全文获取类型
收费全文 | 2107篇 |
免费 | 128篇 |
国内免费 | 111篇 |
出版年
2024年 | 2篇 |
2023年 | 31篇 |
2022年 | 45篇 |
2021年 | 70篇 |
2020年 | 51篇 |
2019年 | 74篇 |
2018年 | 67篇 |
2017年 | 46篇 |
2016年 | 72篇 |
2015年 | 64篇 |
2014年 | 84篇 |
2013年 | 151篇 |
2012年 | 59篇 |
2011年 | 83篇 |
2010年 | 53篇 |
2009年 | 111篇 |
2008年 | 111篇 |
2007年 | 124篇 |
2006年 | 108篇 |
2005年 | 90篇 |
2004年 | 85篇 |
2003年 | 92篇 |
2002年 | 78篇 |
2001年 | 59篇 |
2000年 | 42篇 |
1999年 | 49篇 |
1998年 | 42篇 |
1997年 | 40篇 |
1996年 | 57篇 |
1995年 | 34篇 |
1994年 | 32篇 |
1993年 | 26篇 |
1992年 | 35篇 |
1991年 | 33篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1972年 | 1篇 |
1964年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有2346条查询结果,搜索用时 125 毫秒
51.
Rizky Pasthika Kirana Kumar Gaurav Sanu Arora Gerlinde Wiesenberger Maria Doppler Sebastian Michel Simone Zimmerl Magdalena Matic Chinedu E. Eze Mukesh Kumar Ajla Topuz Marc Lemmens Rainer Schuhmacher Gerhard Adam Brande B. H. Wulff Hermann Buerstmayr Barbara Steiner 《Plant biotechnology journal》2023,21(1):109-121
Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley. 相似文献
52.
53.
泥河湾盆地发现短喙象化石 总被引:1,自引:1,他引:0
本文记述泥河湾盆地河北蔚县两个地点发现的化石,它们被鉴定为短喙象类的?Anancus和Pentalopodon两个属。 相似文献
54.
《Annales de Paléontologie》2023,109(1):102585
A coracoid of an enantiornithine bird from Upper Cretaceous (probably late Campanian) fluvial sediments at Castigno (Villespassans, Hérault, southern France) is described. It differs from all hitherto reported enantiornithine coracoids and is referred a new genus and species, Castignovolucris sebei. This bone is large and robust, indicating a bird that was among the largest known enantiornithines, possibly the size of a Canada Goose (Branta canadensis). The new taxon is an addition to the short list of Late Cretaceous birds from France and confirms that enantiornithines were an important component of European avifaunas until late in the Cretaceous. 相似文献
55.
Acrocyathus是一类块状体或丛状体的四射珊瑚,在北美分布于下石炭统,我国见于上石炭统,但丛状体的在我国系首次发现。在连续切片上,可见两个生长阶段,其繁殖方式有侧芽繁殖和边缘泡沫板内繁殖,系统分类上另置独立的科级分类。根据形态分析,该珊瑚栖息在动水,能量略高及食料丰富的浅水环境。当前标本为一新种:A.jiyuanensissp.nov.。 相似文献
56.
The gastropod fauna of the Upper Devonian Baggy and Pilton formations in south‐west England is revised and includes some 30 taxa. The topmost part of the Upper Famennian succession in Devon is represented by clastic near‐shore and shallow shelf sediments, indicating a short‐term transgressive phase (‘Strunian Transgression’). The sequence yields a highly diverse fauna dominated by brachiopods and ostracodes, locally supplemented by crinoids, bryozoans, trilobites and molluscs. The taxa ‘Patellostium’britannicum sp. nov., Angyomphalus (Angyomphalus) junius sp. nov. and Dictyotomaria eurocapillaria sp. nov. are erected; a junior homonym is replaced by Macrochilina? piltonensis nom. nov. The gastropod fauna displays an independent character, where latest Devonian faunal elements overlap with Late Palaeozoic taxa expressing a transition similar to that of the bivalves, brachiopods, echinoderms and corals, without a sharp faunal break at the Devonian/Carboniferous boundary. Apart from the Caenogastropoda, all subclasses of gastropods are represented. Members of the bellerophontoids, pleurotomarioids and loxonematoids are most abundant, followed by murchisonioids, naticimorphs, euomphalomorphs and platyceratoids. The various gastropod groups represent different ecological demands and trophic categories, and together with the accompanying fauna indicate that nearly all habitats and niches were occupied in the shallow South Laurussian Shelf. 相似文献
57.
Isabel Figueiral 《Vegetation History and Archaeobotany》1996,5(1-2):121-129
The analysis of archaeological charcoal is used to reconstruct the wood resources in north-west Portugal from the late Bronze
Age to the Roman period. In this paper, the results obtained from 12 sites are considered, and their implications for interpreting
historical human behaviour towards the natural environment and vegetation are discussed. The results indicate a similar kind
of exploitation of the vegetation by different populations which used a similar range of wood resources. Fifty-one taxa are
identified and three main natural biotopes are distinguished, including mixed oak forest, wasteland vegetation and riparian
forest. The large number of taxa identified seems to testify to the existence of a good sampling of the woody vegetation growing
in the proximity of the settlements. Both dry and fresh wood were used, and the value and possible uses are suggested for
some of the most frequent taxa identified. 相似文献
58.
Hermann Behling 《Vegetation History and Archaeobotany》1996,5(3):241-246
Palynological studies on late Quaternary lake sediments from the region of the Amazon estuary, 100 km north-east of Belém, Pará State, Brazil, enable reconstruction of lowland Amazonian rain forest during the Late-glacial and Holocene periods. Late-glacial forests included populations of Podocarpus which suggests a distinct climatic cooling. Ilex was abundant in the early Holocene. Records of the mangrove taxon, Rhizophora, indicate rapid Atlantic sea-level rise in the beginning of the Holocene. High charcoal representation may reflect the first arrival of Amerindians in the Amazon coastal area, probably about 10 800 B.P. 相似文献
59.
60.
本实验采用RFLP技术,对中国东部栗疫病菌(Cryphonectria parasitica)进行了群体遗传结构的研究。313个参试菌株来自10个省(市)的16个群体(子群体),样本分布在北纬24°N—41°N。各菌株的DNA分别用限制性内切酶Pst Ⅰ和EcoR Ⅰ酶切,先后以10个低拷贝DNA探针和1个DNA指纹图谱探针进行了杂交和检测。结果表明,两个探针(pCB29和pMS29.1)的杂交图谱呈单态性;探针pCB19的杂交图谱显示,菌株DNA以PstⅠ酶切的为单态性,以EcoR Ⅰ酶切的则呈多态性;其他7个低拷贝探针的杂交图谱都呈多态性(Pst Ⅰ酶切)、指纹图谱探针的检测结果显示,辽宁凤城群体的菌株与中国东部其他群体的菌株相比,具有更多的限制性杂交片段,菌株间的遗传变异性也更大。 相似文献