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21.
Hely Häggman 《Physiologia plantarum》1986,66(1):144-148
The cytosolic and membrane-bound ribosome assemblies were isolated from the microsporangiate strobili of Scots pine ( Pinus sylvestris L.). Both assemblies studied were able to incorporate [3 H]-leucine into trichloroacetic acid-insoluble material throughout the sampling period from October to April, indicating that the isolation procedure employed preserves the ability of the ribosomes to synthesize protein. Samples of identical size, taken from cytosolic as well as from membrane-bound ribosomes isolated from the same source, behaved similarly in vitro: they were both active, their activity was arrested by ribonnuclease and, as shown by aurintricarboxylic acid treatment, most of their mRNA molecules were complexed with the ribosomes. Variation in translation capacities seemed to depend on the season and physiological stage of the bud tissue. 相似文献
22.
23.
Activation of seminal root primordia during wheat domestication reveals underlying mechanisms of plant resilience 下载免费PDF全文
Guy Golan Elisha Hendel Gabriel E. Méndez Espitia Nimrod Schwartz Zvi Peleg 《Plant, cell & environment》2018,41(4):755-766
Seminal roots constitute the initial wheat root system and provide the main route for water absorption during early stages of development. Seminal root number (SRN) varies among species. However, the mechanisms through which SRN is controlled and in turn contribute to environmental adaptation are poorly understood. Here, we show that SRN increased upon wheat domestication from 3 to 5 due to the activation of 2 root primordia that are suppressed in wild wheat, a trait controlled by loci expressed in the germinating embryo. Suppression of root primordia did not limit water uptake, indicating that 3 seminal roots is adequate to maintain growth during seedling development. The persistence of roots at their primordial state promoted seedling recovery from water stress through reactivation of suppressed primordia upon rehydration. Our findings suggest that under well‐watered conditions, SRN is not a limiting factor, and excessive number of roots may be costly and maladaptive. Following water stress, lack of substantial root system suppresses growth and rapid recovery of the root system is essential for seedling recovery. This study underscores SRN as key adaptive trait that was reshaped upon domestication. The maintenance of roots at their primordial state during seedling development may be regarded as seedling protective mechanism against water stress. 相似文献
24.
Steven E. Clark 《Seminars in cell & developmental biology》1996,7(6):873-880
In higher plants, organ formation occurs throughout life. This remarkable process occurs at a collection of stem cells termed the shoot meristem. The shoot meristem originates during embryogenesis and is later responsible for generating the above-ground portion of the plant. The shoot meristem can be thought of as having two zones, a central zone containing meristematic cells in an undifferentiated state, and a surrounding peripheral zone where cells enter a specific developmental pathway toward a differentiated state. Recent advances have revealed several genes that specifically regulate meristem development inArabidopsis. The function of these genes and their genetic interactions are described. 相似文献
25.
Cryopreservation of encapsulated shoot primordia induced in horseradish (Armoracia rusticana) hairy root cultures 总被引:2,自引:0,他引:2
Shoot primordia induced inArmoracia rusticana Gaertn. Mey. et Scherb. (horseradish) hairy root cultures were successfully cryopreserved by two cryogenic procedures. Encapsulated shoot primordia were precultured on solidified Murashige-Skoog medium supplemented with 0.5M sucrose for 1 day and then dehydrated with a highly concentrated vitrification solution (PVS2) for 4 h at 0°C prior to a plunge into liquid nitrogen. The survival rate of encapsulated vitrified primordia amounted to 69%. In a revised encapsulation-dehydration technique, the encapsulated shoot primordia were precultured with a mixture of 0.5M sucrose and 1M or 1.5M glycerol for 1 day to induce dehydration tolerance and then subjected to air-drying prior to a plunge into liquid nitrogen. The survival rate of encapsulated dried primordia was more than 90%, and the revived primordia produced shoots within 2 weeks after plating. A long-term preservation of shoot primordia was also achieved by the technique. Thus, this revised encapsulation-dehydration technique appears promising as a routine method for the cryopreservation of shoot primordia of hairy roots.Abbreviations
PVS2
Vitrification solution
-
LN
liquid nitrogen
-
BA
6-benzyladenine
-
NAA
-naphthalene-acetic acid
-
MS
Murashige and Skoog (1962) medium 相似文献
26.
Winter hardening of first-year black spruce [ Picea mariana (Mill.) B.S.P.] seedlings was studied by assessing a number of morphological and physiological changes under three hardening regimes: 1) early removal (ER), in which seedlings were exposed to natural daylengths and low ambient temperatures outside. 2) extended greenhouse culture (EG), in which seedlings were exposed to natural daylengths and warm temperatures, and 3) short day (SD), in which seedlings were exposed to short daylengths and low ambient temperatures outside. Measurements included needle primordia initiation, embryonic shoot volume, terminal bud mitotic index, embryonic shoot average cell volume, and shoot tip frost hardiness. EG seedlings formed buds containing 4 times as many needle primordia as ER stock. Embryonic shoot volume increased with number of needle primordia initiated, until late in the hardening period, when significant reductions in meristem volumes of SD and EG stock were observed. Frost hardiness increased sooner in seedlings which set bud in response to short days, but SD treatment did not result in significantly greater frost hardiness at the end of the trial. Frost hardiness was correlated with mitotic index of the embryonic shoot. Cell size in the embryonic shoot declined in seedlings of all treatments during hardening, however, EG seedlings had significantly lower cell volumes by the end of the trial in comparison to ER and SD seedlings. 相似文献
27.
The transition from spiral to distichous leaf arrangement during gibberellic-acid (GA3)-induced rejuvenation in Hedera was studied in detail by scanning electron microscopy of the shoot apical meristem. The transition, which involves the initiation of about 14 new leaf primordia, is accomplished by progressive increments in the divergence angle between the leaf primordia from an initial average value of 138.9 ° until it approaches 180 °. This process is preceded, as well as accompanied, by an increased radial displacement of young leaf primordia away from the apical meristem. Although the width of the leaf primordia also increases, this is unlikely to be a causal factor since it occurs only late in the transition. The size of the primordium-free area of the apical meristem is also unlikely to be involved. Quantitative analysis shows that the divergence angle of consecutive leaf primordia commonly fluctuates between relatively large and small values. Thus the transitional stages form a spirodistichous arrangement in which the divergence angle within each pair of leaves is large relative to that between leaf pairs. The stimulation of the radial displacement of the leaf primordia and the associated phyllotactic transition may involve GA3-induced modification in the spatial organization of cortical microtubules in the apical meristem and related changes in directional cell expansion.Abbreviations DA
divergence angle
- GA3
gibberellic acid
We thank Mr. Gilbert Ahlstrand for his advice regarding scanning electron microscopy. This paper is contribution of the University of Minnesota Agricultural Experimental Station No. 18,726. 相似文献
28.
A. González A. Casares T. R. Sánchez R. Rodríguez 《In vitro cellular & developmental biology. Plant》1991,27(3):125-131
Summary An experimental rooting system was developed to study in vitro adventitious root formation in hazelnut cotyledons. Experiments
involveda) assay of several culture media,b) use of different developmental status of the seeds (germinated and ungerminated),c) cotyledons subjected to various light regimes, andd) different size of cotyledons slices. It was observed that higher rooting was induced in cotyledonary portions of 5- or 7-mm
thickness (250 and 350 mm3, respectively) cultured on half-strength basal medium supplemented with 50 μM indole-3-butyric acid and 5 μM kinetin. Rooting was affected by light and the developmental state of seeds. Preinitiation, initiation, and root manifestation
stages were defined according to specific culture periods and in relation with morphologic and histologic changes. The first
histologic changes (cell division and root primordia induction) were observed after 12 days in culture. At 30 days of culture
in rhizogenic medium root primodia were fully differentiated with well-developed vascular tissues. 相似文献
29.
Hiroyuki Akiyama 《Journal of plant research》1990,103(3):269-282
The manner of branch development in mosses was studied. Two types of branch development,Bryum-type andClimacium-type, can be distinguished by their morphology at dormancy. In theBryum-type, the branch primordium does not produce leaves and stays as a primordium at dormancy; the primordium is merely a mass
of thin-walled cells with an apical cell. However, in theClimacium-type, the branch primordium produces leaves even in the very early stages of development, and it is a bud accompanied by
scale-like leaves that goes through dormancy.
Though pseudoparaphyllia have been considered to originate from epidermal cells of a stem, results of the present study show
that they are, whether filamentous or foliose, produced by the branch primordia. TheBryum-type of dormant branch primordium is accompanied by filamentous pseudoparaphyllia in some species, while, that of theClimacium-type is sometimes accompanied by foliose pseudoparaphyllia. Filamentous pseudoparaphyllia are found to be produced adventitiously
from the outermost cell layer of a primordium. Developmental mode of foliose pseudoparaphyllia is left for a future survey. 相似文献
30.
R. C. Hardwick 《Plant Growth Regulation》1984,2(4):393-405
This paper argues against the bicycle pump model of source-sink relationships. It suggests that it is more fruitful to examine the systems which control sink morphogenesis. This argument is illustrated by reference to the cauliflower curd (inflorescence). In any given curd the weights of successive florets (primary branches) fluctuate above and below their expected values. The fluctuations are not due to restricted vascular pipelines, nor to competitive interactions between neighbouring sinks. They are due to highly systematic fluctuations in the timing of floret initiation, and they entail similar fluctuations in primordium position. The phenomenon can be explained by assuming a control system for cytokinesis in which (i) the position of the cell plate responds to mechanical stress (ii) the degree of responsiveness varies cyclically both in time, and around the apical meristem. It seems from this and other evidence that there are strong local controls of sink development in cauliflower. 相似文献