全文获取类型
收费全文 | 153篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 127篇 |
晶体学 | 5篇 |
数学 | 1篇 |
物理学 | 23篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2017年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 7篇 |
2011年 | 12篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有156条查询结果,搜索用时 10 毫秒
1.
Y. Zhang T. M. Benson P. Sewell A. Vukovic D. Zhang W. J. Pan A Loni D. Furniss A. B. Seddon 《Optical and Quantum Electronics》2006,38(1-3):97-110
This paper presents our recent simulation results and novel designs of single mode large cross-section glass-based waveguides for photonic integrated circuits (PICs). Simulations were performed using an in-house Finite Difference (FD) based mode solver and the FD Beam propagation Method (FD-BPM). Our simulation results show that this innovative technology could provide a simplified means to couple optical energy efficiently between optical components in a single chip. This would provide the base for the future large-scale integration of optical components in PICs. The novel idea of using single mode large cross-section glass-based waveguides as an optical integration platform is an evolutionary innovative solution for the monolithic integration of optical components, in which the glass-based structures act both as waveguides and as an optical bench for integration. This allows easy and efficient optical coupling between optical components and optical fibres, removing costly and tedious alignment problems and considerably reducing optical coupling losses in PICs. We expect that the glass-based waveguide PICs technology will enable the emergence of a new generation of compact, reliable, high speed, and multifunctional devices. 相似文献
2.
Kenneth R. Seddon 《Journal of organometallic chemistry》1985,293(1):C21-C25
A close examination of the ESR spectrum of a paramagnetic complex formed from bis(ethoxythiocarbonyl)sulfide and dimanganese decacarbonyl has revealed, for the first in this type of radical adduct, 13C hyperfine coupling in natural abundance from the carbonyl ligands. 相似文献
3.
The results detail a novel methodology for the electrochemical determination of ammonia based on its interaction with hydroquinone in DMF. It has been shown that ammonia reversibly removes protons from the hydroquinone molecules, thus facilitating the oxidative process with the emergence of a new wave at less positive potentials. The analytical utility of the proposed methodology has been examined with a linear range from 10 to 95 ppm and corresponding limit-of-detection of 4.2 ppm achievable. Finally, the response of hydroquinone in the presence of ammonia has been examined in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide, [EMIM][N(Tf)2]. Analogous voltammetric waveshapes to that observed in DMF were obtained, thereby confirming the viability of the method in either DMF or [EMIM][N(Tf)2] as solvent. 相似文献
4.
平行双铂丝微电极用于铁氰化钾电流滴定法测定抗坏血酸的研究 总被引:2,自引:0,他引:2
平行双柱微电极是一种基于可逆氧化还原物质在电极间反馈扩散使得信噪比进一步增大的新型微电极,作者首次将这种电极应用于电流滴定分析中。结果显示,电极间距很小时,终点突跃变敏锐,使灵敏度进一步提高。该方法不需搅拌溶液,单次测量样品量只需约3μ1,是一种有实用价值的新方法。 相似文献
5.
The lattice energies of a series of organic dihydrogenphosphate salts capable of second harmonic generation (SHG) have been calculated. These calculations, coupled with empirical data, indicate that a minimum of 20–25% of the lattice energy arises from hydrogen-bond interactions. Hydrogen bonding is shown to be a strong enough force to have a profound effect on the overall packing and crystal geometry of such ionic materials, and is thus an important factor to consider for crystal engineering. 相似文献
6.
Pulse radiolysis of tetrahydrofuran (THF) and solutions of NaAIH4 in THF shows the formation of solvated electrons (e?s), their conversion to Na+-e?s) ion-pairs and ultimately the alkali metal anion (Na?). 相似文献
7.
Kenneth R. Seddon 《Journal of organometallic chemistry》1985,290(1):c11-c12
2-Aziridine-2-chlorocarboxylic acid alkyl esters have been prepared in basic alcoholic medium from alkyl dichloroacetate and aromatic imines by an extension of the Darzens reaction. 相似文献
8.
Bras W Emsley JW Levine YK Luckhurst GR Seddon JM Timimi BA 《The Journal of chemical physics》2004,121(9):4397-4413
The field-induced alignment of a smectic-A phase is, in principle, a complicated process involving the director rotation via the interaction with the field and the layer rotation via the molecular interactions. Time-resolved nuclear magnetic resonance spectroscopy has revealed this complexity in the case of the director alignment, but provides no direct information on the motion of the layers. Here we describe a time-resolved x-ray diffraction experiment using synchrotron radiation to solve the challenging problem of capturing the diffraction pattern on a time scale which is fast in comparison with that for the alignment of the smectic layers. We have investigated the alignment of the smectic-A phase of 4-octyl-4(')-cyanobiphenyl by a magnetic field. The experiment consists of creating a monodomain sample of the smectic-A phase by slow cooling from the nematic phase in a magnetic field with a flux density of 7 T. The sample is then turned quickly through an angle phi(0) about an axis parallel to the x-ray beam direction but orthogonal to the field. A sequence of two-dimensional small angle x-ray diffraction patterns are then collected at short time intervals. Experiments were carried out for different values of phi(0), and at different temperatures. The results show that the alignment behavior changes fundamentally when phi(0) exceeds 45 degrees, and that there is a sharp change in the alignment process when the temperature is less than 3 degrees C below the smectic-A-nematic transition. The results of the x-ray experiments are in broad agreement with the NMR results, but reveal major phenomena concerning the maintenance of the integrity of the smectic-A layer structure during the alignment process. 相似文献
9.
Pulse radiolysis of solutions of alkali metals in methylamine and ethylamine shows the formation of three distinct species; the solvated electron e?s, the alkali metal anion M? and a species considered to be a metal—electron pair with stoichiometry M. Hitherto no kinetic or conclusive optical evidence has been obtained for the species M in amine solutions. The three species coexist in equilibrium according to the equation c?s + M+ ? M + e? ? M? with the corresponding rate constants markedly dependent on the solvent and nature of the alkali metal. 相似文献
10.
Kenneth R. Seddon 《Journal of organometallic chemistry》1984,270(1):c31-c32
The preparation of the first mixed metal cyclometallated compounds [ClPtCl]n (R = H, Cl) are reported; they were made from monocyclopalladated [(AcO)PCH(p-RC6H4)]2 and PtCl42?. 相似文献