全文获取类型
收费全文 | 670篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
化学 | 558篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 34篇 |
物理学 | 91篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2017年 | 3篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 21篇 |
2013年 | 25篇 |
2012年 | 35篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 19篇 |
2008年 | 42篇 |
2007年 | 42篇 |
2006年 | 47篇 |
2005年 | 37篇 |
2004年 | 42篇 |
2003年 | 48篇 |
2002年 | 46篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有687条查询结果,搜索用时 15 毫秒
51.
A single-atom-sized gold wire was successfully observed in real time by a newly developed defocus-image modulation processing electron microscope. Because of phase retrieval processing with spherical aberration correction, the single-atom strand wire was observed with high contrast and without contrast blurring. By carefully looking at the atomic distance, the contrast, and the dynamic behavior of the wire, we recognized that there are two stages of the wire. In the first stage the wire maintained the atomic distance in the bulk crystal, but in the second stage the wire showed the atomic distance of the nearest-neighbor atoms with weaker contrast. The gold wire was rather stable for a few seconds under strong electron beam illumination. 相似文献
52.
We show that the Nomura algebra of the nonsymmetric Hadamard model coincides with the Bose–Mesner algebra of the directed Hadamard graph. 相似文献
53.
Akiko Ohno Nana Kawasaki Kiyoshi Fukuhara Haruhiro Okuda Teruhide Yamaguchi 《Magnetic resonance in chemistry : MRC》2010,48(2):168-172
Complete NMR analysis of oxytocin (OXT) in phosphate buffer was elucidated by one‐dimensional (1D)‐ and two‐dimensional (2D)‐NMR techniques, which involve the assignment of peptide amide NH protons and carbamoyl NH2 protons. The 1H? 15N correlation of seven amide NH protons and three carbamoyl NH2 protons were also shown by HSQC NMR of OXT without 15N enrichment. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
54.
55.
56.
Junro Yoshino Dr. Akiko Furuta Tetsuya Kambe Hiroaki Itoi Naokazu Kano Prof. Takayuki Kawashima Prof. Yuzuru Ito Dr. Makoto Asashima Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(17):5026-5035
2‐[Bis(pentafluorophenyl)boryl]azobenzenes bearing hydrogen, methoxy, dimethylamino, trifluoromethyl, fluoro, n‐butyl, and tert‐butyldimethylsiloxy groups at the 4′‐position or methoxy and bromo groups at the 4‐position have been synthesized. The 4‐bromo group of the 2‐boryl‐4‐bromoazobenzene derivative was converted to phenyl and diphenylamino groups by palladium‐catalyzed reactions. The absorption and fluorescence properties have been investigated using UV/Vis and fluorescence spectroscopy. The 2‐borylazobenzenes emitted an intense green, yellow, and orange fluorescence, in marked contrast to the usual azobenzene fluorescence. The 4′‐siloxy derivative showed the highest fluorescence quantum yield (0.90) among those reported for azobenzenes to date. The correlation between the substituent and the fluorescence properties was elucidated by studying the effect of the substituent on the relaxation process and from DFT and TD‐DFT calculations. An electron‐donating group at the 4′‐position was found to be important for an intense emission. Application of fluorescent azobenzenes as a fluorescent vital stain for the visualization of living tissues was also investigated by microinjection into Xenopus embryos, suggesting these compounds are nontoxic towards embryos. 相似文献
57.
Yuta Marushima Yuri Uchiumi Kenichi Ogu Akiko Hori 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(8):o406-o409
Two C2‐symmetric meso‐alkynylporphyrins, namely 5,15‐bis[(4‐butyl‐2,3,5,6‐tetrafluorophenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H42F8N4, (I), and 5,15‐bis[(4‐butylphenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H50N4, (II), show remarkable π–π stacking that forms columns of porphyrin centers. The tetrafluorophenylene moieties in (I) show intermolecular interactions with each other through the F atoms, forming one‐dimensional ribbons. No significant π–π interactions are observed in the plane of the phenylene and tetrafluorophenylene moieties in either (I) or (II). The molecules of both compounds lie about inversion centers. 相似文献
58.
Akiko Hori Kohei Naganuma 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(5):o256-o259
In the crystal structures of the fully and partially fluorinated flavone derivatives 5,6,7,8‐tetrafluoro‐2‐(2,3,4,5,6‐pentafluorophenyl)‐4H‐1‐benzopyran‐4‐one, C15HF9O2, (I), and 5,6,7,8‐tetrafluoro‐2‐phenyl‐4H‐1‐benzopyran‐4‐one, C15H6F4O2, (II), the pentafluorophenyl group and the pyranone moiety in (I) are twisted due to repulsion of the F substituents, and a CO(δ−)...π(δ+) intermolecular interaction is observed between the carbonyl O atom and the pentafluorophenyl group. In (II), on the other hand, the phenyl group and the pyranone moiety are almost coplanar, and arene–perfluoroarene interactions are observed in the head‐to‐tail intermolecular columnar stacking between the phenyl group and the tetrafluorophenylene moiety. 相似文献
59.
Asako Shimada Tomoko Haraga Akiko Hoshi Yutaka Kameo Mikio Nakashima Kuniaki Takahashi 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):765-770
In order to analyze actinide elements in radioactive metal waste, the dissolution and chemical separation conditions were optimized. The surfaces of a type 304 stainless steel plate and of pipe waste sampled from the prototype advanced thermal reactor (Fugen) were dissolved in mixed acid solution (HNO3:HCl:H2O = 1:1:4). The resulting solution was evaporated to dryness and dissolved with 2 mol/dm3 of HNO3 to prepare sample solutions. In order to analyze trivalent actinide elements in the sample solution containing a large amount of Fe(III) (>0.1 g) using TRU resin, the effect of Fe(III) concentration on the recovery of Am(III) and reduction effect of Fe(III) to Fe(II) with ascorbic acid were studied. On the basis of results of this study, chemical separation scheme was constructed and Pu and Am in the sample solutions were separated. Thorium and U in the sample solutions were separated with UTEVA resin. High recoveries for all experimented elements were obtained from the analysis of spiked sample solutions, the effectiveness of the method was confirmed. 相似文献
60.
We propose and demonstrate a scheme for boosting the efficiency of entanglement distribution based on a decoherence-free subspace over lossy quantum channels. By using backward propagation of a coherent light, our scheme achieves an entanglement-sharing rate that is proportional to the transmittance T of the quantum channel in spite of encoding qubits in multipartite systems for the decoherence-free subspace. We experimentally show that highly entangled states, which can violate the Clauser-Horne-Shimony-Holt inequality, are distributed at a rate proportional to T. 相似文献