全文获取类型
收费全文 | 501篇 |
免费 | 16篇 |
国内免费 | 9篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 36篇 |
2012年 | 14篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 20篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有526条查询结果,搜索用时 536 毫秒
41.
Y. Ding W. Wu W. Wei R.E. Davis I.‐M. Lee R.W. Hammond J.P. Sheng L. Shen Y. Jiang Y. Zhao 《The Annals of applied biology》2013,162(1):131-139
Phytoplasmas are phloem‐inhabiting, cell wall‐less bacteria that cause numerous plant diseases worldwide. Plants infected by phytoplasmas often exhibit various symptoms indicative of hormonal imbalance. In this study, we investigated the effects of potato purple top (PPT) phytoplasma infection on gibberellin homeostasis in tomato plants. We found that PPT phytoplasma infection caused a significant reduction in endogenous levels of gibberellic acid (GA3). The decrease in GA3 content in diseased plants was correlated with down regulation of genes responsible for biosynthesis of bioactive GAs ( GA20ox1 and GA3ox1) and genes involved in formation of GA precursors [geranyl diphosphate synthase (GPS) and copalyldiphosphate synthase (CPS)]. Exogenous application of GA3 at 200 µmol L?1 was able to restore the GA content in infected plants to levels comparable to those in healthy controls, and to attenuate the characteristic ‘big bud’ symptoms induced by the phytoplasma. The interesting observation that PPT phytoplasma‐infected plants had prolonged low expression of key GA biosynthesis genes GA20ox1 and GA3ox1 under GA deficiency conditions led us to hypothesise that there was a diminished sensitivity of the GA metabolism feedback regulation, especially GA biosynthesis negative feedback regulation, in those affected plants, and such diminished sensitization in early stages of infection may represent a central element of the phytoplasma‐induced disruption of GA homeostasis and pathogenesis. 相似文献
42.
Yaou Shen Zhou Jiang Sifen Lu Haijian Lin Shibin Gao Huanwei Peng Guangsheng Yuan Li Liu Zhiming Zhang Maojun Zhao Tingzhao Rong Guangtang Pan 《Biochemical and biophysical research communications》2013
Genetic transformation of maize is highly dependent on the development of embryonic calli from the dedifferentiated immature embryo. To better understand the regulatory mechanism of immature embryo dedifferentiation, we generated four small RNA and degradome libraries from samples representing the major stages of dedifferentiation. More than 186 million raw reads of small RNA and degradome sequence data were generated. We detected 102 known miRNAs belonging to 23 miRNA families. In total, we identified 51, 70 and 63 differentially expressed miRNAs (DEMs) in the stage I, II, III samples, respectively, compared to the control. However, only 6 miRNAs were continually up-regulated by more than fivefold throughout the process of dedifferentiation. A total of 87 genes were identified as the targets of 21 DEM families. This group of targets was enriched in members of four significant pathways including plant hormone signal transduction, antigen processing and presentation, ECM-receptor interaction, and alpha-linolenic acid metabolism. The hormone signal transduction pathway appeared to be particularly significant, involving 21 of the targets. While the targets of the most significant DEMs have been proved to play essential roles in cell dedifferentiation. Our results provide important information regarding the regulatory networks that control immature embryo dedifferentiation in maize. 相似文献
43.
Eiki Nagano Takayuki Oritani Kyohei Yamashita 《Bioscience, biotechnology, and biochemistry》2013,77(9):2095-2098
Methyl 6′, 6′-didemethyl abscisate (5) was synthesized and assayed to elucidate the physiological activity of methyl substituents on the cyclohexene ring of abscisic acid (ABA). During this study two new chiral stereoisomeric analogs 6 and 7 were synthesized from l-and d-carvone. The rice seedling assay and germination assay of garden radish showed that 6′-methyl groups of ABA were not important in biological activity and that 5′-isopropenyl analogs 6 and 7 were inactive. 相似文献
44.
The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat. 相似文献
45.
P. Gurusaravanan S. Vinoth M. Satheesh Kumar N. Thajuddin N. Jayabalan 《Journal of Genetic Engineering and Biotechnology》2013,11(1):9-16
The challenging task of bringing high efficiency transformed plants attracts lot of attention in recent times. In search for this, there have been many attempts made using, different techniques like tissue culture and plant breeding methods. Here we report a suitable alternative facile route, where cyanobacterial extracellular products are utilized as growth regulators and its performance validated on Gossypium hirsutum L. MS medium is tested with cyanobacterial extracellular products of Nostoc ellipsosporum, Dolichospermum flos-aquae and Oscillatoria acuminata .Our best results show that the addition of O. acuminata extracellular product with plant growth hormones gives the excellent induction and elongation in cotton. In addition to this, the multiple shoot was obtained on MS medium fortified with 1.0 mg L?1 BA with 8% O. acuminata and 1.5 mg L?1 TDZ with 12% O. acuminata. High frequency of shoot elongation supplemented with MS medium, iP 2.5 mg L?1 and 16% O. acuminata and root production MS medium fortified with 12% O. acuminata best responsible for regeneration in cotton plants. The rooted plants were hardened and transferred to soil with 90% survival rate. 相似文献
46.
An Overview of the Biology of Reaction Wood Formation 总被引:1,自引:0,他引:1
Sheng Du Fukuju Yamamoto 《植物学报(英文版)》2007,49(2):131-143
Reaction wood possesses altered properties and performs the function of regulating a tree's form, but it is a serious defect in wood utility. Trees usually develop reaction wood in response to a gravistimulus. Reaction wood in gymnosperms is referred to as compression wood and develops on the lower side of leaning stems or branches. In arboreal, dicotyledonous angiosperms, however, it is called tension wood and is formed on the upper side of the leaning. Exploring the biology of reaction wood formation is of great value for the understanding of the wood differentiation mechanisms, cambial activity, gravitropism, and the systematics and evolution of plants. After giving an outline of the variety of wood and properties of reaction wood, this review lays emphasis on various stimuli for reaction wood induction and the extensive studies carried out so far on the roles of plant hormones in reaction wood formation. Inconsistent results have been reported for the effects of plant hormones. Both auxin and ethylene regulate the formation of compression wood in gymnosperms. However, the role of ethylene may be indirect as exogenous ethylene cannot induce compression wood formation. Tension wood formation is mainly regulated by auxin and gibberellin. Interactions among hormones and other substances may play important parts in the regulation of reaction wood formation. 相似文献
47.
48.
49.
50.