全文获取类型
| 收费全文 | 1525篇 |
| 免费 | 34篇 |
专业分类
| 教育 | 1060篇 |
| 科学研究 | 127篇 |
| 各国文化 | 32篇 |
| 体育 | 173篇 |
| 文化理论 | 16篇 |
| 信息传播 | 151篇 |
出版年
| 2023年 | 6篇 |
| 2022年 | 10篇 |
| 2021年 | 28篇 |
| 2020年 | 61篇 |
| 2019年 | 66篇 |
| 2018年 | 86篇 |
| 2017年 | 76篇 |
| 2016年 | 78篇 |
| 2015年 | 43篇 |
| 2014年 | 54篇 |
| 2013年 | 324篇 |
| 2012年 | 40篇 |
| 2011年 | 40篇 |
| 2010年 | 41篇 |
| 2009年 | 38篇 |
| 2008年 | 34篇 |
| 2007年 | 28篇 |
| 2006年 | 31篇 |
| 2005年 | 18篇 |
| 2004年 | 18篇 |
| 2003年 | 33篇 |
| 2002年 | 28篇 |
| 2001年 | 12篇 |
| 2000年 | 14篇 |
| 1999年 | 17篇 |
| 1998年 | 11篇 |
| 1997年 | 17篇 |
| 1996年 | 11篇 |
| 1995年 | 19篇 |
| 1994年 | 14篇 |
| 1993年 | 10篇 |
| 1992年 | 16篇 |
| 1991年 | 16篇 |
| 1990年 | 11篇 |
| 1989年 | 17篇 |
| 1988年 | 12篇 |
| 1987年 | 17篇 |
| 1986年 | 8篇 |
| 1985年 | 11篇 |
| 1984年 | 17篇 |
| 1983年 | 14篇 |
| 1982年 | 11篇 |
| 1981年 | 6篇 |
| 1980年 | 12篇 |
| 1979年 | 17篇 |
| 1978年 | 14篇 |
| 1977年 | 13篇 |
| 1975年 | 3篇 |
| 1974年 | 5篇 |
| 1965年 | 3篇 |
排序方式： 共有1559条查询结果，搜索用时 0 毫秒
91.
Jonathan Michael Kaplan 《Metascience》2006,15(1):177-181
92.
93.
This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked
ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The
instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and
instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at
60 rev min-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were
compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied
with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods.
An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods
up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight
subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second
period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel
velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas
the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical
efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects
when compared with both the SRM systems and the direct measurement instrumentation. 相似文献
94.
Measurement of ground reaction force (GRF) in running provides a direct indication of the loads to which the body is subjected
at each foot-ground contact, and can provide an objective explanation for performance outcomes. Traditionally, the collection
of three orthogonal component GRF data in running requires an athlete to complete a series of return loops along a laboratory
based runway, within which a force platform is embedded, in order to collect data from a discrete footfall. The major disadvantages
associated with this GRF data collection methodology include the inability to assess multiple consecutive foot contacts and
the fact that measurements are typically confined to the laboratory. The objective of this research was to investigate the
potential for wearable instrumentation to be employed, in conjunction with artificial neural network (ANN) and multiple linear
regression (MLR) models, for the estimation of GRF in middle distance running. A modular wearable data acquisition system
was developed to acquire in-shoe force (ISF) data. Matched data sets from wearable instrumentation (source data) and force
plate (target data) records were collected from elite middle-distance runners under controlled laboratory conditions for the
purposes of ANN and MLR model development (MD) and model validation (MV).
In terms of statistical measures of prediction accuracy the MLR model was found to provide a superior level of accuracy for
the prediction of the vertical and medio-lateral components of GRF and alternatively, the ANN model provided the most accurate
predictions of the anterior-posterior component of GRF. The prediction accuracy of each component of GRF was found to be governed
by the inherent signal variability, in which case the vertical and anterior-posterior components were more reliable and subsequently
predicted significantly more accurately than the medio-lateral component.
The emerging capability for obtaining continuous GRF records from wearable instrumentation has the potential to permit unprecedented
quantification of training stress and competition demands in running. 相似文献
95.
96.
97.
Proposing that bilingual proficiency should produce a more favorable attitude toward bilingualism and should enhance one's self-esteem, the authors compared 57 bilingual and 67 unilingual students from grades 9, 10, and 11, measuring their opinions about bilingualism and their self-esteem. The bilingual students are substantially more favorably disposed toward bilingualism than the unilingual students are. On the Janis-Field scale of self-esteem, the bilingual students show greater self-esteem than the unilingual students. The largest differences between the groups are on questions that measure self-confidence and social ease; differences are less pronounced on questions about self-worth and about shyness. We speculate that bilingual proficiency offers some psychological advantages to students who achieve it. 相似文献
98.
99.
100.