全文获取类型
收费全文 | 174篇 |
免费 | 21篇 |
国内免费 | 13篇 |
专业分类
化学 | 83篇 |
晶体学 | 4篇 |
力学 | 8篇 |
综合类 | 3篇 |
数学 | 7篇 |
物理学 | 103篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1942年 | 2篇 |
1939年 | 1篇 |
排序方式: 共有208条查询结果,搜索用时 15 毫秒
31.
M. Nuñez Portela E. A. Dijck A. Mohanty H. Bekker J. E. van den Berg G. S. Giri S. Hoekstra C. J. G. Onderwater S. Schlesser R. G. E. Timmermans O. O. Versolato L. Willmann H. W. Wilschut K. Jungmann 《Applied physics. B, Lasers and optics》2014,114(1-2):173-182
A single Ra+ ion stored in a Paul radio frequency ion trap has excellent potential for a precision measurement of the electroweak mixing angle at low momentum transfer and as the most stable optical clock. The effective transport and cooling of singly charged ions of the isotopes 209Ra to 214Ra in a gas filled radio frequency quadrupole device is reported. The absolute frequencies of the transition 7s2S1/2–7d2D3/2 at wavelength 828 nm have been determined in 212–214Ra+ with ≤19 MHz uncertainty using laser spectroscopy on small samples of ions trapped in a linear Paul trap at the online facility Trapped Radioactive Isotopes: µicrolaboratories for fundamental Physics (TRIµP) of the Kernfysisch Versneller Instituut. 相似文献
32.
JV Georgieva RP Brinkhuis K Stojanov CA Weijers H Zuilhof FP Rutjes D Hoekstra JC van Hest IS Zuhorn 《Angewandte Chemie (International ed. in English)》2012,51(33):8339-8342
A polymeric nanocarrier: Polymersomes tagged with a dodecamer peptide that recognizes gangliosides GM1 and GT1b are shown to cross the blood-brain barrier, both in an in?vitro model and in?vivo. The combination of polymeric vesicles with a small GM1-binding peptide and GM1/GT1b gangliosides as targeting sites for blood-brain barrier transport is unprecedented. 相似文献
33.
T. Schlathölter O. Hadjar R. Hoekstra R. Morgenstern 《Applied Physics A: Materials Science & Processing》2001,72(3):281-287
The electronic friction experienced by a multiply charged ion interacting with the valence electrons of a single fullerene
is an important aspect of the collision dynamics. It manifests itself in a considerable loss of projectile kinetic energy
transferred to the target, resulting in excitation. The latter mainly leads to direct ionization and multifragmentation and
can be recognized in specific patterns of the fragmentation spectra. These fingerprints can be used to quantify electronic
stopping and to identify its typical properties as known from particle–solid interactions, such as the oscillation of the
electronic stopping with the projectile atomic number Z. These essentially many-body effects can therefore be studied in a
well-defined system of finite size.
Received: 4 April 2000 / Accepted: 6 November 2000 / Published online: 9 February 2001 相似文献
34.
Charge transport properties of polyimide films implanted with 80 keV Co ions at two different fluences (series I: 1.25 × 10^17 ions/cm^2, series Ⅱ: 1.75 × 10^17 ions/cm^2) are studied in detail. For series I, the temperature dependence of surface resistivity fits Mott's equation very well. It is on the insulating side of the insulator-metal transition (IMT). However, for series Ⅱ, the temperature dependence of surface resistivity is not in agreement with Mott's equation. It is on the metallic side of lMT. The magnetotransport properties of these two series are also studied. No significant magnetoresistive effect is observed for series I at both 5 K and 300 K. For series Ⅱ, an obvious magnetoresistive effect is observed at 5 K, while there is no magnetoresistive effect at 300 K. Rutherford backscattering spectrometry (RBS) is applied to confirm the actual fluence for these two series. 相似文献
35.
36.
This last paper in a series of four describes the philosophy and procedures in selecting nuclear-reaction and decay data and mass-spectrometric results as input for the calculation of best values for relative atomic masses. Both accepted and rejected data are presented in a table and there compared with the adjusted values. 相似文献
37.
Horst F. Hoekstra H. J. W. M. Driessen A. Popma Th. J. A. 《Optical and Quantum Electronics》1998,30(5-6):335-341
A two-dimensional time domain finite difference beam propagation method, based on the slowly varying envelope approximation is presented. Expressions to correct this approximation and to include third-order non-linear effects are given. The method is applied on solitary waves in a non-linear Bragg reflector, assuming realistic materials parameters. 相似文献
38.
The role of cladding bilayer material compositions to obtain low-loss hollow-core integrated optical waveguides was studied. Using the simple Fresnel reflection formulae, the optimal material composition was determined. It is shown that using bilayers with higher index-contrast does not always lead to a lower loss for (quasi-)linearly polarized modes. Based on that knowledge, structures that exhibit very low leakage loss for quasi-TE00 mode are proposed and designed using Si-compatible materials. 相似文献
39.
40.
An enantioselective synthesis of (S)-(+)-3-aminomethyl-5-methylhexanoic acid via asymmetric hydrogenation 总被引:2,自引:0,他引:2
Burk MJ De Koning PD Grote TM Hoekstra MS Hoge G Jennings RA Kissel WS Le TV Lennon IC Mulhern TA Ramsden JA Wade RA 《The Journal of organic chemistry》2003,68(14):5731-5734
A concise enantioselective synthesis of (S)-(+)-3-aminomethyl-5-methylhexanoic acid (1, Pregabalin) has been developed. The key step is the asymmetric hydrogenation of a 3-cyano-5-methylhex-3-enoic acid salt 2 with a rhodium Me-DuPHOS catalyst, providing the desired (S)-3-cyano-5-methylhexanoate 3 in very high ee. Subsequent hydrogenation of the nitrile 3 with a heterogeneous nickel catalyst provides Pregabalin 1 in excellent overall yield and purity. 相似文献