全文获取类型
收费全文 | 82篇 |
免费 | 11篇 |
国内免费 | 10篇 |
专业分类
化学 | 16篇 |
数学 | 33篇 |
物理学 | 54篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 3篇 |
2002年 | 9篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
排序方式: 共有103条查询结果,搜索用时 16 毫秒
1.
以配体菲咯啉取代苷脲(L), 分别与CoCl2·6H2O、CuCl2·2H2O进行配位反应, 得到2个配合物{[Co(L)(H2O)3]Cl2·2H2O}n(1)和[Cu2(L)2Cl4]·3C2H5OH(2)。并用元素分析、FTIR和X-射线单晶衍射进行了表征。晶体结构表明:配合物1属于正交晶系, P212121空间群, 每个Co(Ⅱ)的配位环境为扭曲的八面体, 分别与1个配体上菲咯啉单元的2个氮原子、另外1个配体的羰基氧原子和3个水分子配位, 配合物中每个配体 L 表现为三齿配体分别与2个Co(Ⅱ)离子配位桥联形成一维链状结构。配合物2属于单斜晶系, P21/n空间群, Cu(Ⅱ)的配位环境为扭曲的四方锥形, 分别与配体上菲咯啉单元的2个氮原子和3个氯原子配位, 3个氯原子中有2个氯原子同时和2个Cu(Ⅱ)离子配位, 从而使配合物2形成双核配合物。 相似文献
2.
近年来, 过渡金属硫族化合物(TMDs)作为一种新兴的二维材料, 因其独特的层状结构及电学特性成为超级电容器电极材料的理想候选者之一. 本文介绍了二维TMDs的常用合成方法, 阐述了钼基、 钨基和钒基等TMDs在超级电容器中的研究进展, 分析了形貌、 尺寸和改性方法等因素对TMDs材料电化学性能的影响, 并对TMDs在超级电容器领域的工业化应用和挑战进行了总结与展望. 相似文献
3.
4.
5.
Effects of pulse chirp on supercontinuum produced in dispersion decreasing fibre 总被引:1,自引:0,他引:1 下载免费PDF全文
The supercontinuum (SC) source plays a key role in wavelength division multiplexing over the optical time division multiplexing (WDM/OTDM) transmission system. The SC produced in dispersion decreasing fibre (DDF) is wider and flatter than that produced in dispersion shifted fibre (DSF). In this paper, a SC producing process in DDF is numerically simulated, the effects of pump pulse chirp on the SC width and flatness are initially studied and the corresponding theoretical explanations are given. Particularly, we have analysed and compared the evolutions of the SC along DDF pumped by different chirp pulses. Several valuable conclusions are obtained. 相似文献
6.
以1,10-邻菲咯啉为原料,经氧化反应合成了1,10-邻菲咯啉-5,6-二酮(1);1与对氟苯甲醛反应合成了2-苯基(4-氟)-咪唑[4,5]-1,10-邻啡咯啉(2).1和2的结构经1H NMR,MS和X-射线单晶衍射表征.1为正交晶系,Pna21空间群,晶胞参数为:a=14.329 0(4)(A),b=12.370 0(3)(A),c=6.395 6(16)(A),α=90°,β=90°,γ=90°,V=1 133.5(5)(A)~3,Z=14,Dc=2.521 g·cm~(-3),μ=12.430 mm~(-1),F(000)=789,最终偏离因子R=0.039 8,wR=0.114 7.2为单斜晶系,P21/n,空间群晶胞参数为:a=9.810 0(4)(A),b=10.951 0(4)(A),c=17.3670(7)(A),α=90.000°,β=99.042(5)°,γ=90.000°,V=1 842.5(12)(A)~3,Z=4,Dc=1.292 g·cm~(-3),μ=0.095mm~(-1),F(000)=732,最终偏离因子R=0.091 2,wR=0.334 9. 相似文献
7.
8.
Polarization mode dispersion (PMD) mitigation is performed using an optical 3R (re-amplification, reshaping, re-timing) regenerator based on electro-absorption modulator (EAM) with wavelength conversion. System performance without and with 3R regeneration was separately studied by eye analysis and bit-error rate (BER) measurements. The signal quality was significantly improved by 3R regeneration under serious first order PMD (up to 40% of the bit interval) combined with second order PMD (up to about 520 ps2). The PMD mitigation margin of the proposed method is also investigated by measuring the sensitivity at BER 10-10. Further studies indicate that 3R regenerators have the potential to combat with the effects of PMD combined with polarization dependent loss (PDL) and polarization hole-burning (PHB). 相似文献
9.
A Fabry-Perot(F-P)etalon and a semiconductor optical amplifier(SOA)were combined to preprocess thedata signals before clock recovery.With this technology in the 10-Gb/s clock recovery utilizing injectionmode-locked laser(IMLL)based on SOA,the amplitude fluctuation and timing jitters caused by thepattern effect in recovered clock pulses were greatly reduced,experimentally.It also demonstrated thatclock could be recovered from the very degraded signals. 相似文献
10.
A math model that can describe the effect of stimulated Raman scattering (SRS) on pilot-tone detection technique is proposed. Thrugh numerical simulation, it is shown that the effect of SRS could produce ghost-tones. The power of ghost-tones was larger for the channels separated further from the real-tone.The power ratio between real-tone and ghost-tones increases linearly with the increase of transmission length when propagation distance longer than 300 km. 相似文献