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41.
Nitrogen availability and production of bikaverin and gibberellins in Gibberella fujikuroi 总被引:2,自引:0,他引:2
Walter Giordano Javier Avalos Enrique Cerdá-Olmedo Carlos E Domenech 《FEMS microbiology letters》1999,173(2):389-393
Production of bikaverin and gibberellins by Gibberella fujikuroi started after depletion of the nitrogen source, but not after depletion of phosphate. Despite this similarity, the regulation of both pathways by nitrogen involved two different mechanisms. This conclusion was supported by the fact that the production of bikaverin, in contrast to the gibberellins, was not inhibited by nitrate in a mutant that could not utilize it. The different regulation of both pathways was clearly demonstrated by a mutant that overproduced bikaverin but lacked gibberellins. An optimal bikaverin production required a low pH, with a sharp drop at about pH 5. The syntheses of fungal secondary metabolites, such as bikaverin and gibberellins, are not subject to common regulation, but respond to various combinations of signals, such as nitrogen availability, nitrate and the pH of the medium. 相似文献
42.
Sumera Afzal Khan Muhammad Hamayun Ho-Youn Kim Hyeok-Jun Yoon In-Jung Lee Jong-Guk Kim 《World journal of microbiology & biotechnology》2009,25(5):829-833
Endophytic fungi are known to play a vital role in the growth and development of their host plants. We isolated eleven endophytic
fungi from the roots of sand-dune plant Elymus mollis and their growth-promoting ability was studied on waito-c rice and Atriplex gemelinii. We found that eight fungal isolates promoted growth of both plants. Fungal isolate EM-7-1 induced maximum growth promotion
in waito-c rice (9.25 cm) and Atriplex gemelinii (3.1 cm), which was higher than wild-type Gibberella fujikuroi. Gibberellin analysis of EM-7-1 culture filtrate showed the presence of bioactive gibberellins GA1 (0.32 ng/ml), GA3 (5.76 ng/ml), GA4 (0.82 ng/ml) and GA7: (0.1 ng/ml) along with physiologically inactive GA5 (0.59 ng/ml), GA9 (5.38 ng/ml), GA20 (0.25 ng/ml) and GA24 (2.03 ng/ml). The fungal isolate EM-7-1 was identified as new strain of Gliomastix murorum (G. murorum KACC43902) with 99% sequence homology. This study reports the plant growth-promoting ability of genus Gliomastix and the presence of GA5 in the culture filtrate of fungi for the first time.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
43.
Hydrogen sulfide counteracts chlorophyll loss in sweetpotato seedling leaves and alleviates oxidative damage against osmotic stress 总被引:1,自引:0,他引:1
Hua Zhang Yong-Kang Ye Song-Hua Wang Jian-Ping Luo Jun Tang Dai-Fu Ma 《Plant Growth Regulation》2009,58(3):243-250
Sawgrass (Cladium jamaicense) is the predominant plant and vegetation community in the Florida Everglades. Germination of sawgrass seeds in the laboratory
or nursery has been difficult and problematic, yet little is known about the physiological mechanistic regulation of the sawgrass
seed germination process. In the present study, we examined the factors and mechanisms that influence sawgrass seed germination.
We found that removal of seed husk and bracts, pre-soaking with bleach (hypochlorite), breaking the seed coat, or combinations
of these treatments promoted the rate and success of germination, whereas presence of seed-encasing structures or treatment
with husk/bract extract inhibited germination. We further detected the presence of abscisic acid (ABA) in the husk and bract.
Experiments with ABA and gibberellin biosynthesis inhibitors fluridone and tetcyclacis suggested that ABA already presented
in the pre-imbibed seeds, and not derived through post-dormancy de novo synthesis, contributed to the inhibition of seed germination.
Examination of bleach and mechanical treatments indicated the physical barrier presented by the seed-encasing structures provided
additional mechanism for the long-term delay of seed germination. Based on the results of this study and others, we discussed
the implications of sawgrass seed dormancy and germination in relation to its natural habitat and proposed a hypothesis that
the protracted seed dormancy in sawgrass offered an adaptive advantage in the pre-anthropogenic Everglades environment, but
may become a liability in the current man-managed Everglades water system. 相似文献
44.
The role of gibberellins (GAs) in determining sex in the gametophyte of the fern Blechnum spicant L. was studied through (a) the effect of exogenous GA4+7 and GA3 (b) quantitation of the endogenous levels of GA1, GA3, GA4, GA7, GA9, and GA20 in male and female gametophytes, and (c) the effect of flurprimidol, a GAs biosynthesis inhibitor of the steps of oxidation of ent-kaureno to ent-kaurenoic acid. Our results show that GA4+7 had a slight effect of inducing either male or female sexual organs, antheridia and archegonia, respectively. The endogenous GAs content was not significantly different between sexes, but the GA4, GA7, and GA20 levels were raised above those of the other GAs in both sexes. Neither antheridiogen biosynthesis nor antheridia formation was inhibited by flurprimidol. Gametophytes regenerated from homogenized mature gametophytes (HG) show a different physiological behavior than spore-derived gametophytes. In the first case, gametophytes are males and synthesize antheridiogen before they attain maturity, in contrast to what occurs in spore-derived gametophytes which are females and synthesize antheridiogen when mature. 相似文献
45.
Hiroko Yamazaki Takaaki Nishijima Masaji Koshioka Hiroyuki Miura 《Plant Growth Regulation》2002,36(3):223-229
Abscisic acid (ABA) is involved in bulb dormancy of Alliumwakegi Araki. We examined the antagonistic role of gibberellins(GAs)against ABA in the regulation of this dormancy. The concentrations of ABA andGAs in the basal leaf sheaths or bulbs of A. wakegi cv.Kiharawase were investigated during growth in the field and postharveststorage.The concentration of ABA in the basal leaf sheaths began to increase about onemonth before they began to swell, reached a maximum shortly after bulbharvesting, and decreased during postharvest storage. The plants showed bulbdormancy accompanied with the change in ABA concentration. GA1,GA3, GA4, GA12, GA15, GA19, and GA20 were identified in the basal leaf sheaths of A. wakegi from Kovats retention indices (KRI) andfull-scan mass spectra by gas chromatography - mass spectrometry (GC-MS)analysis. The concentrations of all classes of GAs in the basal leaf sheathsestimated by the dwarf rice micro-drop assay increased transitorily shortlybefore they began to swell, and decreased rapidly during bulb development. Bulbdormancy had already been induced when the concentration of the GAs becamemaximum. All the GAs in the bulbs remained at a low level during postharveststorage, when bulbs were gradually released from dormancy. The concentrationsof GA1+3, GA4, GA15, and GA20 inthe bulbs increased after sprouting of the bulbs planted in moist vermiculite.Hence, the state of bulb dormancy is considered to be independent of the GAconcentrations of in the basal leaf sheaths or bulbs of A.wakegi. 相似文献
46.
Slađana Todorović Zlatko Giba Suzana Živković Dragoljub Grubišić Radomir Konjević 《Plant Growth Regulation》2005,47(2-3):141-148
The germination of Empress tree (Paulownia tomentosa Steud.) seeds is phytochrome-controlled. Liquid smoke could not induce germination in darkness but red light irradiation
of liquid smoke imbibed seeds induced a high percentage of germination. Maximum germination was achieved at liquid smoke concentration
of 0.1% (v/v) when present during the imbibition phase or during the phase of phytochrome activity. The light requirement
of these seeds could be completely substituted by exogenously applied gibberellins. In the presence of liquid smoke, optimal
concentrations of GA3, GA4, and GA9 necessary for inducing germination were several times lower than in the controls, while that of GA7 was equally active when applied at a concentration one order of magnitude lower. The inhibitory effect of the applied growth
retardants was strongly reduced and liquid smoke, in the presence of retardants, allowed light-induced germination, if applied
simultaneously or after retardants treatment. 相似文献
47.
Fruit development is a complex yet tightly regulated process. The developing fruit undergoes phases of cell division and expansion
followed by numerous metabolic changes leading to ripening. Plant hormones are known to affect many aspects of fruit growth
and development. In addition to the five classic hormones (auxins, gibberellins, cytokinins, abscisic acid and ethylene) a
few other growth regulators that play roles in fruit development are now gaining recognition. Exogenous application of various
hormones to different stages of developing fruits and endogenous quantifications have highlighted their importance during
fruit development. Information acquired through biochemical, genetic and molecular studies is now beginning to reveal the
possible mode of hormonal regulation of fruit development at molecular levels. In the present article, we have reviewed studies
revealing hormonal control of fruit development using tomato as a model system with emphasis on molecular genetics. 相似文献
48.
49.
In vitro morphogenetic responses of Ilex paraguariensis nodal segments treated with different gibberellins and Prohexadione-Ca 总被引:1,自引:0,他引:1
One-bud nodal segments of Ilex paraguariensis (yerba mate) were cultured in vitro in a sugar-rich medium with different gibberellins or an inhibitor of their synthesis. Bud sprouting, shoot length (assessed as shoots of less or more than 5 mm) and bud abscission were evaluated after 45 d of culture in a growth chamber at 27±2 °C, with a 14 h photoperiod of white fluorescent light. There was a differential effect of the two types of gibberellins used; the double bond ring-A gibberellins (GA3 and GA7) inhibited shoot length, while the non double bond-ring A gibberellins (GA1 and GA4) stimulated shoots with a length of more than 5 mm. Prohexadione-Ca (Bx-112; a late step gibberellin biosynthesis inhibitor), at high doses, restrained bud sprouting up to 75%, but lower doses promoted shoot lengthening. 相似文献
50.
A number of studies have used microspore-derived embryos (MDEs) as amodel for examining a range of processes, including hormonal regulation ofembryo development. We examined the hormonal physiology of MDEs with theprimaryobjective of testing the validity of using the MDE system as a model forhormonally-regulated development in zygotic embryos, through late stages. To dothis we identified and quantified endogenous levels of abscisic acid (ABA),indole-3-acetic acid (IAA) and a number of gibberellins (GAs), includingGA19, GA20, GA1 and GA8 in bothMDEsand zygotic embryos. The presence of GA19, together with itsC19 metabolites indicates that the early-13 hydroxylation pathway isoperative in both embryo systems. Gibberellins A4 and GA9were also identified, thereby confirming the presence of the earlynon-hydroxylation pathway in B. napus MDEs and zygoticembryos. In general, the pattern of change of hormone (ABA, IAA, GA1and GA20) content per embryo through embryogenesis was similar forMDEs and zygotic embryos. Indole-3-acetic acid and GA1 increased toamaximum at day 30 after culture (DAC) before decreasing. Abscisicacid levels increased to a maximum at day 35, and declined in zygoticembryos but not in MDEs. GA20 increased to the final harvest atmaturity, or day 40. The absolute content (g/embryo) of each hormone, howeverwas appreciably lower (5- to 15- fold) in the MDEs. This was not the result ofdilution into surrounding medium for ABA or IAA; GA1, however, didaccumulate in the medium. Although there were absolute quantitative differencesin the levels of IAA and ABA found in the two embryo systems, the similaritiesin the pattern of hormone changes suggests that the MDE system can serve as auseful model for examining the physiological roles of hormones duringembryogenesis. 相似文献