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   34764篇
  免费   407篇
  国内免费   15篇
教育   25445篇
科学研究   3207篇
各国文化   227篇
体育   2247篇
综合类   14篇
文化理论   566篇
信息传播   3480篇
  2022年   179篇
  2021年   272篇
  2020年   405篇
  2019年   648篇
  2018年   2925篇
  2017年   2839篇
  2016年   2278篇
  2015年   570篇
  2014年   797篇
  2013年   4625篇
  2012年   885篇
  2011年   1385篇
  2010年   1328篇
  2009年   915篇
  2008年   1174篇
  2007年   1637篇
  2006年   502篇
  2005年   802篇
  2004年   826篇
  2003年   725篇
  2002年   484篇
  2001年   480篇
  2000年   419篇
  1999年   363篇
  1998年   209篇
  1997年   229篇
  1996年   244篇
  1995年   241篇
  1994年   182篇
  1993年   203篇
  1992年   323篇
  1991年   309篇
  1990年   298篇
  1989年   304篇
  1988年   257篇
  1987年   302篇
  1986年   270篇
  1985年   310篇
  1984年   248篇
  1983年   216篇
  1982年   193篇
  1981年   165篇
  1980年   156篇
  1979年   260篇
  1978年   182篇
  1977年   171篇
  1976年   154篇
  1975年   141篇
  1974年   148篇
  1971年   140篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Although the importance of high motivation to engage in deliberate practice has been acknowledged, no research has directly tested this hypothesis. Therefore, the present study examined this relation in adolescent elite chess players by means of a questionnaire. In addition, to provide an explanation for dropout among promising chess players, differences in motivation between persistent and dropout chess players were analyzed. Competitiveness and the will to excel proved to be predictors of investments in deliberate practice. Moreover, achievement motivation and chess-specific motivation differed to a certain extent between persisters and dropouts. Our results suggest that motivation to engage in deliberate practice not only contains elements of the will to improve performance, but also of the will to attain exceptional levels of performance.  相似文献   
992.
Excess protein intake can adversely affect the bone via an increase in calcium excretion, while suitable mechanical loading promotes osteogenesis. We therefore investigated whether vibration exposure could alleviate the bone mineral losses associated with a metabolic acidosis. Ten healthy individuals aged 22 - 29 years (median = 25) underwent three 5-day study periods while monitoring their dietary intake. The study consisted of recording the participants' usual dietary intake for 5 consecutive days. Participants were then randomly divided into two groups, one of which received a protein supplement (2 g x kg(-1) body mass x day(-1); n = 5) and the other whole-body low-magnitude (3.5 g), low-frequency (30 Hz) mechanical vibration (WBV) delivered through a specially designed vibrating plate for 10 min each day (n = 5). Finally, for the third treatment period, all participants consumed the protein supplement added to their normal diet and were exposed to WBV exercise for 10 min per day. Daily urine samples were collected throughout the experimental periods to determine the excretion of calcium, phosphate, titratable acid, urea, and C-telopeptide. As expected, when the participants underwent the high protein intake, there was an increase in urinary excretion rates of calcium (P < 0.001), phosphate (P < 0.003), urea (P < 0.001), titratable acid (P < 0.001), and C-telopeptide (P < 0.05) compared with baseline values. However, high protein intake coupled with vibration stimulation resulted in a significant reduction in urinary calcium (P = 0.006), phosphate excretion (P = 0.021), and C-telopeptide (P < 0.05) compared with protein intake alone, but did not affect titratable acid and urea output. The participants showed no effect of WBV exercise alone on urinary excretion of calcium, phosphate, urea, titratable acid, or C-telopeptide. The results indicate that vibration stimulation can moderate the increase in bone resorption and reduction in bone formation caused by a metabolic acidosis.  相似文献   
993.
Why young elite athletes fear failure: consequences of failure   总被引:1,自引:0,他引:1  
Fear of failure can have negative effects on children in achievement settings, affecting many aspects of their lives. Perceiving the consequences of failure to be aversive provides the basis for fear of failure, and the anticipation of a threatening outcome elicits fear. Problems attributed to fear of failure in achievement settings are prevalent. Sport is a popular and significant achievement domain for children and adolescents and there is a lack of research on fear of failure in sport among this age group. Therefore, the aim of the present study was to investigate fear of failure in the sport domain among young elite athletes, and to explore their perceptions of the consequences of failure. Interviews were conducted individually with nine athletes aged 14 - 17 years (5 males, 4 females). Analysis identified and organized perceived consequences of failure into themes and categories. Results revealed that the most commonly perceived aversive consequences of failure were diminished perception of self, no sense of achievement, and the emotional cost of failure. These findings are consistent with those reported in adult population, suggesting the potential for generalizing existing results to young elite athletes.  相似文献   
994.
Despite the lack of a clear definition of the concept, “cultural diversity” has remained a core issue for more than a decade (WTO, UNESCO, etc.). The aim of this paper is to begin to fill this gap. We argue that cultural diversity is a multi-dimensional concept and that accurate metrics must rely on three criteria: variety, balance and disparity. We also stress that supplied and consumed diversity have to be distinguished. We apply this set of multiple measures of diversity to publishing data for France over the period 1990–2003. Our main result is that the situation of the publishing industry in terms of cultural diversity is highly dependent on the dimension considered. Hence, diversity increases when variety is the sole consideration, whereas taking balance or disparity into account leads to the opposite conclusion. This issue raises a series of questions about the use of diversity measures in a policy debate concerned with furthering cultural diversity.
Stéphanie PeltierEmail:
  相似文献   
995.
Theatre experts generally agree that the Flemish theatre has flourished artistically over the period 1980–2000. Attendance, on the other hand, has declined significantly. Following Lancaster’s characteristics approach, we identify several output characteristics of individual theatre productions. Using a panel of 59 Flemish theatres, we examine the impact on demand of both these output characteristics and of traditional determinants such as own price, income and the price of substitutes. Differences in the relevant geographical market for touring and non-touring theatres are considered. We find that the nature of the artistic output affects demand. Theatregoers prefer large productions (in terms of cast size), plays by Dutch-speaking playwrights and revivals of old productions. Own price and consumer income have the expected negative and positive effects on attendance. Observed trends toward a decreasing proportion of new plays, an increasing presence of plays by Dutch-speaking playwrights, and increasing consumer income had a stimulating effect on attendance. These trends have been offset, however, by trends toward smaller cast sizes and higher ticket prices as well as by unobserved factors captured by time dummies. The net result has been a considerable drop in attendance.
Kristien WerckEmail:
  相似文献   
996.
We use prices realized for Picasso prints at auctions worldwide, as well as the 100 prints that comprise his Vollard Suite, to test the law of one price: the proposition that identical art objects sold contemporaneously should command the same price regardless of the auction house or geographic region where the sale takes place. Picasso is the most prolific printmaker of the twentieth century and, from 1977 to 2004, his prints appreciated in price significantly faster than the prints of modern masters as a whole. We find that Picasso prints sold in the United States command higher prices than in Europe. However, prices realized at Sotheby’s in New York are no longer higher than at Christie’s in New York, nor at Kornfeld than at other auction houses. We find evidence of “irrational exuberance” in the transitory nature of the extraordinary prices realized for the Picasso prints included in the 1997 sale of the collection of Victor and Sally Ganz at Christie’s in New York. More generally, we find substantial noise in auction outcomes, a result well known to savvy auction goers.
Pauline M. Shum (Corresponding author)Email:
  相似文献   
997.
This article compiles original data relating to artists’ place of birth and work migration patterns using various art history dictionaries. The broad historic pattern, from the 13th to the 20th century, of the birth locations of prominent artists is examined, followed by a detailed study of the work migration patterns of prominent artists in two important situations, namely Renaissance Italy and France in part of the 19th century. The evidence indicates a marked clustering of activity of prominent artists, both arising from birth location and migration patterns. Some possible explanations for the observed patterns are briefly outlined.
John O’HaganEmail:
  相似文献   
998.
The article tests a couple of hypotheses relating to markets where demand is not taken as a given, but subject to sophisticated and encompassing price-building strategies. The study uses a data set that provides quoted dealer prices for medium-sized works of 100 leading visual artists from 1970 to 2004. These data are compared with auction price results for works by the same artists. The study reports significant discrepancies with respect to the relationship between the age of artists and prices paid for their works in the two markets, and with respect to general price developments in the two markets as measured by indices.
Michael HutterEmail:
  相似文献   
999.
The aims of the study were to modify the training impulse (TRIMP) method of quantifying training load for use with intermittent team sports, and to examine the relationship between this modified TRIMP (TRIMP(MOD)) and changes in the physiological profile of team sport players during a competitive season. Eight male field hockey players, participating in the English Premier Division, took part in the study (mean+/-s: age 26+/-4 years, body mass 80.8+/-5.2 kg, stature 1.82+/-0.04 m). Participants performed three treadmill exercise tests at the start of the competitive season and mid-season: a submaximal test to establish the treadmill speed at a blood lactate concentration of 4 mmol . l(-1); a maximal incremental test to determine maximal oxygen uptake ([V]O(2max)) and peak running speed; and an all-out constant-load test to determine time to exhaustion. Heart rate was recorded during all training sessions and match-play, from which TRIMP(MOD) was calculated. Mean weekly TRIMP(MOD) was correlated with the change in [V]O(2max) and treadmill speed at a blood lactate concentration of 4 mmol x l(-1) from the start of to mid-season (P<0.05). The results suggest that TRIMP(MOD) is a means of quantifying training load in team sports and can be used to prescribe training for the maintenance or improvement of aerobic fitness during the competitive season.  相似文献   
1000.
Accurate measurement of physical activity is fundamentally important in epidemiological research of physical activity behavior A widely used telephone-based physical activity questionnaire was compared with other methods of administration and objective measures (pedometers and accelerometers) among 80 adults (43 women). The telephone questionnaire was comparable to both the self-administered form and international telephone-administered equivalent. Although moderate correlation coefficients with objective measures supported the use of the questionnaire, wide prediction intervals generated using Bland Altman methods highlighted large discrepancies between the measures, particularly in the moderate intensity category. These findings illustrate the limitations of correlation coefficients in validation studies and the inaccuracy of self-report questionnaires in measuring physical activity.  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