开关电源稳压器—L4960的原理及应用

简要介绍单片开关集成稳压器Ｌ４９６０的性能特点，阐述同Ｌ４９６０构成的开关电源的工作原理，给出了应用电路的设计方法和设计要点。     

棉花质量的模糊分级方法探讨

利用模糊数学中的模糊聚类思想,本文提出了一套新的评定棉花质量的方法、步骤。其对专家经验的符合率达85％,预报率达100％。它表明可以用该方法替代专家进行评定。     

The Primal Exploration of Space launch and Manned Lunar-landing

The lunar-landing is the continuity of manned spaceflight engineering. Comparing with the manned spacecraft engineering, it requires more reliability , larger scale, and more funds. On the basis of China＇ s achievements and the experiences of foreign com~tries, the paper brings forward the idea that using the existing transportation technology to send the launch vehicles and cosmonauts to the near-earth orbit in batches, assembling the components together on the space-launch platform, and then launching them to the moon to fulfill our dream of manned landing on the moon. The paper also discusses the space launch platform and the launching ways.     

函数空间L~(p_1,p_2,…,p_n)(X_1×X_2×…×X_n)

本文研究函数空间L~(p1,p2,…，pn)（X1×X2×…×Xn），它是L~P（X）的推广。同时还推广了积分型Minkowski不等式和Holder不等式。     

原子吸收限附近Laue情况的摇摆曲线

在Ｇａ的Ｋ吸收限附近，测定了ＧａＡｓ（２００）对称Ｌａｕｅ情况的衍射波和透射波的摇摆曲线，将测定的透射波的摇摆曲线和Ｘ射线衍射动力学理论的相应计算结果作了定量比较     

归纳极限的一些性质

本文继续〔1〕进一步讨论归纳极限的一类特殊有界集——弱紧凸圆集的某些性质,得到定理1及使性质P成立的条件.     

Elastic wave velocity in rocks from Dabieshan and its constraints for lithospheric composition and crust-mantle recycling

P-and S-wave velocities in eclogites and granulites from the Dabie ultrahigh pressures (UHP) meta morphic belt, China, were measured at room temperature under the hydrostatic pressures up to 1.0 GPa. The ultrahigh pressure eclogites had the highest densities (3.3 ～ 3.6 g.cm-3) , high velocities and the lowest anisotropy (1.4%c ～ 2.6 % ) . The lowest densities (2.8 ～ 3.1 g. cm-3 ) and the highest Poisson' s ratios (0.28 ～ 0.29) were found in gran ulites, whereas the strongest anisotropies (6. 1 % ～8.4% ) were found in the high-pressure (HP) eclogites. Compari son of the velocities in rocks with that observed in the deep seismic sounding profile crossing Dabieshan suggests that e clogites might exist in the lower crust of Dabieshan, but the quantity might be small. The upper mantle has very similar velocities as the UHP eclogites and serpentinizated/water-bearing dunite. The formation of eclogite represents the crust mantle recycling processes. Crustal material is delaminated and sinks into the mantle by way of eclogite, whereas only a small part of the eclogite could return to the crust.     

X射线荧光分析测定不同品牌大米中的微量元素

大米是人类从外界获得营养的主要方式之一,大米中的微量元素对人体的健康有重要的意义.为人体合理补充微量元素提供参考意见.本文利用X射线荧光分析方法并结合干灰化样品前处理方法研究了岳阳、五常、新民、哈尔滨、万昌等5种不同品牌大米中K、Ca、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Se、Sr等微量元素的含量;同时,用毛细管X光透镜聚焦的微束X射线荧光扫描了单粒大米中多元素的分布.结果表明,5种品牌大米中所含微量元素种类基本相同,五常大米中对人体有益的元素Ca、Fe、Ni、Zn等含量较高;此外,P、Cl、K、Ca等元素主要富集在大米的胚芽处.大米中微量的金属元素Fe、Cu、Zn等元素分布均匀.     

古代商人阶级的形成及其治生之学

春秋时代,随着宗法制解体,商业和商品经济的发展,古代第一个商人阶级相应形成。作为商人阶级的代表,范蠡、白圭等人总结商业经验和规律,形成了一套不同于管仲富国之学和孔子富民之学的新的经济理论——商人治生之学。它在理论上独特的创新价值值得重视和研究。     

城市电视电波传播特性探讨

选取矩形柱体作城市楼房模型。利用广州14频道电视电波测量楼房外墙反射系数模,确定其等效电参量。用一致性几何绕射理论计算直角导电直劈绕射场,与实测数据进行比较。根据反射系数模曲线、直角劈绕射场曲线,对城市电视电波传播特性进行探讨,估计可能产生的重影。