全文获取类型
收费全文 | 36160篇 |
免费 | 480篇 |
国内免费 | 16篇 |
专业分类
教育 | 26370篇 |
科学研究 | 3300篇 |
各国文化 | 287篇 |
体育 | 2481篇 |
综合类 | 14篇 |
文化理论 | 585篇 |
信息传播 | 3619篇 |
出版年
2022年 | 201篇 |
2021年 | 292篇 |
2020年 | 448篇 |
2019年 | 701篇 |
2018年 | 3003篇 |
2017年 | 2899篇 |
2016年 | 2363篇 |
2015年 | 637篇 |
2014年 | 858篇 |
2013年 | 4930篇 |
2012年 | 930篇 |
2011年 | 1424篇 |
2010年 | 1355篇 |
2009年 | 949篇 |
2008年 | 1227篇 |
2007年 | 1671篇 |
2006年 | 533篇 |
2005年 | 816篇 |
2004年 | 844篇 |
2003年 | 754篇 |
2002年 | 492篇 |
2001年 | 506篇 |
2000年 | 430篇 |
1999年 | 378篇 |
1998年 | 221篇 |
1997年 | 239篇 |
1996年 | 254篇 |
1995年 | 252篇 |
1994年 | 200篇 |
1993年 | 214篇 |
1992年 | 338篇 |
1991年 | 326篇 |
1990年 | 312篇 |
1989年 | 309篇 |
1988年 | 271篇 |
1987年 | 309篇 |
1986年 | 273篇 |
1985年 | 314篇 |
1984年 | 259篇 |
1983年 | 218篇 |
1982年 | 196篇 |
1981年 | 177篇 |
1980年 | 157篇 |
1979年 | 268篇 |
1978年 | 196篇 |
1977年 | 176篇 |
1976年 | 157篇 |
1975年 | 145篇 |
1974年 | 154篇 |
1971年 | 143篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Stewart M Brower 《Journal of the Medical Library Association》2004,92(4):412-420
BACKGROUND: The analysis included forty-one academic health sciences library (HSL) Websites as captured in the first two weeks of January 2001. Home pages and persistent navigational tools (PNTs) were analyzed for layout, technology, and links, and other general site metrics were taken. METHODS: Websites were selected based on rank in the National Network of Libraries of Medicine, with regional and resource libraries given preference on the basis that these libraries are recognized as leaders in their regions and would be the most reasonable source of standards for best practice. A three-page evaluation tool was developed based on previous similar studies. All forty-one sites were evaluated in four specific areas: library general information, Website aids and tools, library services, and electronic resources. Metrics taken for electronic resources included orientation of bibliographic databases alphabetically by title or by subject area and with links to specifically named databases. RESULTS: Based on the results, a formula for determining obligatory links was developed, listing items that should appear on all academic HSL Web home pages and PNTs. CONCLUSIONS: These obligatory links demonstrate a series of best practices that may be followed in the design and construction of academic HSL Websites. 相似文献
133.
134.
135.
Question classification systems play an important role in question answering systems and can be used in a wide range of other domains. The goal of question classification is to accurately assign labels to questions based on expected answer type. Most approaches in the past have relied on matching questions against hand-crafted rules. However, rules require laborious effort to create and often suffer from being too specific. Statistical question classification methods overcome these issues by employing machine learning techniques. We empirically show that a statistical approach is robust and achieves good performance on three diverse data sets with little or no hand tuning. Furthermore, we examine the role different syntactic and semantic features have on performance. We find that semantic features tend to increase performance more than purely syntactic features. Finally, we analyze common causes of misclassification error and provide insight into ways they may be overcome. 相似文献
136.
137.
Scale and Translation Invariant Collaborative Filtering Systems 总被引:1,自引:0,他引:1
Daniel Lemire 《Information Retrieval》2005,8(1):129-150
Collaborative filtering systems are prediction algorithms over sparse data sets of user preferences. We modify a wide range of state-of-the-art collaborative filtering systems to make them scale and translation invariant and generally improve their accuracy without increasing their computational cost. Using the EachMovie and the Jester data sets, we show that learning-free constant time scale and translation invariant schemes outperforms other learning-free constant time schemes by at least 3% and perform as well as expensive memory-based schemes (within 4%). Over the Jester data set, we show that a scale and translation invariant Eigentaste algorithm outperforms Eigentaste 2.0 by 20%. These results suggest that scale and translation invariance is a desirable property. 相似文献
138.
Kristine M Alpi 《Journal of the Medical Library Association》2005,93(1):97-103
OBJECTIVE: The article explores the characteristics of public health information needs and the resources available to address those needs that distinguish it as an area of searching requiring particular expertise. METHODS: Public health searching activities from reference questions and literature search requests at a large, urban health department library were reviewed to identify the challenges in finding relevant public health information. RESULTS: The terminology of the information request frequently differed from the vocabularies available in the databases. Searches required the use of multiple databases and/or Web resources with diverse interfaces. Issues of the scope and features of the databases relevant to the search questions were considered. CONCLUSION: Expert searching in public health differs from other types of expert searching in the subject breadth and technical demands of the databases to be searched, the fluidity and lack of standardization of the vocabulary, and the relative scarcity of high-quality investigations at the appropriate level of geographic specificity. Health sciences librarians require a broad exposure to databases, gray literature, and public health terminology to perform as expert searchers in public health. 相似文献
139.
Linda M Hartman Rebecca A Abromitis Alice B Kuller Barbara A Epstein 《Journal of the Medical Library Association》2005,93(2):271-277
OBJECTIVE: A staff development committee (SDC) was convened to implement staff development opportunities for an academic health sciences library system comprised of three separate facilities. The charge for the SDC was to: (1) develop programs to enhance workplace skills and personal growth, (2) communicate the availability of existing programs at the university and medical center, and (3) encourage the staff to participate in these opportunities. PROGRAM: The committee created goals and objectives and developed a survey designed to give staff the opportunity to provide input for this initiative. With an 80% response rate, the survey results were used to plan 15 events based on staff needs and preferences. First-year attendance for SDC-sponsored events was 459. Committee members served as liaisons for each event. Two forms were developed to facilitate event planning. A monthly announcement sheet, email reminders, and the library's local area network are used to communicate upcoming SDC events and encourage attendance. CONCLUSION: This approach can serve as a useful model for similar program planning in any organization. 相似文献
140.