全文获取类型
收费全文 | 383篇 |
免费 | 49篇 |
出版年
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 17篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 7篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 14篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 2篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 6篇 |
排序方式: 共有432条查询结果,搜索用时 208 毫秒
1.
Protection of iron-catalysed the radical damage to DNA and lipids by copper (II) bleomycin 总被引:3,自引:0,他引:3
J M Gutteridge F Xiao Change 《Biochemical and biophysical research communications》1981,99(4):1354-1360
The ability of Copper(II)-bleomycin to inhibit oxygen-free-radical damage to biomolecules has been assessed. This copper complex showed inhibitory properties towards iron-catalysed damage to phospholipid membranes and cell-free DNA. It was also able to prevent superoxide-dependent reduction of nitroblue tetrazolium (NBT). Unlike iron, copper-bleomycin does not damage DNA . This may result from a site-specific dismutation of superoxide radicals on the DNA molecule. 相似文献
2.
3.
Transition metal ions, especially iron, appear to be important mediators of oxidative damage in vivo. Iron(II) reacts with H2O2 to give more-reactive radicals. On the basis of ESR spin-trapping data with DMPO, supported by aromatic hydroxylation studies and patterns of DNA base modification, it is concluded that hydroxyl radical (OH.) is likely to be the major damaging species formed in Fenton Systems under biologically-relevant conditions (which include iron concentrations no higher than the micromolar range). Although reactive oxo-iron species (such as ferryl and perferryl) may also be important, direct chemical evidence for their formation and identity in biologically relevant Fenton systems is currently lacking. Studies at alkaline pH values show that iron(IV) and iron(V) species are highly oxidizing under those reaction conditions, with a pattern of reactivity different from that of OH.. 相似文献
4.
β-lactam antibiotics in the presence of certain metal ions damage deoxyribose and DNA with the release of thiobarbituric acid-reactive material. This damage can be substantially prevented by catalase, metal chelators and some scavengers of the hydroxyl radical. Ferric salts in the presence of certain β-lactam antibiotics were effective in degrading deoxyribose but they did not appear to damage DNA. In contrast copper salts and p-lactam antibiotics were extremely effective in damaging both DNA and deoxyribose. 相似文献
5.
Antitranspirant-induced increases in leaf water potential increase tuber calcium and decrease tuber necrosis in water-stressed potato plants 总被引:1,自引:0,他引:1 下载免费PDF全文
Experiments were undertaken with field-grown potato (Solanum tuberosum L.) plants to test the hypothesis that altering leaf:tuber water potential gradients within a plant subjected to low soil moisture will allow greater Ca accumulation in tubers and reverse Ca deficiency-related tuber necrosis. Antitranspirant formulations containing a wax emulsion and a spreader/sticker surfactant increased leaf water potential during a drought episode, significantly reducing the potential gradient that develops between leaf and tuber during a period of stress. Increased leaf water potential in treated plants was associated with decreased leaf Ca and increased tuber Ca. Tuber necrosis was found to be reduced in treated plants, thus increasing tuber quality. 相似文献
6.
C P Moorhouse B Halliwell M Grootveld J M Gutteridge 《Biochimica et biophysica acta》1985,843(3):261-268
Co(II) ions react with hydrogen peroxide under physiological conditions to form a 'reactive species' that can hydroxylate aromatic compounds (phenol and salicylate) and degrade deoxyribose to thiobarbituric-acid-reactive material. Catalase decreases the formation of this species but superoxide dismutase or low concentrations of ascorbic acid have little effect. EDTA, present in excess over the Co(II), can accelerate deoxyribose degradation and aromatic hydroxylation. In the presence of EDTA, deoxyribose degradation by the reactive species is inhibited competitively by scavengers of the hydroxyl radical (.OH), their effectiveness being related to their second-order rate constants for reaction with .OH. In the absence of EDTA the scavengers inhibit only at much higher concentrations and their order of effectiveness is changed. It is suggested that, in the presence of EDTA, hydroxyl radical is formed 'in free solution' and attacks deoxyribose or an aromatic molecule. In the absence of EDTA, .OH radical is formed in a 'site-specific' manner and is difficult to intercept by .OH scavengers. The relationship of these results to the proposed 'crypto .OH' radical is discussed. 相似文献
7.
Aluminium salts accelerate peroxidation of membrane lipids stimulated by iron salts 总被引:12,自引:0,他引:12
Aluminium salts do not themselves stimulate peroxidation of ox-brain phospholipid liposomes, but they greatly accelerate the peroxidation induced by iron(II) salts at acidic pH values. This effect of Al(III) is not seen at pH 7.4, perhaps because Al(III) salts form insoluble complexes at this pH in aqueous solution. Peroxidation of liposomes in the presence of Al(III) and Fe(II) salts is inhibited by the chelating agent desferrioxamine, and by EDTA and diethylenetriaminepentaacetic acid at concentrations greater than those of Fe(II) salt. Aluminium salts slightly stimulate the peroxidation of peroxide-depleted linolenic acid micelles, but they do not accelerate the peroxidation induced by addition of iron(II) salts to the micelles at acidic pH. Aluminium salts accelerate the peroxidation observed when human erythrocytes are treated with hydrogen peroxide at pH 7.4. Desferrioxamine decreases the peroxidation. We suggest that Al(III) ions produce an alteration in membrane structure that facilitates lipid peroxidation, and that the increased formation of fluorescent age pigments in the nervous system of patients exposed to toxic amounts of Al(III) may be related to this phenomenon. The ability of desferal to bind both iron (III) and aluminium(III) salts and to inhibit lipid peroxidation makes it an especially useful chelating agent in the treatment of 'aluminium overload'. 相似文献
8.
Bleomycin degrades DNA under aerobic conditions when a ferrous salt is added. This reaction is enhanced by catalase and certain hydroxyl radical scavengers but inhibited by the addition of hydrogen peroxide. A ferricbleomycin complex is, however, stimulated by addition of hydrogen peroxide. These findings suggest that catalase removes hydrogen peroxide and in so doing prevents loss of ferrous ions and formation of hydroxyl radicals (OH.) by a Fenton-type reaction. It further suggests that OH. radicals, when formed, are more involved in the inactivation of bleomycin than in the release of thiobarbituric acid reactive material from DNA. 相似文献
9.
Christopher P. Moorhouse Barry Halliwell Martin Grootveld John M.C. Gutteridge 《Biochimica et Biophysica Acta (BBA)/General Subjects》1985,843(3)
Co(II) ions react with hydrogen peroxide under physiological conditions to form a ‘reactive species’ that can hydroxylate aromatic compounds (phenol and salicylate) and degrade deoxyribose to thiobarbituric-acid-reactive material. Catalase decreases the formation of this species but superoxide dismutase or low concentrations of ascorbic acid have little effect. EDTA, present in excess over the Co(II), can accelerate deoxyribose degradation and aromatic hydroxylation. In the presence of EDTA, deoxyribose degradation by the reactive species is inhibited competitively by scavengers of the hydroxyl radical (OH), their effectiveness being related to their second-order rate constants for reaction with OH. In the absence of EDTA the scavengers inhibit only at much higher concentrations and their order of effectiveness is changed. It is suggested that, in the presence of EDTA, hydroxyl radical is formed ‘in free solution’ and attacks deoxyribose or an aromatic molecule. In the absence of EDTA, OH radical is formed in a ‘site-specific’ manner and is difficult to intercept by OH scavengers. The relationship of these results to the proposed ‘crypto OH’ radical is discussed. 相似文献
10.