近年,在"连接学习"理论的支持下,美国面向青少年开展了大量基于"连接学习"的数字阅读推广项目,其中"你的媒体"(Youmedia)、"探索学习"(Quest to Learn,简称Q2L)等项目已经取得了一定的推广效果...近年,在"连接学习"理论的支持下,美国面向青少年开展了大量基于"连接学习"的数字阅读推广项目,其中"你的媒体"(Youmedia)、"探索学习"(Quest to Learn,简称Q2L)等项目已经取得了一定的推广效果,在美国多个州立学校和公共图书馆得到推广。基于"连接学习"的数字阅读推广项目采取"兴趣驱动"的设计,为青少年塑造同辈文化环境和明确的学术目标,以青少年数字内容创作和生产能力培养为重点,着力为数字时代"创造性人才"培养服务,对于我国创新创业人才培养和数字阅读推广项目的设计和开展具有一定的启发意义。展开更多
The problem of reconstructing a signalφ（x） from its magnitude ｜φ（x）] isof considerable interest to engineers and physicists. This article concerns the problem of determining a time-limited signal f with period ...The problem of reconstructing a signalφ（x） from its magnitude ｜φ（x）] isof considerable interest to engineers and physicists. This article concerns the problem of determining a time-limited signal f with period 2π when ｜f（eix）l is known for x∈[-π,π]. It is shown that the conditions ｜g（eix）｜ = ｜f（eix）｜ and ｜g（ci（x＋b）） -g（eix）｜ =f（ei（x＋b）） - f（eix）｜, b ≠ 27π, together imply that either g = wf or g = v f, where both w and v have period b. Furthermore, if b/2π is irrational then the functions w and v b is rational then w takes the form reduce to some constants c1 and c2, respectively; ifb/2π is rational then w takes the form w=elexB1（e1x）B2（elx）and v takes the form ei（x2πN/b＋a）B1（elx）B2（elx）,where B1 and B2 are Blaschke products.展开更多
Purpose： We want to contribute to the evaluation of Chinese research, focusing on contributions in top journals. Design/methodology/approach： Using a Mann-Whitney test we investigate if contributions in Nature, Scie...Purpose： We want to contribute to the evaluation of Chinese research, focusing on contributions in top journals. Design/methodology/approach： Using a Mann-Whitney test we investigate if contributions in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America （PNAS） by Chinese or American authors only, i.e. articles for which all authors have a Chinese or an American address, have a different citation potential. Findings： There is no reason to state that Chinese and American contributions in these top journals have a different citation potential. Research limitations： Because of the small numbers involved we were not able to make a distinction between publications in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America. Practical implications： These results suggest that the better Chinese research results are of a similar level as those by American colleagues. Originality/value： It is well-known that the number of citations per publication by Chinese authors is still lagging with respect to leading scientific nations and in particular compared with the USA. We have shown that this difference does not necessarily hold in contributions in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America.展开更多
文摘近年,在"连接学习"理论的支持下,美国面向青少年开展了大量基于"连接学习"的数字阅读推广项目,其中"你的媒体"(Youmedia)、"探索学习"(Quest to Learn,简称Q2L)等项目已经取得了一定的推广效果,在美国多个州立学校和公共图书馆得到推广。基于"连接学习"的数字阅读推广项目采取"兴趣驱动"的设计,为青少年塑造同辈文化环境和明确的学术目标,以青少年数字内容创作和生产能力培养为重点,着力为数字时代"创造性人才"培养服务,对于我国创新创业人才培养和数字阅读推广项目的设计和开展具有一定的启发意义。
基金Supported by Foundation of Hubei Educational Committee (Q20091004)NSFC (10771053)+1 种基金the National Research Foundation for the Doctoral Program of Higher Education of China (SRFDP) (20060512001)Natural Science 373 Foundation of Hubei Province (2007ABA139)
文摘The problem of reconstructing a signalφ（x） from its magnitude ｜φ（x）] isof considerable interest to engineers and physicists. This article concerns the problem of determining a time-limited signal f with period 2π when ｜f（eix）l is known for x∈[-π,π]. It is shown that the conditions ｜g（eix）｜ = ｜f（eix）｜ and ｜g（ci（x＋b）） -g（eix）｜ =f（ei（x＋b）） - f（eix）｜, b ≠ 27π, together imply that either g = wf or g = v f, where both w and v have period b. Furthermore, if b/2π is irrational then the functions w and v b is rational then w takes the form reduce to some constants c1 and c2, respectively; ifb/2π is rational then w takes the form w=elexB1（e1x）B2（elx）and v takes the form ei（x2πN/b＋a）B1（elx）B2（elx）,where B1 and B2 are Blaschke products.
基金supported by the National Natural Science Foundation of China(Grant No.:71173185)
文摘Purpose： We want to contribute to the evaluation of Chinese research, focusing on contributions in top journals. Design/methodology/approach： Using a Mann-Whitney test we investigate if contributions in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America （PNAS） by Chinese or American authors only, i.e. articles for which all authors have a Chinese or an American address, have a different citation potential. Findings： There is no reason to state that Chinese and American contributions in these top journals have a different citation potential. Research limitations： Because of the small numbers involved we were not able to make a distinction between publications in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America. Practical implications： These results suggest that the better Chinese research results are of a similar level as those by American colleagues. Originality/value： It is well-known that the number of citations per publication by Chinese authors is still lagging with respect to leading scientific nations and in particular compared with the USA. We have shown that this difference does not necessarily hold in contributions in Nature, Science or the Proceedings of the National Academy of Sciences of the United States of America.
