全文获取类型
收费全文 | 2987篇 |
免费 | 181篇 |
国内免费 | 1篇 |
出版年
2022年 | 11篇 |
2021年 | 25篇 |
2020年 | 13篇 |
2019年 | 23篇 |
2018年 | 27篇 |
2017年 | 41篇 |
2016年 | 50篇 |
2015年 | 85篇 |
2014年 | 99篇 |
2013年 | 292篇 |
2012年 | 149篇 |
2011年 | 144篇 |
2010年 | 120篇 |
2009年 | 108篇 |
2008年 | 175篇 |
2007年 | 187篇 |
2006年 | 213篇 |
2005年 | 183篇 |
2004年 | 202篇 |
2003年 | 176篇 |
2002年 | 146篇 |
2001年 | 46篇 |
2000年 | 38篇 |
1999年 | 50篇 |
1998年 | 32篇 |
1997年 | 28篇 |
1996年 | 28篇 |
1995年 | 33篇 |
1994年 | 36篇 |
1993年 | 27篇 |
1992年 | 37篇 |
1991年 | 25篇 |
1990年 | 37篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 19篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 8篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1968年 | 6篇 |
排序方式: 共有3169条查询结果,搜索用时 31 毫秒
71.
Role of hydrosulfide ions (HS-) in methylmercury resistance in Saccharomyces cerevisiae. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Methylmercury-resistant mutants were obtained from Saccharomyces cerevisiae. They were divided into two complementation groups, met2 (homoserine O-acetyltransferase deficiency) and met15 (enzyme deficiency unknown), as reported previously. It was found that met15 was allelic to met17 (O-acetylserine and O-acetylhomoserine sulfhydrylase deficiency). Methylmercury toxicity was counteracted by exogenously added HS-, and both met2 and met17 (met15) mutants overproduced H2S. On the basis of these results, we conclude that met2 and met17 (met15) cause accumulation of hydrosulfide ions in the cell and that the increased level of hydrosulfide is responsible for detoxification of methylmercury. 相似文献
72.
Isolation of a neuropeptide corresponding to the N-terminal 27 residues of the pituitary adenylate cyclase activating polypeptide with 38 residues (PACAP38) 总被引:16,自引:0,他引:16
A Miyata L Jiang R D Dahl C Kitada K Kubo M Fujino N Minamino A Arimura 《Biochemical and biophysical research communications》1990,170(2):643-648
A novel neuropeptide with 38 residues (PACAP38) was isolated from ovine hypothalamic tissues using the pituitary adenylate cyclase activation in rat pituitary cell cultures as a parameter of the biological activity (Miyata et al, Biochem. Biophys. Res. Commun. 164, 567-574, 1989). From the side fractions obtained during the purification of PACAP38, a shorter form peptide with 27 residues corresponding to the N-terminal 27 amino acids of PACAP38 and amidated C-terminus was isolated and named as PACAP27. Synthetic PACAP27 showed a biological activity of adenylate cyclase stimulation comparable to PACAP38. Moreover PACAP27 which shows a considerable homology with vasoactive intestinal polypeptide (VIP) demonstrated a similar vasodepressor activity as VIP, but the adenylate cyclase stimulating activity was about 1000 times greater than VIP. 相似文献
73.
Adrenal pheochromocytoma PC12h cells respond to pituitary adenylate cyclase activating polypeptide 总被引:2,自引:0,他引:2
T Watanabe T Ohtaki C Kitada M Tsuda M Fujino 《Biochemical and biophysical research communications》1990,173(1):252-258
An adrenal pheochromocytoma cell line, PC12h, was found to respond to a novel hypothalamic neuropeptide, Pituitary Adenylate Cyclase Activating Polypeptide (PACAP). The cells elevated both intracellular and extracellular cAMP levels on stimulation by PACAP, whereas they showed little response to VIP which is structurally related to PACAP. Using [125I]PACAP27 (a shorter form of the peptide) and [125I]VIP, we found large amounts of specific binding sites for PACAP but few binding sites for VIP in PC12h cells. These results indicate that PC12h cells respond to PACAP via a specific PACAP receptor. 相似文献
74.
75.
Purification and properties of an endo-1,4-beta-glucanase translated from a Clostridium josui gene in Escherichia coli.
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An endoglucanase encoded by a gene of Clostridium josui was expressed in Escherichia coli and purified. The homogeneous enzyme, with a molecular weight of 39,000, revealed maximum endoglucanase activity at pH 7.2 to 7.5 and a temperature of 65 to 70 degrees C. The enzyme was stable at a temperature lower than 45 degrees C (the growth temperature of the bacterium) in the range of pH 4.5 to 9.0. The amino acid sequence of the enzyme at the N terminus was Val-Glu-Glu-Asp-Ser-Ser-His-Leu-Ile-Thr-Asn-Gln-Ala-Lys-Lys----. The enzyme hydrolyzed cellotetraose to cellobiose and then transferred cellobiose to the residual cellotetraose. The resulting cellohexaose was cleaved to cellotriose. 相似文献
76.
Stereospecific Reduction of Ethyl 2′ -Ketopantothenate to Ethyl D-(+)-Pantothenate with Microbial Cells as a Catalyst
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michihiko Kataoka Sakayu Shimizu Yukiko Doi Hideaki Yamada 《Applied microbiology》1990,56(11):3595-3597
A novel enzymatic process for the synthesis of D-(+)-pantothenic acid through the asymmetric reduction of the 2′ -ketopantothenate ester is described. Candida macedoniensis AKU 4588 was found to convert ethyl 2′ -ketopantothenate (80 mg/ml) almost specifically to ethyl D-(+)-pantothenate (>98% enantiomeric excess), with a molar yield of 97.2%. 相似文献
77.
Increase in Alkaline Phosphatase Activity in Cucumber Roots during Calcium Starvation 总被引:1,自引:0,他引:1
Alkaline phosphatase activity in cucumber roots increased withcalcium deficiency. However, acid phosphatase was scarcely affectedby the treatment. Re-addition of calcium not only suppressedthe continuous increase in alkaline phosphatase activity butalso reduced the already formed activity. Alkaline phosphatase activity increased with a deficiency ofcalcium, phosphate, minor elements and iron in this order. Eithercycloheximide or actinomycin D completely suppressed the increasein the activity caused by calcium deficiency. (Received April 16, 1981; Accepted July 17, 1981) 相似文献
78.
Hideaki Yamada Toru Nagasawa Haruyuki Ohkishi Bunsei Kawakami Yoshiki Tani 《Biochemical and biophysical research communications》1981,100(3):1104-1110
Synthesis of D-cysteine from 3-chloro-D-alanine and hydrogen sulfide is catalyzed by highly purified 3-chloro-D-alanine hydrogen chloride-lyase from . The synthetic reaction proceeds optimally at pH 8.5, as a function of enzyme concentration and incubation time. The enzymatically synthesized D-cysteine was isolated from the large scale reaction mixture and identified by physicochemical means. 相似文献
79.
80.