全文获取类型
收费全文 | 6738篇 |
免费 | 212篇 |
国内免费 | 31篇 |
专业分类
化学 | 5216篇 |
晶体学 | 82篇 |
力学 | 124篇 |
数学 | 506篇 |
物理学 | 1053篇 |
出版年
2022年 | 58篇 |
2021年 | 58篇 |
2020年 | 76篇 |
2019年 | 95篇 |
2018年 | 59篇 |
2017年 | 47篇 |
2016年 | 114篇 |
2015年 | 110篇 |
2014年 | 150篇 |
2013年 | 318篇 |
2012年 | 360篇 |
2011年 | 392篇 |
2010年 | 223篇 |
2009年 | 215篇 |
2008年 | 415篇 |
2007年 | 436篇 |
2006年 | 447篇 |
2005年 | 372篇 |
2004年 | 341篇 |
2003年 | 317篇 |
2002年 | 289篇 |
2001年 | 97篇 |
2000年 | 88篇 |
1999年 | 79篇 |
1998年 | 58篇 |
1997年 | 90篇 |
1996年 | 89篇 |
1995年 | 48篇 |
1994年 | 64篇 |
1993年 | 59篇 |
1992年 | 68篇 |
1991年 | 56篇 |
1990年 | 46篇 |
1989年 | 34篇 |
1988年 | 49篇 |
1987年 | 42篇 |
1986年 | 42篇 |
1985年 | 89篇 |
1984年 | 99篇 |
1983年 | 43篇 |
1982年 | 89篇 |
1981年 | 82篇 |
1980年 | 76篇 |
1979年 | 77篇 |
1978年 | 76篇 |
1977年 | 58篇 |
1976年 | 65篇 |
1975年 | 45篇 |
1974年 | 46篇 |
1973年 | 64篇 |
排序方式: 共有6981条查询结果,搜索用时 15 毫秒
41.
Hiroshi Sakurai Fumitake Itoh Katsuyoshi Takano Hiromi Oike 《Journal of Physics and Chemistry of Solids》2004,65(12):2083-2088
A novel technique of measuring a magnetic Compton profile using the grazing angle geometry against a sample surface (Grazing Incidence Magnetic Compton Profile) has been successively developed. Measurements of a magnetic moment and a magnetic Compton profile are possible for a Fe 200 nm film on a thick glass substrate. The estimated thinnest limit for measurements is 100 nm for a Fe film. 相似文献
42.
Hiroshi DanjoWataru Sasaki Takehiro MiyazakiTsuneo Imamoto 《Tetrahedron letters》2003,44(17):3467-3469
P-Chirogenic trialkylphosphonium salts were prepared from the corresponding free phosphines by treatment with a strong acid (HBF4 or HOTf). No racemization of the phosphonium salts occurred in methanol or water even at considerably high temperature. The salts were conveniently used in rhodium-catalyzed asymmetric hydrogenation of enamides. 相似文献
43.
Dihydroboronium derivatives of (S,S)-1,2-bis(t-butylmethylphosphino)ethane (t-Bu-BisP*) were prepared and used as chiral diphosphine ligand precursors in Rh-catalyzed asymmetric hydrogenation of methyl (Z)-acetamidocinnamate to afford the hydrogenation product in up to 94% enantioselectivity. 相似文献
44.
Hiroshi Maehara 《Discrete and Computational Geometry》1989,4(1):15-18
The unit distance graphE
n
is the graph whose vertices are the points in Euclideann-space, and two vertices are adjacent if and only if the distance between them is 1. We prove that for anyn there is a finite bipartite graph which cannot be embedded inE
n
as an induced subgraph and that every finite graph with maximum degreed can be embedded inE
N
,N=(d
3 –d)/2, as an induced subgraph. 相似文献
45.
Hiroshi Sawai 《Topology and its Applications》2007,154(18):3125-3134
The purpose in this paper is to prove that there exists a lattice on certain solvable Lie groups and to construct a symplectic solvmanifold with the Hard Lefschetz property, and a locally conformal Kähler solvmanifold. We see that minimal models for these solvmanifolds are formal. 相似文献
46.
Hiroshi Sato 《Journal of Theoretical Probability》1992,5(2):349-353
The aim of this paper is to characterize the nuclearity of an integral operator, defined by a continuous non-negative definite square integrable kernel on a separable metric space, in terms of the integrability of the trace of the kernel function. Nuclearity here plays a role forU-statistics. 相似文献
47.
48.
Gui-Chang Wang Ling Jiang Yoshitada Morikawa Junji Nakamura Zun-Sheng Cai Yin-Ming Pan Xue-Zhuang Zhao 《Surface science》2004,570(3):205-217
The adsorption behavior and thermal activation of carbon dioxide on the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces have been investigated by means of density functional theory calculations and cluster models and periodic slabs. According to the cluster models, the optimized results indicate that the basis set of C and O atoms has a distinct effect on the adsorption energy, but an indistinct one on the equilibrium geometry. For the CO2/Cu(hkl) adsorption systems studied here, the final structure of adsorbed CO2 is near linear and the preferred modes for the adsorption of CO2 onto the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces are the side-on adsorption at the cross bridge site with an adsorption energy of 13.06 kJ/mol, the side-on adsorption at the short bridge site (13.54 kJ/mol), and the end-on adsorption on the on-top site with C–O bonds located along the short bridge site (26.01 kJ/mol), respectively. However, the calculated adsorption energies from periodic slabs are lower as compared to the experimental data as well as the cluster model data, indicating that the periodic slab approach of generalized gradient approximation in the density function theory may be not suitable to obtain quantitative information on the interaction of CO2 with Cu(hkl) surfaces. 相似文献
49.
50.
Hiroshi Aoki Ken Hosoya Tomohisa Norisuye Nobuo Tanaka Daisuke Tokuda Norio Ishizuka Kazuki Nakanishi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(2):949-958
An investigation was made of the gelation of dimethacrylate‐type crosslinking agents in view of an application for separation media. The study mainly centered on a crosslinking agent, glycerol dimethacrylate (GDMA), which is relatively hydrophilic because of a hydroxyl group in the middle of its structure. The gelation of GDMA was compared with that of other hydrophobic crosslinking agents such as ethylene glycol dimethacrylate and 1,6‐hexanediol dimethacrylate. The diluents used in the study were toluene, toluene with methanol, and cyclohexanol. The gelation was observed in real time with a charge coupled device camera and dynamic light scattering (DLS). Also, the separated dry gels were extensively characterized with scanning electron microscopy, BET (N2 absorption and desorption isotherm), and Fourier transform infrared. DLS analysis showed a stronger molecular interaction of GDMA gelation in toluene, whereas this interaction was much weaker in an alcoholic solvent such as toluene with methanol or cyclohexanol. This indicated that GDMA gelation might proceed through hydrogen bonding as well as a crosslinking reaction of vinyl groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 949–958, 2006 相似文献