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   22256篇
  免费   257篇
  国内免费   12篇
教育   15737篇
科学研究   2169篇
各国文化   401篇
体育   1709篇
综合类   11篇
文化理论   141篇
信息传播   2357篇
  2021年   180篇
  2020年   261篇
  2019年   412篇
  2018年   542篇
  2017年   580篇
  2016年   514篇
  2015年   330篇
  2014年   445篇
  2013年   4031篇
  2012年   473篇
  2011年   533篇
  2010年   380篇
  2009年   371篇
  2008年   531篇
  2007年   425篇
  2006年   466篇
  2005年   347篇
  2004年   357篇
  2003年   283篇
  2002年   315篇
  2001年   450篇
  2000年   436篇
  1999年   396篇
  1998年   206篇
  1997年   233篇
  1996年   237篇
  1995年   235篇
  1994年   196篇
  1993年   236篇
  1992年   352篇
  1991年   340篇
  1990年   336篇
  1989年   366篇
  1988年   343篇
  1987年   306篇
  1986年   304篇
  1985年   360篇
  1984年   300篇
  1983年   339篇
  1982年   259篇
  1981年   233篇
  1980年   232篇
  1979年   347篇
  1978年   258篇
  1977年   234篇
  1976年   223篇
  1975年   197篇
  1974年   204篇
  1973年   194篇
  1971年   169篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Employee book clubs are simple, inexpensive tools for professional development that may be more effective than traditional training methods. Library staff at Brigham Young University participated in professional development book clubs, and they reported that they found these trainings to be more enjoyable than classroom-style trainings and more effective in helping them understand, retain, and apply the principles learned. This article will discuss the success of these book clubs and suggest ways that other libraries can implement cost-effective book clubs to develop professional and leadership skills.  相似文献   
72.
The purpose of this study was to examine if steps/day taken by middle school students varied based on aerobic fitness classification. Middle school students (N = 223; 112 girls, 111 boys) were assigned to three aerobic fitness categories (HIGH, MOD, LOW) based on results of the FlTNESSGRAM PACER test. Four weekdays of pedometer monitoring determined activity levels (steps/day). Boys accumulated significantly more steps/day than girls, 11,589 +/- 3,270 and 10,232 +/- 2,517 steps/day, respectively; F(1,219) = 16.0, p < .001, eta2 = .055. There were no differences in steps/day between grades. HIGH fit participants accumulated significantly more steps/day, F(2, 217) = 12.2, p < .101, eta2 = .101, than moderately fit and low fit participants (approximately 1,491 and ; 2,867 steps/day, respectively). Middle school students who participated in sports in addition to physical education (PE) accumulated significantly more steps/day (approximately 980 steps/day) than those participating in PE only, F(1, 219) = 10.0, p < .01, eta2 = .044. Although the relationship between physical activity and aerobic fitness was moderate (0.35; p < .01), these data demonstrated significant differences in accumulated steps/day among youth of varying aerobic fitness levels. Whether improved fitness levels were the result of additional activity or the cause of it remains to be determined. Regardless, the fittest middle school students were also the most active and accumulated a significant amount of steps/day through organized extracurricular physical activities.  相似文献   
73.
This study extended validity evidence for multidimensional measures of coaching competency derived from the Coaching Competency Scale (CCS; Myers, Feltz, Maier, Wolfe, & Reckase, 2006) by examining use of the original rating scale structure and testing how measures related to satisfaction with the head coach within teams and between teams. Motivation, game strategy, technique, and character building comprised the dimensions of coaching competency. Data were collected from athletes (N = 585) nested within intercollegiate men's (g = 8) and women's (g = 13) soccer and women's ice hockey (g = 11) teams (G = 32). Validity concerns were observed for the original rating scale structure and the predicted positive relationship between motivation competency and satisfaction with the coach between teams. Validity evidence was offered for a condensed post hoc rating scale and the predicted relationship between motivation competency and satisfaction with the coach within teams.  相似文献   
74.
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a thorough review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction.  相似文献   
75.
76.
77.
The case is considered in which, during the operation of an optimal control system, the optimizer, in addition to applying his usual control, may switch structures. Necessary and sufficient conditions are derived and emphasis is placed on the special characteristics of this problem. Continuous and discrete time set-ups are considered and the separation principle is shown not to hold for the linear quadratic case in the presence of noise.  相似文献   
78.
79.
80.
The chief purpose of this study was to identify characteristics that distinguish approach as an attachment behavior from approach serving other behavioral systems. Locomotor approaches of 16 male and 10 female white middle-class infants to an attachment figure (the mother) and to a nonattachment figure (the visitor-observer) were examined under naturalistic conditions at home. Observations were made during 4-hour home visits at 3-week intervals; those from 26 to 54 weeks were used. When approach was examined in a free-choice situation and without regard to behavioral context, infants approached the mother proportionally (though slightly) more often than the visitor (p less than .05). In 2 behavioral contexts, however, spontaneous infant approaches were sharply differential to the mother; approaches accompanied by crying and approaches terminating in a pickup appeal were directed almost exclusively to the mother (p less than .0001 for both). Touching upon completion of the approach was not differential, except in the context of a pickup appeal. Object-oriented approaches were more often directed to the visitor than to the mother (p less than .002) and may be either exploratory or affiliative. It is suggested that neither approach nor touching can be assumed to serve the attachment system without consideration of context- both environmental and behavioral.  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