全文获取类型
收费全文 | 80篇 |
免费 | 12篇 |
国内免费 | 17篇 |
专业分类
化学 | 50篇 |
晶体学 | 1篇 |
力学 | 7篇 |
综合类 | 2篇 |
数学 | 9篇 |
物理学 | 40篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 2篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 9篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 46 毫秒
51.
First-principles identification of two- and four-membered-ring hybrid structures of silica nanorings
Zexiao Xi Mingwen Zhao Tao He Xuejuan Zhang Hongyu Zhang Zhenhai Wang Keyu Hou Yingcai Fan Xiangdong Liu Yueyuan Xia 《Physics letters. A》2009,373(47):4376-4380
We performed first-principles calculations to study the energetics, IR spectra, and electronic structures of silica nanorings (NR) consisting of two- and four-membered ring (2-4MR) units. A comparison study of other silica clusters, such as nanochains (NC) and nanorings formed by two-membered rings (2MRs) was made. The results show that for small-size (SiO2)n clusters with n<24, the nanochains composed of 2-4MRs (2-4MR-NCs) are more stable than other kinds of NRs and NCs. When n>24 the 2-4MR-NRs structures become energetically favorable. 2-4MR-NRs have the narrowest HOMO–LUMO gaps which increase with increasing cluster size, distinctive IR spectra characterized by several peaks at the 1000–1150 cm−1 region. 相似文献
52.
Based on the study and manufacture of the technical integration experiment line (TIL) prototype laser facility, and using the method that theoretical simulations guide experiments and experimental results check programs, the factors affecting third harmonic generation (THG) efficiency for a large-aperture, high-intensity inertial confinement fusion (ICF) laser facility have been analyzed and studied in detail. Furthermore, in the year 2004-2005, the output ability of a THG system for a TIL driver has been discussed adequately in a first beam eligibility experiment. As shown by experimental results, when the average drive irradiance of fundamental light, I1ω, is 2.7 GW/cm2, the measured value of THG efficiency is 50-55% and the theoretical value is 60%, which indicates that the experimental result agrees well with the theoretical value. 相似文献
53.
54.
由焦面附近光强分布实现波前重构 总被引:1,自引:0,他引:1
介绍了一种由光束在焦面附近几个面上的强度分布重构出光束近场波前的方法。把波前重构问题作为一个非线性优化问题,利用光束口径区域内的正交多项式模拟光束波前相位分布,通过优化多项式各项的系数,使对应的波前分布在焦面附近相应的几个面上的强度分布与已知强度分布的偏差最小,即认为由此时的多项式系数决定的近场波前代表了真实的光束波前。针对方光束口径,利用Legendre多项式模拟光束波前分布,利用共轭梯度算法对多项式系数进行了优化计算;优化过程分为几步进行以减少计算时间。重构得到的波前分布与参考波前分布符合得很好。 相似文献
55.
Zhang Wei Wang Zhiyuan Tao Li Duan Keyu Wang Hao Zhang Jun Pan Xu Huo Zhipeng 《Journal of Solid State Electrochemistry》2019,23(5):1563-1570
Journal of Solid State Electrochemistry - A series of Fe(III)-based coordination-driven metallogel (MOG) electrolytes are obtained by absorbing liquid electrolytes with MOGs and applied to... 相似文献
56.
Nan Li Qian Ye Kun Zhang Huibo Yan Chao Shen Bingqing Wei Keyu Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18414-18419
Inducing uniform deposition of lithium from the stage of metal crystallization nucleation is of vital importance to achieve dendrite‐free lithium anodes. Herein, using experiments and simulation, homogenization of Li nucleation and normalization of Li growth can be achieved on PNIPAM polymer brushes with lithiophilic functional groups modified Cu substrates. The lithiophilic functional groups of amide O can homogenize ion mass transfer and induce the uniform distribution of Li nucleation sites. What is more, the ultra‐small space between each brush can act as the channels for Li transportation and normalization growth. Owing to the synergistic effect of homogenization and normalization of electrodeposited Li, the obtained planar columnar Li anode exhibits excellent cycle stability at an ultra‐high current density of 20 mA cm?2. 相似文献
57.
钛酸钠纳米管-碳复合材料用作钠离子电容电池负极材料 总被引:1,自引:0,他引:1
以二氧化钛、氢氧化钠溶液和葡萄糖作为初始原料,通过水热方法合成了钛酸钠纳米管-碳复合材料。 使用XRD和TEM等方法测试了材料的结晶情况和形貌, 通过氮气吸-脱附和热重实验测试了材料的孔结构和碳含量。 采用复合材料作为负极材料,和石墨正极材料配伍,组装成不对称型电容电池,在钠基有机系电解液中其电压可高达3.5 V。 探讨了负极材料的储能机理,并考察了正负极质量比对负极储钠容量的影响。 电化学性能测试结果显示,电容电池具有较高能量密度和功率密度,其数值分别为72 Wh/Kg和1256 W/Kg,电容电池也表现出了较好的循环稳定性,在0.17 A/g电流密度下,经1000次循环后容量保持率高达100%。 相似文献
58.
59.
Fuyong Xu Jiao Li Keyu Zhao 《International Journal of Infrared and Millimeter Waves》1998,19(12):1745-1757
In this paper, a new type of horizontal-flat and vertical-flat closed elliptic-groove guides is firstly presented. The field components and characteristic equations for some main transmission modes of the closed elliptic-groove guides are derived by with the help of the mode-matching method and Mathieu function. The variations of the cut-off wavelengths along with eccentricities, widths and lengths of the parallel plates for a number of lower order transmission modes of the closed elliptic-groove guides are also analysed in detail. The calculated results in good agreement with ones in the relevant references are of very important values in theoretical researches and actual applications of closed elliptic-groove guides for millimeter and submillimeter waves. 相似文献
60.
Transmission characteristics of several kinds of closed groove waveguides for millimeter waves 总被引:1,自引:0,他引:1
Fuyong Xu Keyu Zhao Ling Zhao 《International Journal of Infrared and Millimeter Waves》1997,18(6):1307-1315
An advantage of closed groove guide over open groove guide is attended. In this paper, the several kinds of closed groove
guides including the trapezoidal-, elliptic- and parabolic-groove guides as new types of millimeter wave transmission lines
are presented. Their dispersion and cut-off characteristics of the dominant mode are analysed and compared with ones of the
closed V-and circular- groove guides by using the equivalent network method. The obtained results have important meaning in
theoretical studies and actual applications of groove waveguides. 相似文献