全文获取类型
收费全文 | 1225篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
教育 | 824篇 |
科学研究 | 147篇 |
各国文化 | 22篇 |
体育 | 83篇 |
综合类 | 1篇 |
文化理论 | 33篇 |
信息传播 | 127篇 |
出版年
2019年 | 21篇 |
2018年 | 32篇 |
2017年 | 26篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 15篇 |
2013年 | 337篇 |
2012年 | 15篇 |
2011年 | 31篇 |
2010年 | 16篇 |
2009年 | 24篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 23篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 22篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 16篇 |
1986年 | 18篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1975年 | 10篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1970年 | 7篇 |
1966年 | 9篇 |
1920年 | 8篇 |
排序方式: 共有1237条查询结果,搜索用时 15 毫秒
171.
Abstract The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption ([Vdot]O2max) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts [Vdot]O2max at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 – 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of [Vdot]O2max (low-intensity trial: mean 40.5 ml · kg?1 · min?1, s = 9.3; high-intensity trial: 47.5 ml · kg?1 · min?1, s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a [Vdot]O2max test (mean 47.9 ml · kg?1 · min?1, s = 8.9). The low-intensity trial underestimated (mean difference = ?3.5 ml · kg?1 · min?1; 95% CI = ?6.4 to ?0.6 ml · kg?1 · min?1; P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml · kg?1 · min?1; 95% CI = 1.1 to 6.0 ml · kg?1 · min?1; P = 0.01) the measured [Vdot]O2max. The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range. 相似文献
172.
173.
Neil Edward Bezodis Aki Ilkka Tapio Salo Grant Trewartha 《Journal of sports sciences》2013,31(8):738-746
AbstractThis study analysed the first stance phase joint kinetics of three elite sprinters to improve the understanding of technique and investigate how individual differences in technique could influence the resulting levels of performance. Force (1000 Hz) and video (200 Hz) data were collected and resultant moments, power and work at the stance leg metatarsal-phalangeal (MTP), ankle, knee and hip joints were calculated. The MTP and ankle joints both exhibited resultant plantarflexor moments throughout stance. Whilst the ankle joint generated up to four times more energy than it absorbed, the MTP joint was primarily an energy absorber. Knee extensor resultant moments and power were produced throughout the majority of stance, and the best-performing sprinter generated double and four times the amount of knee joint energy compared to the other two sprinters. The hip joint extended throughout stance. Positive hip extensor energy was generated during early stance before energy was absorbed at the hip as the resultant moment became flexor-dominant towards toe-off. The generation of energy at the ankle appears to be of greater importance than in later phases of a sprint, whilst knee joint energy generation may be vital for early acceleration and is potentially facilitated by favourable kinematics at touchdown. 相似文献
174.
175.
Clinical features of chronic hepatitis B patients with YMDD mutation after lamivudine therapy 总被引:5,自引:0,他引:5
INTRODUCTION Chronic hepatitis B(CHB)remains a major public health problem,affecting more than350mil-lion people worldwide.Cirrhosis,liver failure,or hepatocellular carcinoma will develop in approxi-mately15to40percent of infected patients(Ganem and Prince,2004).Lamivudine,an oral nucleoside analogue,inhibits HBV replication(de Clercq,2001;2004;Lai et al.,1997;1998;Marcellin et al.,2004).It can markedly reduce serum HBV DNA levels and normalize alanine aminotransferase(ALT)levels … 相似文献
176.
177.
Rosalind Latiner Raby Janice Nahra Friedel Edward J. Valeau 《Community College Journal of Research & Practice》2016,40(11):961-964
This article is a comparative study of community colleges and global counterparts at 41 institutions in 25 countries. Policies from each country link completion of a college program to career entry and to advancement opportunities. National and institutional policies are being defined, benchmark data is being collected on goals in the process, and specific programs are being offered to increase the likelihood that students finish their educational programs. This article examined the emerging trajectories as defined by those who work in these institutions; and in so doing, it provided a discussion of completion in an international context. 相似文献
178.
Infant Affective Reactions to the Resumption of Maternal Interaction after the Still-Face 总被引:4,自引:0,他引:4
To investigate infants' reactions to the Face-to-Face Still-Face Paradigm and in particular the reunion episode, 50 6-month-olds' affective, behavioral, and physiologic reactions were recorded and analyzed. Infants reacted to the still-face with negative affect, a drop in vagal tone, and an increase in heart rate. By contrast, they reacted to the reunion episode with a mixed pattern of positive and negative affect. There was a carryover of negative affect from the still-face, an increase in fussiness and crying, and a rebound of positive affect. During this episode, the infants' heart rate and vagal tone returned to initial levels. The data indicate that infant affective displays are specifically related to different interactive events, but that their physiologic reactions do not show the same level of specificity. The findings also highlight the complexity of the affective and reparatory processes that take place in mother-infant interactions. 相似文献
179.
We trained 7 pigeons to discriminate visual displays of 16same items from displays of 16different items. The specific stimulus features of the items and the relations among the items could serve as discriminative stimuli.
Unlike in most studies of same-different discrimination behavior, we gave a small number of probe tests during each session
of acquisition to measure the time-course of control by the learning of specific stimulus features and relational cues. Both
the specific stimulus features and relational cues exerted reliable stimulus control, with the specific stimulus features
exerting more control during the final three fourths of same-different learning. These findings replicate research suggesting
that pigeons encode both the specific stimulus features and relational cues, and for the first time document the time-course
of control by each kind of cue. 相似文献
180.
Neuropsychology of Early-treated Phenylketonuria: Specific Executive Function Deficits 总被引:14,自引:0,他引:14
Marilyn C. Welsh Bruce F. Pennington Sally Ozonoff Bobbye Rouse Edward R. B. McCabe 《Child development》1990,61(6):1697-1713
This study explored the hypothesis that children with early-treated phenylketonuria (PKU) are selectively impaired on executive function measures, even when still on diet. The rationale for this hypothesis is that even mild elevations in phenylalanine (Phe) can lead to lower central levels of biogenic amines, including dopamine (DA). We hypothesize that this mild DA depletion causes subtle prefrontal dysfunction, which in turn affects executive functions such as set maintenance, planning, and organized search. 11 preschool early-treated PKU children (M age = 4.64) and a sample of age- and IQ-matched unaffected peers (n = 11) were evaluated on a battery of executive function (EF) measures. In addition, a "non-executive function" task, recognition memory, was administered to all subjects. Group comparisons demonstrated that PKU children were significantly impaired on an executive function composite score; there were no group differences, however, in recognition memory. These results supported the hypothesized specific deficit in executive function. Furthermore, within the PKU group the executive function composite score was significantly negatively correlated with concurrent phenylalanine levels, even after controlling for the correlation between IQ and executive function skills. This second finding provides support for the proposed biochemical mechanism underlying the specific cognitive deficits. 相似文献