排序方式： 共有15条查询结果，搜索用时 15 毫秒
1.
2.
3.
耶稣会士所制《时宪历》被清朝用作官方历法后，朝鲜宫廷立即发起了掌握这一体系秘密的计划。此后一个多世纪中，朝鲜宫廷派遣了一系列官方使团到北京，向耶稣会士和清朝天文学家学习天文计算。之前的历史叙述把这一过程描绘成朝鲜对“西方”科学的引进。与此相反，本文将朝鲜后期引入西方天文学的事件重置于更恰当的历史背景，即中朝科学关系之中。首先，比起朝鲜人对新奇的西方科学纯智力上的兴趣，这一计划的产生，更多是由于李朝宫廷迫切需要同新的中国朝代保持一致的计时体系。第二，领导这个计划的官员们认为他们自己是在沿袭一个重要的历史先例，即15世纪早期世宗大王引入元朝《授时历》的计划。最后，为使由西方神父制作、“野蛮的”清王朝使用的历法体系合法化，朝鲜天文学家们赋予它一个新的文化身份；他们认为它并非完全源于西方，而是来自由徐光启和梅文鼎等中国士人发起的中西综合。更重要的是，因为《授时历》最初是由明朝主持制作的，可以看成是朝鲜王朝正确地采用了中国的高贵遗产——明朝灭亡后朝鲜是中国文化唯一合法的继承者。 相似文献
4.
5.
苏州河底泥重金属形态分析 总被引：2，自引：0，他引：2
Nine elements （As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn） in sediment samples at 7 sites （Site 1-7） from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference （BCR） （sequential extraction （SE）） protocol and simultaneously extracted metals （SEM）/acid volatile sulfide （AVS） procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 （Site 5） was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction （more than 50%）. While Cd, Ni and Zn （more than 35%） were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni （〉 40%） were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high Dorewater concentration. 相似文献
6.
This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless steel.The purpose of this study is to investigate the ultimate behaviors,such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel(low cost steel) rather than austenitic stainless steel(high cost steel).Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted connections.Specimens have a constant dimension of edge distance perpendicular to the loading direction,bolt diameter,pitch,and gauge.A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling(out of plane deformation) occurrence which led to strength reduction.The ultimate behaviors such as fracture mode,ultimate strength are compared with those predicted by current design codes.Further,conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect. 相似文献
7.
确定支配学生学习成绩的因素是一个具有挑战性的任务,这些因素包括：心理因素、社会因素、经济因素和环境因素等。马来西亚高教部开放入学政策强调学习者的年龄和他们以前的学术资格或学习经验。宏愿开放大学（WOU）研究结果显示,来自不同学术背景的学生注册课程的数量和年龄的差异并没有影响到他们的GPA成绩。然而,学生的学术背景或年龄差异单独作用时对GPA成绩就会产生很大影响。这一发现将为学生的学习支持服务系统的发展与改善提供有用信息。 相似文献
8.
目的:目前手动冲击锤设备缺乏对冲击时间的控制,容易引起冲击相位和周期荷载的周期性响应的相位同步问题。本文旨在通过使用异步自动冲击激励的自动冲击装置代替同步冲击模态分析中传统手动冲击锤的方法来解决上述问题。创新点:1.引入具有可调冲击参数的自动冲击装置;2.该装置可通过控制施加冲击的时间步来确保冲击和来自循环载荷组件的响应异步;3.当周期性响应的相位与装置所施加的冲击信号不一致时,加速响应中未知力源的影响会被降到最小。方法:1.分别使用数字方波信号的波峰和波谷来控制自动冲击装置的"开"和"关"状态;2.通过调控样本大小(1024个)、采样率(50 000个/秒)、占空比(0.5%)和冲击频率(97.78 Hz)(或周期)等参数得到不同的冲击图形。结论:1.使用可实现异步冲击的自动冲击装置可以估算第3阶自然模态;2.前3种自然模态可以被成功确定并与基准实验模态分析结果具有良好的相关性,表现为低于1.67%的自然频率差异,1.79%~12.54%的阻尼比差异以及介于0.893和0.925之间的模态置信度。3.针对谐波干扰对相位的影响,相比于使用手动冲击锤来增强频率响应函数估计和模态提取数据,使用可实现异步冲击的自动冲击装置是一种更可行的选择。 相似文献
9.
Developing reflective teachers: the experience of two modules in the teacher training programme at the national institute of education,Singapore 总被引：1，自引：0，他引：1
Pak?Tee?NgEmail author Lana?Khong?Yiu?Lan Jason?Tan?Eng?Thye 《Asia Pacific Education Review》2004,5(2):200-206
The Singaporean education system is undergoing many changes in order to develop schools and nation which cultivate learning
and education. A crucial success factor to these initiatives is the teacher. Singapore needs reflective teachers who can continually
reflect upon their own practices to find better ways of teaching as well as maintain their purpose and direction amid a sea
of changes. This article describes attempts during the years of 2002 to 2004 to develop trainee teachers into more reflective
teachers at the National Institute of Education (NIE), focusing specifically on the experience of two revamped pre-service
teacher education modules. The experience suggests that a social constructivist approach, in which trainee teachers discuss
and debate critical issues impinging on their professional practice, is more successful than the traditional ‘tell and regurgitate’
approach, in developing reflective teachers. 相似文献
10.