全文获取类型
收费全文 | 197篇 |
免费 | 8篇 |
国内免费 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有207条查询结果,搜索用时 109 毫秒
51.
52.
Epidermal peels of Valerianella locusta were acid-treated for 1 h at pH 3.9 to kill all cells other than guard cells. These guard-cell preparations were used to explore the steady-state one-way fluxes and the cytoplasmic and vacuolar contents of abscisic acid (ABA). The method of compartmental analysis has been applied. The intracellular ABA concentrations were surprisingly high. At an external pH of 5.8 the cytoplasm contained 1.28 mmol·dm-3 of ABA, twice of the amount which accumulated in the vacuoles (0.57 mmol·dm-3). The fluxes of ABA at the plasmalemma (oc=oc=0.43 fmol · cell –1 · h –1) were higher than those at the tonoplast (cv=vc=0.12 fmol · cell –1 · h –1). Moderate stress (0.1 and 0.3 mol·dm-3 sorbitol in the medium) caused a change in the kinetics of ABA movement. The rate constants of the fluxes from the cytoplasm into the vacuole (cv) and into the apoplast (co) were increased while the rate constant of the flux from the vacuoles into the cytoplasm (vc) was decreased. As a consequence the amount of ABA sequestered in the vacuole remained unchanged; the cytoplasmic ABA content, however, was reduced to only 20% of that found in the control treatments (no sorbitol in the medium). Under moderate stress, one Valerianella guard cell released rapidly about 0.36 fmol·cell-1 to its direct cell-wall space. This surprising result is discussed in regard to rapid stomatal closure under reduced water supply.Abbreviations ABA
abscisic acid
- FC
fusicoccin 相似文献
53.
Summary Ion flux relations in the unicellular marine algaAcetabularia have been investigated by uptake and washout kinetics of radioactive tracers (22Na+,42K+,36Cl– and86Rb+) in normal cells and in cell segments with altered compartmentation (depleted of vacuole or of cytoplasm). Some flux experiments were supplemented by simultaneous electrophysiological recordings. The main results and conclusions about the steady-state relations are: the plasmalemma is the dominating barrier for translocation of K+ with influx and efflux of about 100 nmol·m–2·sec–1×K+ passes three- to sevenfold more easily than Rb+ does. Under normal conditions, Cl– (the substrate of the electrogenic pump, which dominates the electrical properties of the plasmalemma in the resting state) shows two efflux components of about 17 and 2 mol·m–2·sec–1, and a cytoplasmic as well as vacuolar [Cl–] of about 420mm ([Cl–]
o
=529mm). At 4°C, when the pump is inhibited, both influx and efflux, as well as the cellular [Cl–], are significantly reduced. Na+ ([Na+]
i
: about 70mm, [Na+]
o
: 461mm), which is of minor electrophysiological relevance compared to K+, exhibits rapid and virtually temperature-insensitive (electroneutral) exchange (two components with about 2 and 0.2 mol·m–2·sec–1 for influx and efflux). Some results with Na+ and Cl– are inconsistent with conventional (noncyclic) compartmentation models: (i) equilibration of the vacuole (with the external medium) can be faster than equilibration of the cytoplasm, (ii) absurd concentration values result when calculated by conventional compartmental analysis, and (iii) large amounts of ions can be released from the cell without changes in the electrical potential of the cytoplasm. These observations can be explained by the particular compartmentation of normalAcetabularia cells (as known by electron micrographs) with about 1 part cytoplasm, 5 parts central vacuole, and 5 parts vacuolar vesicles. These vesicles communicate directly with the central vacuole, with the cytoplasm and with the external medium. 相似文献
54.
55.
Measurement of intracellular nitrate concentrations in Chara using nitrate-selective microelectrodes
Nitrate-selective microelectrodes have been made using a quaternary ammonium sensor, methyl-tridodecylammonium nitrate, in a Polyvinylchloride matrix. These electrodes showed a log-linear response from 0.1 to 100 mol · m?3 nitrate with a typical slope of 55.6 mV per decade change in nitrate concentration. The only physiologically significant interfering anion was chloride but the lower limit of nitrate detection was 0.5 mol · m?3 in the presence of 100 mol · m?3 chloride which means this interference will not be important in most physiological situations. These microelectrodes were used to measure nitrate concentrations in internodal cells of Chara corallina cultured under low nitrate and nitrate-replete conditions for 6 to 30 weeks. Cells maintained in low nitrate only showed measurements which were less than the detection limit of the electrodes, while cells grown under nitrate-replete conditions showed two populations of measurements having means of 1.6 and 6.2 mol · m?3. Chemical analysis of the high-nitrate cells indicated that they contained a mean nitrate concentration of 5.9 mol · m?3. As vacuolar nitrate concentration would dominate this whole-cell measurement, it is concluded that the higher concentration measured with the electrodes represents vacuolar nitrate concentration and the lower value represents the cytoplasmic concentration. This intracellular distribution of nitrate could only be achieved passively if the electrical potential difference across the tonoplast is between +25 and + 35 mV. 相似文献
56.
57.
58.
59.
Hendrik F��hrs Christof Behrens S��bastien Gallien Dimitri Heintz Alain Van Dorsselaer Hans-Peter Braun Walter J. Horst 《Annals of botany》2010,105(7):1129-1140
Background and Aims
Research on manganese (Mn) toxicity and tolerance indicates that Mn toxicity develops apoplastically through increased peroxidase activities mediated by phenolics and Mn, and Mn tolerance could be conferred by sequestration of Mn in inert cell compartments. This comparative study focuses on Mn-sensitive barley (Hordeum vulgare) and Mn-tolerant rice (Oryza sativa) as model organisms to unravel the mechanisms of Mn toxicity and/or tolerance in monocots.Methods
Bulk leaf Mn concentrations as well as peroxidase activities and protein concentrations were analysed in apoplastic washing fluid (AWF) in both species. In rice, Mn distribution between leaf compartments and the leaf proteome using 2D isoelectic focusing IEF/SDS–PAGE and 2D Blue native BN/SDS–PAGE was studied.Key Results
The Mn sensitivity of barley was confirmed since the formation of brown spots on older leaves was induced by low bulk leaf and AWF Mn concentrations and exhibited strongly enhanced H2O2-producing and consuming peroxidase activities. In contrast, by a factor of 50, higher Mn concentrations did not produce Mn toxicity symptoms on older leaves in rice. Peroxidase activities, lower by a factor of about 100 in the rice leaf AWF compared with barley, support the view of a central role for these peroxidases in the apoplastic expression of Mn toxicity. The high Mn tolerance of old rice leaves could be related to a high Mn binding capacity of the cell walls. Proteomic studies suggest that the lower Mn tolerance of young rice leaves could be related to Mn excess-induced displacement of Mg and Fe from essential metabolic functions.Conclusions
The results provide evidence that Mn toxicity in barley involves apoplastic lesions mediated by peroxidases. The high Mn tolerance of old leaves of rice involves a high Mn binding capacity of the cell walls, whereas Mn toxicity in less Mn-tolerant young leaves is related to Mn-induced Mg and Fe deficiencies. 相似文献60.