全文获取类型
收费全文 | 2878篇 |
免费 | 162篇 |
国内免费 | 2篇 |
出版年
2022年 | 19篇 |
2021年 | 33篇 |
2020年 | 23篇 |
2019年 | 44篇 |
2018年 | 44篇 |
2017年 | 43篇 |
2016年 | 62篇 |
2015年 | 77篇 |
2014年 | 94篇 |
2013年 | 206篇 |
2012年 | 159篇 |
2011年 | 190篇 |
2010年 | 104篇 |
2009年 | 104篇 |
2008年 | 155篇 |
2007年 | 143篇 |
2006年 | 141篇 |
2005年 | 131篇 |
2004年 | 119篇 |
2003年 | 146篇 |
2002年 | 113篇 |
2001年 | 83篇 |
2000年 | 93篇 |
1999年 | 91篇 |
1998年 | 51篇 |
1997年 | 37篇 |
1996年 | 30篇 |
1995年 | 26篇 |
1994年 | 21篇 |
1993年 | 19篇 |
1992年 | 34篇 |
1991年 | 41篇 |
1990年 | 32篇 |
1989年 | 33篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 27篇 |
1985年 | 34篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1975年 | 17篇 |
1974年 | 10篇 |
1973年 | 16篇 |
1972年 | 10篇 |
1966年 | 8篇 |
排序方式: 共有3042条查询结果,搜索用时 62 毫秒
101.
102.
103.
Yoshikazu Takagi Takane Fujimori Hajime Kaneko Kunio Kato 《Bioscience, biotechnology, and biochemistry》2013,77(11):2395-2396
Carcinogenesis is believed to be induced through the oxidative damage of DNA, and antioxidants are expected to suppress it. So, the polyphenolic antioxidants in daily foods were investigated to see whether they protect against genetic damage by active oxygen. In the evaluation, we used a bioassay and a chemical determination, a Salmonella mutagenicity test for mutation by a N-hydroxyl radical from one of the dietary carcinogens 3-amino-1-methyl-5H-pyrido[4,3-b]indole and the formation of 8-hydroxyl (8-OHdG) from 2′-deoxyguanosine (2′-dG) in a Fenton OH-radical generating system. Thirty-one antioxidants including flavonoids were compared in terms of radical-trapping activity with bacterial DNA and 2′-dG. Antioxidants inhibited the mutation but the IC50 values were in the mM order. Against 8-OHdG formation, only α-tocopherol had a suppressive effect with an IC50 of 1.5 μM. Thus, except α-tocopherol, the dietary antioxidants did not scavenge the biological radicals faster than bacterial DNA and intact 2′-dG, indicating that they failed to prevent oxidative gene damage and probably carcinogenesis. 相似文献
104.
The nature of aromatic amino acid residues in Japanese-radish peroxidase a and the apoprotein was investigated by means of spectrophotometry and fluorospectrophotometry. The tyrosine residues in the holoenzyme were masked in the alkali-titration, giving an abnormally high value of 12.6, while they were exposed in the apoenzyme, exhibiting a value of 10.8. The difference spectra in the ultraviolet region between the holo-and apo-enzyme showed characteristic bands of tryptophan and phenylalanine as well as tyrosine. The perturbation of the aromatic amino acid residues by 50% ethyleneglycol was observed in the apoenzyme but not in the holoenzyme. The fluorophotometric experiments also revealed that the aromatic amino acid residues were in different environments in the holo- and apoenzyme. The difference between the conformation of peroxidase and that of the apoprotein was discussed. 相似文献
105.
Yoshikazu Takagi Takane Fujimori Hajime Kaneko Kunio Kato 《Bioscience, biotechnology, and biochemistry》2013,77(3):787-788
The tetradecapeptide of a renin substrate, DRVYIHPFHLLVYS, was used as a substrate for assaying several fungal aspartic and acidic proteinases in the acidic pH range. Aspartic and acidic proteinases froll) Phycomycetes, Mucor and Rhizopus, and Deuteromycotina, Aspergillus and Penicillium, cleaved the tetradecapeptide at its tyrosyl4-isoleucyl5 (Y4-I5),histidyI6-proly7 (H6_P7) and leucyl11-valyl12 (L11-V12) bonds in the acidic pH range, while acidic proteinases type B and type A-I from Scytalidium lignicolumn, and those from Cladosporium and Basidiomycetes, Pycnoporus sanguineus, and the yeast, Rhodotorula glutinis; showed slightly different specificities towards the tetradecapeptide. Pepsin primarily cleaved the valy3-tyrosyl4 (V3-Y4) and leucyl10-leucyl11 (L10-L11) bonds. All of the aspartic and acidic proteinases of fungal origin tested in the present study have different specificities from that of pepsin. 相似文献
106.
Yuhei Morita Chiaki Yoshida Ikuo Kitamura Shoji Ida 《Bioscience, biotechnology, and biochemistry》2013,77(8):1191-1197
Japanese-radish root contained eighteen isoenzymes of peroxidase distinguishable on polyacrylamide gel electropherograms. The isoenzymes were found to be quite similar to those of horseradish peroxidase, although their quantities were different between two plants. The acidic components were the major isoenzyme in Japanese-radish peroxidase, while the neutral ones were the major one in horseradish. The chromatographic purification of the isoenzymes was performed on CM- and DEAE-Sephadex columns to characterize the components. The components in the preparations purified by the previously reported procedures of Morita et al. were also identified. 相似文献
107.
Tetsuo Fukuzumi Hiroyasu Takahara Hajime Kaneko 《Bioscience, biotechnology, and biochemistry》2013,77(5):513-514
A new method determining the activity of tannin acyl hydrolase (tannase) was made. This method was based on the change in optical density of substrate tannic acid at 310 mμ. In this method, the error of measurement was about 1~3%, and many samples could be tested at one time because of its simplicity.The procedure was as follows; To four parts of substrate (0.350 w/v% of tannic acid dissolved in 0.05m citrate buffer, pH 5.5), one part of the enzyme solution was added.After t minutes reaction at 30°C, 0.1 part of the mixture was added to ten parts of 90% ethanol.The optical density of the ethanol solution at 310 mμ was measured. Tannase activity (unit/ml) was given by following equation. Where Et1 and Et2 mean the optical density of the ethanol solution at 310 mμ prepared after t1 and t2 minutes reaction, and one unit of the enzyme means the amount of the enzyme which is able to hydrolyze one μ mole of the ester bond in tannic acid in one minute.The substrate tannic acid used in this determining method was purified. It was composed of one mole of glucose and nine moles of gallic acid, and eight moles of which formed four moles of m-digallic acid. 相似文献
108.
109.
All globulin components hitherto found in many species of seeds, α, β, γ and δ globulins, were identified in rice grain by ultracentrifugal experiments and gel-filtration chromatography. Among them, γ globulin was found to occur in high concentration in embryo and bran which were the most active parts in biological functions of rice grain. Then γ globulin was isolated from embryo by gel-filtration chromatography on a Sephadex G-200 column. Purified γ globulin was homogeneous in ultracentrifugal analysis and it was found to be insoluble in cold saline solution. On the other hand, α and β globulins were found to be more concentrated in endosperm with considerable heterogeneity. 相似文献
110.
Toshihiro Itoh Hatsue Waki Hiroshi Kaneko 《Bioscience, biotechnology, and biochemistry》2013,77(12):2365-2371
Qualitative and quantitative profiles of phospholipids, neutral lipids, and fatty acid composition in Cr. neoformans during the growth phase were investigated in relation to pyrophosphatidic acid. A marked increase of the total lipid content, which depended on the accumulation of triglyceride in yeast cells with the growth, was observed. The total phospholipid contents in yeast cells remained almostly constant during the exponential phase and slightly decreased in the stationary phase. The major phospholipids of this yeast were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and cardiolipin, the next groups being pyrophosphatidic acid, phosphatidic acid, lysophos-phatidylcholine, and unidentified components. The amounts of phosphatidylcholine, phosphatidylinositol, and cardiolipin were fairly constant throughout the growth phase, but the amount of phosphatidylethanolamine increased and that of phosphatidylserine decreased with progressive growth. The pyrophosphatidic acid contents were 0.9~0.7% for total phospholipid during the growth phase. The major fatty acids of pyrophosphatidic acid were C16:0, C18:1, and C18:2 acids. The changing patterns of fatty acid composition in pyrophosphatidic acid through the growth phase closely resembled that of phosphatidic acid, which contained larger amounts of C18:1 acid (35~45%) than C16:0 acid (30~25%) and C18:2 acid (30~25%). Phosphatidylserine and phosphatidylinositol contained considerable amounts of saturated fatty acid (C16:0 acid, more than 55%). On the other hand, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin contained extremely large amounts of unsaturated fatty acid (C18:1 and C18:2 acid, 85ç90%). 相似文献