全文获取类型
收费全文 | 472篇 |
免费 | 20篇 |
国内免费 | 6篇 |
专业分类
化学 | 334篇 |
晶体学 | 4篇 |
力学 | 7篇 |
数学 | 34篇 |
物理学 | 119篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 28篇 |
2010年 | 10篇 |
2009年 | 17篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 19篇 |
2005年 | 20篇 |
2004年 | 19篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1978年 | 9篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1971年 | 6篇 |
1965年 | 5篇 |
排序方式: 共有498条查询结果,搜索用时 15 毫秒
101.
In order to evaluate the effect of annealing treatment on the proton conductivity of ??-alumina, the electrical conductivity of Mg-doped polycrystalline ??-alumina kept at 1,873?K under various conditions of the surrounding atmosphere and then cooled in the furnace was measured in the temperature range 1,173?C1,473?K. The H+/D+ isotope effect on the electrical conductivity was also examined under a hydrogen atmosphere at 1,273?K. The protonic conductivity measured at 1,273?K increased with the increase in the activity of oxygen and water vapor in the annealing atmosphere at 1,873?K. It is considered that the solubility limit of magnesium ions in ??-alumina in equilibrium with the small amount of the spinel phase increased with the increase in the activity of oxygen and water vapor at 1,873?K. This enhanced amount of magnesium ions is frozen in a non-equilibrium state to 1,273?K and works as the enriched acceptor dopant for the incorporation of protons. 相似文献
102.
Asahi K. Ogawa H. Ueno H. Kobayashi Y. Sato W. Yoshimi A. Watanabe H. Kameda D. Miyoshi H. Sakai K. Imai N. Yoneda K. Watanabe Y. X. Fukuda N. Aoi N. Yoshida A. Kubo T. Ishihara M. 《Hyperfine Interactions》2001,136(3-8):183-187
Magnetic dipole and electric quadrupole moments of nuclei in the light-mass neutron-rich region have been studied by taking
advantage of spin-polarized radioactive nuclear beams that have been obtained from the projectile fragmentation reaction.
Analyses of the results reveal a few interesting phenomena characteristic of nuclear structures in this region. In particular,
we report in some detail the latest result on the magnetic moment of the 17C ground state. The distinctly small value of the g-factor obtained, |g(17C)|=0.5054±0.0025, clearly excludes a I
π=1/2+ candidate for the spin-parity assignment of this marginally bound nucleus, providing a reasonable account of the non-halo
nature reported in recent breakup reaction experiments. Finally, future plans at the upcoming radioactive beam facility presently
under construction at RIKEN are briefly mentioned.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
103.
104.
S Sumiya T Yoneda K Kitamura M Murata C Yokoo M Tamai A Yamamoto M Inoue T Ishida 《Chemical & pharmaceutical bulletin》1992,40(2):299-303
To design a potent inhibitor specific for cathepsin B (rat liver), the tertiary structure was predicted based on the crystal structure of the papain complexed with (+)-(2S,3S)-3-(1-[N-(3-methylbutyl)amino]leucylcarbonyl)oxirane-2- carbolylic acid (E-64-c), a thiol protease inhibitor. Taking advantage of the structural characteristics of the predicted active site, seventeen inhibitors were chemically synthesized by molecular modeling, and one of them, N-(L-3-trans-propylcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-p rol ine (CA-074) was shown to be the first potent inhibitor specific for cathepsin B. The relationship between the structure and inhibitory activity is discussed based on the model structure of the cathepsin B-inhibitor complex. 相似文献
105.
A new synthetically useful decarboxylative reduction of γ-carbamoyloxy-α,β-unsaturated esters with lithium dialkylcuprate under mild condition was described. 相似文献
106.
1,4-Dianion of acetophenone N-ethoxycarbonylhydrazone (2) reacts with α-chloroketones such as phenacyl chloride, 1-chloroacetone, 3-chloro-2-butanone, and 1,3-dichloroacetone to give pyrazoline derivatives in good yields. In the reactions of 2-chlorocyclohexanone and 3-chloro-2-norbornanone with 2, cis-chlorohydrin and exo-chlorohydrin were selectively obtained, respectively. 相似文献
107.
108.
H. Iwasaki T. Motobayashi H. Sakurai K. Yoneda T. Gomi N. Aoi N. Fukuda Zs. Fülp U. Futakami Z. Gacsi Y. Higurashi N. Imai N. Iwasa T. Kubo M. Kunibu M. Kurokawa Z. Liu T. Minemura A. Saito M. Serata S. Shimoura S. Takeuchi Y.X. Watanabe K. Yamada Y. Yanagisawa M. Ishihara 《Physics letters. [Part B]》2005,620(3-4):118-124
The excitation of the neutron-rich nucleus 28Ne has been investigated via heavy-ion inelastic scattering in reversed kinematics. The value was determined to be , which is smaller than expected from the low excitation energy of the first state. A comparison with theoretical predictions suggests that the suppressed collectivity in 28Ne is characteristic of nuclei lying on the boundary of the ‘island of inversion’. 相似文献
109.
N. Aoi K. Yoneda H. Miyatake H. Ogawa Y. Yamamoto E. Ideguchi T. Kishida T. Nakamura M. Notani H. Sakurai T. Teranishi H. Wu S. S. Yamamoto Y. Watanabe A. Yoshida M. Ishihara 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(2):253-255
Experimental studies of β-decay measurements of the neutron drip line nuclei 11Li and 14Be are presented. β- decay schemes of these nuclei are determined by measuring β-rays, delayed neutrons and γ-rays in triple coincidence. The decay schemes of both 11Li and 14Be associated with single neutron emission are unambiguously determined. New levels in their daughter nuclei, 11Be and 14B, are found. In addition, the deduced level scheme of 14B indicates the lowering of 2s 1/2 single neutron orbital with respect to 1p 1/2 orbital in the N=9 isotones. Such behavior is known to exist in N=7. 相似文献
110.
Kazuhiko Tonooka Norihiko Kamata Koji Yamada Koji Matsumoto Fumio Maruyama 《Journal of Non》1992,150(1-3):185-191
The distribution functions of doped Tb3+ and Nd3+ in silicate, germanate, borate and phosphate glasses, in which cross-relaxation among active ions plays an important role, have been estimated by fluorescence measurements. In order to analyze both the steady state and the transient fluorescence characteristics, a non-linear model for the resonant energy transfer has recently been developed. The experimental fluorescence intensity and decay curves, measured as a function of acceptor concentration, suggested a modified distribution function, which included the effect of the segregation of donors and acceptors. The number of segregated Tb3+ ions at the second nearest neighbor position around a Tb3+ ion was estimated to be 0.1–3.4, depending on the host glass. 相似文献