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   173篇
  免费   115篇
  2022年   1篇
  2021年   4篇
  2020年   8篇
  2019年   4篇
  2018年   12篇
  2017年   48篇
  2016年   22篇
  2015年   22篇
  2014年   31篇
  2013年   50篇
  2012年   41篇
  2011年   10篇
  2010年   5篇
  2009年   9篇
  2008年   7篇
  2007年   4篇
  2006年   3篇
  2002年   1篇
  2000年   2篇
  1999年   1篇
  1985年   1篇
  1984年   2篇
排序方式: 共有288条查询结果,搜索用时 15 毫秒
281.
Boule is a conserved gene in meiosis, which encodes RNA binding protein required for spermatocyte meiosis. Deletion of Boule was found to block meiosis in spermatogenesis, which contributes to infertility. Up to date, the expression and function of Boule in the goat testis are not known. The objectives of this study were to investigate the expression pattern of Boule in dairy goat testis and their function in male germline stem cells (mGSCs). The results first revealed that the expression level of Boule in adult testes was significantly higher than younger and immature goats, and azoospermia and male intersex testis. Over‐expression of Boule promoted the expression of meiosis‐related genes in dairy goat mGSCs. The expression of Stra8 was up‐regulated by over‐expression of Boule analyzed by Western blotting and Luciferase reporter assay. While, Cdc25a, the downstream regulator of Boule, was found not to affect the expression of Stra8, and our data illustrated that Cdc25a did not regulate meiosis via Stra8. The expression of Stra8 and Boule was up‐regulated by RA induction. Taken together, results suggest the Boule plays an important role in dairy goat spermatogenesis and that over‐expression of Boule may promote spermatogenesis and meiosis in dairy goat. J. Cell. Biochem. 114: 294–302, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   
282.
283.
Abstract

The purpose of this study is to design a digital game design-based STEM activity for fifth-grade students learning about endangered organisms and significance of biodiversity for living. This activity was carried out with twenty students in a public school in Eastern Black Sea Region of Turkey during academic year of 2018–2019 spring term. This study planned as eight-lesson time (8?×?40?minutes) and completed at this lesson time. The students were given the digital game design challenge in real-life problem context that has been created based on design-based science learning and for which they shall use their knowledge and skills in each of the STEM disciplines. During this design challenge, students worked like a scientist and an engineer. They carried out scientific research and inquiry process in the science discipline, understood the engineering design process in the engineering discipline, established mathematical relations in the mathematics discipline, learned how to make coding in the technology discipline, and used this knowledge and skills thus acquired in their suggested solutions for the design challenge. They designed a digital game by coding and presented science knowledge and skills that acquired from inquiry process.  相似文献   
284.
285.
286.
287.
288.
Abstract

This study involves the development and implementation of a STEM activity containing 3?D printer technology, which is commonly used in STEM education. Out of school STEM courses were organized with seven middle school students studying in the 7th grade and the activities in the course were carried out with a 3D printer. One of the activities in the course is the Balance model. The study reveals the skills students used in the Balance Model activity, which is a 3D STEM activity. The students’ engineering skills were effective through the STEM activity, and they actively used skills such as planning, designing, explaining the design process, creating a realistic product, and testing and evaluating product performance. In addition, it was concluded that the students use their academic and technical skills effectively. The study presents in detail the preparation and implementation process of this activity, which we think may help educators uncover and improve students’ engineering skills.  相似文献   
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