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   23870篇
  免费   285篇
  国内免费   14篇
教育   16987篇
科学研究   1944篇
各国文化   258篇
体育   2317篇
综合类   7篇
文化理论   219篇
信息传播   2437篇
  2021年   237篇
  2020年   362篇
  2019年   551篇
  2018年   736篇
  2017年   677篇
  2016年   670篇
  2015年   409篇
  2014年   540篇
  2013年   4309篇
  2012年   491篇
  2011年   547篇
  2010年   415篇
  2009年   442篇
  2008年   482篇
  2007年   445篇
  2006年   416篇
  2005年   360篇
  2004年   398篇
  2003年   309篇
  2002年   330篇
  2001年   466篇
  2000年   514篇
  1999年   440篇
  1998年   257篇
  1997年   253篇
  1996年   310篇
  1995年   252篇
  1994年   263篇
  1993年   229篇
  1992年   354篇
  1991年   370篇
  1990年   345篇
  1989年   367篇
  1988年   343篇
  1987年   328篇
  1986年   330篇
  1985年   374篇
  1984年   295篇
  1983年   306篇
  1982年   245篇
  1981年   251篇
  1980年   261篇
  1979年   352篇
  1978年   264篇
  1977年   242篇
  1976年   202篇
  1975年   182篇
  1974年   185篇
  1973年   177篇
  1971年   176篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
Measures of word recognition (REC) and two component skills, phonological coding (PHON) and orthographic coding (ORTH), were subjected to multivariate behavioral genetic analysis. Data were obtained from a sample of identical and fraternal twin pairs wherein at least one member of each pair was reading disabled (RD), and from a sample of twins wherein both members of each pair read in the normal range. Confirmatory factor analysis was used to fit the genetic, common environmental, and specific environmental covariance components for REC, PHON, and ORTH within the RD and normal simples. The resulting heritability estimates for REC, PHON, and ORTH were 0.59, 0.41, and 0.05 in the RD sample, and 0.35, 0.52, and 0.20 in the normal sample. After dropping the nonsignificant common environment parameters from the models, the genetic correlations between REC and PHON and between REC and ORTH were respectively 0.81 and 0.45 in the RD sample, and 0.68 and 0.45 in the normal sample. Differences between the genetic correlations were significant in the RD sample (p<0.005), marginally significant in the normal sample (p<0.10), and highly significant in the combined sample (p<0.001), indicating that genetic influences on individual differences in REC are more strongly related to genetic variance in PHON than in ORTH. These results are consistent with previous demonstrations of substantial genetic covariance between the disabled group's deficits in REC and PHON, but not between REC and ORTH (Olson et al., 1989; Olson and Rack, 1990).  相似文献   
992.
The medical education literature is growing, and the result is not only greater knowledge, but an increasing complexity in locating quality evidence-based information. In 2008, eight librarians partnered with the Association of American Medical Colleges to research, conceptualize, and build an online module to develop medical educators’ search skills. Developing an online instructional module is a time-consuming, multi-stage process requiring the expertise of content, technical, and design specialists working in concert. Many lessons were learned, including the power of collaborative tools; the benefits of including specialists, such as graphic designers; the benefit of thoroughly surveying existing resources; and the importance of choosing technology wisely.  相似文献   
993.
Zusammenfassung.   Die intelligente Ressourcenadaption ist eine der gro?en Herausforderungen für die n?chste Generation mobiler Navigationssysteme. Da man typischerweise mehrere Fortbewegungsarten oder Verkehrsmittel kombinieren muss, um an einen Zielort zu gelangen, muss sichergestellt werden, dass mobile, allgegenw?rtige Navigationshilfen dies über eine jeweils situationsangepasste Benutzerschnittstelle unterstützen. Der notwendige Wechsel zwischen verschiedenen Positionierungstechnologien soll für den Endbenutzer m?glichst unbemerkt bleiben. Im folgenden wird ein hybrides Personennavigationssystem vorgestellt, das die in bestimmten Fortbewegungssituationen verfügbaren Positionierungstechnologien und deren Genauigkeit optimal nutzt, um die Pr?sentation der Wegbeschreibung auf verschiedene Endger?te und Ausgabemodalit?ten sowie die kognitive Ressourcenlage des Benutzers zu adaptieren. Eingegangen am 28. Februar 2001 / Angenommen am 8. August 2001  相似文献   
994.
Journalists and readers of celebrity news regularly bash celebrities online, a behavior that is easily accepted among adolescents. This study investigates whether these attitudes of acceptance differ according to the perpetrator of the bashing (media versus public) and the likeability of the involved celebrity (liked versus disliked). Using a vignette study, we examine adolescent girls’ attitudes toward media (journalists’) and public (readers’) bashing of a generally disliked celebrity (Miley Cyrus) and a generally liked celebrity (Selena Gomez). All participants read an identical negative news story (media bashing) and two related negative reader comments (public bashing). Participants were randomly assigned to read this information about either Miley Cyrus or Selena Gomez. Results of a mixed-design ANOVA showed that the girls had less negative attitudes toward media bashing compared with public bashing. Moreover, they more easily accepted the bashing of a disliked celebrity than the bashing of a liked celebrity.  相似文献   
995.
Developmental, gender, and academic domain differences in causal attributions and the influence of attributions on classroom engagement were explored longitudinally in 115 African American adolescents. In Grades 8 and 11, adolescents reported attributions for success and failure in math, English and writing, and science. In Grade 11, English and mathematics teachers rated students' classroom engagement. Boys were more likely than girls to attribute math successes to high ability and to attribute English failures to low ability. Both genders' ability attributions for math became more negative from eighth to eleventh grades. Grade 8 attributions of math failure to lack of ability were negatively related to Grade 11 math classroom engagement. Results illustrate the gendered nature of motivational beliefs among Black youth.  相似文献   
996.
J Srinivasan 《Resonance》2001,6(11):42-48
The second law of thermodynamics is one of the enigmatic laws of physics. Sadi Carnot, a French engineer played an important role in its discovery in the 19th century. We recount here how he proposed the basic postulates of this law although he did not fully understand the first law of thermodynamics.  相似文献   
997.
Educators must address several challenges inherent to the instruction of scientific disciplines such as physics -- expensive or insufficient laboratory equipment, equipment error, difficulty in simulating certain experimental conditions. Augmented reality (AR) can be a promising approach to address these challenges. In this paper, we discuss the design and implementation of an AR and motion-sensing learning technology that teaches magnetic fields in a junior high school physics course. The purpose of this study is to explore the effects of using natural interaction on students’ physics learning and deep understanding compared to traditional learning tools. The 38 eighth graders who participated in this study were assigned to either an experimental group or a control group. Analysis of the results shows that the AR-based motion-sensing software can improve students’ learning attitude and learning outcome. This study provides a case for the application of AR technology in secondary physics education.  相似文献   
998.
Three-dimensional (3D) printing technology has become more affordable, accessible, and relevant in healthcare, however, the knowledge of transforming medical images to physical prints still requires some level of training. Anatomy educators can play a pivotal role in introducing learners to 3D printing due to the spatial context inherent to learning anatomy. To bridge this knowledge gap and decrease the intimidation associated with learning 3D printing technology, an elective was developed through a collaboration between the Department of Anatomy and the Makers Lab at the University of California, San Francisco. A self-directed digital resource was created for the elective to guide learners through the 3D printing workflow, which begins with a patient's computed tomography digital imaging and communication in medicine (DICOM) file to a physical 3D printed model. In addition to practicing the 3D printing workflow during the elective, a series of guest speakers presented on 3D printing applications they utilize in their clinical practice and/or research laboratories. Student evaluations indicated that their intimidation associated with 3D printing decreased, the clinical and research topics were directly applicable to their intended careers, and they enjoyed the autonomy associated with the elective format. The elective and the associated digital resource provided students with the foundational knowledge of 3D printing, including the ability to extract, edit, manipulate, and 3D print from DICOM files, making 3D printing more accessible. The aim of disseminating this work is to help other anatomy educators adopt this curriculum at their institution.  相似文献   
999.
1000.
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