全文获取类型
收费全文 | 2237篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
教育 | 1476篇 |
科学研究 | 284篇 |
各国文化 | 15篇 |
体育 | 189篇 |
综合类 | 8篇 |
文化理论 | 11篇 |
信息传播 | 296篇 |
出版年
2022年 | 22篇 |
2021年 | 21篇 |
2020年 | 27篇 |
2019年 | 48篇 |
2018年 | 49篇 |
2017年 | 81篇 |
2016年 | 70篇 |
2015年 | 60篇 |
2014年 | 68篇 |
2013年 | 395篇 |
2012年 | 59篇 |
2011年 | 64篇 |
2010年 | 52篇 |
2009年 | 38篇 |
2008年 | 48篇 |
2007年 | 47篇 |
2006年 | 37篇 |
2005年 | 29篇 |
2004年 | 40篇 |
2003年 | 33篇 |
2002年 | 30篇 |
2001年 | 25篇 |
2000年 | 42篇 |
1999年 | 52篇 |
1998年 | 21篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1993年 | 14篇 |
1992年 | 21篇 |
1991年 | 33篇 |
1990年 | 45篇 |
1989年 | 34篇 |
1988年 | 30篇 |
1987年 | 21篇 |
1986年 | 32篇 |
1985年 | 39篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 26篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 27篇 |
1978年 | 29篇 |
1977年 | 21篇 |
1976年 | 17篇 |
1974年 | 17篇 |
1971年 | 17篇 |
1970年 | 14篇 |
1968年 | 19篇 |
排序方式: 共有2279条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Externalities as conventionally defined miss many of the spillovers that are both causes and consequences of the technological changes that underlie economic growth. We introduce a much wider concept called technological complementarities. New general purpose technologies (GPTs) rejuvenate the growth process by creating technological complementarities, which are adequately measured neither by total factor productivity (TFP) nor by externalities. There would be major gains from technological change even if the returns on capital invested in innovation never exceeded the returns on investing in existing technologies so that there were neither externalities nor positive changes in TFP. 相似文献
85.
Three aspects of the most important problem questionused in agenda-setting research to measure issue salience amongthe public were examined. A split-ballot design in a state-widesurvey compared versions of the public agenda with a socialframe of reference versus a personal frame of reference, versionsusing the traditional term problem versus issue,and the effects of question order. High correlations betweenthe different versions were found in all three sets of comparisons. 相似文献
86.
Islam MR Khandoker MA Afroz S Rahman MG Khan RI 《Journal of Zhejiang University. Science. B》2007,8(7):465-469
Goat ovaries were collected from the slaughterhouse and categorized as right, left, corpus luteum (CL)-present and -absent group and evaluated on the basis of weight (g), length (cm), width (cm), number of follicles, follicles aspirated and number and state ofcumulus-oocyte-complexes (COCs). Comparatively higher weight [(0.66±0.02) vs (0.64±0.02) g], length [(1.17±0.02) vs (1.1 ±0.02) cm] and width [(0.77±0.02) vs (0.74±0.02) cm] were found in right ovaries than those of left. On the other hand significantly (P〈0.05) higher weight [(0.71±0.03) vs (0.64±0.01) g] and width [(0.76±0.03) vs (0.75±0.01) cm] were found in CL-present group than those of CL-absent group of ovaries. The left ovaries contained comparatively higher number of normal COCs [(1.06±0.09) per ovary] than fight ovaries [(1.03±0.10) per ovary] and the similar trend was found in total number of follicles [(4.51±0.25) vs (4.30±0.23) per ovary] and follicles aspirated [(2.55±0.14) vs (2.52±0.12) per ovary]. But the total COCs per ovary was almost similar in both ovaries [right and left: (1.85±0.12) and (1.85±0.11) per ovary, respectively]. Higher number of total COCs [(1.87±0.09) vs (1.76±0.16) per ovary], total number of follicles [(4.45±0.19) vs (4.16±0.37) per ovary], follicles aspirated [(2.55±0.10) vs (2.48±0.21) per ovary] and normal COCs [(1.12±0.07) vs (0.76±0.14) per ovary] were found in CL-absent group than those of CL-present group of ovaries. 相似文献
87.
The perceived spatiotemporal continuity of objects depends on the way they appear and disappear as they move in the spatial layout. This study investigated whether infants' predictive tracking of a briefly occluded object is sensitive to the manner by which the object disappears and reappears. Five-, 7-, and 9-month-old infants were shown a ball rolling across a visual scene and briefly disappearing via kinetic occlusion, instantaneous disappearance, implosion, or virtual occlusion. Three different measures converged to show that predictive tracking increased with age and that infants were most likely to anticipate the reappearance of the ball following kinetic occlusion. These results suggest that infants' knowledge of the permanence and nonpermanence of objects is embodied in their predictive tracking. 相似文献
88.
Margarete I. Bolten 《Parenting, science and practice》2019,19(1-2):168-172
SYNOPSISParental working is not unambiguously beneficial for children. On the one hand, working parents can be positive role models for their children, and income can improve children’s lives in many ways. On the other hand, work can impair parent-child interactions, especially when the parents experience high levels of working stress. In my commentary, I conclude that the paper by River, enjoys strong support for the impact of maternal state anxiety (attachment anxiety) and work-interfering-with-family (WIF)-conflict related guilt on parents behaviors. Considering the cognitive-relational stress-theory by Lazarus and Folkman, the balance of personal resources and external demands can explain parental stress, which could be associated with parental behavior. Full-time-working parents, who experience high levels of guilt and report high levels of attachment anxiety, are more prone to show low levels of stress resistance toward crying infants. However, these associations are not studied in families with high risk factors. Furthermore, future studies should include aspects of mental health status in a theoretical model. Taken together, the target article provides a solid foundation for further research. I also propose to transfer the findings into more realistic research setting, which includes high-risk groups (parents with low socioeconomic status, low-income, mental health problems) to study how infant cry can influence parents’ patterns of care and abuse. The commentary tries to enrich the study by including Fraiberg’s “ghosts in the nursery” to further integrating parental mentalizing processes in the model explaining parents’ reactions to infant cry signal in the context of WIF conflicts. 相似文献
89.
90.
Harry F. Dorrell Joseph M. Moore Mark F. Smith Thomas I. Gee 《Journal of sports sciences》2019,37(1):67-73
This study investigated the validity and reliability of the GymAware PowerTool (GPT). Thirteen resistance trained participants completed three visits, consisting of three repetitions of free-weight back squat, bench press, deadlift (80% one repetition maximum), and countermovement jump. Bar displacement, peak and mean velocity, peak and mean force, and jump height were calculated using the GPT, a three-dimensional motion capture system (Motion Analysis Corporation; 150 Hz), and a force plate (Kistler; 1500 Hz). Least products regression were used to compare agreeability between devices. A within-trial one-way ANOVA, typical error (TE; %), and smallest worthwhile change (SWC) were used to assess reliability. Regression analysis resulted in R2 values of >0.85 for all variables excluding deadlift mean velocity (R2 = 0.54–0.69). Significant differences were observed between visits 3-2 for bench press bar displacement (0.395 ± 0.055 m; 0.383 ± 0.053 m), and deadlift bar displacement (0.557 ± 0.034 m; 0.568 ± 0.034 m). No other significant differences were found. Low to moderate TE (0.6–8.8%) were found for all variables, with SWC ranging 1.7–7.4%. The data provides evidence that the GPT can be used to measure kinetic and kinematic outputs, however, care should be taken when monitoring deadlift performance. 相似文献