全文获取类型
收费全文 | 737篇 |
免费 | 70篇 |
国内免费 | 52篇 |
出版年
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2016年 | 10篇 |
2014年 | 18篇 |
2013年 | 30篇 |
2012年 | 39篇 |
2011年 | 31篇 |
2010年 | 39篇 |
2009年 | 39篇 |
2008年 | 35篇 |
2007年 | 25篇 |
2006年 | 26篇 |
2005年 | 27篇 |
2004年 | 17篇 |
2003年 | 7篇 |
2002年 | 13篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1998年 | 20篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1969年 | 10篇 |
1968年 | 7篇 |
1967年 | 7篇 |
1966年 | 6篇 |
1965年 | 6篇 |
1959年 | 8篇 |
1958年 | 16篇 |
1957年 | 13篇 |
1956年 | 25篇 |
1955年 | 14篇 |
1954年 | 10篇 |
1953年 | 20篇 |
1952年 | 13篇 |
1951年 | 15篇 |
1950年 | 15篇 |
排序方式: 共有859条查询结果,搜索用时 15 毫秒
1.
2.
M. Bartley 《BMJ (Clinical research ed.)》1994,309(6963):1177-1178
3.
4.
ANDRÉ PICARD JEAN-CLAUDE LABBÉ GÉRARD PEAUCELLIER FRANÇOISE LE BOUFFANT CHRISTIAN LE PEUCH MARCEL DOREE 《Development, growth & differentiation》1987,29(1):93-103
Many studies suggest that MPF activation depends on protein phosphorylation or that MPF is itself a protein kinase. In the present report, cyclic variations of MPF activity have been correlated in vivo with changes in the extent of protein phosphorylation or in vitro with changes of a major protein kinase during the first cell cycles of fertilized starfish eggs. This cycling protein kinase neither requires cAMP nor Ca2+ . Neither colchicine nor aphidicoline, which inhibits cleavage and chromosome replication respectively, was found to suppress the synchronous and cyclic variations of both MPF and protein kinase activities. Protein synthesis was found to be required for both MPF and protein kinase activities to reappear after their simultaneous drop at the time of mitotic or meiotic cleavages. Production of either MPF or protein kinase activities is not the immediate result of protein synthesis since there is a delay at each cell cycle between the time when protein synthesis is required and the time when both MPF and protein kinase activities are produced. This suggests that both MPF and protein kinase activities might involve some post-translational modification of a precursor protein synthesized during the preceeding cell cycle. 相似文献
5.
6.
中国平脉树螽属五新种记述:直翅目:螽斯科:树螽亚科 总被引:2,自引:0,他引:2
本文报道中国平脉树螽属5个新种。每个新种皆有详细的形态描述和形态特征图。所有模式标本存于北京农业大学昆虫标本室。 相似文献
7.
8.
Prevost, I. and Le PageDegivry, M. Th. 1985. Changesin absicisic acid content in axis and cotyledons of developingPhaseolus vulgaris embryos and their physiological consequences.J.exp. Bot. 36: 19001905.Changes in abscisic acid (ABA)content with time were measured in embryonic axes and in cotyledonsof Phaseolus vulgaris embryos using a radioimmunoassay.During embryogenesis, a similar pattern was observed in bothtissues: ABA increased to a maximum 29 d after an thesis, followedby a decrease as the seed matured. The level of ABA in the cotyledonswas always much higher than that in the axes. In in vitro cultures,the duration of the lag phase before germination of isolatedembryonic axes increased with ABA content. The presence of cotyledonsalways lengthened the lag phase; longer lag phases were associatedwith greater concentrations of ABA in the cotyledons. Moreoverthe presence of cotyledons stimulated the growth of seedlings. Key words: ABA distribution, embryo maturation, axis and embryo germinability 相似文献
9.
10.
Adenosine phosphates and the control of glycolysis and gluconeogenesis in yeast 总被引:5,自引:0,他引:5 下载免费PDF全文
1. Changes in dry weight, protein, RNA and DNA were measured in yeast during adaptation to glycolytic metabolism. 2. Only RNA increased significantly during the lag phase, but during the exponential phase all these cellular components increased in parallel. 3. The concentrations of ATP, ADP, AMP and glucose 6-phosphate were measured in respiring yeast and during the transition to glycolytic metabolism. 4. In respiring cells the concentration of AMP was at its highest and that of ATP was at its lowest; this relationship was reversed in glycolysing cells. 5. ADP concentration was similar in respiring and glycolysing cells, but glucose 6-phosphate concentration was much higher in the glycolysing cells. 6. A possible reason for mitochondrial repression is suggested. 7. It is concluded that adenosine phosphates do not control the direction of glycolytic flux in yeast and an alternative control of glycolysis and gluconeogenesis by enzyme activation and inactivation is suggested. 相似文献