全文获取类型
收费全文 | 693篇 |
免费 | 24篇 |
专业分类
化学 | 544篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 28篇 |
物理学 | 137篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 6篇 |
2013年 | 22篇 |
2012年 | 30篇 |
2011年 | 54篇 |
2010年 | 28篇 |
2009年 | 27篇 |
2008年 | 41篇 |
2007年 | 54篇 |
2006年 | 49篇 |
2005年 | 58篇 |
2004年 | 39篇 |
2003年 | 31篇 |
2002年 | 27篇 |
2001年 | 18篇 |
2000年 | 17篇 |
1999年 | 5篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 13篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有717条查询结果,搜索用时 933 毫秒
71.
Harding DJ Gruene P Haertelt M Meijer G Fielicke A Hamilton SM Hopkins WS Mackenzie SR Neville SP Walsh TR 《The Journal of chemical physics》2010,133(21):214304
The geometric structures of small cationic rhodium clusters Rh(n)(+) (n = 6-12) are investigated by comparison of experimental far-infrared multiple photon dissociation spectra with spectra calculated using density functional theory. The clusters are found to favor structures based on octahedral and tetrahedral motifs for most of the sizes considered, in contrast to previous theoretical predictions that rhodium clusters should favor cubic motifs. Our findings highlight the need for further development of theoretical and computational methods to treat these high-spin transition metal clusters. 相似文献
72.
Helmich F Lee CC Schenning AP Meijer EW 《Journal of the American Chemical Society》2010,132(47):16753-16755
Chiral memory at the supramolecular level is obtained via a new approach using chiral Zn porphrins and achiral Cu porphyrins. In a "sergeant-and-soldiers" experiment, the Zn "sergeant" transfers its own chirality to Cu "soldiers" and, after chiral amplification, the "sergeant" is removed from the coaggregates by axial ligation with a Lewis base. After this extraction, the preferred helicity observed for the aggregates containing achiral Cu porphyrins reveals a chiral memory effect that is stable and can be erased and partially restored upon subsequent heating and cooling. 相似文献
73.
J. Riedel S. Hoekstra W. Jäger J. J. Gilijamse S. Y. T. van de Meerakker G. Meijer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):161-166
Here we report on the accumulation of ground-state NH molecules in a static magnetic trap. A pulsed supersonic beam of NH (a1Δ) radicals is produced and brought to a near standstill at the center of a quadrupole magnetic trap using a Stark decelerator. There, optical pumping of the metastable NH radicals to the X3Σ? ground state is performed by driving the spin-forbidden A3Π ← a1Δ transition, followed by spontaneous A → X emission. The resulting population in the various rotational levels of the ground state is monitored via laser induced fluorescence detection. A substantial fraction of the ground-state NH molecules stays confined in the several milliKelvin deep magnetic trap. The loading scheme allows one to increase the phase-space density of trapped molecules by accumulating packets from consecutive deceleration cycles in the trap. In the present experiment, accumulation of six packets is demonstrated to result in an overall increase of only slightly over a factor of two, limited by the trap-loss and reloading rates. 相似文献
74.
D. Steinmetz E. Neu J. Meijer W. Bolse C. Becher 《Applied physics. B, Lasers and optics》2011,102(3):451-458
We present investigations on single Ni/Si related color centers produced via ion implantation into single crystalline type IIa CVD diamond. By testing different ion dose combinations we show that there is an upper limit for both the Ni and the Si dose (1012 cm?2 and 1010 cm?2 resp.) due to the creation of excess fluorescent background. We demonstrate creation of Ni/Si related centers showing emission in the spectral range between 767?nm and 775?nm and narrow line-widths of ??2?nm FWHM at room temperature. Measurements of the intensity autocorrelation functions prove single-photon emission. The investigated color centers can be coarsely divided into two groups: Drawing from photon statistics and the degree of polarization in excitation and emission, we find that some color centers behave as two-level, single-dipole systems whereas other centers exhibit three levels and contributions from two orthogonal dipoles. In addition, some color centers feature stable and bright emission with saturation count rates up to 78?kcounts/s whereas others show fluctuating count rates and three-level blinking. 相似文献
75.
76.
77.
78.
79.
80.
Abdelmounaim Safer Mustapha Rahmouni François Carreaux Ludovic Paquin Olivier Lozach Laurent Meijer Jean Pierre Bazureau 《Chemical Papers》2011,65(3):332-337
A series of nine 5-arylidenerhodanine derivatives was prepared in good yields and purity without the use of a solvent or catalyst
under microwave-assisted condensation with some substituted isatins. All 5-arylidenerhodanines were evaluated as possible
inhibitors of the CK1α/β, CDK5/p25, and GSK-3α/β kinases. None of them showed substantive inhibitory activity against these kinases when evaluated at the concentration of
10 μM. 相似文献