贵州蕨类植物科,属检索（中）

（按上文）45（44）t绿植物;根状茎上的鳞片厚,不透明-·--··5.粉背蔽属AICuritoptCriSFb45X绿植物;根状茎上的鳞片薄而半透明……………………80.薄鳞g属LeptolepidiumShingetS.K.Wu46（4）叶下面密生绒毛;抱于囊群仅幼时为多少反卷的叶边覆盖,成熟后无盖—…………………………………·103.隐囊蔽属NotholacnaR.Br.46叶下面无浓密的黄色绒毛;羹群盖明显……………………………………………4747（4）囊群盖不连续,彼此分离呈三角形或半圆形等—……………………………………·26.碎米废属ChcilosonaTroy.47羹群盖连续,线形,偶中断…     

运动粒子全息测试仪

本文论述了用序列脉冲激光在4F光学系统中测量各种情况下的喷雾粒子大小、分布及运动速度的同轴全息和离轴全息方法。并讨论了仪器的结构原理,特点。文章共分了四个部分: 1)用4F光学系统测量微粒子的基本原理。 2)光学系统结构的特点。 3)红宝石脉冲激光光源。 4)仪器的组成及性能指标。     

《大学物理学》（音像文字结合教材）现代教育技术在大学物理教学中应用研讨会纪要

经国家教委高教司[1997]74号文批准，由江苏省教委和东南大学联合主办的“《大学物理学》(音像文字结合教材)暨现代教育技术在大学物理教学中应用研讨会”于1997年12月15日至17日在南京东南大学召开，来自全国17个省、市的32所高校代表50余人出席了这次会议。     

贵州蕨类植物科,属检索（上_

本文根据贵州现知材料，依秦依昌１９８７年系统编制蕨类植物科、属检索表，供应用，教学及理论研究之需。     

V2Ga5的晶体结构

本文利用单晶与粉末衍射方法测定了V₂Ga₅的晶体结构。V₂Ga₅属四方晶系,其单相区约为VGa₂—V₂Ga₅。在18℃的点阵常数是a=8.9540?,c=2.6892?,每个晶胞含有二个化合式量,空间羣为D_4h⁵—P4/mbm。V原子与Ga原子分别占据在4(h)与8(i),2(d)的等效位置上。参数为:x相似文献   

几何光学的现代理论—光线力学

本文介绍了几何光学的最新发展，系统论述了经典光线力学和量子光线力学的基本概念，讨论了光线力学对传统几何光学和波动光学的影响及其发展前景．     

含有长程拓扑性无序螺位错晶格中因势场引起的散射态和束缚态

螺位错的长程拓扑性无序对固体中所传播的波提供特殊的介体。用这种介体研究电势对电子态的影响。作为简单的例子要使用方势阱模型。在这种介体中用相移分析法能成功地得到散射解。未微扰的波函数不是平面波而是Aharouov-Bohm方程的严格解。束缚态能级的数目和位置依赖于电子的耦合和拓扑性无序。     

铝、铜、镍三元合金系中τ相的晶体结构变迁

A thorough investigation by means of X-rays has been carried out with the purpose to determine the nature of the ternary phase τ in Al-Cu-Ni alloys. In contrast with the conventional concept of alloy phase which is characterized by a definite type of crystal structure, systematic structure changes are found in the single phase field of τ which occupies quite an extensive area in the isothermal section of the phase diagram at room temperature. There are eight types of structures altogether, all derived from a basic rhombohedron with corners occupied by Al atoms and centres either occupied by the heavy atoms or remaining vacant. The basic rhombohedron is the building stone in the crystal architecture. By transforming the basic rhombohedron into a hexagonal prism in the usual way, all structures may be considered to be built up by stacking together a number of these hexagonal prisms along the triad. The transformation of one structure into another is quite systematic in the way that the number of the stacking stories in the unit cell increases according to the order 10, 11, 12, 13, 14, 15, 16, 17. The atomic arrangements in the different structures are closely related too, in the respect that they are all superstructures due to the presence of ordered vacancies in the rhombohedral centres.The principal factor controlling the formation of these structures has been fully considered. In view of the fact that the change of structure types follows closely with the content of Ni or Cu for alloys of constant Al content, the atomic size factor appears to be unimportant in the formation of these alloys. It has been shown that for alloy phases of the defect lattice type as the r-phase, the most fundamental factor is the average number of valency electrons per structural unit which is the basic rhombohedron in the present case. By assuming Hume-Rothery's valencies, the average number of valency electrons remains remarkably constant throughout the entire phase field, while the electron concentration varies with compositions. It has also been pointed out that for alloy phases where there is no unit cell change, the average number of electrons per structural unit is equivalent to the number of electrons per unit cell, and for alloy phase where there is no defect, this is in effect equivalent to the electron concentration.