全文获取类型
收费全文 | 877篇 |
免费 | 90篇 |
出版年
2022年 | 5篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 23篇 |
2014年 | 26篇 |
2013年 | 42篇 |
2012年 | 43篇 |
2011年 | 52篇 |
2010年 | 32篇 |
2009年 | 36篇 |
2008年 | 49篇 |
2007年 | 47篇 |
2006年 | 45篇 |
2005年 | 55篇 |
2004年 | 33篇 |
2003年 | 36篇 |
2002年 | 36篇 |
2001年 | 22篇 |
2000年 | 23篇 |
1999年 | 25篇 |
1998年 | 16篇 |
1997年 | 21篇 |
1996年 | 13篇 |
1995年 | 22篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 14篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有967条查询结果,搜索用时 93 毫秒
901.
Mateusz Sikora Sren von Bülow Florian E. C. Blanc Michael Gecht Roberto Covino Gerhard Hummer 《PLoS computational biology》2021,17(4)
The primary immunological target of COVID-19 vaccines is the SARS-CoV-2 spike (S) protein. S is exposed on the viral surface and mediates viral entry into the host cell. To identify possible antibody binding sites, we performed multi-microsecond molecular dynamics simulations of a 4.1 million atom system containing a patch of viral membrane with four full-length, fully glycosylated and palmitoylated S proteins. By mapping steric accessibility, structural rigidity, sequence conservation, and generic antibody binding signatures, we recover known epitopes on S and reveal promising epitope candidates for structure-based vaccine design. We find that the extensive and inherently flexible glycan coat shields a surface area larger than expected from static structures, highlighting the importance of structural dynamics. The protective glycan shield and the high flexibility of its hinges give the stalk overall low epitope scores. Our computational epitope-mapping procedure is general and should thus prove useful for other viral envelope proteins whose structures have been characterized. 相似文献
902.
Marker-assisted pyramiding of two cereal cyst nematode resistance genes from <Emphasis Type="Italic">Aegilops variabilis</Emphasis> in wheat 总被引:1,自引:0,他引:1
Dominique Barloy Jocelyne Lemoine Paulette Abelard A. M. Tanguy Roger Rivoal Joseph Jahier 《Molecular breeding : new strategies in plant improvement》2007,20(1):31-40
The cereal cyst nematode (CCN) Heterodera avenae, is a significant pathogen of wheat. The wild grass Aegilops variabilis Accession No.1 has been found to be resistant to pathotypes of CCN; at least two genes transferred to wheat, designated as
CreX and CreY, are involved in the resistance response. The CreY gene may be the same as Rkn-mn1, which confers resistance to root knot nematode (RKN) Meloidogyne naasi. The objective of this work was to pyramid the two CCN resistance genes in a wheat background through marker-assisted selection.
As a first step, molecular markers flanking CreX were identified. The completely linked RAPD marker of Rkn-mn1 (CreY), OpY16-1065, previously obtained, was converted into a SCAR. All these dominant markers were used to incorporate in the same genotype the
two Ae. variabilis chromosome segments carrying the two genes for resistance. CCN bioassays with the Ha12 pathotype showed that the level of
resistance of the pyramided line was significantly higher than that of CreX and CreY single introgression lines, but lower than that of Ae. variabilis. This study thus illustrates the utilization of molecular markers in breeding for host resistance. 相似文献
903.
904.
905.
Isolated gut segments of Oryctes nasicornis larvae were incubated in vitro after injection with 14C-cellulose. The incubation medium became progressively richer in labelled volatile fatty acids (VFA), demonstrating the process of cellulolysis and the absorption of carbohydrate degradation products. The mesenteron and the proctodeal dilation were both shown to be sites of cellulolysis and VFA absorption. The major acid formed and absorbed was acetic acid which, in the absence of any detectable glucose, would seem to constitute the essential product of carbon metabolism in Oryctes larvae as in ruminant mammals. The cellulolytic capacities of the different intestinal segment were tested and compared to each other. 相似文献
906.
The authors show that the process of the inversion aragonite-calcite is unfinished and fossilized in the cretaceous Scleratinians. This phenomenon is very likely connected with a limited arrival of fresh water in the sediment. 相似文献
907.
908.
909.
Acanthodactylus is a widespread lacertid genus including about thirthy species whose systematics remains much debated.The present study is aimed at improving the taxonomic status of the Tunisian species whose geographical distribution and ecological requirements have been studied elsewhere. Allozymic variation at 22 loci was scored in 14 populations for a total of 249 individuals. High genetic variability is confirmed in all samples; it is higher in species displaying a wide bioclimatic habitat range. No reduction of genetic variability was observed in two insular populations.Any interspecific hybrid could be detected from our genetic data, even in sympatric areas arguing in favor of specific status of four taxons in Northern, Central and Southern Tunisia.Phylogenetic relationships are discussed on the basis of UPGMA and Fitch-Margoliash procedures applied to the genetic distances matrix and centered data analysis of allozyme frequencies. 相似文献
910.
Bouillass Ghada Blanc Isabelle Perez-Lopez Paula 《The International Journal of Life Cycle Assessment》2021,26(12):2408-2435
The International Journal of Life Cycle Assessment - Investigating potential social and socio-economic impacts should play a key role for the development of sustainable mobility alternatives.... 相似文献