全文获取类型
收费全文 | 236篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 140篇 |
晶体学 | 3篇 |
力学 | 8篇 |
数学 | 48篇 |
物理学 | 47篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有246条查询结果,搜索用时 0 毫秒
21.
We discuss the influence of the higher-order Kerr effect (HOKE) in wide bandgap solids at extreme intensities below the onset of optically induced damage. Using different theoretical models, we employ multiphoton absorption rates to compute the nonlinear refractive index by a Kramers-Kronig transform. Within this theoretical framework we provide an estimate for the appearance of significant deviations from the standard optical Kerr effect predicting a linear index change with intensity. We discuss the role of the observed saturation behavior in practically relevant situations, including Kerr lens mode-locking and supercontinuum generation in photonic crystal fibers. Furthermore, we present experimental data from a multiwave mixing experiment in BaF2, which can be explained by the appearance of the HOKE. 相似文献
22.
23.
We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the third-order nonlinear optical absorption coefficients for the 1s-1p, 1p-1d, and 1d-1f transitions are examined as a function of the incident photon energy for three different values of the stoichiometric ratio. The results show that the stoichiometric ratio, impurity, relaxation time, and dot size have great influence on the optical absorption coefficients of QDs. 相似文献
24.
U. Kürüm R. M. Öksüzoğlu M. Yüksek H. G. Yaglioglu H. Çınar Ayhan Elmali 《Applied Physics A: Materials Science & Processing》2011,104(4):1025-1030
We studied the nonlinear absorptive characteristics (saturation intensity threshold and effective nonlinear absorption coefficients)
and nonlinear refraction in a 50-nm-thick VO
x
thin amorphous film prepared by pulsed DC magnetron reactive sputtering. The absorptive and refractive nonlinearities were
investigated by pump–probe and Z-scan techniques. The closed-aperture Z-scan results reveal self-defocussing characteristics
of the amorphous VO
x
thin film for both nanosecond and picosecond pulse durations. Experimental results show that a phase transition does not
occur in the range of intensities used for the experiments and the investigated sample can be treated as an amorphous semiconductor
structure. The open-aperture Z-scan curves with nanosecond pulses exhibit saturable absorption for all input intensities.
On the other hand, the open-aperture Z-scan curves with picosecond pulses exhibit nonlinear absorption/saturable absorption
for low/high input intensities, respectively. Saturation intensity thresholds were found to be 15.3 MW/cm2 for 4-ns pulse duration and 586 MW/cm2 for 65-ps pulse duration. 相似文献
25.
Vagif Sabir Guliyev Turhan Karaman Rza Chingiz Mustafayev Ayhan Şerbetçi 《Czechoslovak Mathematical Journal》2014,64(2):365-386
In this paper, the boundedness of a large class of sublinear commutator operators T b generated by a Calderón-Zygmund type operator on a generalized weighted Morrey spaces \({M_{p,\varphi }}(w)\) with the weight function w belonging to Muckenhoupt’s class A p is studied. When 1 < p < ∞ and b ∈ BMO, sufficient conditions on the pair (φ 1, φ 2) which ensure the boundedness of the operator T b from \({M_{p,\varphi 1}}(w)\) to \({M_{p,\varphi 2}}(w)\) are found. In all cases the conditions for the boundedness of T b are given in terms of Zygmund-type integral inequalities on (φ 1, φ 2), which do not require any assumption on monotonicity of φ 1(x, r), φ 2(x, r) in r. Then these results are applied to several particular operators such as the pseudo-differential operators, Littlewood-Paley operator, Marcinkiewicz operator and Bochner-Riesz operator. 相似文献
26.
27.
28.
29.
Ayhan Elmali Yalcn Elerman Ingrid Svoboda 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):375-376
The crystal structure of the title compound, {bis[2‐(2‐oxido‐2‐naphthylideneamino)phenyl] disulfide‐κ5O,N,S,N′,O′}chloroiron(III), [FeCl(C34H22N2O2S2)], has been determined. The structure consists of monomeric iron(III) complexes with distorted octahedral coordination. The disulfide functions as a pentadentate ligand and the FeIII atom is coordinated through two N, two O and one S atom, and one chloride ion. The distance between the second S atom and the FeIII atom is a non‐bonding 3.8473 (14) Å. 相似文献
30.
Produced water constitutes a large amount of waste fluids during the production operation of an oil field. Underground injection for disposing the wastewater from hydrocarbon production is an engineering problem due to the possibility of leakage of injected pollutant material from receiving medium to a drinking water source. This paper describes a method for optimization of polluted aquifer remediation design using one of the artificial intelligence optimization methods, namely Genetic Algorithms (GAs). As a case study, the contaminated area was created by using a groundwater transport simulator, which is based on Method of Characteristics (MOC). Then, the developed computer program was run to find the optimum solution for remediation, and the solution yielded from the program was verified by using a groundwater simulator. The plume was captured and the concentration level of chloride ion within the aquifer was diminished by using extraction wells. The analytical model approach provided different alternatives for appropriate isolation of plume. GAs were used as an optimization technique for making a decision among the alternatives, by considering operation time, number of wells, pumping rate and drawdown as decision variables and constraints. 相似文献