全文获取类型
收费全文 | 3076篇 |
免费 | 166篇 |
国内免费 | 2篇 |
出版年
2022年 | 14篇 |
2021年 | 23篇 |
2020年 | 9篇 |
2019年 | 17篇 |
2018年 | 26篇 |
2017年 | 21篇 |
2016年 | 51篇 |
2015年 | 96篇 |
2014年 | 91篇 |
2013年 | 235篇 |
2012年 | 165篇 |
2011年 | 176篇 |
2010年 | 92篇 |
2009年 | 109篇 |
2008年 | 145篇 |
2007年 | 166篇 |
2006年 | 153篇 |
2005年 | 181篇 |
2004年 | 188篇 |
2003年 | 185篇 |
2002年 | 167篇 |
2001年 | 55篇 |
2000年 | 58篇 |
1999年 | 62篇 |
1998年 | 45篇 |
1997年 | 55篇 |
1996年 | 37篇 |
1995年 | 46篇 |
1994年 | 41篇 |
1993年 | 33篇 |
1992年 | 46篇 |
1991年 | 30篇 |
1990年 | 35篇 |
1989年 | 29篇 |
1988年 | 40篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 25篇 |
1982年 | 32篇 |
1981年 | 22篇 |
1980年 | 25篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1976年 | 20篇 |
1975年 | 15篇 |
1974年 | 14篇 |
1973年 | 10篇 |
排序方式: 共有3244条查询结果,搜索用时 484 毫秒
121.
Yoshimitsu Ueno Takao Ikami Ryo Yamauchi Koji Kato 《Bioscience, biotechnology, and biochemistry》2013,77(11):2623-2629
An α-galactosidase from tubers of S. affinis was purified about 130 fold by ammonium sulfate fractionation, chromatography on DEAE-cellulose and gel filtration on Sephadex G-75. The purified enzyme showed a single protein band on disc gel electrophoresis. The molecular weight of the enzyme was determined to be approximately 42,000 by gel filtration and 44,000 by SDS disc gel electrophoresis. The optimum reaction pH was 5.2. The enzyme hydrolyzed raffinose more rapidly than planteose. The activation energy of raffinose and planteose by the enzyme was estimated to be 7.89 and 11.4 kcal/mol, respectively. The enzyme activity was inhibited by various galactosides and structural analogs of d-galactose. Besides hydrolytic activity, the enzyme also catalyzed the transfer reaction of d-galactosyl residue from raffinose to methanol. 相似文献
122.
Akira Isogai Akinori Suzuki Shizuo Higashikawa Shimpei Kuyama Saburo Tamura 《Bioscience, biotechnology, and biochemistry》2013,77(4):1023-1024
The structure of the xyloglucan synthesised in vitro by the particulate fraction of suspension-cultured soybean (Glycine max) cells from UDP-glucose and UDP-xylose is mainly composed of two kinds of oligosaccharide-building blocks, a heptasaccharide unit and a pentassaccharide unit [T. Hayashi and K. Matsuda, J. Biol Chem., 256, 11117 (1981)]. The synthesis of the pentasaccharide unit is probably the first step in the construction of oligosaccharide building blocks to elongate the ²-1,4-glucan backbone. This enzymatically synthesized xyloglucan was shown to have the same molecular size (Mw, 180,000) as the xyloglucan prepared from soybean cell walls by gel filtration on a Sepharose CL-6B column, and the same building blocks distributed among each fraction. A pulse-chase experiment indicated that the pentasaccharide unit was converted into the heptasaccharide unit. The conversion was regulated by the concentration of UDP-xylose. 相似文献
123.
Michihiro Sugahara Takao Morimoto Takaaki Kobayashi Shujiro Ariyoshi 《Bioscience, biotechnology, and biochemistry》2013,77(1):77-84
The nutritional values of 16 D-amino acids in chick growth were studied on the purified diets containing crystalline amino acids as a sole source of nitrogen. Growth rate, feed consumption and nitrogen retention were measured. The nutritional values of D-amino acids were studied by comparing individually with the control groups fed on the diet containing all L-amino acids and negative control groups fed with the diet omitted the corresponding L-isomer. The following results were obtained. Essential amino acids: 1. Equal or almost equal nutritional value to the corresponding L-isomer; methionine, phenylalanine, leucine, proline. 2. Half nutritional value compared with L-isomer; valine. 3. Small nutritional value compared with L-isomer; tryptophan, isoleucine, histidine. 4. No nutritional value; lysine, threonine, arginine. Non-essential amino acid: 1. Equal or almost equal nutritional value to the corresponding L-isomer; serine, tyrosine, cystine. 2. There is a possibility that it has a slight growth retardation effect; alanine. 3. The growth retardation effect was found; aspartic acid. 相似文献
124.
Shoichi Takao 《Bioscience, biotechnology, and biochemistry》2013,77(11):765-769
Metal ions had little influence on riboflavin production by Candida robusta, except that Ag, Cu and Hg were strongly inhibitory. The inhibiting action of iron on its production was comparatively small, so that any previous treatment for the removal of iron from the medium was not necessary. Addition of GaCO3 was found to be essential in media containing sucrose or acetate as a carbon source, as pointed out in the previous paper. This effect of CaCO3 was attributed to its neutralizing action. When the reaction of the medium was kept at the optimum pH, about 7.0, high yields of riboflavin could be obtained without the presence of CaCO3. 相似文献
125.
126.
127.
Takao Terashita Kōhei Oda Matashi Kōno Sawao Murao 《Bioscience, biotechnology, and biochemistry》2013,77(9):1937-1943
A Streptomyces-pepsin inhibitor (S-PI or Pepstatin Ac), and DAN-insensitive carboxyl proteinase was found in a still culture filtrate of Lentinus edodes. The new carboxyl proteinase was purified, and about 9 mg purified enzyme was obtained from 19 liters of culture filtrate, with 11% recovery. The enzyme showed a single band on polyacrylamide gel electrophoresis. The molecular weight and isoelectric point were 40,000 and pH 4.2, respectively. The enzyme did not contain histidine and was composed of 387 amino acid residues. The enzyme was most active between pH 2.7 ~ 2.9, and stable over a pH of 3.2 ~ 5.2 for 3 hr at 37°C. The enzyme was not inhibited by S-PI or synthetic pepsin inhibitors such as DAN and EPNP. The physicochemical and enzymological properties were very similar to those of Scytalidium lignicolum carboxyl proteinase A, which was reported to be an S-PI-, and DAN-insensitive carboxyl proteinase. 相似文献
128.
129.
Akira Isogai Akinori Suzuki Shizuo Higashkawa Shimpei Kuyama Saburo Tamura 《Bioscience, biotechnology, and biochemistry》2013,77(12):3033-3035
( + )-α-Kainic acid (1) was synthesized by starting from a building block, N-Boc-3-acetoxyallylglycine ethyl ester (2). The key intermediate, a methyl 4-[(tert-butoxycarbonyl)prenylamino]-5-hydroxy-2-pentenoate derivative (9), was prepared from 2 in eight synthetic steps. After converting 10 into a methyl ester (11), intramolecular ene-carbocyclization of 11 gave a pyrrolidine derivative (12), which was converted to 1 in a moderate yield. 相似文献
130.
Kunikazu Hiraga Susumu Kawabe Takao Yokota Noboru Murofushi Nobutaka Takahashi 《Bioscience, biotechnology, and biochemistry》2013,77(12):2521-2527
From the immature seeds of Phaseolus vulgaris cv. Kentucky Wonder GA1, GA8, GA38, ABA and GA8 glucoside were isolated, and GA4, GA5, GA6 and GA37 were identified by GC or GC-MS. Unknown substance, AB–II, was also suggested to be present in the immature seeds. In the etiolated seedlings glucosyl esters of GA1 and GA38 were identified by GC. GA8 glucoside and AB–II were shown to be present by the histograms. 相似文献