全文获取类型
收费全文 | 3381篇 |
免费 | 73篇 |
国内免费 | 19篇 |
专业分类
化学 | 2389篇 |
晶体学 | 37篇 |
力学 | 30篇 |
数学 | 153篇 |
物理学 | 864篇 |
出版年
2022年 | 22篇 |
2020年 | 30篇 |
2019年 | 49篇 |
2018年 | 23篇 |
2017年 | 24篇 |
2016年 | 51篇 |
2015年 | 59篇 |
2014年 | 65篇 |
2013年 | 148篇 |
2012年 | 152篇 |
2011年 | 167篇 |
2010年 | 102篇 |
2009年 | 98篇 |
2008年 | 183篇 |
2007年 | 156篇 |
2006年 | 191篇 |
2005年 | 139篇 |
2004年 | 165篇 |
2003年 | 137篇 |
2002年 | 122篇 |
2001年 | 89篇 |
2000年 | 69篇 |
1999年 | 44篇 |
1998年 | 31篇 |
1997年 | 39篇 |
1996年 | 54篇 |
1995年 | 51篇 |
1994年 | 34篇 |
1993年 | 51篇 |
1992年 | 57篇 |
1991年 | 42篇 |
1990年 | 32篇 |
1989年 | 37篇 |
1988年 | 43篇 |
1987年 | 37篇 |
1986年 | 24篇 |
1985年 | 75篇 |
1984年 | 62篇 |
1983年 | 41篇 |
1982年 | 48篇 |
1981年 | 44篇 |
1980年 | 39篇 |
1979年 | 35篇 |
1978年 | 38篇 |
1977年 | 40篇 |
1976年 | 36篇 |
1975年 | 30篇 |
1974年 | 17篇 |
1973年 | 29篇 |
1966年 | 17篇 |
排序方式: 共有3473条查询结果,搜索用时 15 毫秒
81.
Tokumoto T Brooks JS Oshima Y Choi ES Brunel LC Akutsu H Kaihatsu T Yamada J van Tol J 《Physical review letters》2008,100(14):147602
Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets. 相似文献
82.
Masahide Tona Hirofumi Watanabe Satoshi Takahashi Nobuo Yoshiyasu Toshifumi Terui Chikashi Yamada 《Surface science》2007,601(3):723-727
Using scanning tunneling microscopy (STM) and time of flight secondary ion mass spectrometry (TOF/SIMS), we observed radiation effects on a Si(1 1 1)-(7 × 7) surface in the collision of a single highly charged ion (HCI) with a charge state q up to q = 50. The STM observation with atomic resolution revealed that a nanometer sized crater-like structure was created by a single HCI impact, where the size increased rapidly with q. The secondary ion yields also increased with q in which multiply charged Si ions (Sin+) were clearly observed in higher q HCI-collisions. The sputtering mechanism is briefly discussed, based on the so-called Coulomb explosion model. 相似文献
83.
Yamazaki Kazuyoshi Hosaka Makoto Yamada Kenichiro Ogata Takeshi Shimada Kenichi 《Optical Review》2016,23(5):848-858
Optical Review - A precise and fast method for controlling the reference-beam angle of an angular-multiplexed holographic data storage system (HDSS)—to achieve larger capacity and faster... 相似文献
84.
A binary alloy Schottky barrier diode on zinc oxide (ZnO) was developed using the combinatorial ion beam-assisted deposition system. The compositional fraction of the binary alloy was continuously varied using the composition-spread technique, to control the Schottky barrier height. After metal deposition, patterned Schottky diodes were fabricated on a ZnO single-crystal substrate. Pt-Ru alloy was selected from the work function viewpoint. Our experiments showed that the compositional fraction of the Schottky binary alloys changed continuously as designed and the Schottky barrier heights measured by current-voltage (I-V) measurements increased with increasing Pt content. Maximum barrier height difference for ZnO was 137 meV. Using ion beam deposition in parallel with the combinatorial system showed that the Schottky barrier heights for ZnO can be controlled by binary metal alloying. 相似文献
85.
A multi-layer chip inductor (MCI) was fabricated using polycrystalline Li–Zn–Cu–Mn ferrite and the green-sheet technique, and its complex impedance spectrum was evaluated with the help of numerical calculations. The complex impedance spectra of the MCI component using Ni–Zn–Cu ferrite, which have been widely used for this application, were very sensitive to the residual stress and deviated much from the calculated values; however, it was found that the complex impedance spectrum of the MCI component using Li–Zn–Cu–Mn ferrite is quite well reproduced by calculation, where the complex permittivity and permeability of the polycrystalline ferrite as well as the MCI dimensions, were used. It implied that the magneto-striction effect was negligible in case of MCI using Li–Zn–Cu–Mn ferrite, and that the difference was related to magneto-strictive coefficient of the polycrystalline ferrite. Consequently, utilization of Li–Zn–Cu–Mn ferrite enabled us to easily design the complex impedance of MCI component. 相似文献
86.
Kazuhiko Hosomi Toshihiko Fukamachi Hiroji Yamada Toshio Katsuyama Yasuhiko Arakawa 《Photonics and Nanostructures》2006,4(1):30-34
We demonstrate optical properties of one-dimensional photonic crystals (PC), which are fabricated using high-aspect-ratio etching on a V-grooved silicon wafer. The measured transmission spectrum has an obvious band gap; the suppression is over 30 dB. The quite small insertion loss of 1.9 dB is achieved by induced coupled plasma (ICP) cryogenic etching and direct coupling to the optical fiber aligned in the V-groove. We also successfully observed peaks originating from a localized cavity mode. Such a microcavity enables control of the light, which qualifies photonic crystal as a fundamental structure of optical functional devices. These results lead to achievement of integrated Si-based photonic circuits. 相似文献
87.
Abstract
A stereoscopic method of identifying story patterns in literary works is newly developed. The pattern is extracted from textual information by the detection of thematically assigned keywords, and depicted as visual imageries. The applicability of the method is demonstrated in several of Shakespeare’s plays. The complex scenario patterns in Shakespeare’s tragedies are successfully captured with applying the method for two different themes in each play. As the result, the organization of story accompanying multiple themes in a single play has been obtained as a pair of visual imageries, i.e. stereoscopic story visualization. This approach, in combination with a quadrant analysis of the plots, allows us in interpretation further complexity of human psychology in the characters and scene-by-scene transitions in each play. 相似文献88.
The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators. 相似文献
89.
Yuki?KanazawaEmail authorView authors OrcID profile Tetsuya?Yamada Aki?Kido Koji?Fujimoto Kyoko?Takakura Hiroaki?Hayashi Yasutaka?Fushimi Satoshi?Kozawa Koji?Koizumi Makiko?Okuni Naomi?Ueda Kaori?Togashi 《Applied magnetic resonance》2017,48(2):125-134
To visualize the condition of impregnation of polyethylene glycol (PEG) in waterlogged wood, we demonstrated magnetic transfer (MT) magnetic resonance imaging (MRI) through a series of process of PEG impregnation. Three different samples were examined; reference wood, 10 cm cut wood, and 5 cm cut wood. During this study, the upper section sample was kept immersed in water, for the middle and lower sections the concentration of PEG solution was changed at 20 wt% intervals from 20 to 100 wt%. The impregnated periods of each PEG solution concentration were 14 days. Then, MR imaging were performed with/without MT pulse. The MTR value for both 10 cm- and 5 cm-samples were shown to decrease at 20 wt% PEG at peak concentration. When the sample volume was large, e.g., 10 cm-sample, the MTR value decreased to 100 wt% PEG concentration. In contrast, when a sample volume was small, e.g., 5 cm-sample, MTR value decreased to 60 wt% PEG concentration. In conclusion, MTR analysis makes it possible to nondestructively visualize and evaluate the inner condition concerning the PEG impregnation method for waterlogged wood. 相似文献
90.
Lucarelli A Lupi S Ortolani M Calvani P Maselli P Capizzi M Giura P Eisaki H Kikugawa N Fujita T Fujita M Yamada K 《Physical review letters》2003,90(3):037002
While there is increasing evidence for antiferromagnetic (AF) ordering in the Cu-O planes of high-T(c) superconductors, either static or fluctuating, there is no direct evidence so far for the charge stripes that should separate the AF domains. By investigating the optical response of La2-xSrxCuO4 for 0相似文献