and 2nd highest spectral lines. An approach using three principal spectral lines is proposed. This new approach combines both directions of the complex spectrum based IFFT with the Hanning window. The optimal weight to minimize the estimation variance is established on the first order Taylor series expansion of noise interference. A numerical simulation is carried out, and the results are compared with the Cramer-Rao bound. It is demonstrated that the proposed approach has a lower estimation variance than the two-spectral-line approach. The improvement depends on the extent of sampling deviating from the coherent condition, and the best is decreasing variance by 2/7. However, it is also shown that the estimation variance of the windowed IFFT with the Hanning is significantly higher than that of without windowing. 相似文献
999.
1000.