全文获取类型
收费全文 | 207篇 |
免费 | 6篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 34篇 |
2012年 | 6篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 14篇 |
2002年 | 10篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有213条查询结果,搜索用时 31 毫秒
171.
172.
Previous studies have demonstrated that the large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase (Rubisco) is site-specifically cleaved by a hydroxyl radical (*OH) generated in the illuminated chloroplast lysates or by an artificial *OH-generating system. However, it is not known whether such cleavage of the LSU by reactive oxygen species (ROS) actually occurs in an intact leaf. When leaf discs of chilling-sensitive cucumber (Cucumis sativus L.) were illuminated at 4 degrees C, five major fragments of the LSU were observed. This fragmentation was completely inhibited by ROS scavengers, such as n-propyl gallate (for *OH) and 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) (for superoxide). FeSO4 stimulated this fragmentation, whereas an iron-specific chelator, deferoxamine, suppressed it. Furthermore, such fragments were identical to those generated from the purified Rubisco by an *OH-generating system in vitro on two-dimensional PAGE. These results indicate that the direct fragmentation of the LSU by reactive oxygen species also occurs in an intact leaf. 相似文献
173.
174.
175.
Miura M Inami K Yoshida M Yamaguchi K Mashino T Mochizuki M 《Bioorganic & medicinal chemistry》2011,19(18):5693-5697
N-Nitrosodialkylamines show their mutagenicity by forming α-hydroxynitrosamines in the presence of rat S9 mix in the Ames assay. The hydroxyl radical derived from Fe(2+)-H(2)O(2) (Fenton's reagent) with Cu(2+) activates N-nitrosamines, with an alkyl chain longer than a propyl constituent, to a direct-acting mutagen. The reactivity of Fe(2+)-Cu(2+)-H(2)O(2) on nitrosamines in relation to their metabolic activation is not fully characterized. Here, we report the identification of the direct-acting mutagen derived from N-nitroso-N-methylpentylamine (NMPe) in the presence of Fe(2+), Cu(2+), H(2)O(2) and nitric oxide (NO), which is a product of nitrosamine metabolism. A dichloromethane extract of the NMPe reaction mixtures was fractionated by silica gel column chromatography several times and by a preparative high performance liquid chromatography (HPLC); we obtained white crystals as a product. The direct-acting mutagen that was isolated was provisionally identified as 5-ethyl-5-nitro-1-pyrazoline 1-oxide by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and X-ray crystallography. To confirm the structure of the mutagen, the authentic compound was synthesized from 2-nitrobutene and diazomethane, followed by N-oxidation with m-chloroperoxybenzoic acid. The (1)H NMR spectral data from the direct-acting mutagen that was synthesized was identical to the data from the isolated mutagen. Furthermore, the authentic 5-ethyl-5-nitro-1-pyrazoline 1-oxide was mutagenic in Salmonella typhimurium TA1535. The results showed that 5-ethyl-5-nitro-1-pyrazoline 1-oxide was a direct-acting mutagen derived from the reaction of NMPe and Fe(2+)-Cu(2+)-H(2)O(2)-NO. 相似文献
176.
Tadahiko Kajiwara Jiro Sekiya Masashi Asano Akikazu Hatanaka 《Bioscience, biotechnology, and biochemistry》2013,77(12):3087-3088
A protease with strict specificity to lysyl peptide bonds like that of Achromobacter protease I was purified from a crude enzyme powder obtained from a culture filtrate of Achromobacter lyticus M497-1 and characterized. The purified enzyme had the following differences from protease I. The enzyme had an isoelectric point of 5.3, lower than the value of 6.9 for protease I. The amino acid composition of the enzyme had higher proportions of His, Glu, and Gly and lower proportions of Arg and Thr than protease I. The enzyme was unstable (30% residual activity) in the presence of 7 m urea (pH 8.0, 30°C, 20 min); protease I was resistant to the same conditions (80% residual activity). The kcat/Km values for the hydrolysis of Tos-Lys-OMe and Lys-pNA by the enzyme were lower than those of protease I. 相似文献
177.
178.
Tadahiko Kajiwara Jiro Sekiya Yoshinobu Odake Akikazu Hatanaka 《Bioscience, biotechnology, and biochemistry》2013,77(8):1481-1484
3Z,6Z-Dienoic acids (C8-C12 and C18) were for the first time synthesized by coupling 2-acetylenic bromides and 2-(3′-butynyloxy)-tetrahydropyrane followed by stereoselective hydrogenation and oxidation. 相似文献
179.
von Akikazu Hatanaka Tadahiko Kajiwara Minoru Ohno 《Bioscience, biotechnology, and biochemistry》2013,77(7):662-664
2-Propyl-5-ethyl-benzylalcohol (IX) was synthesized by an unequivocal route from propylbenzene, thereby establishing the previous deduction tentatively assigned to the leaf alcohol reaction product.1) This benzyl alcohol surmises one of a lemon-like flavor characteristic of manufactured black tea and an attempted search for this compound in the essential oil obtained by steamdistillation of manufactured black tea was made, but its existence has not so far been confirmed with a neutral fraction examined. 相似文献
180.
Mashino T Takigawa Y Saito N Wong LQ Mochizuki M 《Bioorganic & medicinal chemistry letters》2000,10(24):2783-2785
Reductic acid (2,3-dihydroxy-2-cyclopentenone, 1) decreased the ESR signal of 5,5-dimethyl-1-pyrroline 1-oxide (DMPO)-OH produced by hydroxyl radical and DMPO. 1 also inhibited lipid peroxidation initiated by cytochrome P450 and tert-butyl hydroperoxide. 1 inhibited xanthine oxidase activity, while ascorbic acid and 2-hydroxytetronic acid, an ascorbic acid analogue without side chain, did not. 相似文献