全文获取类型
收费全文 | 15446篇 |
免费 | 1248篇 |
国内免费 | 7篇 |
出版年
2024年 | 10篇 |
2023年 | 89篇 |
2022年 | 71篇 |
2021年 | 411篇 |
2020年 | 243篇 |
2019年 | 312篇 |
2018年 | 424篇 |
2017年 | 367篇 |
2016年 | 600篇 |
2015年 | 870篇 |
2014年 | 951篇 |
2013年 | 1121篇 |
2012年 | 1440篇 |
2011年 | 1429篇 |
2010年 | 889篇 |
2009年 | 682篇 |
2008年 | 1042篇 |
2007年 | 930篇 |
2006年 | 900篇 |
2005年 | 855篇 |
2004年 | 741篇 |
2003年 | 625篇 |
2002年 | 617篇 |
2001年 | 109篇 |
2000年 | 79篇 |
1999年 | 102篇 |
1998年 | 121篇 |
1997年 | 78篇 |
1996年 | 64篇 |
1995年 | 54篇 |
1994年 | 52篇 |
1993年 | 60篇 |
1992年 | 50篇 |
1991年 | 31篇 |
1990年 | 43篇 |
1989年 | 44篇 |
1988年 | 17篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1968年 | 7篇 |
1967年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Andrea Schneider Manuela Ruppert Oliver Hendrich Thomas Giang Maite Ogueta Stefanie Hampel Marvin Vollbach Ansgar Büschges Henrike Scholz 《PloS one》2012,7(12)
The decision to move towards a mating partner or a food source is essential for life. The mechanisms underlying these behaviors are not well understood. Here, we investigated the role of octopamine – the invertebrate analogue of noradrenaline – in innate olfactory attraction to ethanol. We confirmed that preference is caused via an olfactory stimulus by dissecting the function of the olfactory co-receptor Orco (formally known as OR83b). Orco function is not required for ethanol recognition per se, however it plays a role in context dependent recognition of ethanol. Odor-evoked ethanol preference requires the function of Tbh (Tyramine β hydroxalyse), the rate-limiting enzyme of octopamine synthesis. In addition, neuronal activity in a subset of octopaminergic neurons is necessary for olfactory ethanol preference. Notably, a specific neuronal activation pattern of tyraminergic/octopaminergic neurons elicit preference and is therefore sufficient to induce preference. In contrast, dopamine dependent increase in locomotor activity is not sufficient for olfactory ethanol preference. Consistent with the role of noradrenaline in mammalian drug induced rewards, we provide evidence that in adult Drosophila the octopaminergic neurotransmitter functions as a reinforcer and that the molecular dissection of the innate attraction to ethanol uncovers the basic properties of a response selection system. 相似文献
13.
14.
15.
Lazzaro Lorenzo Colzi Ilaria Ciampi Daniele Gonnelli Cristina Lastrucci Lorenzo Bazihizina Nadia Viciani Daniele Coppi Andrea 《Plant and Soil》2021,460(1-2):105-121
Plant and Soil - We investigated whether individuals of Silene paradoxa L., grown in serpentine and non-serpentine soils, displayed variation in functional traits and adaptive strategies... 相似文献
16.
17.
Andrea J Webster Andy Purvis 《Proceedings. Biological sciences / The Royal Society》2002,269(1487):143-149
Many methods are available for estimating ancestral values of continuous characteristics, but little is known about how well these methods perform. Here we compare six methods: linear parsimony, squared-change parsimony, one-parameter maximum likelihood (Brownian motion), two-parameter maximum likelihood (Ornstein-Uhlenbeck process), and independent comparisons with and without branch-length information. We apply these methods to data from 20 morphospecies of Pleistocene planktic Foraminifera in order to estimate ancestral size and shape variables, and compare these estimates with measurements on fossils close to the phylogenetic position of 13 ancestors. No method produced accurate estimates for any variable: estimates were consistently less good as predictors of the observed values than were the averages of the observed values. The two-parameter maximum-likelihood model consistently produces the most accurate size estimates overall. Estimation of ancestral sizes is confounded by an evolutionary trend towards increasing size. Shape showed no trend but was still estimated very poorly: we consider possible reasons. We discuss the implications of our results for the use of estimates of ancestral characteristics. 相似文献
18.
19.
Patrizia Vaccino Heinz-Albert Becker Andrea Brandolini Francesco Salamini Benjamin Kilian 《Molecular genetics and genomics : MGG》2009,281(3):289-300
The celiac disease (CD) is an inflammatory condition characterized by injury to the lining of the small-intestine on exposure
to the gluten of wheat, barley and rye. The involvement of gluten in the CD syndrome has been studied in detail in bread wheat,
where a set of “toxic” and “immunogenic” peptides has been defined. For wheat diploid species, information on CD epitopes
is poor. In the present paper, we have adopted a genomic approach in order to understand the potential CD danger represented
by storage proteins in diploid wheat and sequenced a sufficiently large number of cDNA clones related to storage protein genes
of Triticum monococcum. Four bona fide toxic peptides and 13 immunogenic peptides were found. All the classes of storage proteins were shown to contain harmful
sequences. The major conclusion is that einkorn has the full potential to induce the CD syndrome, as already evident for polyploid
wheats. In addition, a complete overview of the storage protein gene arsenal in T. monococcum is provided, including a full-length HMW x-type sequence and two partial HMW y-type sequences.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献