全文获取类型
收费全文 | 586篇 |
免费 | 27篇 |
国内免费 | 9篇 |
专业分类
化学 | 403篇 |
晶体学 | 4篇 |
力学 | 14篇 |
数学 | 28篇 |
物理学 | 173篇 |
出版年
2023年 | 4篇 |
2022年 | 18篇 |
2021年 | 22篇 |
2020年 | 16篇 |
2019年 | 16篇 |
2018年 | 27篇 |
2017年 | 15篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 30篇 |
2013年 | 43篇 |
2012年 | 31篇 |
2011年 | 46篇 |
2010年 | 18篇 |
2009年 | 26篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 12篇 |
2005年 | 16篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1997年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 6篇 |
1969年 | 6篇 |
1968年 | 7篇 |
1967年 | 6篇 |
1966年 | 5篇 |
排序方式: 共有622条查询结果,搜索用时 14 毫秒
1.
International Journal of Theoretical Physics - A realizable delayed-choice quantum eraser, using a modified Mach-Zehnder (MZ) interferometer and polarization entangled photons, is theoretically... 相似文献
2.
3.
Khan M. Ijaz Qayyum Sumaira Waqas M. Hayat T. Alsaedi A. 《Journal of Thermal Analysis and Calorimetry》2020,139(2):1291-1299
Journal of Thermal Analysis and Calorimetry - Here, MHD stagnation point flow of non-Newtonian fluid over a stretchable surface is considered. Process of modeling is characterized for basic... 相似文献
4.
In an erbium-doped fiber amplifier(EDFA), erbium ions act as a three-level system. Therefore, much higher pump energy is required to achieve the population inversion in an erbium-doped fiber(EDF). This higher pump energy requirement complicates the efficient design of an EDFA. However, efficient use of the pump power can improve the EDFA performance. The improved performance of an EDFA can be obtained by reducing the doping radius of the EDF. A smaller doping radius increases pump–dopant interactions and subsequently increases the pump–photon conversion efficiency. Decreasing the doping radius allows a larger proportion of dopant ions,which are concentrated near the core, to interact with the highest pump intensity. However, decreasing the doping radius beyond a certain limit will bring the dopant ions much closer and introduce detrimental ion–ion interaction effects. In this Letter, we show that an optimal doping radius in an EDF can provide the best gain performance. Moreover, we have simulated the well-known numerical aperture effects on EDFA gain performance to support our claim. 相似文献
5.
The paper is devoted to the study of elliptic quadratic operator equations over the finite dimensional Euclidean space. We provide necessary and sufficient conditions for the existence of solutions of elliptic quadratic operator equations. The iterative Newton-Kantorovich method for stable solutions is also presented.
相似文献6.
7.
Tanoori Betsabeh Zolghadri Jahromi Mansoor Mansoori Eghbal G. 《Journal of computer-aided molecular design》2021,35(8):883-900
Journal of Computer-Aided Molecular Design - In the field of drug–target interactions prediction, the majority of approaches formulated the problem as a simple binary classification task.... 相似文献
8.
9.
10.
Muhammad Ali Ehsan Muhammad Adil Mansoor Muhammad Mazhar Asif Ali Tahir Mazhar Hamid K. G. Upul Wijayantha 《应用有机金属化学》2012,26(9):493-498
A single molecular heterobimetallic complex, [Co2Ti(μ3‐O)(TFA)6(THF)3] (1) [TFA = trifluoroacetate, THF = tetrahydrofuran], was synthesized, structurally and spectroscopically characterized and implemented as a single‐source precursor for the preparation of CoTiO3–CoO composite thin films by aerosol‐assisted chemical vapour deposition (AACVD). The precursor complex was prepared by interaction of Co(OAc)2.4H2O [OAc = (CH3COO?)] with Ti(iso‐propoxide)4 in the presence of trifluoroacetic acid in THF, and was analysed by melting point, CHN, FT‐IR, single‐crystal X‐ray diffraction and thermogravimetric analysis. The precursor complex thermally decomposed at 480 °C to give a residual mass corresponding to a CoTiO3–CoO composite material. Good‐quality crystalline CoTiO3–CoO composite thin films deposited at 500 °C by AACVD and characterized through powder X‐ray diffraction and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy show that the crystallites have a rose‐flower‐like morphology with an average petal size in the range of 2–6 µm. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献