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811.
本文基于对江苏城乡居民的一项旨在研究“新闻传媒与全面建设小康社会“的入户调查.调查发现,传媒对于小康社会的建设具有较为积极的推动作用:这一方面体现在传媒对“小康社会“这一概念的广泛传播有着明显的效果;另一方面,尽管在经济、制度等现代观念的培养上效果并不明显,但总地说来,传媒对于培养小康社会所需要的受众各个方面的现代意识具有积极的帮助. 相似文献
812.
在美国,课程信息服务已经成为大学图书馆常规信息服务业务之一,其课程信息服务的形式、内容和运行模式等方面对于我国高技图书馆开展课程信息服务均有值得借鉴的地方.在分析课程信息服务的内容、特征以及作用,简要地介绍我国高校图书馆课程信息服务现状的基础上,重点研究了美国几所大学图书馆基于web的课程信息服务,对我国高校图书馆开展课程信息服务提出了几点建议. 相似文献
813.
文章在对中国书业库存现状进行描述的基础上,分析其成因,并针对目前常见的几种消化库存的方法,探究其对图书馆的利弊影响。 相似文献
814.
815.
A pipelined architecture for distributed text query evaluation 总被引:1,自引:0,他引:1
Alistair Moffat William Webber Justin Zobel Ricardo Baeza-Yates 《Information Retrieval》2007,10(3):205-231
Two principal query-evaluation methodologies have been described for cluster-based implementation of distributed information
retrieval systems: document partitioning and term partitioning. In a document-partitioned system, each of the processors hosts
a subset of the documents in the collection, and executes every query against its local sub-collection. In a term-partitioned
system, each of the processors hosts a subset of the inverted lists that make up the index of the collection, and serves them
to a central machine as they are required for query evaluation.
In this paper we introduce a pipelined query-evaluation methodology, based on a term-partitioned index, in which partially
evaluated queries are passed amongst the set of processors that host the query terms. This arrangement retains the disk read
benefits of term partitioning, but more effectively shares the computational load. We compare the three methodologies experimentally,
and show that term distribution is inefficient and scales poorly. The new pipelined approach offers efficient memory utilization
and efficient use of disk accesses, but suffers from problems with load balancing between nodes. Until these problems are
resolved, document partitioning remains the preferred method.
Alistair Moffat was supported by the Australian Research Council, the ARC Special Research Center for Perceptive and Intelligent
Machines in Complex Environments, and the NICTA Victoria Laboratory.
William Webber and Justin Zobel were supported by the Australian Research Council.
Ricardo Baeza-Yates was supported by Grant P01-029-F from Millennium Initiative of Mideplan, Chile; and by the University
of Melbourne as a visiting scholar at the time this project was undertaken. 相似文献
816.
817.
Robert E. Baensch 《Publishing Research Quarterly》2007,23(4):262-269
The essential demographic data and related information for India is provided specifically for the publishing industry. The
focus has been placed on the economics, education and computer industry in relation to the complex cultural factors of different
languages and religions. The role of India in relation to the other three BRIC countries or Brazil, China and Russia is explored. 相似文献
818.
本文研究的重点是以网络传播环境为大背景,以网络环境下个人成功模式的构建为切入点,来探讨网络环境和个人成功之间的关系,并提出构建个人成功模式的新途径. 相似文献
819.
Jacques Savoy 《Information Retrieval》2007,10(6):509-529
This paper reports on the underlying IR problems encountered when indexing and searching with the Bulgarian language. For
this language we propose a general light stemmer and demonstrate that it can be quite effective, producing significantly better
MAP (around + 34%) than an approach not applying stemming. We implement the GL2 model derived from the Divergence from Randomness paradigm and find its retrieval effectiveness better than other probabilistic, vector-space and language models. The resulting
MAP is found to be about 50% better than the classical tf idf approach. Moreover, increasing the query size enhances the MAP by around 10% (from T to TD). In order to compare the retrieval
effectiveness of our suggested stopword list and the light stemmer developed for the Bulgarian language, we conduct a set
of experiments on another stopword list and also a more complex and aggressive stemmer. Results tend to indicate that there
is no statistically significant difference between these variants and our suggested approach. This paper evaluates other indexing
strategies such as 4-gram indexing and indexing based on the automatic decompounding of compound words. Finally, we analyze
certain queries to discover why we obtained poor results, when indexing Bulgarian documents using the suggested word-based
approach. 相似文献
820.