全文获取类型
收费全文 | 651篇 |
免费 | 60篇 |
国内免费 | 3篇 |
专业分类
化学 | 534篇 |
晶体学 | 2篇 |
力学 | 14篇 |
数学 | 19篇 |
物理学 | 145篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 22篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 27篇 |
2015年 | 28篇 |
2014年 | 38篇 |
2013年 | 46篇 |
2012年 | 41篇 |
2011年 | 59篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 28篇 |
2007年 | 49篇 |
2006年 | 34篇 |
2005年 | 44篇 |
2004年 | 46篇 |
2003年 | 24篇 |
2002年 | 20篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有714条查询结果,搜索用时 15 毫秒
701.
702.
Tada M Ishiguro N Uruga T Tanida H Terada Y Nagamatsu S Iwasawa Y Ohkoshi S 《Physical chemistry chemical physics : PCCP》2011,13(33):14910-14913
μ-XAFS analysis using an X-ray μ-beam (1000 nm (h) × 800 nm (v)) was successfully carried out on a single particle of a practical catalyst NiO(x)/Ce(2)Zr(2)O(y) (0 ≤x≤ 1, 7 ≤y≤ 8). The oxidation state and local coordination structure of the NiO(x)/Ce(2)Zr(2)O(y) particle were characterized by Ni K-edge μ-XANES and μ-EXAFS, which showed the catalytically active and inactive phases of a single catalyst particle. 相似文献
703.
An efficient method for the synthesis of aldehydes was achieved by using air-microbubble techniques in aerobic copper/TEMPO-catalyzed oxidation of primary alcohols. Use of air-microbubbles to improve gas absorption into liquid phase is proven to be highly beneficial for gas/liquid phase reactions. 相似文献
704.
Go Obara Yuto Tanaka Tomoya Miyanishi Minoru Obara 《Applied Physics A: Materials Science & Processing》2011,102(3):551-557
We present localized optical field distribution properties in the vicinity of gold particles on a silicon substrate by backward
and forward irradiation. It is technically difficult to fabricate nanostructures on the surface by a conventional forward
laser incident to the substrate because gold nanoparticles easily aggregate to form double-layered particle arrays. We calculated
enhanced optical field properties in order to pattern the substrate surface only with a template of the bottom-layered particle
arrays in the case that the backward irradiation of a femtosecond laser is used in the system of aggregated double-layered
gold nanoparticle arrays. With the backward irradiation, the optical field intensity in the substrate for the double-layered
hexagonal arrays is found to be only 30% lower than the mono-layered system. Moreover, a near field cannot be generated with
the forward irradiation. As a result, only the backward irradiation scheme is found to be effective for uniform surface nanopatterning
at enhanced plasmonic near-field zones. 相似文献
705.
Abstract With the increased biochemical interests of fluorocarbohydrates, several approaches have been establised toward the synthesis of 2-deoxy-2-fluorocarbohydrates by taking advantage of the ease of the addition reaction to readily available peracetylated glycals by employing either CF3OF,1 F2,2 or XeF2,3 More stereochemically controlled approaches utilize the epoxide opening reaction with KHF2 4 or the displacement of 2-0-triflate by CsF.5 相似文献
706.
Radiation-induced grafting of monochlorotrifluoroethylene onto polyethylene was carried out by a pre-irradiation method. It was observed that the grafting proceeds rapidly at temperatures from -35 to 0°C in the liquid monomer phase. By measuring ESR spectra, it was found that the grafting can be initiated by allyl radicals trapped in polyethylene. An absorption band characteristic to the grafting site was found and the band was tentatively assigned to the stretching vibration of the C-F bond situated in the vicinity of the branching position (the initiating site). 相似文献
707.
Nishi N Uruga T Tanida H Kakiuchi T 《Langmuir : the ACS journal of surfaces and colloids》2011,27(12):7531-7536
The effect of the temperature on the surface layering of ionic liquids has been studied for two ionic liquids, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide([TOMA(+)][C(4)C(4)N(-)]) and trihexyltetradecylphosphonium bis(nonafluorobutanesulfonyl)amide ([THTDP(+)][C(4)C(4)N(-)]), using X-ray reflectivity measurements at 285, 300, and 315 K. Both [TOMA(+)][C(4)C(4)N(-)] and [THTDP(+)][C(4)C(4)N(-)] develop multilayers at the surface. The structure of the multilayers at the [TOMA(+)][C(4)C(4)N(-)] surface shows little temperature-dependent change, whereas that at the [THTDP(+)][C(4)C(4)N(-)] surface clearly becomes diffused with increasing temperature. The different temperature dependence seems to be related to the difference in the recently reported ultraslow dynamics of the interfacial structure of [TOMA(+)][C(4)C(4)N(-)] and [THTDP(+)][C(4)C(4)N(-)] at the ionic liquid|water interface. 相似文献
708.
709.
Yutaka Mori Tomoya Yamauchi Masato Kanasaki Yusuke Maeda Keiji Oda Satoshi Kodaira Teruaki Konishi Nakahiro Yasuda Rémi Barillon 《Radiation measurements》2011,46(10):1147-1153
Chemical modification along ion tracks in PADC films has been studied by means of FT-IR spectrometry, which was exposed to proton and heavy ions of He, C, Ne, Ar, Fe, Kr and Xe with energies around the Bragg peaks. This study covers a wide region of the stopping power ranging from 10 to 10,000 keV/μm. Removal cross sections for the loss of ether and carbonate ester bonds are assessed for each ion, as a function of the stopping power. Chemical damage parameters like the damage density, the effective track core radius and the radiation chemical yields, G values (scissions/100 eV), for each bond are also derived. We have found anomalous dependence of these parameters on the stopping power. The G value for the loss of carbonate ester bond decreased from 20 for proton down to 5 for C and Ne ions, and then increased with atomic number of heavy ions up to 8 for Xe ion. Radial dose distribution for each ion has been also calculated. Results are discussed from the viewpoint of polymeric structure of PADC that consists of two parts with different radio-sensitivities. 相似文献
710.
We theoretically study possible methods how to obtain imaging of magnetic atoms by use of photoelectron diffraction (PD). We propose a novel method to apply Daimon effect where PD peaks are rotated around forward focusing peaks. In usual circular dichroism, we simply use the difference of the PD intensities for different X-ray circular polarization. In contrast to this dichroism, we rather use the difference of the PD intensities for different circular polarizations but - is used for the – circular polarization only in the data handling. This technique allows us to obtain clear atomic image only of spin polarized atoms, and to distinguish magnetic atoms with up-spins from those with down spins. Some illustrative calculations demonstrate the potential use and also the limitation of this technique. 相似文献