全文获取类型
收费全文 | 304篇 |
免费 | 27篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 15篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 25篇 |
2012年 | 23篇 |
2011年 | 23篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有331条查询结果,搜索用时 15 毫秒
11.
Successful lateral transfer requires codon usage compatibility between foreign genes and recipient genomes 总被引:1,自引:0,他引:1
Medrano-Soto A Moreno-Hagelsieb G Vinuesa P Christen JA Collado-Vides J 《Molecular biology and evolution》2004,21(10):1884-1894
We present evidence supporting the notion that codon usage (CU) compatibility between foreign genes and recipient genomes is an important prerequisite to assess the selective advantage of imported functions, and therefore to increase the fixation probability of horizontal gene transfer (HGT) events. This contrasts with the current tendency in research to predict recent HGTs in prokaryotes by assuming that acquired genes generally display poor CU. By looking at the CU level (poor, typical, or rich) exhibited by putative xenologs still resembling their original CU, we found that most alien genes predominantly present typical CU immediately upon introgression, thereby suggesting that the role of CU amelioration in HGT has been overemphasized. In our strategy, we first scanned a representative set of 103 complete prokaryotic genomes for all pairs of candidate xenologs (exported/imported genes) displaying similar CU. We applied additional filtering criteria, including phylogenetic validations, to enhance the reliability of our predictions. Our approach makes no assumptions about the CU of foreign genes being typical or atypical within the recipient genome, thus providing a novel unbiased framework to study the evolutionary dynamics of HGT. 相似文献
12.
13.
14.
15.
Macedo ML das Graças Machado Freire M Novello JC Marangoni S 《Biochimica et biophysica acta》2002,1571(2):83-88
Bruchid larvae cause major losses in grain legume crops throughout the world. Some bruchid species, such as the cowpea weevil and the Mexican bean weevil, are pests that damage stored seeds. Plant lectins have been implicated as antibiosis factors against insects, particularly the cowpea weevil, Callosobruchus maculatus. Talisia esculenta lectin (TEL) was tested for anti-insect activity against C. maculatus and Zabrotes subfasciatus larvae. TEL produced ca. 90% mortality to these bruchids when incorporated in an artificial diet at a level of 2% (w/w). The LD(50) and ED(50) for TEL was ca. 1% (w/w) for both insects. TEL was not digested by midgut preparations of C. maculatus and Z. subfasciatus. The transformation of the genes coding for this lectin could be useful in the development of insect resistance in important agricultural crops. 相似文献
16.
Martins LO Soares CM Pereira MM Teixeira M Costa T Jones GH Henriques AO 《The Journal of biological chemistry》2002,277(21):18849-18859
The Bacillus subtilis endospore coat protein CotA shows laccase activity. By using comparative modeling techniques, we were able to derive a model for CotA based on the known x-ray structures of zucchini ascorbate oxidase and Cuprinus cereneus laccase. This model of CotA contains all the structural features of a laccase, including the reactive surface-exposed copper center (T1) and two buried copper centers (T2 and T3). Single amino acid substitutions in the CotA T1 copper center (H497A, or M502L) did not prevent assembly of the mutant proteins into the coat and did not alter the pattern of extractable coat polypeptides. However, in contrast to a wild type strain, both mutants produced unpigmented colonies and spores unable to oxidize syringaldazine (SGZ) and 2'2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The CotA protein was purified to homogeneity from an overproducing Escherichia coli strain. The purified CotA shows an absorbance and a EPR spectra typical of blue multicopper oxidases. Optimal enzymatic activity was found at < or =pH 3.0 and at pH 7.0 for ABTS or SGZ oxidation, respectively. The apparent K(m) values for ABTS and SGZ at 37 degrees C were of 106 +/- 11 and 26 +/- 2 microm, respectively, with corresponding k(cat) values of 16.8 +/- 0.8 and 3.7 +/- 0.1 s(-1). Maximal enzyme activity was observed at 75 degrees C with ABTS as substrate. Remarkably, the coat-associated or the purified enzyme showed a half-life of inactivation at 80 degrees C of about 4 and 2 h, respectively, indicating that CotA is intrinsically highly thermostable. 相似文献
17.
Moreno-Valenzuela OA Minero-García Y Brito-Argáez L Carbajal-Mora E Echeverría O Vázquez-Nin G Loyola-Vargas VM 《Molecular biotechnology》2003,23(1):11-18
We investigated the intracellular distribution of tryptophan decarboxylase (TDC) (EC 4.1.1.28) in Catharanthus roseus hairy roots using immunofluorescence and immunogold techniques. TDC was detected by immunofluorescence localization in the
cytosol and in the apoplastic region of the meristematic cells of the roots, with a slight enrichment in the epidermal cells
of the root cap and in the meristematic region. In the enlargement zone, TDC was localized only in the first three layers
of the cortex. In the maturation zone, the enzyme was not present. Immunogold studies confirmed that the enzyme was localized
in the cytosol of the meristematic region, and intense gold labeling was found in the apoplastic zone. A protein fraction
isolated from the apoplastic zone and assayed for TDC activity showed high activity. 相似文献
18.
19.
20.