首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   48651篇
  免费   510篇
  国内免费   30篇
教育   35607篇
科学研究   4271篇
各国文化   373篇
体育   3549篇
综合类   24篇
文化理论   674篇
信息传播   4693篇
  2021年   381篇
  2020年   570篇
  2019年   885篇
  2018年   3225篇
  2017年   3120篇
  2016年   2602篇
  2015年   804篇
  2014年   986篇
  2013年   6998篇
  2012年   1084篇
  2011年   1637篇
  2010年   1504篇
  2009年   1078篇
  2008年   1437篇
  2007年   1807篇
  2006年   770篇
  2005年   930篇
  2004年   1024篇
  2003年   828篇
  2002年   677篇
  2001年   725篇
  2000年   774篇
  1999年   655篇
  1998年   385篇
  1997年   409篇
  1996年   473篇
  1995年   404篇
  1994年   385篇
  1993年   371篇
  1992年   535篇
  1991年   549篇
  1990年   518篇
  1989年   564篇
  1988年   539篇
  1987年   495篇
  1986年   500篇
  1985年   549篇
  1984年   455篇
  1983年   488篇
  1982年   396篇
  1981年   377篇
  1980年   392篇
  1979年   536篇
  1978年   407篇
  1977年   376篇
  1976年   325篇
  1975年   288篇
  1974年   287篇
  1973年   285篇
  1971年   258篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
131.
Time series analysis was used to investigate the hypothesis that during acquisition of a motor skill, knowledge of results (KR) information is used to generate a stable internal referent about which response errors are randomly distributed. Sixteen subjects completed 50 acquisition trials of each of three movements whose spatial-temporal characteristics differed. Acquisition trials were either blocked, with each movement being presented in series, or randomized, with the presentation of movements occurring in random order. Analysis of movement time data indicated the contextual interference effect reported in previous studies was replicated in the present experiment. Time series analysis of the acquisition trial data revealed the majority of individual subject response patterns during blocked trials were best described by a model with a temporarily stationary, internal reference of the criterion and systematic, trial-to-trial variation of response errors. During random trial conditions, response patterns were usually best described by a "White-noise" model. This model predicts a permanently stationary, internal reference associated with randomly distributed response errors that are unaffected by KR information. These results are not consistent with previous work using time series analysis to describe motor behavior (Spray & Newell, 1986).  相似文献   
132.
133.
134.
135.
Serials, one of the more complicated areas of library technical endeavors, has lacked the benefit of standards for a long time. Even now, with standards beginning to be available, the majority of institutions are not working within standard serials formats. A survey to determine the use of serials standards in libraries was conducted in 1988 by the American Library Association, Resources and Technical Services Division, Serials Section, Committee to Study Serials Standards. In the spring of 1988 a survey was sent to a group encompassing the Association of Research Libraries members, CONSER participants, United States Newspaper Program participants, Microform Project libraries, and some vendors and librarians who attended the Committee meetings on a regular basis. The survey questionnaire assessed the current level of serials standards awareness of librarians and vendors. Topics included the type of serials systems used, standards relevant to serials control and union listing and whether or not they are implemented, types and levels of training staff received in the application of standards, benefits of the standards, and areas where standards are most needed.  相似文献   
136.
Physician information seeking: improving relevance through research   总被引:1,自引:0,他引:1  
Health sciences libraries have considerable potential as resources for both formal continuing professional education, as well as the informal continuing education that results from the professional's efforts to solve problems in daily practice. While there is a growing interest in making the resources of health sciences libraries more accessible to practitioners on a routine, day-to-day basis, there also needs to be more awareness of how, when, where, and why professionals look for information in the context of practical problems. This paper reviews recent research that identifies the context in which physicians seek information and advice from external sources, the information sources that physicians access, and the factors that influence which particular sources are sought. The results indicate that physicians vary in their information needs, preferences, motivations, and strategies for seeking information. This diversity suggests that health sciences libraries, in their efforts to be more accessible, should consider "market research" to determine the needs, preferences, and use patterns of the library's targeted users. Libraries may also benefit from exploring alternative methods of improving access to their resources.  相似文献   
137.
This article discusses HIV infection in terms of the risk manager's information needs in the health care environment. The malpractice problem, increasing workman's compensation suits, the greater role of the ombudsman, implementation of the National Practitioner Data Bank, and the Joint Commission on Accreditation of Health Care Organizations' (JCAHO) emphasis on clinical excellence are conditions which have given greater importance to the risk manager's position. Included in this article are hedges to retrieve various components of risk management and a select bibliography from AIDSLINE.  相似文献   
138.
139.
The current societal and professional context presents a variety of ethical challenges to decision makers. The importance of educational preparation for ethical decision-making and ethical leadership has been addressed in the literature of library and information science (LIS), among other professions. However, it can be quite difficult to measure the impact of professional ethics education on students. This article is based on an evaluation of published original research related to ethics education in disciplines supported by professional education, including education, nursing, allied health, journalism, social work, public health, engineering, and LIS. The study considers data related to research design, methodologies used, populations studied, approaches to measuring impact, levels of impact, and publication in the journal literature. Results indicate more extensive research in education and nursing as compared with other fields, a lack of baseline data gathering for comparison, a reliance on a limited number of data-gathering techniques, and a tendency toward studying alumni over current students  相似文献   
140.
We present an overview of previous research results on the molecular phylogenetic analyses in Agaricales and its higher ranks (Agaricomycetes/Agaricomycotina/Basidiomycota) along with the most recent treatments of taxonomic systems in these taxa. Establishing phylogenetic hypotheses using DNA sequences, from which an understanding of the natural evolutionary relationships amongst clades may be derived, requires a robust dataset. It has been recognized that single-gene phylogenies may not truly represent organismal phylogenies, but the concordant phylogenetic genealogies from multiple-gene datasets can resolve this problem. The genes commonly used in mushroom phylogenetic research are summarized.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号