全文获取类型
收费全文 | 296篇 |
免费 | 17篇 |
国内免费 | 63篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 22篇 |
2012年 | 27篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 21篇 |
2008年 | 10篇 |
2007年 | 19篇 |
2006年 | 18篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有376条查询结果,搜索用时 4 毫秒
81.
Shiping Wang Xiaoxia Yang Xingwu Lin Yigang Hu Caiyun Luo Guangping Xu Zhenhua Zhang Ailing Su Xiaofen Chang Zengguo Chao Jichuang Duan 《Biology letters》2009,5(4):535-538
Recently, plant-derived methane (CH4) emission has been questioned because limited evidence of the chemical mechanism has been identified to account for the process. We conducted an experiment with four treatments (i.e. winter-grazed, natural alpine meadow; naturally restored alpine meadow eight years after cultivation; oat pasture and bare soil without roots) during the growing seasons of 2007 and 2008 to examine the question of CH4 emission by plant communities in the alpine meadow. Each treatment consumed CH4 in closed, opaque chambers in the field, but two types of alpine meadow vegetation reduced CH4 consumption compared with bare soil, whereas oat pasture increased consumption. This result could imply that meadow vegetation produces CH4. However, measurements of soil temperature and water content showed significant differences between vegetated and bare soil and appeared to explain differences in CH4 production between treatments. Our study strongly suggests that the apparent CH4 production by vegetation, when compared with bare soil in some previous studies, might represent differences in soil temperature and water-filled pore space and not the true vegetation sources of CH4. 相似文献
82.
Fruit senescence has been reported to be an oxidative phenomenon, but the detailed mechanisms by which ROS regulate this process remain largely unknown. Here we show that senescence process of apple fruit was concomitant with the dynamic alterations in the mitochondrial proteome. Mitochondrial proteins involved in tricarboxylic acid cycle, electron transport chain, carbon metabolism, and stress response were found to be differentially expressed during fruit senescence. Alleviating oxidative stress by lowering the ambient oxygen concentration noticeably decreased the number of changed proteins and delayed fruit senescence, indicating the involvement of ROS in this process. To further investigate the regulatory effect of ROS on senescence process, we analyzed the mitochondrial proteome variations upon exposure to high oxygen (100%), which induces oxidative stress and accelerates fruit senescence. High oxygen treatment led to a further identification of differentially expressed proteins such as mitochondrial manganese superoxide dismutase, an antioxidant scavenging superoxide radicals produced in the mitochondria. Activity of manganese superoxide dismutase was reduced after high oxygen exposure, accompanied by an increase in oxidative protein carbonylation (damaged proteins). These data suggest that ROS may regulate fruit senescence by changing expression profiles of specific mitochondrial proteins and impairing the biological function of these proteins. 相似文献
83.
84.
Plasma Membrane Damage Contributes to Antifungal Activity of Silicon Against Penicillium digitatum 总被引:1,自引:0,他引:1
Putative penicillin-binding proteins (PBPs) were identified in the genome of the Burkholderia cenocepacia strain J2315 based on homology to E. coli PBPs. The three sequences identified as homologs of E. coli PBP1a, BCAL2021, BCAL0274, and BCAM2632, were cloned and expressed as His6-tagged fusion proteins in E. coli. The fusion proteins were isolated and shown to bind β-lactams, indicating these putative PBPs have penicillin-binding activity. 相似文献
85.
Zhiyong Pan Shiping Zhu Rui Guan Xiuxin Deng 《Plant Cell, Tissue and Organ Culture》2010,103(2):145-153
The compound 2,4-Dicholorophenoxyacetic acid (2,4-D) is an important growth regulator which is used in the majority of embryogenic
cell and tissue culture systems. However, 2,4-D also appears to have a negative effect on growth and development of plant
tissues and organs cultured in vitro. For example, 2,4-D exerts inhibition on in vitro somatic embryo initiation and/or development
of most citrus species. To understand the molecular mechanism by which 2,4-D inhibits somatic embryogenesis (SE), proteomic
changes of Valencia sweet orange (Citrus sinensis) embryogenic callus induced by treatments with a high concentration of 2,4-D (6 mg l−1) was investigated. Nine 2,4-D-responsive proteins were identified, of which eight were up-regulated and one was down-regulated.
Interestingly, three of the eight up-regulated proteins were osmotic stress-associated, suggesting that 2,4-D induced osmotic
stress in Valencia embryogenic callus. This speculation was supported by results from our physiological studies: 2,4-D treated
callus cells exhibited increased cytoplasm concentration with a significant reduction in relative water content (RWC) and
an obvious increase in levels of two osmolytes (proline and soluble sugar). Taken together, our results suggested that 2,4-D
could inhibit somatic embryo initiation by, at least in part, inducing osmotic stress to citrus callus cells. 相似文献
86.
The synthesis and crystal structure of an anionic phosphorescent iridium complex TBA[Ir(dfppy)2(NCS)2] (1) were reported. 1 can selectively detect Hg2+ with the help of UV-Vis absorption and emission spectra titration. In the presence of Hg2+, the obvious decrease of the luminescence intensity at 475 nm was investigated, which could be observed by the naked eyes. The phosphorescence quantum efficiency in CH3CN solution changed from 0.07 to 0.00085. No obvious spectra changes were observed upon addition of a large excess of other transition metals. Due to its strong thiophilic affinity, the special chemical reaction induced by Hg2+ is responsible for the significant change of absorption and luminescence spectra, which is confirmed by ESI-MS. 相似文献
87.
88.
89.
石油中长链烷烃微生物降解及分子机制研究进展 总被引:1,自引:1,他引:0
中长链烷烃是石油烃中的重要组成部分,由于其疏水性强、黏度大、化学活性低、难降解,是地下原油黏度大、石油采收率低、泄漏后长期污染生态环境的重要原因,因此成为提高石油采收率和石油污染环境治理中的重要降解目标。微生物降解中长链烷烃作为一种新型高效的绿色技术日益受到重视。本文总结了微生物降解中长链烷烃的间期适应与转运过程,与转运过程相关的膜蛋白,微生物好氧与厌氧降解的代谢途径,以及好氧降解过程中的基因调控机制,并对微生物降解中长链烷烃的研究方向提出了展望,以期为后续的相关研究工作提供参考。 相似文献
90.