全文获取类型
收费全文 | 1014篇 |
免费 | 83篇 |
出版年
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 38篇 |
2014年 | 34篇 |
2013年 | 61篇 |
2012年 | 43篇 |
2011年 | 38篇 |
2010年 | 30篇 |
2009年 | 36篇 |
2008年 | 37篇 |
2007年 | 29篇 |
2006年 | 38篇 |
2005年 | 41篇 |
2004年 | 36篇 |
2003年 | 37篇 |
2002年 | 42篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 34篇 |
1991年 | 34篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 25篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 13篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1970年 | 7篇 |
1928年 | 4篇 |
排序方式: 共有1097条查询结果,搜索用时 15 毫秒
1.
2.
3.
G. Duménil G. Mattei M. Sergent J. C. Bertrand M. Laget R. Phan-Tan-Luu 《Applied microbiology and biotechnology》1988,27(4):405-409
Summary Crude oil was degraded by a mixed bacterial community grown in continuous culture on sea water. The fermentation process included an emulsification step prior to the introduction of the substrate in the reactor, with external cell recycling by a tangential-flow filtration system. Optimization of the fermentation technique was achieved by using the surface response methodology (Doehlert experimental design). Besides reducing the number of experiments, this approach allowed optimal experimental conditions to be chosen, for the particular goal: percent degradation of crude oil (80%), biomass (7.6 g·l-1) and degradation rate (0.73 g·l-1·h-1). This biodegradation process could be used as a tool to fight against pollutions by petroleum products. 相似文献
4.
In order to verify the applicability of biochemical methods for species identification of Trypanosomatidae, 13 species of monoxenic trypanosomatids plus the heteroxenous Trypanosoma cruzi were comparatively analyzed by three different biochemical methods. Insect trypanosomatids examined were: Crithidia acanthocephali, C. fasciculata (three varieties), C. luciliae luciliae, C. luciliae thermophila, C. deanei, C. oncopelti, Herpetomonas muscarum muscarum, H. megaseliae, H. samuelpessoai, H. mariadeanei, Leptomonas seymouri, L. collosoma, L. samueli, and Blastocrithidia culicis. Also included in the survey were aposymbiotic strains of C. deanei and C. oncopelti. Methods used were: electrophoretic profiling of endonuclease-generated fragments of k-DNA, esterase isoenzymes profiling, and polyacrylamide-gel electrophoresis (SDS-PAGE) of radioiodinated cell surface proteins. Interspecific but not intraspecific differences were detected by all three methods among the 13 monoxenic species examined. Thus, it is concluded that these methods can be successfully used, in addition to classical criteria, for species identification of insect trypanosomatids. 相似文献
5.
6.
7.
Frank C. Eve 《BMJ (Clinical research ed.)》1952,2(4789):879-880
8.
The alpha 2(VIII) collagen gene. A novel member of the short chain collagen family located on the human chromosome 1 总被引:3,自引:0,他引:3
Y Muragaki O Jacenko S Apte M G Mattei Y Ninomiya B R Olsen 《The Journal of biological chemistry》1991,266(12):7721-7727
Type VIII collagen is a major component of Descemet's membrane, the specialized basement membrane of corneal endothelial cells. Sequence analysis of a cDNA isolated from a library made with mRNA from rabbit corneal endothelial cells has indicated that type VIII molecules contain a polypeptide chain, alpha 1(VIII), consisting of a short triple-helical domain of 454 amino acid residues flanked by non-triple-helical domains of 117 and 173 amino acid residues at the amino and carboxyl ends, respectively (Yamaguchi, N., Benya, P. D., van der Rest, M., and Ninomiya, Y. (1989) J. Biol. Chem. 264, 16022-16029). The sequence of alpha 1(VIII) is strikingly similar to that of alpha 1(X) collagen, a product of hypertrophic chondrocytes. Also, characterization of the alpha 1(VIII) and alpha 1(X) collagen genes has shown that they are quite similar in their exon organization. It has been concluded, therefore, that they are homologous members of a distinct subclass of collagen genes (Yamaguchi, N., Mayne, R., and Ninomiya, Y. (1991) J. Biol. Chem. 266, 4508-4513). We have given this subclass the name short chain collagens because of the relatively small size of the triple-helical domain. In the present study, we report on the identification and characterization of a collagen gene encoding a polypeptide which is co-expressed with the alpha 1(VIII) chain in corneal endothelial cells. This collagen chain contains a triple-helical and a carboxyl non-triple-helical domain encoded by a single, large exon both in mice and humans. We conclude, therefore, that the genes encodes a novel member of the short chain collagen family, and we have given this chain the designation alpha 2(VIII) collagen. By in situ hybridization we demonstrate that the alpha 2(VIII) gene is located in the p32.3-p34.3 region of the short arm of chromosome 1. 相似文献
9.
Monosomy 21: a new case confirmed by in situ hybridization 总被引:4,自引:0,他引:4
M. C. Pellissier N. Philip M. A. Voelckel-Baeteman M. G. Mattei J. F. Mattei 《Human genetics》1987,75(1):95-96
Summary A new case of total monosomy 21 in a newborn is described. The diagnosis was first made using the cytogenetic data; it was then confirmed by the dosage of copper-superoxide dismutase (SOD-1) which showed a 50% decrease. In situ hybridization with a probe previously assigned to chromosome 21 was used to rule out the possibility of a partial monosomy with an unbalanced reciprocal translocation. 相似文献