首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   41014篇
  免费   591篇
  国内免费   48篇
教育   29837篇
科学研究   3730篇
各国文化   368篇
体育   2933篇
综合类   41篇
文化理论   381篇
信息传播   4363篇
  2021年   350篇
  2020年   539篇
  2019年   795篇
  2018年   1604篇
  2017年   1699篇
  2016年   1452篇
  2015年   701篇
  2014年   900篇
  2013年   7524篇
  2012年   932篇
  2011年   1262篇
  2010年   993篇
  2009年   843篇
  2008年   1041篇
  2007年   1010篇
  2006年   782篇
  2005年   688篇
  2004年   714篇
  2003年   598篇
  2002年   654篇
  2001年   735篇
  2000年   690篇
  1999年   665篇
  1998年   358篇
  1997年   420篇
  1996年   441篇
  1995年   411篇
  1994年   374篇
  1993年   376篇
  1992年   544篇
  1991年   528篇
  1990年   548篇
  1989年   549篇
  1988年   521篇
  1987年   460篇
  1986年   462篇
  1985年   539篇
  1984年   464篇
  1983年   496篇
  1982年   393篇
  1981年   380篇
  1980年   343篇
  1979年   487篇
  1978年   408篇
  1977年   372篇
  1976年   316篇
  1975年   272篇
  1974年   249篇
  1973年   279篇
  1971年   214篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
232.
Neuroanatomy education is a challenging field which could benefit from modern innovations, such as augmented reality (AR) applications. This study investigates the differences on test scores, cognitive load, and motivation after neuroanatomy learning using AR applications or using cross-sections of the brain. Prior to two practical assignments, a pretest (extended matching questions, double-choice questions and a test on cross-sectional anatomy) and a mental rotation test (MRT) were completed. Sex and MRT scores were used to stratify students over the two groups. The two practical assignments were designed to study (1) general brain anatomy and (2) subcortical structures. Subsequently, participants completed a posttest similar to the pretest and a motivational questionnaire. Finally, a focus group interview was conducted to appraise participants’ perceptions. Medical and biomedical students (n = 31); 19 males (61.3%) and 12 females (38.7%), mean age 19.2 ± 1.7 years participated in this experiment. Students who worked with cross-sections (n = 16) showed significantly more improvement on test scores than students who worked with GreyMapp-AR (P = 0.035) (n = 15). Further analysis showed that this difference was primarily caused by significant improvement on the cross-sectional questions. Students in the cross-section group, moreover, experienced a significantly higher germane (P = 0.009) and extraneous cognitive load (P = 0.016) than students in the GreyMapp-AR group. No significant differences were found in motivational scores. To conclude, this study suggests that AR applications can play a role in future anatomy education as an add-on educational tool, especially in learning three-dimensional relations of anatomical structures.  相似文献   
233.
ABSTRACT

The length of telomeres is an objective measure of biologic ageing. This study evaluated the extent minutes of walking per week are associated with leukocyte telomere length (LTL) in a random sample of 5,823 U.S. adults. The investigation was cross-sectional and data were obtained from the National Health and Nutrition Examination Survey (NHANES). LTL was measured by the quantitative polymerase chain reaction method. Walking minutes was calculated from walking frequency and duration measures. Results showed that for each year of chronological age, telomeres were 15.6 base pairs shorter (P < 0.0001). With walking minutes and LTL treated as continuous variables, the relationship was quadratic, not linear (F = 11.2, P = 0.0023). With walking time divided into three categories, adults who performed ≥ 150 minutes of walking per week had longer telomeres than those who did no regular walking, and those who did some, but less than the recommendation (F = 5.0, P = 0.0137). Regular walkers were estimated to have a biologic ageing advantage associated with 6.5–7.6 years less biologic ageing compared to non-walkers, after adjusting for covariates. Additional investigations designed to study causality and the mechanisms associated with the walking and LTL relationship are needed.  相似文献   
234.
235.
ABSTRACT

Amid rising controversy around the alleged distinctions between merit and excellence lies a familiar refrain, scarcity. The narrative of academic scarcity, proclaiming the insufficient numbers of scholars and academics of color, permeates conversations in higher education. We suggest that the academic scarcity narrative, a remnant of stagnant logics of diversity, circulates as a contemporary mechanism of what we name disciplinary containment. Extending disciplinary conversations around rhetorical containment, we argue that disciplinary containment perpetuates whiteness.  相似文献   
236.
This paper demonstrates the application of module arithmetic for controlling the level of information security by a new technique referred as integer splitting. The basic definitions and concepts of the method are provided. The mathematical function of arising transformation is described in detail; its properties were studied and the basic theorems were proven that justify the use of splitting in practical applications. An active system was designed and characteristic cases of its operation are considered.  相似文献   
237.
At the University of Maine, middle and high school teachers observed more than 250 university science, technology, engineering, and mathematics classes and collected information on the nature of instruction, including how clickers were being used. Comparisons of classes taught with (n = 80) and without (n = 184) clickers show that, while instructional behaviors differ, the use of clickers alone does not significantly impact the time instructors spend lecturing. One possible explanation stems from the observation of three distinct modes of clicker use: peer discussion, in which students had the opportunity to talk with one another during clicker questions; individual thinking, in which no peer discussion was observed; and alternative collaboration, in which students had time for discussion, but it was not paired with clicker questions. Investigation of these modes revealed differences in the range of behaviors, the amount of time instructors lecture, and how challenging the clicker questions were to answer. Because instructors can vary their instructional style from one clicker question to the next, we also explored differences in how individual instructors incorporated peer discussion during clicker questions. These findings provide new insights into the range of clicker implementation at a campus-wide level and how such findings can be used to inform targeted professional development for faculty.  相似文献   
238.
239.
240.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号