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51.
Hiroji Sato Keiichi Konoma Sadao Sakamura Akio Furusaki Takeshi Matsumoto Takao Matsuzaki 《Bioscience, biotechnology, and biochemistry》2013,77(3):795-797
The milk fat globule membrane (MFGM) enclosing fat droplets in bovine milk was isolated, and its effects on hydrolysis of milk fat by lipases were investigated by using a gum arabic-stabilized milk fat emulsion as substrate. The addition of isolated MFGM to the reaction mixture markedly inhibited hydrolysis by pancreatic and microbial (Rhizopus delemer) lipases. The inhibition was completely lost on tryptic digestion of MFGM, suggesting that the protein moiety of MFGM played a role in the inhibition. Soluble glycoprotein (SGP) which was isolated from delipidated MFGM produced marked inhibitory activity. The inhibition by SGP was dependent on substrate concentration, suggesting that the inhibition was at least partly due to coverage and blockage of the substrate surface by SGP. 相似文献
52.
Keiichi Fukuyama Tomitake Tsukihara Yukiteru Katsube Takashi Hamasaki Yuichi Hatsuda 《Bioscience, biotechnology, and biochemistry》2013,77(5):1053-1054
Streptomyces sp. No. 280 produced several kinds of amylase inhibitors (amylase inhibitor A, B, B' and C). Two amylase inhibitors (designated as AI-A1 and AI-A2) were obtained from an amylase inhibitor A fraction by paper chromatography. AI-A1 inhibited muscle phosphorylase a much more than AI-A2 and was hydrolyzed by sweet potato β-amylase whereas AI-A2 was not. Both amylase inhibitors had a carbohydrate and were hydrolyzed by some kinds of amylases or acids. They lost their inhibitory activity against phosphorylase a after treatment with acids or hog pancreatic α-amylase, but they showed increased inhibitory activity toward porcine small intestinal sucrase.Both AI-A1 and AI-A2 were composed of glucose and a basic moiety which gave a positive ninhydrin reaction. The molecular weights of AI-A1 and AI-A2 were estimated to be approximately 1300 ? 1500 by gel filtration on a Sephadex G-15 column. The nitrogen content of the amylase inhibitors was found to be about 1.3% by elementary analysis 相似文献
53.
54.
Takashi Uemura Manami Fujimori Ho-Hi Lee Sakio Ikeda Keiichi Aso 《Bioscience, biotechnology, and biochemistry》2013,77(9):2277-2281
Comparative studies were made of the polymerization of l-aspartic and l-glutamic acid dialkyl esters using polyethylene glycol–modified papain as a catalyst in phosphate buffer (pH 7.5) and in benzene. Changes in the substrate specificity of papain and in the composition of oligomerized products were observed. In the buffer, the diethyl and di-n-propyl esters of l-glutamic acid were sufficiently converted to high molecular weight oligomers with the accumulation of dimer and trimer, but l-aspartic acid esters were very poor substrates. In benzene, l-aspartic acid esters became more reactive than L-glutamic acid esters. In particular, from l-aspartic acid dimethyl ester the product, which was mainly composed of heptamer to decamer, was obtained in a 90% yield. The reaction in benzene required desalted substrates and a small amount of water to proceed extensively. 相似文献
55.
Keiichi Shimazaki Shunrokuro Arima 《Bioscience, biotechnology, and biochemistry》2013,77(6):1229-1235
The ionization of tyrosyl groups in bovine κ-casein and S-carboxyamidomethyl-κ-casein (CAM-κ) was studied by spectrophotometric titration at 295 mµ. In the denaturing solvent 8 m urea, the titration curves are reversible and the pKapp values of eight tyrosyl groups both in κ-casein and in CMA-κ-casein are 10.7. In 0.2 m KCl solution, κ-casein has six tyrosyl groups with normal pKapp value of 10.5 and two groups with higher pKapp value of 11.4. CAM-κ-casein has eight tyrosyl groups with pKapp value of 10.6 in 0.2 m KCl solution. These observations suggest that -S-S- bondings in κ-casein are concerned with the ‘masking’ of the tyrosyl groups. The evidence of the rupture of intermolecular -S-S- bondings of κ-casein in alkaline solution was shown by the study of gel Chromatograph y on Sephadex G–150. One of the possible explanation is that the ionization of tyrosyl groups with higher pKapp value is associated with the destruction of hydrophobic regions, and this destruction is due to the rupture of intermolecular -S-S- bondings under alkaline conditions. 相似文献
56.
Keiichi Nitta Chikako Takura Isao Yamamoto Yuzuru Yamamoto Junzo Imai Saburo Yamatodani 《Bioscience, biotechnology, and biochemistry》2013,77(12):813-827
The chemical structure of oospolactone which is the metabolic product of Oospora astringenes was confirmed by the synthetical approach. 相似文献
57.
Yuji Nagano Keiichi Inuzuka Hirotoshi Samejima Shukuo Kinoshita 《Bioscience, biotechnology, and biochemistry》2013,77(3):254-260
A coupled enzyme system of orotidine-5′-phosphate pyrophosphorylase and orotidine-5′-phosphate decarboxylase has been purified approximately 30-fold from cell-free extract of Micrococcus glutamicus 534 Co–147 by means of acid treatment and fractionations with ammonium sulfate and ethanol addition, and properties of the enzyme system have been studied.Optima of pH, temperature and substrate concentrations for the activity of the purified enzyme system have been investigated, and compared with those of the same enzyme system from dried brewer’s yeast. Furthermore, effects of various inhibitors on the enzyme activity have been examined and it has become evident that the enzyme system is completely inactivated by addition of chelating agent such as EDTA, and regenerated by further addition of magnesium ion. 相似文献
58.
Keiichi Kobayashi Takasumi Hattori Rie Hayashi 《Bioscience, biotechnology, and biochemistry》2013,77(7):1246-1253
In the tricarboxylic acid (TCA) cycle, NADP+-specific isocitrate dehydrogenase (NADP+-ICDH) catalyzes oxidative decarboxylation of isocitric acid to form α-ketoglutaric acid with NADP+ as a cofactor. We constructed an NADP+-ICDH gene (icdA)-overexpressing strain (OPI-1) using Aspergillus niger WU-2223L as a host and examined the effects of increase in NADP+-ICDH activity on citric acid production. Under citric acid-producing conditions with glucose as the carbon source, the amounts of citric acid produced and glucose consumed by OPI-1 for the 12-d cultivation period decreased by 18.7 and 10.5%, respectively, compared with those by WU-2223L. These results indicate that the amount of citric acid produced by A. niger can be altered with the NADP+-ICDH activity. Therefore, NADP+-ICDH is an important regulator of citric acid production in the TCA cycle of A. niger. Thus, we propose that the icdA gene is a potentially valuable tool for modulating citric acid production by metabolic engineering. 相似文献
59.
Takashi Hamasaki Harumitsu Kuwano Kunihiro Isono Yuichi Hatsuda Keiichi Fukuyama Tomitake Tsukihara 《Bioscience, biotechnology, and biochemistry》2013,77(3):749-751
Two β-glucosidases, G1 and G2, were purified from the culture supernatant of Penicillium herquei Banier and Sartory. Both the purified enzymes were homogeneous on polyacrylamide disc gel electrophoresis. The molecular weights of G1 and G2 were estimated to be 125,000 and 122,000, respectively, by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis. G1 and G2 contained 12.7% and 16.1% carbohydrate as glucose, and had isoelectric points of 5.02 and 5.24, respectively. Both enzymes had optimum pHs of 4.0~4.5 and optimum temperatures at 60°C, but pH - and thermo-stabilities of G1 were higher than those of G2. Both enzymes were active not only on p-nitrophenyl β-d-glucopyranoside, salicin, and the p-glucobioses tested but also on laminarin. CM-Cellulose was a very poor substrate for both enzymes. The activities of G1 toward the substrates except for laminarin and CM-cellulose were apparently higher than those of G2. Both enzymes acted on cellobiose to produce a transfer product. 相似文献
60.
Shu Bian Xiaofeng Sun Aiping Bai Chunqing Zhang Linglin Li Keiichi Enjyoji Wolfgang G. Junger Simon C. Robson Yan Wu 《PloS one》2013,8(4)