全文获取类型
收费全文 | 1154篇 |
免费 | 35篇 |
国内免费 | 5篇 |
专业分类
化学 | 921篇 |
晶体学 | 7篇 |
力学 | 17篇 |
数学 | 66篇 |
物理学 | 183篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 29篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 63篇 |
2012年 | 66篇 |
2011年 | 87篇 |
2010年 | 40篇 |
2009年 | 41篇 |
2008年 | 75篇 |
2007年 | 89篇 |
2006年 | 90篇 |
2005年 | 75篇 |
2004年 | 63篇 |
2003年 | 50篇 |
2002年 | 50篇 |
2001年 | 23篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1956年 | 1篇 |
排序方式: 共有1194条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
Jiro Tsuji Yuichi Kobayashi Hideaki Kataoka Takashi Takahashi 《Tetrahedron letters》1980,21(35):3393-3394
2-Substituted 2-alkoxycarbonyl-3-vinylcyclopentanones (2), easily prepared by the palladium-catalyzed cyclization of 2-substituted 3-oxo-8-phenoxy-6-octenoates (1), are very suitable building blocks for CD rings of steroids, bearing particularly a functionalized 18-methyl group. 相似文献
106.
A simple Raman probe was realized using a single flexible hollow waveguide (HW). A HW coated with a silver film, which had reasonable transmission and little optical background noise, was used as a bidirectional transmission fiber for both the excitation and collection of Raman scattered light. The HW itself generated no Raman scattering or fluorescence noise during transmission. A complex filtering system at the end of the waveguide was thus unnecessary. In addition, the measured Raman spectra showed better signal-to-noise ratios than a conventional Raman fiber probe. The HW's suitability as a Raman fiber probe was also demonstrated. 相似文献
107.
We report the field-orientation dependent specific heat of the spin-triplet superconductor Sr2RuO4 under the magnetic field aligned parallel to the RuO2 planes with high accuracy. Below about 0.3 K, striking fourfold oscillations of the density of states reflecting the superconducting gap structure have been resolved for the first time. We also obtained strong evidence of multiband superconductivity and concluded that the superconducting gap in the active band, responsible for the superconducting instability, is modulated with a minimum along the [100] direction. 相似文献
108.
[reaction: see text] Only 1-3 mol % of PtCl(2) or AuBr(3) was sufficient to promote generation and [3+2] cycloaddition of transition-metal-containing azomethine ylides derived from N-(o-alkynylphenyl)imines bearing an internal alkyne moiety. A highly efficient method for the preparation of synthetically useful tricyclic indole derivatives having a substituent at the 3-position of the indole nucleus was established by this method. 相似文献
109.
Hiroshi Mitsui Yuichi Shimizu 《Journal of polymer science. Part A, Polymer chemistry》1980,18(3):1115-1122
The γ radiolysis of polyethylene preirradiated with electron beams to 3 Mrad was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 105 rad/hr. The hydrogen formation in the γ radiolysis was little affected by the preirradiation of electron beams, whereas the formation of trans-vinylene unsaturation and gel was somewhat retarded. The rates of the formation of hydrogen and trans-vinylene unsaturation were described by the zero-order formation kinetics with respect to each concentration combined with the first-order disappearance. The apparent rate constants and activation energies for the formation and disappearance of hydrogen and trans-vinylene unsaturation were almost independent of the preirradiation. The gel fraction was analyzed by using the Charlesby–Pinner equation. The G values of crosslinking and main chain scission were increased by the preirradiation, whereas their activation energies remained unaltered. On the basis of these results the effects of preirradiation on the reactions induced by γ rays in polyethylene were discussed. 相似文献
110.
Tozuka Y Sasaoka S Nagae A Moribe K Oguchi T Yamamoto K 《Journal of colloid and interface science》2005,291(2):471-476
Changes in the molecular state of benzoic acid (BA) in the presence of folded sheet mesoporous material (FSM-16), which has uniformly sized cylindrical mesopores and a large surface area, were assessed with several analyses. When BA was blended with FSM-16 for 5 min (BA content=30%), the X-ray diffraction peaks of BA crystals disappeared, suggesting an amorphous state. Fluorescence analysis of the mixture showed a new fluorescence emission peak for BA at 386 nm after mixing with FSM-16. Fluorescence lifetime analysis of the BA component in the mixture at 386 nm showed a longer lifetime in comparison with that of BA crystals. The solid-state (13)C CP/MAS and PST/MAS NMR spectra of the mixture with FSM-16 showed a significantly different spectral pattern from the mixture with nonporous glass, whose NMR spectra were identical to those of BA crystals. These results indicate that BA molecules disperse quickly into the hexagonal channels of FSM-16 by a simple blending procedure and adsorbed BA molecules had clearly different physicochemical properties to BA crystals. 相似文献