全文获取类型
收费全文 | 200篇 |
免费 | 9篇 |
专业分类
化学 | 159篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 19篇 |
物理学 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 4篇 |
排序方式: 共有209条查询结果,搜索用时 0 毫秒
11.
M.J. Grosskopf R.P. Drake C.C. Kuranz E.M. Rutter J.S. Ross N.L. Kugland C. Plechaty B.A. Remington A. Spitkovsky L. Gargate G. Gregori A. Bell C.D. Murphy J. Meinecke B. Reville Y. Sakawa Y. Kuramitsu H. Takabe H.-S. Park 《High Energy Density Physics》2013,9(1):192-197
Experiments investigating the physics of interpenetrating, collisionless, ablated plasma flows have become an important area of research in the high-energy-density field. In order to evaluate the feasibility of designing experiments that will generate a collisionless shock mediated by the Weibel instability on the National Ignition Facility (NIF) laser, computer simulations using the Center for Radiative Shock Hydrodynamics (CRASH) radiation-hydrodynamics model have been carried out. This paper reports assessment of whether the experiment can reach the required scale size while maintaining the low interflow collisionality necessary for the collisionless shock to form. Comparison of simulation results with data from Omega experiments shows the ability of the CRASH code to model these ablated systems. The combined results indicate that experiments on the NIF are capable of reaching the regimes necessary for the formation of a collisionless shock in a laboratory experiment. 相似文献
12.
Spatial and seasonal variations in attenuation of solar ultraviolet radiation in Lake Biwa, Japan 总被引:2,自引:0,他引:2
Seasonal changes in diffuse ultraviolet (UV) and visible light attenuations and inherent optical properties in the lake water were monitored at the pelagic and littoral shallow zones of Lake Biwa which features a broad range of optical conditions within a single large water body. We considered the absorption factors that affect UV attenuation, and clarified the contribution of the absorption of suspended particles and chromophoric dissolved organic matter (CDOM) by multiple regression analyses of the monitoring data. The variability of UV attenuations in the lake demonstrated a strong contrast between the pelagic and the shallow zones. The latter were characterized by turbid systems supplying suspended matter as well as CDOM, whereas the former was far from the turbid systems in the littoral zone or the lake bottom. In this lake, the regulation of UV and light attenuations is rendered competitive by the absorption of suspended particles and CDOM in the lake water, hence, the UV penetration has both spatial and temporal variability based on changes in the physical and biological condition of the lake. 相似文献
13.
14.
Kunihiko Takabe Suguru Ohkawa Toshio Sato Gia Hien Tang Takao Katagiri 《Tetrahedron letters》1980,21(40):3883-3884
Dimerization of 3-methyl-3-butenenitrile (1) by lithium dialkylamide gave selectively 3,5,5-trimethyl-1-amino-4-cyanocyclohexa-1,3-diene (2), which was easily hydrolyzed by aqueous acid to afford 4-cyanoisophorone (3,5,5-trimethyl-4-cyano-cyclohex-2-enone) (3) quantitatively. 相似文献
15.
16.
Kwang‐hoi Lee Ho‐Jin Lee Kazuhide Morino Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1427-1433
π‐Conjugated polymers, PBDT‐CNETT and PBDT‐CNECPDT , were prepared by the Stille cross‐coupling polymerization. Optical and thermal properties of the obtained polymers were investigated by UV–vis spectroscopy and thermogravimetric analysis. PBDT‐CNETT and PBDT‐CNECPDT exhibited very narrow band gaps of 1.39 and 1.13 eV, respectively. Highest occupied molecular orbital energy levels estimated by surface analyzer were ?5.17 and ?5.11 eV for PBDT‐CNETT and PBDT‐CNECPDT , respectively. The solar cells based on these polymers were evaluated with the cell configuration of ITO/PEDOT‐PSS/polymer:PC61BH/LiF/Al. The power conversion efficiencies of the solar cells were estimated to be 1.57 and 0.16% for PBDT‐CNETT and PBDT‐CNECPDT , respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
17.
Treatment of sulfur-substituted aromatic lactams with carbonyl compounds in the presence of samarium(II) diiodide was found to undergo novel tandem desulfurization and reductive coupling reactions to generate -hydroxyalkylated lactams in high yield. Stereochemistry of the coupling products was researched and the results that decreasing the steric bulkiness of the N-substituents as well as raising the reaction temperature leads to an increase of the erythro-selectivity were observed. The mechanistic origins of this stereoselectivity are also briefly documented. 相似文献
18.
19.
On-line preconcentration system for the selective, sensitive and simultaneous determination of chromium species was investigated. Dual mini-columns containing chelating resin were utilized for the speciation and preconcentration of Cr(III) and Cr(VI) in water samples. In this system, Cr(III) was collected on first column packed with iminodiacetate resin. Cr(VI) in the effluent from the first column was reduced to Cr(III), which was collected on the second column packed with iminodiacetate resin. Hydroxyammonium chloride was examined as a potential reducing agent for Cr(VI) to Cr(III).The effects of pH, sample flow rate, column length, and interfering ions on the recoveries of Cr(III) were carefully studied. Five millilitres of a sample solution was introduced into the system. The collected species were then sequentially washed by 1 M ammonium acetate, eluted by 2 M nitric acid and measured by ICP-AES. The detection limit for Cr(III) and Cr(VI) was 0.08 and 0.15 μg l−1, respectively. The total analysis time was about 9.4 min.The developed method was successfully applied to the speciation of chromium in river, tap water and wastewater samples with satisfied results. 相似文献
20.
Kazuhide Nakajo 《Journal of Mathematical Analysis and Applications》2003,279(2):372-379
In this paper, we show strong convergence theorems for nonexpansive mappings and nonexpansive semigroups in Hilbert spaces by the hybrid method in the mathematical programming. 相似文献