全文获取类型
收费全文 | 5908篇 |
免费 | 165篇 |
国内免费 | 24篇 |
专业分类
化学 | 4512篇 |
晶体学 | 81篇 |
力学 | 57篇 |
数学 | 253篇 |
物理学 | 1194篇 |
出版年
2022年 | 38篇 |
2021年 | 39篇 |
2020年 | 69篇 |
2019年 | 79篇 |
2018年 | 67篇 |
2017年 | 42篇 |
2016年 | 110篇 |
2015年 | 103篇 |
2014年 | 126篇 |
2013年 | 289篇 |
2012年 | 310篇 |
2011年 | 357篇 |
2010年 | 219篇 |
2009年 | 209篇 |
2008年 | 321篇 |
2007年 | 338篇 |
2006年 | 334篇 |
2005年 | 331篇 |
2004年 | 253篇 |
2003年 | 287篇 |
2002年 | 255篇 |
2001年 | 119篇 |
2000年 | 118篇 |
1999年 | 97篇 |
1998年 | 56篇 |
1997年 | 70篇 |
1996年 | 86篇 |
1995年 | 41篇 |
1994年 | 53篇 |
1993年 | 59篇 |
1992年 | 68篇 |
1991年 | 65篇 |
1990年 | 62篇 |
1989年 | 47篇 |
1988年 | 56篇 |
1987年 | 55篇 |
1986年 | 48篇 |
1985年 | 108篇 |
1984年 | 91篇 |
1983年 | 34篇 |
1982年 | 72篇 |
1981年 | 72篇 |
1980年 | 55篇 |
1979年 | 62篇 |
1978年 | 56篇 |
1977年 | 55篇 |
1976年 | 47篇 |
1975年 | 32篇 |
1974年 | 26篇 |
1973年 | 30篇 |
排序方式: 共有6097条查询结果,搜索用时 15 毫秒
71.
Norihiro?SadatoEmail author Hiroki?Yamada Tomohisa?Okada Masaki?Yoshida Takehiro?Hasegawa Ken-Ichi?Matsuki Yoshiharu?Yonekura Harumi?Itoh 《BMC neuroscience》2004,5(1):56
Background
Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language. 相似文献72.
Takeshi Eitoku Kazuya Taniguchi Yuta Nakazato Shunichi Ono Kenji Katayama 《Optical Review》2010,17(1):5-9
Formation process of gold nanoparticles was investigated by near-field heterodyne transient grating method. In the absence of the protective agents, although the diffusion of H[AuICl2] could be observed after the photo-reduction of H[AuIIICl4], the diffusion of nanoparticle-seeds was not observed. On the other hand, in the presence of the protective agents, the diffusion of a complex molecule (Au and protective agent) and nanoparticle-seeds could be observed. From these results, it was found that enough amount of the complex is essential for the nanoparticle formation. We also investigated the formation process with four different chemicals as a protective agent. The hydrodynamic radius of nanoparticle-seeds generated in the poly(vinyl pyrrolidone) and TritonX-100 solutions were larger than those generated in the Tween 20 and Brij 58 solutions. The former two have hydrophilic chain in the molecular structure; on the other hand, the latter two have hydrophobic alkyl chain. Based on those facts, we concluded that the interaction between the chains of the complex molecule plays an important role in the nanoparticle formation process. 相似文献
73.
Pulsed laser deposition of iron atoms on graphite substrates was performed to produce iron carbide films. Mössbauer spectra of the sample revealed that iron carbide was produced on the substrate surface and that an α-Fe layer was produced above the iron carbide layer. When the substrate temperature was maintained at 300 K, the iron carbide layer had a hyperfine magnetic distribution because it contained high density of defects. Laser deposition of Fe at 570 K produced cementite Fe3C with fewer defects due to enhancement of thermal reactions or annealing of the films. The orientation of hyperfine field of the Fe3C film was parallel to the substrate surface. 相似文献
74.
We have investigated the influence of the vacuum level upon the growth of carbon nanotubes (CNTs) on 6H-SiC () surface.CNTs of about 160 nm in length were formed densely and uniformly on the 6H-SiC surface during annealing at 1700 °C in a high vacuum (∼10−2 Pa). CNTs of about 1 μm in length were formed during annealing at 1700 °C in an ultra-high vacuum (∼10−7 Pa). However, CNTs were not formed and SiO2 layers were formed on the SiC surface at 1700 °C in air. It is found that longer CNTs can grow up in an ultra-high vacuum, moreover, a little aligned and low-density graphite layers, or carbon nanofibers can also grow up. 相似文献
75.
Ohmori K 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(6):167-175
Coherent control is based on optical manipulation of the amplitudes and phases of wave functions. It is expected to be a key technique to develop novel quantum technologies such as bond-selective chemistry and quantum computing, and to better understand the quantum worldview founded on wave-particle duality. We have developed high-precision coherent control by imprinting optical amplitudes and phases of ultrashort laser pulses on the quantum amplitudes and phases of molecular wave functions. The history and perspective of coherent control and our recent achievements are described. 相似文献
76.
Kenji Yajima 《Communications in Mathematical Physics》1984,96(3):349-360
We study the large time behavior of solutions of time dependent Schrödinger equationsiu/t=–(1/2)u+t
V(x/t)u with bounded potentialV(x). We show that (1) if>–1, all solutions are asymptotically free ast, (2) if–1 a solution becomes asymptotically free if and only if it has the momentum support outside of suppV for large time, (3) if –1 <0 all solutions are still asymptotically modified free ast and that (4) if 0 <2, for each local minimumx
0 ofV(x), there exist solutions which are asymptotically Gaussians centered atx=tx
0 and spreading slowly ast. 相似文献
77.
Beni Yoshida 《Annals of Physics》2011,326(1):15-95
Searches for possible new quantum phases and classifications of quantum phases have been central problems in physics. Yet, they are indeed challenging problems due to the computational difficulties in analyzing quantum many-body systems and the lack of a general framework for classifications. While frustration-free Hamiltonians, which appear as fixed point Hamiltonians of renormalization group transformations, may serve as representatives of quantum phases, it is still difficult to analyze and classify quantum phases of arbitrary frustration-free Hamiltonians exhaustively. Here, we address these problems by sharpening our considerations to a certain subclass of frustration-free Hamiltonians, called stabilizer Hamiltonians, which have been actively studied in quantum information science. We propose a model of frustration-free Hamiltonians which covers a large class of physically realistic stabilizer Hamiltonians, constrained to only three physical conditions; the locality of interaction terms, translation symmetries and scale symmetries, meaning that the number of ground states does not grow with the system size. We show that quantum phases arising in two-dimensional models can be classified exactly through certain quantum coding theoretical operators, called logical operators, by proving that two models with topologically distinct shapes of logical operators are always separated by quantum phase transitions. 相似文献
78.
Fraunhofer diffraction patterns of off-axis Gaussian beams passing through an optical system having primary spherical aberration are investigated. The resultant diffraction patterns show a nearly elliptical form with a transverse focal shift which depends on the incident position of the Gaussian beams on the pupil and on their radius. 相似文献
79.
80.
The luminescence induced by heavy charged particle irradiation has been measured. The bi-exciton lines (MT and ML) and the line at 3926 Å were observed. It is concluded that these lines arise from the densely excited region in particle tracks. 相似文献