全文获取类型
收费全文 | 12279篇 |
免费 | 867篇 |
国内免费 | 3篇 |
出版年
2023年 | 51篇 |
2022年 | 85篇 |
2021年 | 237篇 |
2020年 | 175篇 |
2019年 | 205篇 |
2018年 | 278篇 |
2017年 | 235篇 |
2016年 | 386篇 |
2015年 | 574篇 |
2014年 | 663篇 |
2013年 | 993篇 |
2012年 | 1073篇 |
2011年 | 955篇 |
2010年 | 636篇 |
2009年 | 515篇 |
2008年 | 796篇 |
2007年 | 719篇 |
2006年 | 713篇 |
2005年 | 582篇 |
2004年 | 588篇 |
2003年 | 580篇 |
2002年 | 524篇 |
2001年 | 106篇 |
2000年 | 94篇 |
1999年 | 116篇 |
1998年 | 117篇 |
1997年 | 107篇 |
1996年 | 100篇 |
1995年 | 74篇 |
1994年 | 96篇 |
1993年 | 81篇 |
1992年 | 65篇 |
1991年 | 53篇 |
1990年 | 41篇 |
1989年 | 33篇 |
1988年 | 31篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 26篇 |
1984年 | 31篇 |
1983年 | 38篇 |
1982年 | 33篇 |
1981年 | 41篇 |
1980年 | 28篇 |
1979年 | 20篇 |
1978年 | 20篇 |
1977年 | 30篇 |
1974年 | 22篇 |
1973年 | 13篇 |
1969年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
161.
162.
Giuseppe Caporale Gabbriella Innocenti Adriano Guiotto Paolo Rodighiero Franceso DallAcqua 《Phytochemistry》1981,20(6):1283-1287
adioactivity from [3H] 5-hydroxymarmesin was incorporated into 5-methoxypsoralen by administration to leaves of Ficus carica and cut ends of Ruta graveolens. No other furanocoumarins were labelled. Trapping experiments, in which [3H]marmesin together with 5-hydroxymarmesin was administered to fig leaves and to cut ends of rue, provided good evidence that 5-hydroxymarmesin is formed by hydroxylation of marmesin. These results, together with those obtained previously with 8-hydroxymarmesin demonstrate that, in addition to the pathway which involves the hydroxylation of psoralen, the O-alkylfuranocoumarins are also formed by a pathway which involves the hydroxylation of marmesin. 相似文献
163.
Elisabetta Gianazza Francesco Chillemi Marcello Duranti Pier Giorgio Righetti 《Journal of biochemical and biophysical methods》1983,8(4):339-351
A new method for peptide analysis and purification is described, based on isoelectric focusing in immobilized pH gradients. On the analytical scale, the peptide zones can now be revealed by an stain for primary and secondary amino group (e.g. ninydrin, fluorescamine, dansyl chloride) since the buffering species, unlike conventional carrier ampholytes, contain only carboxyl and tertiary amino groups. For preparative purposes, conditions have been described to remove most contaminants (e.g. unreacted monomers, non-cross-linked, short polyacrylamide chains) from the gel matrix before the electrophoretic run. However, ca. 2% of the gel dry mass is still present as extractable material. The focused peptides can be recovered in higly yields (ca. 90%) with a fairly high degree of purity (75%), the contaminants being mostly components eluted from the polyacrylamide gel. 相似文献
164.
165.
166.
167.
Michel Rathbone Lara Pilutti Francesco Caciagli Shucui Jiang 《Nucleosides, nucleotides & nucleic acids》2013,32(6-7):666-672
Central nervous system (CNS) astrocytes release guanosine extracellularly, that exerts trophic effects. In CNS, extracellular guanosine (GUO) stimulates mitosis, synthesis of trophic factors, and cell differentiation, including neuritogenesis, is neuroprotective, and reduces apoptosis due to several stimuli. Specific receptor-like binding sites for eGUO in the nervous system may mediate its effects through both MAP kinase and PI3-kinase signalling pathways. Extracellular guanine (eGUA) also exerts several effects; the trophic effects of eGUO are likely regulated by conversion of eGUO to eGUA by a membrane located purine nucleoside phosphorylase (ecto-PNP) and by conversion of eGUA to xanthine by guanine deaminase. 相似文献
168.
169.
170.