全文获取类型
收费全文 | 1283篇 |
免费 | 111篇 |
国内免费 | 1篇 |
出版年
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 24篇 |
2015年 | 33篇 |
2014年 | 46篇 |
2013年 | 138篇 |
2012年 | 63篇 |
2011年 | 67篇 |
2010年 | 39篇 |
2009年 | 47篇 |
2008年 | 57篇 |
2007年 | 74篇 |
2006年 | 68篇 |
2005年 | 71篇 |
2004年 | 72篇 |
2003年 | 63篇 |
2002年 | 52篇 |
2001年 | 33篇 |
2000年 | 46篇 |
1999年 | 37篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 20篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1982年 | 4篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有1395条查询结果,搜索用时 15 毫秒
51.
Nobuhiro Mori Bunsei Kawakami Yoshiki Tani Hideaki Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(6):1383-1389
Dimethylglycine oxidase was purified to homogeneity from the cell extract of Cylindrocarpon didymum M–1, aerobically grown in medium containing betaine as the carbon source. The molecular weight of the enzyme was estimated to be 170,000 by the gel filtration method and 180,000 by the sedimentation velocity method. The enzyme exhibited an absorption spectrum characteristic of a flavoprotein with absorption maxima at 277, 345 and 450 nm. The enzyme consisted of two identical subunits with a molecular weight of 82,000, and contained two mol of FAD per mol of enzyme. The flavin was shown to be covalently bound to the protein. The enzyme was inactivated by Ag+, Hg2+, Zn2+ and iodoacetate. The enzyme oxidized dimethylglycine but was inert toward choline, betaine, sarcosine and alkylamines. Km and Vmax values for dimethylglycine were 9.1 mm and 1.22 μmol/min/mg, respectively. The enzyme catalyzed the following reaction: Dimethylglycine+O2+H2O → sarcosine+formaldehyde+H2O2. 相似文献
52.
Sakayu Shimizu Hazimu Morioka Keiko Inoue Koji Yasui Yoshiki Tani Hideaki Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(11):2659-2665
The distribution of acyl-CoA synthetase was investigated among microorganisms. High enzyme activity was found in some strains in genera of Pseudomonas, Fusarium, Gibberella and Cylindrocarpon, and in many strains of basidiomycetes. There were two groups in respect to enzyme formation. The enzyme activities of Escherichia, Klebsiella, Enterobacter, Citrobacter and Serratia were detected only when they were grown with fatty acids as the carbon source. On the other hand, the activities of many fungal strains and pseudomonads were easily detected regardless of the carbon source for growth.Gel filtration on Sephadex G-200 showed that the enzymes of Escherichia coli and Gibberella fujikuroi were mostly present around the void volume of the column and retarded by the gel after treatment with Triton X-100. Pseudomonas aeruginosa produced two kinds of enzymes, one was eluted around the void volume of the column and the other retarded by the gel. This elution pattern did not change upon treatment with Triton X-100. Some catalytic properties of acyl-CoA synthetases from P. aeruginosa and G. fujikuroi were also described. 相似文献
53.
Kousaku Murata Keiko Tani Jyoji Kato Ichiro Chibata 《Bioscience, biotechnology, and biochemistry》2013,77(9):2131-2132
Certain edible large jellyfishes belonging to the order Rhizostomeae are consumed in large quantities in China and Japan. The exumbrella part of the edible jellyfish Stomolophus nomurai was cut and soaked in dilute hydrochloric acid solution (pH 3.0) for 12 h, and heated at 121 °C for 20 min. The immunostimulation effects of the jellyfish extract were examined. The jellyfish extract enhanced IgM production of human hybridoma HB4C5 cells 34-fold. IgM and IgG production of human peripheral blood lymphocytes (PBL) were also accelerated, 2.8- and 1.4-fold respectively. Moreover, production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α by human PBL was stimulated 100- and 17-fold respectively. Collagenase treatment inactivated the immunostimulation activity of the jellyfish extract. In addition, purified collagen from bovine Achilles’ tendon accelerated IgM production of hybridoma cells. These facts mean that collagen has an immunostimulation effect, and that the active substance in jellyfish extract is collagen. 相似文献
54.
Yoshiki Tani Koichi Ogata Masao Ukita Tsuyoshi Nakamatsu Yoshikazu Izumi 《Bioscience, biotechnology, and biochemistry》2013,77(2):173-197
Escherichia freundii alkaline phosphatase was found in a membrane fraction and was purified by procedures involving spheroplast formation with lysozyme and EDTA, and DEAE-cellulose and Sephadex G-150 column chromatographies. Then this enzyme along with other phosphatases was investigated on the ability to transfer the phosphoryl group from p-nitrophenyl phosphate to pyridoxine. It was found that the ability of the transphosphorylation varied with these phosphatases. The transphosphorylation to hydroxy compounds such as alcohols, sugars and nucleosides was also compared. Escherichia freundii acid phosphatase showed the highest activity of transphosphorylation among phosphatases tested. The mechanism of transphosphorylation was discussed.An enzyme, pyridoxamine 5′-phosphate transaminase, was purified from the cell-free extract of Clostridium kainantoi. The purification procedures involved ammonium sulfate fractionation, protamine sulfate treatment and, DEAE-cellulose, hydroxylapatite, DEAE-Sephadex and Sephadex G-200 column chromatographies. The purified enzyme, which had approximately 2700-fold higher specific activity over the original extract, showed a single schlieren pattern in the ultracentrifuge. From the spectral analysis, it seemed that pyridoxamine 5′-phosphate transaminase did not contain pyridoxal 5′-phosphate as a prosthetic group. It was recognized that the transamination was accelerated by the addition of amino acid and was inhibited by diisopropyl phosphofluoride. Glutamic acid formed in the reaction was identified to be a D-isomer. A study on the substrate specificity showed that the enzyme might be possible to be specific for pyridoxamine 5′-phosphate.The extracellular formation of vitamin B6 was searched in marine and terrestrial microorganisms. Two bacterial strains were selected and were identified as Vibrio and Flavobacterium, respectively. Marine microorganisms showed the considerable formation of vitamin B6 and the presence of vitamin B6 in sea water was also recognized. The cultural and reaction conditions for vitamin B6 formation by these strains were investigated. Glycerol was commonly the most effective compound on vitamin B6 formation among the compounds tested. It was suggested that both bacteria did not have the control system on vitamin B6 biosynthesis by the amount of possible end products. 相似文献
55.
Koichi Ogata Sakayu Shimizu Yoshiki Tani 《Bioscience, biotechnology, and biochemistry》2013,77(1):84-100
The ability of the formation of coenzyme A from pantothenic acid and cysteine in the presence of AMP or ATP was searched in yeasts and bacteria. The result of screening showed that the activity was found in several yeasts and the bacteria belonging to the genera Sarcina, Corynebacterium and Brevibacterium. Particularly, Brevibacterium ammoniagenes IFO 12071 (ATCC 6871) accumulated a large amount of coenzyme A.Isolation of the reaction products, which were synthesized by Brevibacterium ammoniagenes IFO 12071, were carried out. The isolates were identified as coenzyme A, dephosphocoenzyme A and phosphopantothenic acid.The possibility for the formation of coenzyme A in a larger amount from pantothenic acid and cysteine was investigated with baker’s yeast under the condition coupled with ATP-generating system.Effect of various factors affecting the accumulation of coenzyme A was investigated. Among them, glucose concentration and inorganic phosphorus concentration were the most important factors for its accumulation. Coenzyme A was not accumulated without the phosphorylation of AMP to ATP. Several cationic surfactants stimulated the accumulation of coenzyme A.The amount of coenzyme A accumulated reached about 200 μg per ml of the reaction mixture under the suitable reaction conditions employed. 相似文献
56.
Yoshikazu Izumi Kuninori Sato Yoshiki Tani Koichi Ogata 《Bioscience, biotechnology, and biochemistry》2013,77(6):1335-1340
The 7-keto-8-aminopelargonic acid (KAPA) synthetase activities of cell-free extracts from various bacteria were investigated. The experiments on the substrate specificity of KAPA synthetase, using crude cell-free extracts from bacteria having high enzyme activity, showed that l-serine and pyruvic acid could replace l-alanine, but that, when the enzyme was partially purified, these compounds were not effective. Many kinds of amino acids such as l-cysteine, l-serine, d-alanine, glycine, d-histidine, and l-histidine, inhibited the enzyme activity. This inhibition was found to be competitive with l-alanine. Pyridoxal 5′-phosphate, which is a cofactor of the enzyme, also inhibited the enzyme activity at high concentrations. The repression of KAPA synthetase by biotin occurred in Bacillus subtilis and B. sphaericus but not in Micrococcus roseus and Pseudomonas fluorescens, even at a concentration of 1000 mµg per ml of biotin. 相似文献
57.
Tatsuma Matsutani Takashi Nagai Kazutoshi Kinjyo Yasuhiro Nakanishi 《Wetlands Ecology and Management》2013,21(2):107-115
To reveal the role of tannins in mangroves, tannins in mangrove leaves and the Fe eluted from mangrove soil by adding tannin solutions of different salinity levels was investigated. Leaves of six mangrove and 16 non-mangrove species, and samples of a mangrove floor, Andosol and dark red soil were collected. Results were: (1) Increasing tannic acid concentration to ~50 mM, increased the Fe eluted from mangrove soil to ~20 μgg?1. (2) When a 100 mM tannic acid solution was added, the Fe eluted from mangrove soil was 5.5 times higher than dark red soil. (3) Although elution of Fe from mangrove soil was higher than in Andosol one day after submersion in a 10 mM tannic acid solution, the difference was stable after 2 days. (4) The elution of Fe from all soils significantly decreased with increasing salinity of a 10 mM tannic acid solution. However, the amount from mangrove soil was 6.1 times higher than dark red soil even with 35 ‰ salinity. (5) The tannin content in the mangrove leaves was 99 ± 16 mgg?1 and non-mangrove leaves was 76 ± 19 mgg?1. (6) The Fe eluted from mangrove soil had a positive correlation with the tannin concentrations in the added leaf solution. Tannins in mangrove species promote the elution of Fe from mangrove floor soil even in saline water. Fe complexes were formed when mangrove soil was mixed with leaf tannins suggesting that Fe produced by tannins in mangrove leaves growing in land/sea interfaces likely plays a direct role in marine ecosystems. 相似文献
58.
Hitomi Yatsuki Ken Higashimoto Kosuke Jozaki Kayoko Koide Junichiro Okada Yoriko Watanabe Nobuhiko Okamoto Yoshinobu Tsuno Yoko Yoshida Kazutoshi Ueda Kenji Shimizu Hirofumi Ohashi Tsunehiro Mukai Hidenobu Soejima 《Genes & genomics.》2013,35(2):141-147
Beckwith-Wiedemann syndrome (BWS) is an imprinting-related human disease that is characterized by macrosomia, macroglossia, abdominal wall defects, and variable minor features. BWS is caused by several genetic/epigenetic alterations, such as loss of methylation at KvDMR1, gain of methylation at H19-DMR, paternal uniparental disomy of chromosome 11, CDKN1C mutations, and structural abnormalities of chromosome 11. CDKN1C is an imprinted gene with maternal preferential expression, encoding for a cyclin-dependent kinase (CDK) inhibitor. Mutations in CDKN1C are found in 40 % of familial BWS cases with dominant maternal transmission and in ~5 % of sporadic cases. In this study, we searched for CDKN1C mutations in 37 BWS cases that had no evidence for other alterations. We found five mutations—four novel and one known—from a total of six patients. Four were maternally inherited and one was a de novo mutation. Two frame-shift mutations and one nonsense mutation abolished the QT domain, containing a PCNA-binding domain and a nuclear localization signal. Two missense mutations occurred in the CDK inhibitory domain, diminishing its inhibitory function. The above-mentioned mutations were predicted by in silico analysis to lead to loss of function; therefore, we strongly suspect that such anomalies are causative in the etiology of BWS. 相似文献
59.
Yusuke Tani Keisuke Araki Takehiro Nagai Kowa Koida Shigeki Nakauchi Michiteru Kitazaki 《PloS one》2013,8(1)
It has been argued that when an observer moves, a contingent retinal-image motion of a stimulus would strengthen the perceived glossiness. This would be attributed to the veridical perception of three-dimensional structure by motion parallax. However, it has not been investigated whether the effect of motion parallax is more than that of retinal-image motion of the stimulus. Using a magnitude estimation method, we examine in this paper whether cross-modal coordination of the stimulus change and the observer''s motion (i.e., motion parallax) is essential or the retinal-image motion alone is sufficient for enhancing the perceived glossiness. Our data show that a retinal-image motion simulating motion parallax without head motion strengthened the perceived glossiness but that its effect was weaker than that of motion parallax with head motion. These results suggest the existence of an additional effect of the cross-modal coordination between vision and proprioception on glossiness perception. That is, motion parallax enhances the perception of glossiness, in addition to retinal-image motions of specular surfaces. 相似文献
60.
Natalia J. Martinez Ganesha Rai Adam Yasgar Wendy A. Lea Hongmao Sun Yuhong Wang Diane K. Luci Shyh-Ming Yang Kana Nishihara Shunichi Takeda Mohiuddin Irina Earnshaw Tetsuya Okada Kazutoshi Mori Kelli Wilson Gregory J. Riggins Menghang Xia Maurizio Grimaldi Ajit Jadhav David J. Maloney Anton Simeonov 《PloS one》2016,11(11)