全文获取类型
收费全文 | 22915篇 |
免费 | 361篇 |
国内免费 | 15篇 |
专业分类
教育 | 16346篇 |
科学研究 | 2032篇 |
各国文化 | 218篇 |
体育 | 1903篇 |
综合类 | 13篇 |
文化理论 | 175篇 |
信息传播 | 2604篇 |
出版年
2022年 | 180篇 |
2021年 | 261篇 |
2020年 | 382篇 |
2019年 | 601篇 |
2018年 | 827篇 |
2017年 | 800篇 |
2016年 | 700篇 |
2015年 | 420篇 |
2014年 | 658篇 |
2013年 | 4429篇 |
2012年 | 636篇 |
2011年 | 646篇 |
2010年 | 469篇 |
2009年 | 484篇 |
2008年 | 539篇 |
2007年 | 480篇 |
2006年 | 426篇 |
2005年 | 408篇 |
2004年 | 367篇 |
2003年 | 356篇 |
2002年 | 341篇 |
2001年 | 475篇 |
2000年 | 393篇 |
1999年 | 359篇 |
1998年 | 203篇 |
1997年 | 210篇 |
1996年 | 240篇 |
1995年 | 235篇 |
1994年 | 181篇 |
1993年 | 200篇 |
1992年 | 321篇 |
1991年 | 298篇 |
1990年 | 298篇 |
1989年 | 298篇 |
1988年 | 255篇 |
1987年 | 301篇 |
1986年 | 265篇 |
1985年 | 304篇 |
1984年 | 246篇 |
1983年 | 211篇 |
1982年 | 190篇 |
1981年 | 163篇 |
1980年 | 153篇 |
1979年 | 258篇 |
1978年 | 182篇 |
1977年 | 168篇 |
1976年 | 153篇 |
1975年 | 141篇 |
1974年 | 147篇 |
1971年 | 140篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A method of assessment, involving six one-hour tests, with provision to repeat four of them, has been used with favourable student and staff reaction in first year, two semester undergraduate physics courses. The style of question and marking criteria used previously in a conventional examination are retained.The relationship between performance in Physics I, high school background and mark in the first physics test, held in the fifth week of the university course. are investigated through a series of regression analyses. An attempt is made to arrive at an appropriate entry criterion for admission to Physics I. 相似文献
992.
You've Been Warned: Does Information About Pitfalls of Technological Toys Affect Caregiver Behavior?
Although the presence of toys in childhood has remained steady for decades, the types of toys that fill children's toy boxes have changed, especially over the last 10–15 years. Many of today's toys are marked by technological enhancements, from a shape sorter driven by a singing bear to robotic plastic animals designed to match a toddler's favorite television show. Although examining the effects of these changes is still an unexplored area, research to date suggests that there may be costs to the quality of caregiver–child interaction when using these toys together. This leads to two possibilities: (1) the design of the enhancements themselves hurt interactions; or (2) these toys can still be beneficial to interactions, but caregivers simply need to be aware of the potential pitfalls. In this study, we explore whether providing caregivers with a subtle cue about the potential negative impacts of technological toys on caregiver–child interaction affects their behavior. 相似文献
993.
994.
995.
M A Flower 《Bulletin of the Medical Library Association》1978,66(3):296-301
A report is given on Canadian hospital library standards as recently developed and incorporated in a new Guide to Hospital Accreditation, 1977. The new Canadian standards are compared with MLA recommendations to the Joint Commission on Accreditation of Hospitals. Their development is sketched and the contribution from Quebec of a model of hospital classification is examined. This model provides differential minimal library standards based on the function of the hospital rather than on its size alone. Use of these minimal standards as a practical means of developing hospital libraries is discussed and their implications for accreditation visits are underlined. 相似文献
996.
G W Gayle R L Pohlman R M Glaser G M Davis 《Research quarterly for exercise and sport》1990,61(3):224-232
The purpose of the present study was to determine the effects of 10-in [0.25-m] versus 16-in [0.41-m] wheelchair handrims on cardiorespiratory and psychophysiological exercise responses during wheelchair propulsion at selected velocities. Fifteen male paraplegics (27.0 +/- 5.5 yrs) performed three discontinuous exercise tests (ACE = arm crank ergometer; WERG = wheelchair roller ergometer) and two 1600-m performance-based track trials (TRACK) under simulated race conditions. There were no significant differences in HR, VO2, VE, HLa, or category-ratio ratings of perceived exertion (RPE) using different handrims during wheelchair propulsion at 4 km.h-1. In contrast, at 8 km.h-1 subjects demonstrated a 13% lower steady state VO2 (p less than .05) using the 10-in handrims, coincident with a 23% lower VE. Steady state HR during WERG at 8 km.h-1 using the 10-in (124.4 +/- 3.9 b.min-1) or 16-in (130.6 +/- 4.6 b.min-1) handrims were not significantly different. There were also no significant differences between ACE or WERG conditions during maximal effort for VO2 or VE. However, HRpeak during ACE was 7% higher than HRpeak during WERG16 (183 +/- 15 b.min-1 vs. 171 +/- 12 b.min-1, p less than .05), and whole blood HLa during ACE was also significantly higher (by 2.3-2.5 mmol; p less than .05) compared to WERG. There were no significant differences for HR, performance time, or RPE between trials using different handrim diameters during the 1600-m event.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
997.
998.
999.
1000.