全文获取类型
收费全文 | 3428篇 |
免费 | 325篇 |
出版年
2023年 | 20篇 |
2021年 | 64篇 |
2020年 | 26篇 |
2019年 | 43篇 |
2018年 | 57篇 |
2017年 | 30篇 |
2016年 | 56篇 |
2015年 | 130篇 |
2014年 | 132篇 |
2013年 | 181篇 |
2012年 | 234篇 |
2011年 | 224篇 |
2010年 | 125篇 |
2009年 | 116篇 |
2008年 | 152篇 |
2007年 | 163篇 |
2006年 | 155篇 |
2005年 | 143篇 |
2004年 | 151篇 |
2003年 | 154篇 |
2002年 | 145篇 |
2001年 | 61篇 |
2000年 | 56篇 |
1999年 | 68篇 |
1998年 | 49篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 27篇 |
1994年 | 23篇 |
1993年 | 23篇 |
1992年 | 57篇 |
1991年 | 49篇 |
1990年 | 40篇 |
1989年 | 35篇 |
1988年 | 58篇 |
1987年 | 41篇 |
1986年 | 49篇 |
1985年 | 38篇 |
1984年 | 30篇 |
1983年 | 28篇 |
1982年 | 24篇 |
1981年 | 36篇 |
1980年 | 31篇 |
1979年 | 28篇 |
1978年 | 36篇 |
1977年 | 27篇 |
1976年 | 33篇 |
1975年 | 32篇 |
1974年 | 30篇 |
1972年 | 25篇 |
排序方式: 共有3753条查询结果,搜索用时 62 毫秒
1.
The Asian Tree Toad genus Pedostibes, as currently understood, exhibits a conspicuously disjunct distribution, posing several immediate questions relating to the biogeography and taxonomy of this poorly known group. The type species, P. tuberculosus and P. kempi, are known only from India, whereas P. hosii, P. rugosus, and P. everetti are restricted to Southeast Asia. Several studies have shown that these allopatric groups are polyphyletic, with the Indian Pedostibes embedded within a primarily South Asian clade of toads, containing the genera Adenomus, Xanthophryne, and Duttaphrynus. Southeast Asian Pedostibes on the other hand, are nested within a Southeast Asian clade, which is the sister lineage to the Southeast Asian river toad genus Phrynoidis. We demonstrate that Indian and Southeast Asian Pedostibes are not only allopatric and polyphyletic, but also exhibit significant differences in morphology and reproductive mode, indicating that the Southeast Asian species’ are not congeneric with the true Pedostibes of India. As a taxonomic solution, we describe a new genus, Rentapia
gen. nov. to accommodate the Southeast Asian species. 相似文献
2.
3.
The effect of a 30-day treatment with Madiol was studied on the activity of some enzymes, nucleic acids, protein and glycogen content of the liver of adult female rats and youngs born from mothers treated during pregnancy. Madiol caused a significant increase in SDH and Atp-ase activity, and decreased glycogen and acid phosphatase. 相似文献
4.
5.
Yedael Y. Waldman Tamir Tuller Tomer Shlomi Roded Sharan Eytan Ruppin 《Nucleic acids research》2010,38(9):2964-2974
Various studies in unicellular and multicellular organisms have shown that codon bias plays a significant role in translation efficiency (TE) by co-adaptation to the tRNA pool. Yet, in humans and other mammals the role of codon bias is still an open question, with contradictory results from different studies. Here we address this question, performing a large-scale tissue-specific analysis of TE in humans, using the tRNA Adaptation Index (tAI) as a direct measure for TE. We find tAI to significantly correlate with expression levels both in tissue-specific and in global expression measures, testifying to the TE of human tissues. Interestingly, we find significantly higher correlations in adult tissues as opposed to fetal tissues, suggesting that the tRNA pool is more adjusted to the adult period. Optimization based analysis suggests that the tRNA pool—codon bias co-adaptation is globally (and not tissue-specific) driven. Additionally, we find that tAI correlates with several measures related to the protein functionally importance, including gene essentiality. Using inferred tissue-specific tRNA pools lead to similar results and shows that tissue-specific genes are more adapted to their tRNA pool than other genes and that related sets of functional gene groups are translated efficiently in each tissue. Similar results are obtained for other mammals. Taken together, these results demonstrate the role of codon bias in TE in humans, and pave the way for future studies of tissue-specific TE in multicellular organisms. 相似文献
6.
7.
8.
9.
10.