全文获取类型
收费全文 | 846篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
化学 | 705篇 |
晶体学 | 3篇 |
力学 | 9篇 |
综合类 | 1篇 |
数学 | 54篇 |
物理学 | 105篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2016年 | 16篇 |
2015年 | 15篇 |
2014年 | 36篇 |
2013年 | 35篇 |
2012年 | 31篇 |
2011年 | 60篇 |
2010年 | 26篇 |
2009年 | 33篇 |
2008年 | 37篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 46篇 |
2004年 | 31篇 |
2003年 | 35篇 |
2002年 | 41篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 18篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 20篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 4篇 |
1986年 | 15篇 |
1985年 | 2篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有877条查询结果,搜索用时 734 毫秒
41.
David Rombach Hans‐Achim Wagenknecht 《Angewandte Chemie (International ed. in English)》2020,59(1):300-303
SF6 was applied as pentafluorosulfanylation reagent to prepare ethers with a vicinal SF5 substituent through a one‐step method involving photoredox catalysis. This method shows a broad substrate scope with respect to applicable alcohols for the conversion of α‐methyl and α‐phenyl styrenes. The products bear a new structural motif with two functional groups installed in one step. The alkoxy group allows elimination and azidation as further transformations into valuable pentafluorosulfanylated compounds. These results confirm that non‐toxic SF6 is a useful SF5 transfer reagent if properly activated by photoredox catalysis, and toxic reagents are completely avoided. In combination with light as an energy source, a high level of sustainability is achieved. Through this method, the proposed potential of the SF5 substituent in medicinal chemistry, agrochemistry, and materials chemistry may be exploited in the future. 相似文献
42.
43.
Ana Leonor Rivera Miguel Gómez-Lim Francisco Fernández Achim M. Loske 《Physics of life reviews》2012,9(3):308-345
Production of transgenic plants is a routine process for many crop species. Transgenes are introduced into plants to confer novel traits such as improved nutritional qualities, tolerance to pollutants, resistance to pathogens and for studies of plant metabolism. Nowadays, it is possible to insert genes from plants evolutionary distant from the host plant, as well as from fungi, viruses, bacteria and even animals. Genetic transformation requires penetration of the transgene through the plant cell wall, facilitated by biological or physical methods. The objective of this article is to review the state of the art of the physical methods used for genetic plant transformation and to describe the basic physics behind them. 相似文献
44.
Instruments for surgical and dental application based on oscillatory mechanics submit unwanted vibrations to the operator’s hand. Frequently the weight of the instrument’s body is increased to dampen its vibration. Based on recent research regarding the optimization of granular damping we developed a prototype granular damper that attenuates the vibrations of an oscillatory saw twice as efficiently as a comparable solid mass. 相似文献
45.
46.
47.
48.
We report on a test of Lorentz invariance performed by comparing the resonance frequencies of one stationary optical resonator and one continuously rotating on a precision air bearing turntable. Special attention is paid to the control of rotation induced systematic effects. Within the photon sector of the standard model extension, we obtain improved limits on combinations of 8 parameters at a level of a few parts in 10(-16). For the previously least well known parameter we find [EQUATION: SEE TEXT]. Within the Robertson-Mansouri-Sexl test theory, our measurement restricts the isotropy violation parameter [EQUATION: SEE TEXT]. corresponding to an eightfold improvement with respect to previous nonrotating measurements. 相似文献
49.
Hagen A Steiner M Raschke MB Lienau C Hertel T Qian H Meixner AJ Hartschuh A 《Physical review letters》2005,95(19):197401
The dynamics of excitons in individual semiconducting single-walled carbon nanotubes was studied using time-resolved photoluminescence (PL) spectroscopy. The PL decay from tubes of the same (n,m) type was found to be monoexponential, however, with lifetimes varying between less than 20 and 200 ps from tube to tube. Competition of nonradiative decay of excitons is facilitated by a thermally activated process, most likely a transition to a low-lying optically inactive trap state that is promoted by a low-frequency phonon mode. 相似文献
50.
Goennenwein ST Wassner TA Huebl H Brandt MS Philipp JB Opel M Gross R Koeder A Schoch W Waag A 《Physical review letters》2004,92(22):227202
We show that upon exposure to a remote dc hydrogen plasma, the magnetic and electronic properties of the dilute magnetic semiconductor Ga1-xMnxAs change qualitatively. While the as-grown Ga1-xMnxAs thin films are ferromagnetic at temperatures T less, similar 70 K, the samples are found to be paramagnetic after the hydrogenation, with a Brillouin-type magnetization curve even at T=2 K. Comparing magnetization and electronic transport measurements, we conclude that the density of free holes p is significantly reduced by the plasma process, while the density of Mn magnetic moments does not change. 相似文献