全文获取类型
收费全文 | 1470篇 |
免费 | 148篇 |
出版年
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 50篇 |
2017年 | 32篇 |
2016年 | 38篇 |
2015年 | 81篇 |
2014年 | 78篇 |
2013年 | 110篇 |
2012年 | 117篇 |
2011年 | 113篇 |
2010年 | 84篇 |
2009年 | 46篇 |
2008年 | 84篇 |
2007年 | 79篇 |
2006年 | 75篇 |
2005年 | 55篇 |
2004年 | 52篇 |
2003年 | 50篇 |
2002年 | 42篇 |
2001年 | 25篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1974年 | 7篇 |
1969年 | 6篇 |
1968年 | 8篇 |
1967年 | 5篇 |
1964年 | 6篇 |
排序方式: 共有1618条查询结果,搜索用时 15 毫秒
11.
12.
Structural Genes for a Newly Recognized Acetolactate Synthase in Escherichia coli K-12 总被引:23,自引:15,他引:8
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maurilio De Felice John Guardiola Bruno Esposito Maurizio Iaccarino 《Journal of bacteriology》1974,120(3):1068-1077
Evidence is reported that shows the presence in Escherichia coli K-12 of a newly found acetolactate synthase. This enzyme is the product of two genes, ilvH and ilvI, both located very close to leu. Amber mutations have been found in both genes and therefore their products are polypeptides. Mutations in the ilvH gene cause the appearance of an acetolactate synthase activity which is relatively resistant to valine inhibition and can be separated by adsorption on hydroxylapatite from another activity present in the extract and more sensitive to valine inhibition than the former. A mutant altered in the ilvI gene was isolated among the revertants sensitive to valine inhibition of an ilvH mutant. Such a mutant lacks the resistant acetolactate synthase. A temperature-sensitive revertant of the ilvI mutant contained a temperature-sensitive acetolactate synthase. Thus ilvI is the structural gene for a specific acetolactate synthase. The activity of the ilvH gene product has been measured by adding an extract containing it to a purified ilvI acetolactate synthase, which, upon incubation, became more sensitive to valine inhibition. Conversely, a valine-sensitive acetolactate synthase (the product of the ilvH and the ilvI genes) became more resistant to valine inhibition upon incubation with an extract of a strain containing a missense ilvH gene product. 相似文献
13.
14.
15.
16.
17.
18.
19.
G Esposito S Cauci F Fogolari E Alessio M Scocchi F Quadrifoglio P Viglino 《Biochemistry》1992,31(31):7094-7103
The reaction between the antitumor octahedral complex trans-RuCl2(DMSO)4 and d(GpG) leads to the formation of a stable compound characterized by a covalent bifunctional coordination of the bases to the metal center. The structure of the compound has been fully characterized by NMR and molecular modeling studies, showing the presence of two N7-coordinated guanine moieties in a head to head conformation, two dimethyl sulfoxide molecules, and one halogen atom in the coordination sphere of the ruthenium. The glycosidic chi angles are essentially in the anti range, the sugar puckering of the 5'G is 3'-endo (100% N), whereas that of the 3'G is more flexible but mainly in 2'-endo conformation (85% S), the two bases are strongly destacked. The compound shows structural features which are surprisingly similar to those exhibited by the corresponding cisplatin complex, indicating that such a way of interaction with DNA is not exclusive to Pt or to metals with square planar coordination geometries. 相似文献
20.
“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species
B. Nicolaus Licia Lama Enrico Esposito Maria Cristina Manca Guido di Prisco Agata Gambacorta 《Polar Biology》1996,16(2):101-104
A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature
of 63°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular
alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572).
Received : 3 February 1995/Accepted : 12 May 1995 相似文献