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   906篇
  免费   12篇
  国内免费   10篇
教育   572篇
科学研究   119篇
各国文化   10篇
体育   117篇
综合类   11篇
文化理论   8篇
信息传播   91篇
  2022年   7篇
  2021年   9篇
  2020年   20篇
  2019年   33篇
  2018年   43篇
  2017年   22篇
  2016年   30篇
  2015年   28篇
  2014年   38篇
  2013年   146篇
  2012年   38篇
  2011年   50篇
  2010年   24篇
  2009年   25篇
  2008年   42篇
  2007年   38篇
  2006年   22篇
  2005年   26篇
  2004年   20篇
  2003年   23篇
  2002年   16篇
  2001年   22篇
  2000年   7篇
  1999年   15篇
  1998年   17篇
  1997年   10篇
  1995年   5篇
  1994年   6篇
  1993年   4篇
  1992年   5篇
  1991年   5篇
  1990年   8篇
  1989年   10篇
  1988年   9篇
  1987年   5篇
  1986年   8篇
  1984年   3篇
  1982年   4篇
  1981年   3篇
  1980年   10篇
  1979年   7篇
  1978年   6篇
  1977年   8篇
  1976年   9篇
  1975年   3篇
  1967年   2篇
  1960年   2篇
  1957年   2篇
  1947年   2篇
  1934年   2篇
排序方式: 共有928条查询结果,搜索用时 31 毫秒
1.
A significant number of archaeological finds of the 13th–16th century from the Tuscan sites of Germagnana and Gambassi in Valdelsa—FI, was studied by different physico-chemical investigations (SEM–EDS, ICP, Mössbauer spectroscopy, XRD, XRF, TG-DTA) in order to contribute to clarify the production methodology and the pre-industrial glass manufacture technology. The studied samples are mainly non-vitreous finds as production waste, refractory materials, crucibles and raw materials; also vitreous finds as frits, skims, glasses (glass masses, glass working waste and finished products) have been taken into consideration. The obtained petrographic and physico-chemical data strongly suggest that both Gambassi and Germagnana glass manufactures were strictly connected with the sources of vitrifiable materials, situated in Tuscan sand quarries. In particular a comparison between sands from the neighbouring quarries and appropriate finds of the two archaeological sites evidences that the employed vitrifiable materials possibly belong to La Casina La Cava resort. The archaeological classification, based on macroscopic observation and stratigraphic position, was compared and verified with the scientific classification of the examined finds of Germagnana and Gambassi sites based on their composition, morphology and physico-chemical properties.  相似文献   
2.
3.
4.
5.
对语法开发平台中算法性很强的功能模块进行了算法剖析,包括句法结构线性表达的分析算法,规则与词典的提取算法,成分结构树图与功能结构集图的生成算法,成分结构与功能结构的转换算法.最后对系统作了简单的功能测试.  相似文献   
6.
This study investigates the information needs of faculty and graduate students in agricultural and biological sciences. Qualitative research methods, interviews and focus groups, were used to examine what types of information these scholars need for their research, teaching and learning, how they seek that information, and perceptions. The implications for library service are discussed.  相似文献   
7.
从信息构建看未来的知识管理   总被引:4,自引:0,他引:4  
化柏林 《情报学报》2004,23(4):463-468
本文从信息构建出发 ,进而引申到知识管理与知识推理 ,最终提出了知识基础工程。在设计并实现自然语言的语法开发平台时 ,产生了构建知识库的设想。利用语法开发平台 ,就可以对自然语言的语法进行开发 ,加上一个好的算法 ,就可以对大规模文本进行自动分析。对分析过的句子进行内容提取 ,并用面向对象方法和逻辑形式进行格式化 ,得到以面向对象为特征的常识知识库和以逻辑命题为特征的专家知识库 ,这应该是知识发现、知识管理的最高层次 ,也是知识工程的核心  相似文献   
8.
9.
This study estimated the expected point value for starting possessions in different field locations during rugby league match-play and calculated the mean expected points for each subsequent play during the possession. It also examined the origin of tries scored according to the method of gaining possession. Play-by-play data were taken from all 768 regular-season National Rugby League (NRL) matches during 2010–2013. A probabilistic model estimated the expected point outcome based on the net difference in points scored by a team in possession in a given situation. An iterative method was used to approximate the value of each situation based on actual scoring outcomes. Possessions commencing close to the opposition’s goal-line had the highest expected point equity, which decreased as the location of the possession moved towards the team’s own goal-line. Possessions following an opposition error, penalty or goal-line dropout had the highest likelihood of a try being scored on the set subsequent to their occurrence. In contrast, possessions that follow an opposition completed set or a restart were least likely to result in a try. The expected point values framework from our model has applications for informing playing strategy and assessing individual and team performance in professional rugby league.  相似文献   
10.
Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.  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