全文获取类型
收费全文 | 1618篇 |
免费 | 36篇 |
国内免费 | 7篇 |
专业分类
化学 | 1125篇 |
晶体学 | 18篇 |
力学 | 19篇 |
数学 | 45篇 |
物理学 | 454篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 19篇 |
2016年 | 19篇 |
2015年 | 28篇 |
2014年 | 46篇 |
2013年 | 61篇 |
2012年 | 89篇 |
2011年 | 92篇 |
2010年 | 46篇 |
2009年 | 60篇 |
2008年 | 77篇 |
2007年 | 102篇 |
2006年 | 89篇 |
2005年 | 90篇 |
2004年 | 54篇 |
2003年 | 56篇 |
2002年 | 63篇 |
2001年 | 51篇 |
2000年 | 27篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 21篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 31篇 |
1991年 | 22篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 29篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1975年 | 12篇 |
1974年 | 19篇 |
1973年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有1661条查询结果,搜索用时 0 毫秒
21.
Abe K Abe K Adachi I Ahn BS Aihara H Akatsu M Alimonti G Aoki K Asai K Asai M Asano Y Aso T Aulchenko V Aushev T Bakich AM Banas E Behari S Behera PK Beiline D Bondar A Bozek A Browder TE Casey BC Chang P Chao Y Cheon BG Choi SK Choi Y Doi Y Dragic J Eidelman S Enari Y Enomoto R Everton CW Fang F Fujii H Fujita Y Fukunaga C Fukushima M Garmash A Gordon A Gotow K Guler H Guo R Haba J Haji T Hamasaki H Hanagaki K Handa F Hara K Hara T Hastings NC Hayashi K Hayashii H Hazumi M Heenan EM Higuchi I 《Physical review letters》2001,86(15):3228-3232
We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations. 相似文献
22.
Kim YK Auchincloss P Blanis D Bodek A Budd H Eno S Fry CA Harada H Ho YH Kumita T Mori T Olsen SL Shaw NM Sill A Thorndike EH Ueno K Zheng HW Imlay R Kirk P Lim J McNeil RR Metcalf W Myung SS Cheng CP Gu P Li J Li YK Mao ZP Xu YT Zhu YC Abashian A Gotow K Hu KP Low EH Mattson ME Piilonen L Sterner KL Lusin S Rosenfeld C Wang AT Wilson S Frautschi M Kagan H Kass R Trahern CG Breedon RE Kim GN Ko W Lander RL Maeshima K Malchow RL Smith JR Stuart D Williams MC Abe K Fujii Y Higashi Y Kim SK 《Physical review letters》1989,63(17):1772-1775
23.
T. Kasai S. Yamashita H. Nakajima T. Fujii I. Terasaki T. Watanabe H. Shibata A. Matsuda 《Physica C: Superconductivity and its Applications》2010
Local density of states (LDOS) and the lattice structure of highly underdoped Bi2Sr2CaCu2O8+δ with Tc = 22 K and 30 K were investigated by a low temperature scanning tunneling microscope. The modulation structure of the Bi–O surface was strongly depressed in the highly underdoped samples. The depression was observed only in the samples subject to the strong reduction annealing process, suggesting that the strong reduction in excess oxygen could destroy the modulation structure. At a time, patch-like inhomogeneity in the gap map sometimes disappeared, indicating that the existence of excess oxygen has an important role in the patch formation. Analysis on the LDOS with various doping levels showed that there was no crossover energy, which separates a pseudogap and a superconducting gap and is proportional to Tc. 相似文献
24.
Naofumi Nishida Yuki Hori Akane Yamauchi Hazuki Fujiwara Makoto Sakurai Yuya Fujiwara Shin-ichi Honda Shunjiro Fujii Hiroyuki A. Sakaue Daiji Kato Tomohiro Yamaguchi Koji Ishibashi Toshifumi Terui Kuei-Yi Lee 《X射线光谱测定》2020,49(1):99-103
Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Arq+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials. 相似文献
25.
Kawada Y Hirata H Fujii H 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,184(1):29-38
This article reports experimental investigations on the use of RF resonators for continuous-wave electron paramagnetic resonance (cw-EPR) and proton nuclear magnetic resonance (NMR) imaging. We developed a composite resonator system with multi-coil parallel-gap resonators for co-registration EPR/NMR imaging. The resonance frequencies of each resonator were 21.8MHz for NMR and 670MHz for EPR. A smaller resonator (22mm in diameter) for use in EPR was placed coaxially in a larger resonator (40mm in diameter) for use in NMR. RF magnetic fields in the composite resonator system were visualized by measuring a homogeneous 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (4-hydroxy-TEMPO) solution in a test tube. A phantom of five tubes containing distilled water and 4-hydroxy-TEMPO solution was also measured to demonstrate the potential usefulness of this composite resonator system in biomedical science. An image of unpaired electrons was obtained for 4-hydroxy-TEMPO in three tubes, and was successfully mapped on the proton image for five tubes. Technical problems in the implementation of a composite resonator system are discussed with regard to co-registration EPR/NMR imaging for animal experiments. 相似文献
26.
Toshiyuki Arakane Takafumi Sato Takenori Fujii 《Journal of Physics and Chemistry of Solids》2011,72(5):552-555
We have investigated three-dimensional electronic structure for NaxCoO2 (x=0.77 and 0.65) by high-resolution angle-resolved photoemission spectroscopy to study the origin of antiferromagnetic (AF) transition of highly doped NaxCoO2(x>0.75). The a1g large hole-like Fermi surface (FS) in x=0.77 shows distinct three-dimensionality along the kz direction, and a three-dimensional small electron pocket appears around Γ point, indicating strong inter-layer electronic correlation. On the other hand, x=0.65 sample does not show three-dimensional behavior. This result indicates that transition of FS as a function of band filling is closely related to the occurrence of the magnetic transition in highly doped NaxCoO2. 相似文献
27.
T. Watanabe P. Bydžovský K. Dobashi S. Endo Y. Fujii O. Hashimoto T. Ishikawa K. Itoh H. Kanda M. Katoh T. Kinoshita O. Konno K. Maeda A. Matsumura F. Miyahara H. Miyase T. Miyoshi K. Mizunuma Y. Miura S.N. Nakamura H. Nomura Y. Okayasu T. Osaka M. Oyamada A. Sasaki T. Satoh H. Shimizu M. Sotona T. Takahashi T. Tamae H. Tamura T. Terasawa H. Tsubota K. Tsukada M. Ukai M. Wakamatsu H. Yamauchi H. Yamazaki 《Physics letters. [Part B]》2007
28.
29.
K. Yamaguchi M. Fujii T. Inoue M. Haraguchi T. Okamoto M. Fukui 《Applied Physics A: Materials Science & Processing》2011,103(3):721-724
A planar bilayered silver prisms with rounded corner is shown to have a singular optical mode depends of gaps by numerical
simulation. Such behavior results from the plasmon resonance in the pairs of nanoprisms both the electric and the magnetic
components of light. 相似文献
30.
MgB2 tapes were fabricated through an ex situ process in a powder-in-tube (PIT) technique using powders treated at elevated temperatures in benzene solutions of benzoic acid with various concentrations. The amount of carbon substitution in MgB2 in heat-treated tapes with treatment at the boiling points (BPs) of the solutions is smaller than that at room temperature (RT). This carbon substitution improves the Jc property in the high-field region. For RT treatment, the Jc property is improved with increasing the solution concentration. In contrast, the Jc property is deteriorated with increasing the concentration for BP treatment. On the other hand, treatment with pure solvent does not bring about the Jc enhancement and carbon substitution at all at both RT and the BPs. This suggests that acidity essential for the dissolution of MgO layers attached to the surface of MgB2 is required for carbon substitution. The BP treatment enhances the acting of the acidity and possibly inflicts damage on MgB2 itself. 相似文献