全文获取类型
收费全文 | 4961篇 |
免费 | 438篇 |
国内免费 | 1篇 |
出版年
2021年 | 37篇 |
2018年 | 43篇 |
2016年 | 62篇 |
2015年 | 116篇 |
2014年 | 134篇 |
2013年 | 192篇 |
2012年 | 231篇 |
2011年 | 208篇 |
2010年 | 132篇 |
2009年 | 138篇 |
2008年 | 194篇 |
2007年 | 221篇 |
2006年 | 224篇 |
2005年 | 193篇 |
2004年 | 182篇 |
2003年 | 187篇 |
2002年 | 189篇 |
2001年 | 66篇 |
2000年 | 66篇 |
1999年 | 68篇 |
1998年 | 76篇 |
1997年 | 45篇 |
1996年 | 39篇 |
1995年 | 35篇 |
1994年 | 37篇 |
1993年 | 49篇 |
1992年 | 65篇 |
1991年 | 54篇 |
1990年 | 50篇 |
1989年 | 55篇 |
1988年 | 55篇 |
1987年 | 56篇 |
1986年 | 69篇 |
1985年 | 75篇 |
1984年 | 68篇 |
1983年 | 64篇 |
1982年 | 62篇 |
1981年 | 63篇 |
1980年 | 72篇 |
1979年 | 71篇 |
1978年 | 72篇 |
1977年 | 60篇 |
1976年 | 70篇 |
1975年 | 48篇 |
1974年 | 59篇 |
1973年 | 42篇 |
1970年 | 39篇 |
1968年 | 45篇 |
1967年 | 33篇 |
1961年 | 38篇 |
排序方式: 共有5400条查询结果,搜索用时 875 毫秒
1.
2.
Ivonne J. Garzn‐Ordua Shaun L. Winterton Yunlan Jiang Laura C.V. Breitkreuz Peter Duelli Michael S. Engel Norman D. Penny Catherine A. Tauber Atsushi Mochizuki Xingyue Liu 《Systematic Entomology》2019,44(3):499-513
We present a time‐calibrated phylogeny of the charismatic green lacewings (Neuroptera: Chrysopidae). Previous phylogenetic studies on the family using DNA sequences have suffered from sparse taxon sampling and/or limited amounts of data. Here we combine all available previously published DNA sequence data and add to it new DNA sequences generated for this study. We analysed these data in a supermatrix using Bayesian and maximum likelihood methods and provide a phylogenetic hypothesis for the family that recovers strong support for the monophyly of all subfamilies and resolves relationships among a large proportion of chrysopine genera. Chrysopinae tribes Leucochrysini and Belonopterygini were recovered as monophyletic sister clades, while the species‐rich tribe Chrysopini was rendered paraphyletic by Ankylopterygini. Relationships among the subfamilies were resolved, although with relatively low statistical support, and the topology varied based on the method of analysis. Greatest support was found for Apochrysinae as sister to Nothochrysinae and Chrysopinae, which is in contrast to traditional concepts that place Nothochrysinae as sister to the rest of the family. Divergence estimates suggest that the stem groups to the various subfamilies diverged during the Triassic‐Jurassic, and that stem groups of the chrysopine tribes diverged during the Cretaceous. 相似文献
3.
C Berche J P Mach J D Lumbroso C Langlais F Aubry F Buchegger S Carrel P Rougier C Parmentier M Tubiana 《BMJ (Clinical research ed.)》1982,285(6353):1447-1451
Transaxial tomoscintigraphy (or single-photon emission computerised tomography) was used to detect secondary deposits of carcinoma in 17 patients who had been injected with iodine-131-labelled monoclonal antibodies against carcinoembryonic antigen. Of 17 tumor sites studied by tomoscintigraphy 16 were detected (sensitivity 94%); five sites had a volume smaller than 10 cm3. Tomoscintigraphy also detected three unknown tumour deposits later confirmed by surgery or radiology. In contrast, when 21 tumour sites in the same patients were studied by rectilinear scintigraphy, only nine tumour sites were detected (sensitivity 43%), of which eight had a volume larger than 50 cm3. 相似文献
4.
Timothy J. French Anthony W. Good T. Norman Palmer Mary C. Sugden 《Bioscience reports》1985,5(9):729-734
The in vivo effects of dexamethasone administration on liver and extrahepatic tissue carnitine concentrations were assessed in 48-h-starved rats. In heart and kidney, but not in liver, dexamethasone significantly increased total carnitine concentration. Acute (2.5 h) treatment with 2-tetradecylglycidate (TDG), a specific inhibitor of carnitine palmitoyl transferase 1, not only increased total hepatic carnitine concentrations, but also permitted an effect of dexamethasone (a further increase in hepatic carnitine concentration). The results are discussed in terms of acute (substrate-mediated) and chronic (hormonal) control of carnitine turnover. 相似文献
5.
6.
7.
8.
9.
10.