全文获取类型
收费全文 | 681篇 |
免费 | 66篇 |
国内免费 | 1篇 |
出版年
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 28篇 |
2013年 | 30篇 |
2012年 | 35篇 |
2011年 | 29篇 |
2010年 | 33篇 |
2009年 | 16篇 |
2008年 | 25篇 |
2007年 | 30篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 20篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 17篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1969年 | 4篇 |
排序方式: 共有748条查询结果,搜索用时 15 毫秒
81.
Mayr JA Haack TB Graf E Zimmermann FA Wieland T Haberberger B Superti-Furga A Kirschner J Steinmann B Baumgartner MR Moroni I Lamantea E Zeviani M Rodenburg RJ Smeitink J Strom TM Meitinger T Sperl W Prokisch H 《American journal of human genetics》2012,90(2):314-320
Exome sequencing of an individual with congenital cataracts, hypertrophic cardiomyopathy, skeletal myopathy, and lactic acidosis, all typical symptoms of Sengers syndrome, discovered two nonsense mutations in the gene encoding mitochondrial acylglycerol kinase (AGK). Mutation screening of AGK in further individuals with congenital cataracts and cardiomyopathy identified numerous loss-of-function mutations in an additional eight families, confirming the causal nature of AGK deficiency in Sengers syndrome. The loss of AGK led to a decrease of the adenine nucleotide translocator in the inner mitochondrial membrane in muscle, consistent with a role of AGK in driving the assembly of the translocator as a result of its effects on phospholipid metabolism in mitochondria. 相似文献
82.
83.
Stable isotope patterns in lichens are known to vary largely, but effects of substrate on carbon and nitrogen stable isotope signatures of lichens were previously not investigated systematically. N and C contents and stable isotope (δ15N, δ13C) patterns have been measured in 92 lichen specimens of Xanthoria parietina from southern Bavaria growing on different substrates (bark and stone). Photobiont and mycobiont were isolated from selected populations and isotopically analyzed. Molecular investigations of the internal transcribed spacer of the nuclear ribosomal DNA (ITS nrDNA) region have been conducted on a subset of the specimens of X. parietina. Phylogenetic analysis showed no correlation between the symbionts X. parietina and Trebouxia decolorans and the substrate, isotope composition, or geographic origin. Instead specimens grown on organic substrate significantly differ in isotope values from those on minerogenic substrate. This study documents that the lichens growing on bark use additional or different N sources than the lichens growing on stone. δ15N variation of X. parietina apparently is controlled predominantly by the mass fraction of the mycobiont and its nitrogen isotope composition. In contrast with mycobionts, photobionts of X. parietina are much more 15N‐depleted and show less isotopic variability than mycobionts, probably indicating a mycobiont‐independent nitrogen acquisition by uptake of atmospheric ammonia. 相似文献
84.
Gerald Mayr 《Journal of Ornithology》2004,145(4):281-286
A partial skeleton of a new fossil loon (Aves, Gaviiformes), ?Colymboides metzleri n.sp., is described from the early Oligocene (Rupelian) of Frauenweiler in Germany. The new species resembles the early Miocene species Colymboides minutus in size and overall morphology, but differs in several osteological details. The specimen represents the first associated remains of an early Tertiary loon. Preserved stomach content further provides the first direct evidence that early Tertiary loons were already specialized towards a piscivorous diet, hunting fishes in a marine environment.Communicated by F. Bairlein 相似文献
85.
86.
pAd5-Blue: direct ligation system for engineering recombinant adenovirus constructs. 总被引:4,自引:0,他引:4
We have engineered a new vector that makes use of direct ligation for the generation of replication-defective recombinant adenovirus constructs. In the pAd5-Blue vector, unique yet common restriction endonuclease sites exist, that allow cloning in a directional manner of a gene of interest under control of a cytomegalovirus promoter, upstream of a simian virus 40 polyadenylation signal. The insertion of the new gene replaces the beta-galactosidase alpha gene fragment in the pAd5-Blue vector, allowing the identification of recombinants in bacterial culture by the selection of white colonies. Plasmid DNA from white colonies is digested with PacI and transfected into 293 cells, resulting in the generation of a homogenous population of adenovirus containing the gene of interest. The pAd5-Blue vector system does not rely on recombination either in mammalian or bacterial cells. Furthermore, because of compatible overhangs, the variety of restriction endonucleases that can be used to generate the inserted gene gives flexibility to the process for greater ease of use. The system is quick and straightforward, allowing the generation of recombinant adenoviruses within three weeks of obtaining an appropriate insert. This new vector should greatly enhance the ease and speed with which new recombinant adenovirus constructs can be made. 相似文献
87.
The HLA system encompasses approximately one thousandth of the human genome and contains a series of closely linked loci coding for molecules which provide the context for the recognition of antigens by T lymphocytes. Within the HLA system, several phenotypically expressed and genomic polymorphisms can be distinguished. These polymorphisms are described and the main objectives for the future research are discussed. 相似文献
88.
89.
IN MEMORIAM 总被引:1,自引:0,他引:1
90.
Vanesa L. De Pietri Gerald Mayr 《Journal of Zoological Systematics and Evolutionary Research》2014,52(4):312-322
In Europe, Miocene rails (Aves, Rallidae) are quite abundant, but their phylogenetic placement in the context of recent forms has remained elusive. Rails from the early Miocene of the Saint‐Gérand‐le‐Puy area in central France were first described in the 19th century, and currently, only two species are recognized, namely Palaeoaramides christyi and Paraortygometra porzanoides. Our examination of the material however suggests the presence of four, likely coeval, species of rail from these deposits. Palaeoaramides eximius, previously synonymized with Palaeoaramides christyi, is here shown to probably be a distinct species, and a previously unrecognized rail, Baselrallus intermedius gen. et sp. nov., is described. To find out how these fossil rails are related to modern Rallidae, we compared them with an extensive sample of extant rails and identified plesiomorphic and derived features for crown group Rallidae. Our assessment does not support a particularly close relationship of either Palaeoaramides to Aramides or Paraortygometra to Crex (Ortygometra), and overall, these fossil rails are more primitive than previously assumed. Based on our observations of the morphology of the previously undescribed humerus of Palaeoaramides, we show this taxon to be outside crown group Rallidae, and perhaps closely related to the early Oligocene taxon Belgirallus. On the other hand, Paraortygometra porzanoides bears a resemblance to recent flufftails (Sarothrura spp.) in some elements, but whether it can be included in a clade together with flufftails is uncertain. 相似文献