全文获取类型
收费全文 | 929篇 |
免费 | 17篇 |
专业分类
化学 | 657篇 |
晶体学 | 16篇 |
力学 | 9篇 |
数学 | 30篇 |
物理学 | 234篇 |
出版年
2022年 | 3篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 17篇 |
2014年 | 19篇 |
2013年 | 32篇 |
2012年 | 38篇 |
2011年 | 51篇 |
2010年 | 39篇 |
2009年 | 35篇 |
2008年 | 41篇 |
2007年 | 33篇 |
2006年 | 49篇 |
2005年 | 61篇 |
2004年 | 50篇 |
2003年 | 41篇 |
2002年 | 32篇 |
2001年 | 34篇 |
2000年 | 18篇 |
1999年 | 19篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 20篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1971年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有946条查询结果,搜索用时 15 毫秒
61.
K. Yatsui M. Yatsuzuka T. Fujii M. Yokoyama M. Masuzaki T. Tsuzuki K. Narihara A. Mohri 《Physics letters. A》1979,73(4):321-323
We study experimentally the interaction of a current-modulated relativistic electron beam with a mirror-confined plasma. A high-power transmitter (500 MHz, 1 GW) is developed. Rapid heating takes place up to ≈ 900 eV, which is interpreted as a lower-hybrid parametric instability. 相似文献
62.
New polyesters containing phenoxaphosphine rings were prepared from 2,8-dichloroformyl-10-phenylphenoxaphosphine 10-oxide (I) and bisphenols by interfacial polycondensation. The investigations of polymerization conditions using (I) and bisphenol A showed that addition of quarternary ammonium salts was effective in the preparation of polyesters. The highest viscosities were obtained when tetrabutylammonium chloride was used as accelerator. Some of the resulting polyesters had reduced viscosities of 0.85–1.92 dl/g in DMA of m-cresol and they dissolved in chloroform, m-cresol and nitrobenzene. These polymers melted in the range of 288–355′, hardly degraded below 400′ and were self-extinguishing. They appeared to have better thermal stability than linear open-chain phosphorus-containing polyesters. 相似文献
63.
Archiv der Mathematik - 相似文献
64.
Moment bounds for stationary mixing sequences 总被引:11,自引:0,他引:11
Ryozo Yokoyama 《Probability Theory and Related Fields》1980,52(1):45-57
65.
We investigated the effect of charge-charge interactions on the mobilities of rhodamine 6G (R6G), Nile Red, sulforhodamine B, and Oregon Green 514 (ORG) guest molecules within a silica sol-gel host as the guest charge progressed from positive to neutral to negative. Through classification of the mobility as fixed, tumbling, or intermediate behavior, we were able to distinguish differences in surface attraction as the guest charge was varied. On the basis of our results, an attractive charge (as tested by cationic R6G) does not contribute significantly to mobility within dry films. However, an increase in the cationic influence is observed in water-equilibrated environments. A comparison of ORG in dry and water- and phosphate-buffer-equilibrated films indicates that charge repulsion does significantly increase dye rotational mobility (to a maximum of 24 +/- 3% tumbling molecules). However, in view of the percentage of tumbling molecules found, charge-charge interactions do not appear to be the dominant force controlling guest mobility. 相似文献
66.
Cho T Yoshida M Kohagura J Hirata M Numakura T Higaki H Hojo H Ichimura M Ishii K Islam KM Itakura A Katanuma I Nakashima Y Saito T Tatematsu Y Yoshikawa M Kojima Y Tokioka S Yokoyama N Tomii Y Imai T Pastukhov VP Miyoshi S;GAMMA Group 《Physical review letters》2005,94(8):085002
Vortexlike turbulent structures in hot-ion mode plasmas with several keV are observed in the case with a radially produced weak shear of electric fields E(r). However, a strong E(r) shear formation due to a high ion-confining potential phi(c) production clears up these vortices together with plasma-confinement improvement and disappearance of both drift-wave and turbulencelike Fourier spectral signals. These findings are based on three-time progress in phi(c) in comparison to phi(c) attained 1992-2002. The significant advance of phi(c) is well extended in line with proposed potential-formation physics scalings. 相似文献
67.
68.
Nine 1-[2-(1-substituted)ethyl-3-benzothienyl]-2-(2-methyl-3-benzothienyl)hexafluorocyclopentenes (4-substituted benzoyloxy, N-arylcarbamoyloxy, and aryloxycarbonyloxy) were synthesized. They showed diastereoselective photochromic ring closure upon UV irradiation. Among them, 4-nitrophenoxycarbonyloxy-substituted compound recorded a remarkable 94% diastereomer excess with 91% conversion to the closed form. 相似文献
69.
Takeishi S Rant U Fujiwara T Buchholz K Usuki T Arinaga K Takemoto K Yamaguchi Y Tornow M Fujita S Abstreiter G Yokoyama N 《The Journal of chemical physics》2004,120(12):5501-5504
DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5' end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3'-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method. 相似文献
70.
Kondoh H Iwasaki M Shimada T Amemiya K Yokoyama T Ohta T Shimomura M Kono S 《Physical review letters》2003,90(6):066102
The adsorption structure of methylthiolate (CH3S) adsorbed on Au(111), a long-standing controversial issue, has been unambiguously determined by scanned-energy and scanned-angle S 2p photoelectron diffraction. The methylthiolate molecules are found to occupy atop sites with a S-Au distance of 2.42 +/- 0.03 A. The angular distribution of the S 2p photoelectrons due to forward scattering reveals that the S-C bond is inclined by approximately 50 degrees from the surface normal towards both the [211] and [121] (nearest-neighbor thiolate) directions. 相似文献