全文获取类型
收费全文 | 821篇 |
免费 | 83篇 |
出版年
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 14篇 |
2016年 | 16篇 |
2015年 | 32篇 |
2014年 | 33篇 |
2013年 | 50篇 |
2012年 | 52篇 |
2011年 | 49篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 43篇 |
2007年 | 40篇 |
2006年 | 35篇 |
2005年 | 34篇 |
2004年 | 24篇 |
2003年 | 29篇 |
2002年 | 40篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1981年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1975年 | 5篇 |
1973年 | 8篇 |
1970年 | 4篇 |
1969年 | 6篇 |
1967年 | 3篇 |
1966年 | 5篇 |
1965年 | 7篇 |
排序方式: 共有904条查询结果,搜索用时 694 毫秒
11.
Properties of the xanthine oxidase from human liver 总被引:4,自引:0,他引:4
12.
G. Cassinelli E. Cotta G. D'Amico C. Della Bruna A. Grein R. Mazzoleni M. L. Ricciardi R. Tintinelli 《Archives of microbiology》1970,70(3):197-210
Summary A new microorganism, isolated in our laboratories and identified as Streptomyces michiganensis var. amylolyticus var. nova is described.Thaimycins can be obtained by submerged fermentation of this microorganism on a suitable culture medium.Three new related compounds, thaimycins A, B and C have been obtained and characterized by their physical and chemical properties.Data on the antiprotozoal and anthelmintic activities in vitro as well as in vivo are reported. 相似文献
13.
NAD(P) aldehyde dehydrogenases (EC 1.2.1.3) are a family of enzymes that oxidize a wide variety of aldehydes into acid or activated acid compounds. Using site-directed mutagenesis, the essential nucleophilic Cys 149 in the NAD-dependent phosphorylating glyceraldehyde-3-phosphate dehydrogenase from Escherichia coli has been replaced by alanine. Not unexpectedly, the resulting mutant no longer shows any oxidoreduction phosphorylating activity. The same mutation, however, endows the enzyme with a novel oxidoreduction nonphosphorylating activity, converting glyceraldehyde 3-phosphate into 3-phosphoglycerate. Our study further provides evidence for an alternative mechanism in which the true substrate is the gem-diol entity instead of the aldehyde form. This implies that no acylenzyme intermediate is formed during the catalytic event. Therefore, the mutant C149A is a new enzyme which catalyzes a distinct reaction with a chemical mechanism different from that of its parent phosphorylating glyceraldehyde-3-phosphate dehydrogenase. This finding demonstrates the possibility of an alternative route for the chemical reaction catalyzed by classical nonphosphorylating aldehyde dehydrogenases. 相似文献
14.
Two homologous genes, originated by duplication, encode the human hnRNP proteins A2 and A1. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 belongs, with A1, B1 and B2, to the basic protein subset of the hnRNP complex in mammalian cells. All these proteins share a modular structure consisting of two conserved RNA binding domains linked to less conserved Gly-rich domains (2xRBD-Gly). In the framework of our studies on the genetic basis of hnRNP proteins structure and diversity we have isolated and sequenced the A2 gene and compared it to the previously described A1 gene. The A2 gene, which exists in a single copy on Ch. 7 band p15, is split in 12 exons including an alternatively spliced 36 nt mini exon specific for the human hnRNP protein B1. In this work we show that the intron/exon organisation of the A2 gene is identical to that of the A1 gene over the entire length, indicating a common origin by gene duplication. Moreover the comparison of corresponding exons evidences significant conservation also in the apparently divergent Gly-rich domains that could define previously unenvisaged structural and/or functional motifs. The A2 gene promoter is also analysed in comparison to that of the A1 gene. 相似文献
15.
16.
G P Sgaragli R Ninci L Della Corte R Borghesi M Nardini N Battistini 《Bollettino della Società italiana di biologia sperimentale》1984,60(9):1727-1733
Data obtained in this preliminary study show that in patients chronically treated either with Chlorimipramine (n = 6) or with Chlorpromazine (n = 2), significant amounts of the corresponding Nor1- and Nor2-metabolites were detected in plasma. The role of these metabolites in the overall therapeutic effect is under investigation. 相似文献
17.
The presence of keratinophilic fungi was revealed by sampling the air of Pavia (Italy) from March 1981 to February 1982. The species isolated were: Chrysosporium indicum, Geomyces pannorum var.pannorum, Microsporum gypseum, Myceliophtora vellerea and Trichophyton terrestre. Several filamentous fungi tolerating high levels of cycloheximide were also recovered. 相似文献
18.
M. Fraccaro O. Zuffardi E. Bühler A. Schinzel G. Simoni R. Witkowski E. Bonifaci D. Caufin G. Cignacco N. Delendi L. Gargantini T. Losanowa L. Marca E. Ullrich V. Vigi 《Human genetics》1983,64(4):388-394
Seven patients are described who have some or all of the symptoms of Prader-Willi syndrome. They were ascertained by varying criteria starting either from the clinical picture or from the identification of a chromosome abnormality involving the proximal portion of the long arm of chromosome 15. The chromosome abnormalities consisted of two balanced translocations (15;18 and 8;15), three unbalanced ones (15;18, 15;19, and 9;15), and one interstitial deletion of bands 15q11 and q12. The seventh case had an unidentified extra chromosome. These data and a review of the literature led to the conclusion that deficiency, transposition, and even duplication of the region(s) 15q11-q13 may all result in a syndrome which is identifiable with or similar to the Prader-Willi syndrome. 相似文献
19.
20.
F Roman O Della Zuana M Lonchampt G Saint Romas J Duhault 《Comptes rendus des séances de la Société de biologie et de ses filiales》1984,178(4):372-381
Biogenic amines in pons and striatum have been dosed in twenty-four months old Wistar male rats. Choline acetyltransferase (CAT) and acetylcholine esterase (ACHesterase) activities, [3H] choline uptake by a synaptosomal preparation, [3H] quinuclidinyl benzylate (QNB) binding to muscarinic cholinergic receptors have been determined in hippocampus. Malondialdehyde (MDA) levels in plasma, in liver and in lungs and the characteristics of the skin collagen have been evaluated. Important differences are shown in comparison with three months old of the same strain animals. 相似文献