全文获取类型
收费全文 | 494篇 |
免费 | 13篇 |
专业分类
化学 | 327篇 |
晶体学 | 7篇 |
力学 | 5篇 |
数学 | 51篇 |
物理学 | 117篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2015年 | 4篇 |
2014年 | 17篇 |
2013年 | 26篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 22篇 |
2007年 | 28篇 |
2006年 | 24篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1966年 | 3篇 |
排序方式: 共有507条查询结果,搜索用时 15 毫秒
11.
[structure: see text] The novel alkaloids 1 and 4 were isolated from an Australian non-verongid sponge, Oceanapia sp. Compound 1 contains an unprecedented imidazolyl-quinolinone substructure attached to a bromotyrosine-derived spiro-isoxazoline. Three other known alkaloids were isolated in addition to 1 and 4 and together represent the first examples of inhibitors of a new mycobacterial enzyme mycothiol S-conjugate amidase (MCA). 相似文献
12.
Summary Inverse gas chromatography with sulphurated olefinic stationary phases and air as carrier gas has been found to yield characteristic
shifts of retention data. The resulting plots of retention index versus reaction time obtained for a range of squalene vulcanizates
have been found to be similar to those given by oxygen absorption measurements. Furthermore the chromatographic oxidation
curves have been found to be consistent with the known oxidation behaviour of the various sulphur networks formed on vulcanization.
This paper is dedicated to the memory of Dr.Graham Moore (1924–1968). 相似文献
13.
Correlated atomic force microscopy and fluorescence lifetime imaging of live bacterial cells 总被引:3,自引:0,他引:3
Micic M Hu D Suh YD Newton G Romine M Lu HP 《Colloids and surfaces. B, Biointerfaces》2004,34(4):205-212
We report on imaging living bacterial cells by using a correlated tapping-mode atomic force microscopy (AFM) and confocal fluorescence lifetime imaging microscopy (FLIM). For optimal imaging of Gram-negative Shewanella oneidensis MR-1 cells, we explored different methods of bacterial sample preparation, such as spreading the cells on poly-L-lysine coated surfaces or agarose gel coated surfaces. We have found that the agarose gel containing 99% ammonium acetate buffer can provide sufficient local aqueous environment for single bacterial cells. Furthermore, the cell surface topography can be characterized by tapping-mode in-air AFM imaging for the single bacterial cells that are partially embedded. Using in-air rather than under-water AFM imaging of the living cells significantly enhanced the contrast and signal-to-noise ratio of the AFM images. Near-field AFM-tip-enhanced fluorescence lifetime imaging (AFM-FLIM) holds high promise on obtaining fluorescence images beyond optical diffraction limited spatial resolution. We have previously demonstrated near-field AFM-FLIM imaging of polymer beads beyond diffraction limited spatial resolution. Here, as the first step of applying AFM-FLIM on imaging bacterial living cells, we demonstrated a correlated and consecutive AFM topographic imaging, fluorescence intensity imaging, and FLIM imaging of living bacterial cells to characterize cell polarity. 相似文献
14.
15.
A simple and efficient synthesis of the title compounds by modified Grignard methodology is described. 相似文献
16.
17.
Grace Mugumbate Ana S. Newton Philip J. Rosenthal Jiri Gut Rui Moreira Kelly Chibale Rita C. Guedes 《Journal of computer-aided molecular design》2013,27(10):859-871
Increased resistance of Plasmodium falciparum to most available drugs challenges the control of malaria. Studies with protease inhibitors have suggested important roles for the falcipain family of cysteine proteases. These enzymes act in concert with other proteases to hydrolyze host erythrocyte hemoglobin in the parasite food vacuole. In order to find potential new antimalarial drugs, we screened in silico the ZINC database using two different protocols involving structure- and ligand-based methodologies. Our search identified 19 novel low micromolar inhibitors of cultured chloroquine resistant P. falciparum. The most active compound presented an IC50 value of 0.5 μM against cultured parasites and it also inhibited the cysteine protease falcipain-2 (IC50 = 25.5 μM). These results identify novel classes of antimalarials that are structurally different from those currently in use and which can be further derivatized to deliver leads suitable for optimisation. 相似文献
18.
Time‐Resolved,In Situ DRIFTS/EDE/MS Studies on Alumina‐Supported Rhodium Catalysts: Effects of Ceriation and Zirconiation on Rhodium–CO Interactions 下载免费PDF全文
Dr. Anna B. Kroner Dr. Mark A. Newton Prof. Dr. Moniek Tromp Dr. Otello M. Roscioni Prof. Andrea E. Russell Prof. Andrew J. Dent Dr. Carmelo Prestipino Prof. John Evans 《Chemphyschem》2014,15(14):3049-3059
The effects of ceria and zirconia on the structure–function properties of supported rhodium catalysts (1.6 and 4 wt % Rh/γ‐Al2O3) during CO exposure are described. Ceria and zirconia are introduced through two preparation methods: 1) ceria is deposited on γ‐Al2O3 from [Ce(acac)3] and rhodium metal is subsequently added, and 2) through the controlled surface modification (CSM) technique, which involves the decomposition of [M(acac)x] (M=Ce, x=3; M=Zr, x=4) on Rh/γ‐Al2O3. The structure–function correlations of ceria and/or zirconia‐doped rhodium catalysts are investigated by diffuse reflectance infrared Fourier‐transform spectroscopy/energy‐dispersive extended X‐ray absorption spectroscopy/mass spectrometry (DRIFTS/EDE/MS) under time‐resolved, in situ conditions. CeOx and ZrO2 facilitate the protection of Rh particles against extensive oxidation in air and CO. Larger Rh core particles of ceriated and zirconiated Rh catalysts prepared by CSM are observed and compared with Rh/γ‐Al2O3 samples, whereas supported Rh particles are easily disrupted by CO forming mononuclear Rh geminal dicarbonyl species. DRIFTS results indicate that, through the interaction of CO with ceriated Rh particles, a significantly larger amount of linear CO species form; this suggests the predominance of a metallic Rh phase. 相似文献
19.
20.