全文获取类型
收费全文 | 22882篇 |
免费 | 247篇 |
国内免费 | 30篇 |
专业分类
教育 | 15709篇 |
科学研究 | 2738篇 |
各国文化 | 240篇 |
体育 | 1763篇 |
综合类 | 10篇 |
文化理论 | 187篇 |
信息传播 | 2512篇 |
出版年
2021年 | 186篇 |
2020年 | 289篇 |
2019年 | 403篇 |
2018年 | 519篇 |
2017年 | 537篇 |
2016年 | 525篇 |
2015年 | 346篇 |
2014年 | 486篇 |
2013年 | 4208篇 |
2012年 | 449篇 |
2011年 | 465篇 |
2010年 | 406篇 |
2009年 | 362篇 |
2008年 | 441篇 |
2007年 | 403篇 |
2006年 | 394篇 |
2005年 | 344篇 |
2004年 | 343篇 |
2003年 | 314篇 |
2002年 | 280篇 |
2001年 | 560篇 |
2000年 | 419篇 |
1999年 | 361篇 |
1998年 | 198篇 |
1997年 | 229篇 |
1996年 | 221篇 |
1995年 | 196篇 |
1994年 | 239篇 |
1993年 | 213篇 |
1992年 | 309篇 |
1991年 | 326篇 |
1990年 | 332篇 |
1989年 | 339篇 |
1988年 | 283篇 |
1987年 | 282篇 |
1986年 | 303篇 |
1985年 | 352篇 |
1984年 | 303篇 |
1983年 | 293篇 |
1982年 | 244篇 |
1981年 | 241篇 |
1980年 | 212篇 |
1979年 | 300篇 |
1978年 | 271篇 |
1977年 | 219篇 |
1976年 | 188篇 |
1975年 | 204篇 |
1974年 | 180篇 |
1973年 | 195篇 |
1971年 | 171篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
C. I. Jhala U. V. Shah T. K. Shah B. K. Naik J. D. Dafda 《Indian journal of clinical biochemistry : IJCB》1998,13(1):1-7
Fasting samples of 1329 apparently healthy vegetarian Gujarati population were tested for total cholesterol, triglycerides
and three major fractions of lipoproteins, i.e. high density lipoproteins, low density lipoproteins and very low density lipoproteins.
All the values showed marked increase with the age. Except for serum triglycerides, values differ in males and females in
the age group of above 45 years. Compared to Northern Indian population low density lipoprotein and high density lipoprotein
values were higher, but values of triglycerides and very low density lipoproteins were lower. There is no significant difference
in total cholesterol values. Compared to Southern Indian population low density lipoprotein and very low density lipoprotein
values were higher but values of triglycerides, total cholesterol and high density lipoprotein were lower. All serum lipid
values were significantly lower than the Westem population. The range of values for both the sexes is presented for different
age groups. 相似文献
982.
983.
984.
985.
Rebekka Darner Gougis Janet F. Stomberg Alicia T. O’Hare Catherine M. O’Reilly Nicholas E. Bader Thomas Meixner Cayelan C. Carey 《International Journal of Science and Mathematics Education》2017,15(6):1039-1056
The concepts of randomness and variation are pervasive in science. The purpose of this study was to document how post-secondary life science students explain randomness and variation, infer relationships between their explanations, and ability to describe and identify appropriate and inappropriate variation, and determine if students can identify sources of variation. An instrument designed to test statistical concepts was administered to 282 college students from three universities, ranging from introductory non-science majors to science graduate students. Students readily distinguished between causes of variation. A naïve no-pattern concept of randomness persisted from first-year non-science majors to senior-level science majors, contributing to incorrect responses on the variation instrument. Students’ expressions of randomness were better predictors of performance on the variation instrument than their expressions of variation. It is argued that inclusion of everyday language uses of randomness in instruction can bridge the gap between vernacular and scientific uses of this term. 相似文献
986.
987.
988.
989.
Binge-watching—the intensive, consecutive viewing of televised series—has become a prevalent usage pattern of entertainment media, which may influence users’ psychological well-being both positively and negatively: On the one hand, binge-watching could increase viewers’ enjoyment, recovery experiences, and vitality through an increase in perceived autonomy. On the other hand, binge-watching can trigger goal conflicts and feelings of guilt, which may reduce well-being. Drawing on an online survey (N = 499), the present study examines the tension between these two mechanisms and their effects on users’ well-being. The data largely support the hypotheses: Binge-watching is perceived as recreational as long as goal conflicts and feelings of guilt can be avoided. Well-being, on the other hand, is positively affected by binge-watching-induced increases in perceived autonomy. These results corroborate the central role of self-determination as a link between media reception, media enjoyment, and psychological well-being. 相似文献
990.