小朋友学习珠心算

第二节 10以内数的综合认识     

浅议我国近代心算

科学技术的发展一般不能采取与普通历史的划分方法进行划分,这主要是看科技文化本身发展状况。在我国,冲击旧文化建立新文化是以五四运动为标志。因为这个时期,西洋文化向中国传播比较快,从事科学研究的人们主要工作是将西方文化和东方文化结合起来。例如在珠算书上用了一些数学公式,讲究珠算与笔算的结合,强调技巧性的速算。 民国时期对计算方式有所改进,根据一些资料反映,最大的改进是除法。 李曦钟《珠算汇宗》提出“希仲归除法”,实际上是对金蝉脱壳法的改进。在20世纪30年代有陈耿光、俞子夷提倡珠     

俱乐部回音：小学二年级珠心算数学模拟竞赛题分析与解答

这10道题中,有基础题,也有趣味题,还有智慧题,既源于教材,又高于教材。你答对了多少题?拿到了金、银、铜和优胜的哪个奖项?得奖固然可喜,没得奖并不可悲,贵在参与。展卷有益,答题获智。不管得奖者还是没得奖者,希望你们都来关注“俱乐部回音”,从我们的分析与解答中,受到启迪,开阔思路,提高解题的技     

论珠算教练学（续）

在工厂里，师傅带徒弟实质是一个教练过程；母亲教孩子洗衣、做饭，也是一个教练过程。教和练是人们生活中、生产中一个很普通的问题。在现代，生产需要竞争；体育需要技能的角逐；科学需要智力的竞赛；计算需要竞技．……。这些都需要我们从原始的教练方式转化成科学的指导方式。这就是产生教练学的社会基础和需要。     

Holographic and Thermal-Fixing Characteristics of Doubly Doped Zn：Fe：LiNbO3 Crystals

We perform a comprehensive experimental study on holographic and thermal-fixing characteristics of Zn：Fe：LiNbO3 The measured hologram decay time constants, respectively caused by optical readout and under dark condition, with thermal fixing are 15 times and 75 times longer than that obtained without thermal fixing. This suggests that Zn：Fe：LiNbO3 crystals are suitable for thermal fixing. Multiplexed recordings of 300 holograms using different thermal fixing schemes verify that a proper multiplexing scheme such as track-division thermal-fixing scheme for disc-type holographic storage can effectively compensate for the negative effect of zinc-doping on the dynamic range, thus the storage density is enhanced.     

光学神经网络中硬件误差对性能影响的分析

利用统计方法，分析了光学硬件误差对用Ｈｏｐｆｉｅｌｄ神经作联想记忆时出错率的影响，导了系统的误差与错率关第的近似公式，并给出了模拟结果。得到了一定限度的误差对出错率的影响并不显著的的结论，特别坚探讨测器阵列动态范围的要求，可以远远小于其探测到的最大值。这对光学神经网络系统的设计及硬件的选取，具有指导意义。     

Possible Experimental Evidence of a Moderate Proton Halo in ^29S

The total reaction cross sections (TRCSs) of^29S ^28Si have been measured at intermediate energies. An obvious enhancement in TRCS of ^29S is observed as compared with its neighbouring nuclei. The TRCSs of ^29S ^28Si arecal culated with the modified Glauber theory in the optical limit and few-body approaches. The different factor d as a possible measure of halo appearance is deduced from the experimental and theoretical data. It is well accepted that ^27p is a proton halo nucleus. Although not as anomalous as ^27p, the different factor d of ^29S is obviously larger than that of its neighbouring isotones of N = 13. This result indicates that a moderate proton halo may exist in ~9S nucleus. We calculate the total reaction cross sections for ~9S with the modified Glaubertheory as a function of incident energy and compare the results with those for 2rSi which is a core nucleus 0f29S.The measured TRCSs of 27Si4-2SSi can be described to be satisfactory by the modified Glauber theory of theoptical limit approach. Although a diffused nuclear density distribution is used, the theories still inadequatelypredict the experimental TRCSs of 29S4-2SSi, which further indicates the possibility of proton halo in 29S.     

双曲线的定值问题的应用拾零

双曲线的定值问题的应用拾零玉邴图（云南广南一中６６３３００）本文介绍双曲线的几个定值问题，并举例说明它们在解题中的应用．问题１ＡＢ是过双曲线ｂ２ｘ２－ａ２ｙ２＝ａ２ｂ２中心Ｏ的弦，Ｐ是双曲线上任一点，则ｋＰＡ·ｋＰＢ为定值．证设Ｐ，Ａ的坐标分别为（ａ...     

缓蚀剂对金属钆在水介质中腐蚀行为的影响

采用失重法、腐蚀电化学方法研究了NaOH、NH4OH、单宁酸和苯并三氮唑等缓蚀剂对金属钆在水介质中腐蚀行为的影响。在没有缓蚀剂的情况下,钆在水中发生明显的点蚀,腐蚀速度为0.152g.m-2.h-1。NaOH能有效地控制金属钆在水介质中的腐蚀,经8880h的长时间浸泡,钆表面依然呈现明显的金属光泽,没有失重与点蚀发生。当采用NaOH调节苯并三氮唑(BTA)溶液的pH值接近中性时,钆在其中长时间浸泡,同样没有失重发生,表观没有发现点蚀发生。选择合适的缓蚀剂,使得钆能够在水介质中不发生腐蚀,保证了磁制冷机的长时间正常运转。