全文获取类型
收费全文 | 1088篇 |
免费 | 65篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 37篇 |
2014年 | 38篇 |
2013年 | 115篇 |
2012年 | 71篇 |
2011年 | 85篇 |
2010年 | 38篇 |
2009年 | 45篇 |
2008年 | 69篇 |
2007年 | 71篇 |
2006年 | 72篇 |
2005年 | 67篇 |
2004年 | 53篇 |
2003年 | 69篇 |
2002年 | 63篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1990年 | 3篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1967年 | 4篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1959年 | 4篇 |
排序方式: 共有1153条查询结果,搜索用时 218 毫秒
31.
Kazuyoshi Kitaoka Mitsuo Kitamura Shun Aoi Noriyuki Shimizu Kazuo Yoshizaki 《Bioelectromagnetics》2013,34(1):43-51
An extremely low‐frequency magnetic field (ELF‐MF) is generated by power lines and household electrical devices. Many studies have suggested an association between chronic ELF‐MF exposure and anxiety and/or depression. The mechanism of these effects is assumed to be a stress response induced by ELF‐MF exposure. However, this mechanism remains controversial. In the present study, we investigated whether chronic ELF‐MF exposure (intensity, 3 mT; total exposure, 200 h) affected emotional behavior and corticosterone synthesis in mice. ELF‐MF‐treated mice showed a significant increase in total immobility time in a forced swim test and showed latency to enter the light box in a light–dark transition test, compared with sham‐treated (control) mice. Corticosterone secretion was significantly high in the ELF‐MF‐exposed mice; however, no changes were observed in the amount of the adrenocorticotropic hormone and the expression of genes related to stress response. Quantification of the mRNA levels of adrenal corticosteroid synthesis enzymes revealed a significant reduction in Cyp17a1 mRNA in the ELF‐MF‐exposed mice. Our findings suggest the possibility that high intensity and chronic exposure to ELF‐MF induces an increase in corticosterone secretion, along with depression‐ and/or anxiety‐like behavior, without enhancement of the hypothalamic–pituitary–adrenal axis. Bioelectromagnetics 34:43–51, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
32.
Daizo Koga Taiji Imoto Shuhei Tanaka Akio Ide Kazuyoshi Yagishita 《Bioscience, biotechnology, and biochemistry》2013,77(9):1941-1948
The effects of detergents on the lysozyme-catalyzed hydrolysis of Micrococcus lysodeikticus cells were investigated by changing the concentration of Na-phosphate buffer and pH in the presence or absence of sucrose. Also, a parallel study of the hydrolysis of glycolchitin by lysozyme was conducted and compared to the lytic reaction. Electron microscopy was utilized to follow the changes in cell morphology during the various treatments.None of the detergents changed turbidity of the cell suspension. However, they did affect the change in turbidity during lysis in unique ways. SDS, which is an anionic detergent, inhibited lysozyme activity and its addition to the reaction mixture caused a rapid and large decrease in the turbidity. Brij 35 and Triton X-100, which are non-ionic detergents, did not inhibit lysozyme activity, but their presence in the reaction mixture changed the rate of turbidity change. Apparently non-ionic detergents disrupt only the protoplast, while anionic detergents disrupt both the protoplast and the damaged cell. The lytic mechanism of M. lysodeikticus by lysozyme was discussed in detail. 相似文献
33.
Shinsaku Hayashida Kazuyoshi Ohta Perfecto Q. Flor Nobuya Nanri Ichiro Miyahara 《Bioscience, biotechnology, and biochemistry》2013,77(7):1947-1950
1-Pyrroline-5-carboxylate dehydrogenase was purified and crystallized from Bacillus sphaericus. The crystalline preparation gave a single band on polyacrylamide slab gel electrophoresis. The molecular weight of the enzyme was determined to be about 100,000 by gel filtration. The enzyme consists of two subunits which are identical in molecular weight (50,000), as judged on SDS slab gel electrophoresis. The enzyme shows an optimum pH of 6.5 to 7.0. Its activity was 8.1 times higher with NADP+ than with NAD +, and the enzyme was stabilized by NADP+. The apparent Km values for l-l-pyrroline-5-carboxylate, NADP+ and NAD+ are 4.2 × 10–5m (with NADP+), 9.5 × 10~6m and 2.5 × IO-3 m, respectively. The enzyme reaction is irreversible. A simple method for the determination of l-ornithine involving ornithine ¿-aminotransferase and 1- pyrroline-5-carboxylate dehydrogenase from B. sphaericus was developed. A linear relationship was found between the absorbance at 340 nm and the amount of l-ornithine (50 ~ 400 nmol), and between the fluorescence and the amount of l-ornithine (0.2 ~ 10 nmol). 相似文献
34.
Kazuyoshi Nishiyama Naomichi Baba Jun’ichi Oda Yuzo Inouye 《Bioscience, biotechnology, and biochemistry》2013,77(4):821-822
Aiming to get useful steroidal alkaloids by tissue culture of Solanum laciniatum Ait., indefinitely growing callus tissue was prepared from the mother plant. Some nutritional requirements for the growth of the callus tissue were studied. By examining steroidal compounds in callus culture, cholesterol, stigmasterol, β-sitosterol, lanosterol, squalene, diosgenin and a new steroidal alkaloid were found to be formed in the callus culture. The new steroidal alkaloid was found to be solasodine derivative containing rhamnose and other unidentified sugars. 相似文献
35.
Akio Kobayashi Akira Takemura Koichi Koshimizu Hiroshi Nagano Kazuyoshi Kawazu 《Bioscience, biotechnology, and biochemistry》2013,77(2):585-589
Three fungal trichothecenes, verrucarin A, roridin A and 8-β-hydroxyroridin E, were isolated as callus-initiating promoters from Myrothecium sp. 301. These trichothecenes promoted callus induction, synergistically coupled with a low concentration of 2,4-dichlorophenoxyacetic acid. 相似文献
36.
Hitoshi Ohmori Hisashi Ishitani Kazuyoshi Sato Shoichi Shimizu Saburo Fukui 《Bioscience, biotechnology, and biochemistry》2013,77(2):359-365
Purple nonsulfur bacteria, Rhodospirillum rubrum and Rhodopseudomonas spheroides were found to possess coenzyme B12-dependent glutamate mutase activity. Cell-free extracts of these bacteria grown on Co2+-containing media catalyzed the conversion of glutamate to β-methylaspartate and further to mesaconate. The activity of the cell-free extracts of these organisms cultivated on Co2+-deficient media was markedly lower than that of the normal cells. Addition of coenzyme B12 to the former reaction mixture enhanced the mesaconate formation via β-methylaspartate. These results indicate the involvement of coenzyme Independent glutamate mutase of these bacteria in the dissimilation of glutamate to acetyl-CoA and pyruvate through the following pathway.glutamate→β→methylaspartate→mesaconate→citramalate→→acetyl-CoA, pyruvate On the other hand, a greater part of glutamate was converted to α-hydroxyglutarate and succinate with the cell-free extracts of these photosynthetic bacteria. This fact, taking account of the presence of propionyl-CoA carboxylase in these bacteria, implies the participation of coenzyme B12-dependent (R)-methylmalonyl-CoA mutase in the formation of succinate via the following route.glutamate→α-ketoglutarate→α-hydroxyglutarate→propionate→propionyl-CoA→(S)-methylmalonyl-CoA→(R)-methylmalonyl-CoA→succinyl-CoA 相似文献
37.
38.
Shinsaku Hayashida Kazuyoshi Ohta 《Bioscience, biotechnology, and biochemistry》2013,77(11):2561-2567
Chromatographically homogeneous phosphatidylcholine identified by thin-layer chromatography on silica gel G was isolated from mycelia of Aspergillus oryzae or egg yolk by a combination of alumina and silicic acid column chromatography. Although the 2-position in both Asp. oryzae- and egg yolk-phosphatidylcholine was occupied nearly exclusively by unsaturated fatty acids, significant proportions of unsaturated fatty acids were also found in the 1 -position of Asp. oryzae-phosphatidylcholine. In nitrogen gas-sparging anaerobic culture of Saccharomvces sake Kyokai No. 7, supplementing the basal synthetic medium with phosphatidylcholine enhanced the yeast growth and fermentative activity, whereas adding ergosteryl oleate enhanced alcohol-endurability. Supplementation with both phosphatidylcholine and ergosteryl oleate promoted the yeast growth, fermentative activity and alcohol-endurability of cells. 相似文献
39.
As a new adsorbent of lysozyme-like enzymes, chitin coated (CC-)cellulose was prepared. CC-cellulose was stable and had good flow properties for use in column chromatography. Affinity chromatography with CC-cellulose showed that 3~5 mg of lysozyme/ml resin was adsorbed specifically and desorbed quantitatively under mild conditions. The utilities of the method of affinity chromatography with CC-cellulose are discussed. 相似文献
40.
Effects of Aspergillus oryzae-proteolipid (PL) on the formation of high concentrations of alcohol, more than 20% as in sake brewing, have been studied. Electron microscopy revealed that there were no vacuoles but many lipid deposits in cytoplasm of the alcoholtolerant cells of Saccharomyces sake Kyokai No. 7, which were obtained by the anaerobic culture supplemented with PL. Sphaeroplasts from the alcohol-tolerant cells were stable in 20% alcohol, whereas those from the untolerant cells grown anaerobically in the PL-unsupplemented media were ruptured. The cell membrane became alcohol-endurable in the anaerobic cultures with PL. Synthetic phospholipid promoted yeast growth and the fermentative activity, whereas a small amount of sterol ester enhanced the alcohoi-endurability. The supplementation of both lipids anaerobically induced physiological properties characteristic of the alcohol-tolerant cells. 相似文献