全文获取类型
| 收费全文 | 122398篇 |
| 免费 | 1906篇 |
| 国内免费 | 245篇 |
专业分类
| 教育 | 84550篇 |
| 科学研究 | 13532篇 |
| 各国文化 | 2045篇 |
| 体育 | 9695篇 |
| 综合类 | 196篇 |
| 文化理论 | 1093篇 |
| 信息传播 | 13438篇 |
出版年
| 2021年 | 960篇 |
| 2020年 | 1671篇 |
| 2019年 | 2600篇 |
| 2018年 | 3172篇 |
| 2017年 | 3471篇 |
| 2016年 | 3500篇 |
| 2015年 | 2359篇 |
| 2014年 | 3202篇 |
| 2013年 | 27640篇 |
| 2012年 | 2480篇 |
| 2011年 | 2889篇 |
| 2010年 | 2421篇 |
| 2009年 | 2662篇 |
| 2008年 | 2519篇 |
| 2007年 | 2286篇 |
| 2006年 | 2478篇 |
| 2005年 | 2475篇 |
| 2004年 | 3118篇 |
| 2003年 | 2430篇 |
| 2002年 | 2262篇 |
| 2001年 | 2106篇 |
| 2000年 | 1755篇 |
| 1999年 | 1664篇 |
| 1998年 | 1486篇 |
| 1997年 | 1552篇 |
| 1996年 | 1713篇 |
| 1995年 | 1487篇 |
| 1994年 | 1496篇 |
| 1993年 | 1486篇 |
| 1992年 | 1537篇 |
| 1991年 | 1456篇 |
| 1990年 | 1377篇 |
| 1989年 | 1243篇 |
| 1988年 | 1102篇 |
| 1987年 | 1028篇 |
| 1986年 | 1056篇 |
| 1985年 | 1294篇 |
| 1984年 | 1196篇 |
| 1983年 | 1115篇 |
| 1982年 | 1089篇 |
| 1981年 | 1014篇 |
| 1980年 | 970篇 |
| 1979年 | 1090篇 |
| 1978年 | 1062篇 |
| 1977年 | 975篇 |
| 1976年 | 881篇 |
| 1975年 | 717篇 |
| 1974年 | 707篇 |
| 1973年 | 684篇 |
| 1972年 | 529篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
991.
Kristina L. Kendall David H. Fukuda Parker N. Hyde Abbie E. Smith-Ryan Jordon R. Moon Jeffrey R. Stout 《Journal of sports sciences》2017,35(7):624-633
The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. METHODS: Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM. 相似文献
992.
993.
994.
Robert Munro 《Cultural Trends》2015,24(3):276-280
995.
This study examined whether or not activity monitor data collected as part of a typical 7-day physical activity (PA) measurement protocol can be expected to be missing at random. A total of 315 participants (9–18 years) each wore a SenseWear Armband monitor for 7 consecutive days. Participants were classified as “compliant” (86 boys and 124 girls) if they had recorded accelerometer data during 70% or more of the predefined awake time (7 AM–10 PM) on four different days; and “non-compliant” (44 boys and 51 girls) when not meeting these criteria. Linear mixed models were used to examine differences in energy expenditure (EE) levels by compliance across 10 different time periods. The results indicated that non-compliant girls were older (13.4 ± 2.9 vs. 12.2 ± 2.5) and taller (156.8 ± 10.3 vs. 152.8 ± 11.3) than their same gender compliant peers (P < .05). Comparisons of EE rates at segmented portions of the day revealed no differences between compliant and non-compliant groups (P ≥ .05). Differences in EE ranged from ?0.32 kcal · kg?1 · h?1 (before school time) to 0.62 kcal · kg?1 · h?1 (physical education class) in boys and ?0.39 kcal · kg?1 · h?1 (transportation from school) to 0.37 kcal · kg?1 · hour?1 (recess) in girls. The results showed that compliant and non-compliant individuals differed in a few demographic characteristics but exhibited similar activity patterns. This suggests that data were considered to be missing at random, but additional work is needed to confirm this observation in a representative sample of children using other types of activity monitors and protocols. 相似文献
996.
997.
998.
999.
1000.