全文获取类型
| 收费全文 | 25223篇 |
| 免费 | 427篇 |
| 国内免费 | 17篇 |
专业分类
| 教育 | 17812篇 |
| 科学研究 | 2363篇 |
| 各国文化 | 235篇 |
| 体育 | 2106篇 |
| 综合类 | 20篇 |
| 文化理论 | 211篇 |
| 信息传播 | 2920篇 |
出版年
| 2022年 | 165篇 |
| 2021年 | 280篇 |
| 2020年 | 424篇 |
| 2019年 | 648篇 |
| 2018年 | 917篇 |
| 2017年 | 931篇 |
| 2016年 | 806篇 |
| 2015年 | 487篇 |
| 2014年 | 746篇 |
| 2013年 | 4900篇 |
| 2012年 | 735篇 |
| 2011年 | 761篇 |
| 2010年 | 558篇 |
| 2009年 | 551篇 |
| 2008年 | 594篇 |
| 2007年 | 569篇 |
| 2006年 | 472篇 |
| 2005年 | 474篇 |
| 2004年 | 420篇 |
| 2003年 | 404篇 |
| 2002年 | 388篇 |
| 2001年 | 537篇 |
| 2000年 | 454篇 |
| 1999年 | 408篇 |
| 1998年 | 250篇 |
| 1997年 | 245篇 |
| 1996年 | 286篇 |
| 1995年 | 248篇 |
| 1994年 | 191篇 |
| 1993年 | 198篇 |
| 1992年 | 330篇 |
| 1991年 | 308篇 |
| 1990年 | 306篇 |
| 1989年 | 303篇 |
| 1988年 | 269篇 |
| 1987年 | 309篇 |
| 1986年 | 277篇 |
| 1985年 | 321篇 |
| 1984年 | 265篇 |
| 1983年 | 218篇 |
| 1982年 | 199篇 |
| 1981年 | 176篇 |
| 1980年 | 148篇 |
| 1979年 | 263篇 |
| 1978年 | 198篇 |
| 1977年 | 170篇 |
| 1976年 | 149篇 |
| 1975年 | 145篇 |
| 1974年 | 154篇 |
| 1971年 | 130篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
41.
42.
The purpose of this investigation was to describe the morphological parameters that characterize elite age group divers. Comparisons are made to normative age group data from the Coquitlam Growth Study and the constancy of important characteristics from age group to age group is examined. Data were collected on 27 male and 28 female elite divers who participated in the 1990 North American Age Group Diving Championships. Body build, body composition and skinfold corrected diameters were determined from 36 anthropometric parameters and analysed by ANOVA, t-test and Phantom z-scores procedures. All age groups except the 14- to 15-year-old males were significantly (P < or = 0.05) shorter than their norms but recorded higher androgyny index values. The estimated relative muscle mass increased significantly (P < or = 0.05) with age for males at all ages (40.8-46.3%). The 16- to 18-year-old females had a significantly (P < or = 0.05) larger relative muscle component compared to the younger age groups (40.1-38.4%). When normalized for height, active tissue development of the extremities was comparable between the sexes except in the forearm. The results indicate that at all age levels short stature is an important characteristic for divers. Analysis of regional active tissue development provides further insight into sport-specific prerequisites for success at elite levels. 相似文献
43.
This article is a preliminary analysis of the first few years of the Computer Matching and Privacy Protection Act of 1988 (CMPPA). The act requires Federal agencies to establish Data Integrity Boards (DIBs) with responsibility to approve written agreements for computer matches in which their agencies are involved. Information for this analysis was collected from the annual reports on computer matching submitted by agencies to the Office of Management and Budget (OMB) for 1990 and 1991 and from 108 matching agreements. The secretaries of several DIBs were also interviewed. The effectiveness of DIBs and matching agreements are analyzed using McCubbins and Schwartz's distinction between “police-patrol” and “fire- alarm” oversight. The article concludes that more active and direct oversight, which would occur through an independent data protection or privacy board, is necessary. 相似文献
44.
45.
46.
47.
Do physical activity beliefs differ by age and gender? 总被引：1，自引：0，他引：1
Age and gender are consistently related to physical activity (PA), yet theoretical explanation for these associations is scant. The present study compared the mean values and correlations of a population sample, divided by gender and age group, with respect to theory of planned behavior beliefs (behavioral, normative, and control) and PA. Participants were a sample (N=6,739) of adults (M age=49.65, SD=16.04) who completed measures of social and health demographics, theory of planned behavior beliefs, and self-reported PA. Mean analyses identified greater perceived control over PA for seniors than for young and middle-aged adults (N>.025). Belief-behavior correlations, however, were not different across age and gender in 24 of 26 tests (q<.19). Thus, PA beliefs are invariant across age and gender with the exception of mean levels of perceived control, which are lower among younger adults than older adults. Factors such as early parenthood and career demands were considered the likely reasons for differences. Overall, the evidence suggests that adapting theoretical models for specific age groups or based on gender may not be necessary. 相似文献
48.
49.
50.