全文获取类型
收费全文 | 541篇 |
免费 | 18篇 |
专业分类
化学 | 293篇 |
晶体学 | 5篇 |
力学 | 33篇 |
数学 | 57篇 |
物理学 | 171篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 46篇 |
2012年 | 31篇 |
2011年 | 41篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 21篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 24篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1973年 | 4篇 |
1937年 | 2篇 |
1931年 | 2篇 |
1930年 | 2篇 |
1923年 | 1篇 |
排序方式: 共有559条查询结果,搜索用时 15 毫秒
551.
Paul Richardson Dr. Riccardo Marin Yixin Zhang Dr. Bulat Gabidullin Dr. Jeffrey Ovens Dr. Jani O. Moilanen Prof. Muralee Murugesu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2361-2370
We report the formation of a tetranuclear lanthanide cluster, [Yb4(bpzch)2(fod)10] ( 1 ), which occurs from a serendipitous ring opening of the functionalised tetrazine bridging ligand, bpztz (3,6-dipyrazin-2-yl-1,2,4,5-tetrazine) upon reacting with Yb(fod)3 (fod−=6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octandionate). Compound 1 was structurally elucidated via single-crystal X-ray crystallography and subsequently magnetically and spectroscopically characterised to analyse its magnetisation dynamics and its luminescence behaviour. Computational studies validate the observed MJ energy levels attained by spectroscopy and provides a clearer picture of the slow relaxation of the magnetisation dynamics and relaxation pathways. These studies demonstrate that 1 acts as a single-molecule magnet (SMM) under an applied magnetic field in which the relaxation occurs via a combination of Raman, direct, and quantum tunnelling processes, a behaviour further rationalised analysing the luminescent properties. This marks the first lanthanide-containing molecule that forms by means of an asymmetric tetrazine decomposition. 相似文献
552.
553.
554.
555.
Marin Nikolic Alessia Cesarini Emanuel Billeter Fabian Weyand Dr. Pavel Trtik Dr. Markus Strobl Dr. Andreas Borgschulte 《Angewandte Chemie (International ed. in English)》2023,62(45):e202307367
Efficiency losses due to side reactions are one of the main challenges in battery development. Despite providing valuable insights, the results of standard analysis on the individual components cannot be simply extrapolated to the full operating system. Therefore, non-destructive, and high resolution approaches that allow the investigation of the full system are desired. Herein, we combined neutron radiography and tomography with electrical monitoring of the state of charge of commercial Ni-mischmetal hydride batteries, to track the exchange and transport of hydrogen under operating conditions. This non-destructive approach allowed both the quantification of the hydrogen distribution in the electrodes in 4D, and the distinction between the electrochemically exchanged hydrogen and the hydrogen gas pressure generated by side reactions, as a function of the applied potential and current. One of the most counter-intuitive observation is that the generation of hydrogen gas during discharge depends on the charging state of the battery. The results presented provide critical new insights in the mechanisms governing the electrochemical processes during Nimischmetal hydride battery operation, and also pave the way for the extrapolation of this approach to the investigation of state-of-the-art Li-ions batteries. 相似文献
556.
Dagmar R. D'hooge Dominik Konkolewicz Marie‐Franoise Reyniers Guy B. Marin Krzysztof Matyjaszewski 《Macromolecular theory and simulations》2012,21(1):52-69
Kinetic modeling is used to better understand and optimize initiators for continuous activator regeneration atom‐transfer radical polymerization (ICAR ATRP). The polymerization conditions are adjusted as a function of the ATRP catalyst reactivity for two monomers, methyl methacrylate and styrene. In order to prepare a well‐controlled ICAR ATRP process with a low catalyst amount (ppm level), a sufficiently low initial concentration of conventional radical initiator relative to the initial ATRP initiator is required. In some cases, stepwise addition of a conventional radical initiator is needed to reach high conversion. Under such conditions, the equilibrium of the activation/deactivation process for macromolecular species can be established already at low conversion.
557.
Leau Sorina Alexandra Lete Cecilia Marin Mariana del Campo Francisco Javier Diaconu Ioana Lupu Stelian 《Journal of Solid State Electrochemistry》2023,27(7):1755-1766
Journal of Solid State Electrochemistry - The development and analytical applications of electrochemical sensors based on antimony tin oxide (ATO)–Prussian blue (PB) screen-printed electrode... 相似文献
558.
559.
Marin Kosovi Ozren Gamulin Maja Balarin Mile Ivanda Vedran erek Davor Risti Marijan Marciu Mira Risti 《Journal of Raman spectroscopy : JRS》2014,45(6):470-475
Light emitting porous silicon samples with different porosities, i.e. crystalline sizes, were produced from the low level doped p‐type silicon wafers by the anodization process. The effects of strong phonon confinement, redshift and broadening, were found on the O(Γ) phonon mode of the Raman spectra recorded at non‐resonant excitation condition using a near infrared 1064 nm laser excitation wavelength. Similarly, the blueshift of the photoluminescence peak was observed by reducing the crystalline sizes. Vibrational and optical findings were analysed within the existing models of confinement on the vibrational and electronic states of silicon nanocrystals. Since the energy of the photoluminescence peak of small nanocrystals also depends on the oxygen content on the surface of nanocrystals, the surface oxidation states were examined using infrared and energy dispersive spectroscopy. The partial coverage of the surface of nanocrystals was found due to the sample exposure to air. As a consequence, the photoluminescence energy did not increase as would be expected from the quantum confinement model. These results further indicate that the oxygen passivation along with the quantum confinement determines the electronic states of the silicon nanocrystals in porous silicon. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献