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991.
Conditions have been developed that induce maize (Zea mays L.) protoplasts to re-synthesize cell walls and to initiate cell divisions. Two types of embryogenic maize callus were used as a source of protoplasts: a heterogeneous callus (Type I) derived from immature embryos after three weeks in culture, and a friable, rapidly growing callus (Type II) selected from portions of the Type I callus. Many variables in the growth conditions of the donor tissue (type of medium, transfer schedule, age of callus), protoplast isolation solutions (pH, osmolarity, type and concentration of cell wall hydrolyzing enzymes, addition of polyamines) and conditions (amount of time in enzyme, amount of tissue per volume of enzyme incubation medium, agitation, preplasmolysis of source tissue, type of callus), and purification procedures (filtration and-or flotation), were found to affect both yield and viability of protoplasts (based upon fluorescein-diacetate staining). Our isolation procedure yielded high numbers of viable, uninucleated maize callus protoplasts which were densely cytoplasmic and varied in size from 20 to 50 m in diameter. Protoplasts plated in solid medium formed walls and divided several times. Of several gelling agents tested for protoplast propagation, only agarose resulted in protoplasts capable of sustained divisions leading to the formation of microcalli. Plating efficiency was established over a wide range of protoplast densities (103–107 protoplasts/ml). Highest plating efficiency (25%) was obtained at 1·106 protoplasts/ml). The resulting microcalli grew to be dense clusters of about 0.1–0.5 mm in diameter and then stopped growing. Nurse cultures of maize and carrot (Daucus carota L.), were used to establish that individual protoplasts (not contaminating cells or cell clusters) formed walls and divided. Nurse cultures also increased the efficiency of microcallus formation from protoplasts.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- MS
Murashige and Skoog (1962) salts
- MS 1D
Murashige and Skoog salts with 1 mg/l 2,4-D
- MS 2D
Murashige and Skoog salts with 2 mg/l 2,4-D
- N6
medium of Chu et al. (1975)
- NN67-mod
medium of Nitsch and Nitsch (1967) as modified in the present paper
- FDA
fluorescein diacetate
- LMP
low melting point 相似文献
992.
The biosynthetic steps from gibberellin A12-aldehyde (GA12-aldehyde) to C19-GAs were studied by means of a cell-free system from the embryos of immature Phaseolus vulgaris seeds. Stable-isotope-labeled GAs were used as substrates and the products were identified by gas chromatography-mass spectrometry. Gibberellin A12-aldehyde was converted to GA4 via non-hydroxylated intermediates and to GA1 via 13-hydroxylated intermediates. 13-Hydroxylation took place at the beginning of the pathway by the conversion of GA12-aldehyde to GA53-aldehyde. The conversion of GA20 to GA5 and GA6 was also shown but no 2-hydroxylating activity was found. Endogenous GAs from embryos and testas of 17-dold seeds were re-examined by gas chromatography-selected ion monitoring using stable-isotopelabeled GAs as internal standards. Gibberellins A9, A12, A15, A19, A23, A24, and A53 were identified for the first time in P. vulgaris, in addition to GA1, GA4, GA5, GA6, GA8, GA17, GA20, GA29, GA37, GA38 and GA44, which were previously known to occur in this species. The levels of all GAs, except the 2-hydroxylated ones, were greater in the embryos than in the testas. Conversely, the contents of GA8 and GA29, both 2-hydroxylated, were much higher in the testas than in the embryos.Abbreviations GAn
gibberellin An
- GC-MS
gas chromatography-mass spectrometry
- GC-SIM
gas chromatography-selected ion monitoring
- HPLC
high-performance liquid chromatography
- TLC
thin-layer chromatography
-
m/z
ion of mass 相似文献
993.
The effect of tunicamycin, an inhibitor of N-glycosylation of proteins, on growth and on synthesis of DNA and protein was studied in suspension cultures from Nicotiana tabacum and Catharanthus rosea. In the presence of 0.1–1 g · ml-1 tunicamycin, cell division and DNA synthesis stopped in cells which had been proliferating logarithmically, but protein formation continued. Cytophotometric determination of the nuclear DNA content in Catharanthus cells showed that a cell-cycle arrest had occurred in G1 phase. Metabolic labelling of cells with the glycoprotein precursors glucosamine or mannose was inhibited, too. The results indicate that one or more glycoproteins are needed for the cell to pass through the G1 phase, as was recently postulated for animal and yeast cells.Abbreviations TCA
trichloroacetic acid
- TM
tunicamycin 相似文献
994.
Hydrogen-peroxide-scavenging systems within pea chloroplasts 总被引:8,自引:0,他引:8
The subcellular distribution of ascorbate peroxidase and glutathione reductase (EC 1.6.4.2) in pea leaves was compared with that of organelle markers. Enzyme distribution was found to be similar to that of the chloroplast enzyme NADPH-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13). Isolated chloroplasts showed a close correlation between intactness and the percentage of enzyme activity recovered. Chloroplasts of 85% intactness were found to contain a high proportion of leaf dehydroascorbate reductase activity (EC 1.8.5.1), 10% of leaf glutathione and 30% of leaf ascorbate. These results are discussed in relation to the potential role of chloroplast antioxidant systems in plant resistance to environmental and other stress conditions.Abbreviations GSH
reduced glutathione
- GSSG
oxidized glutathione
- NADPH-GPD
glyceraldehyde-3-phosphate dehydrogenase
- SOD
superoxide dismutase 相似文献
995.
A lectin was isolated from tulip (Tulipa) bulbs by affinity chromatography on fetuin-agarose and partially characterized. The tulip lectin is a tetrameric protein composed of four identical subunits of Mr 28 000, which are not held together by disulphide bonds. It is not glycosylated and has an amino-acid composition typified by a high content of asparagine-aspartic acid, leucine, glycine and serine. Tulip lectin agglutinates human red blood cells, but has a much higher specific activity with rabbit erythrocytes. In hapten-inhibition assays with the latter type of red blood cell the lectin exhibits a complex specificity, whereas its agglutination with human erythrocytes is readily inhibited by N-acetylgalactosamine, lactose, fucose and galactose.Abbreviations DEAE
diethylaminoethyl
- PBS
phosphate-buffered saline
- TL
Tulipa lectin
- Mr
relative molecular mass
- SDS-PAGE
sodium dodecyl sulphate-polyacrylamide gel electrophoresis 相似文献
996.
Selective expression of a probable amylase/protease inhibitor in barley aleurone cells: Comparison to the barley amylase/subtilisin inhibitor 总被引:5,自引:0,他引:5
We have cloned and sequenced a 650-nucleotide cDNA from barley (Hordeum vulgare L.) aleurone layers encoding a protein that is closely related to a known -amylase inhibitor from Indian finger millet (Eleusine coracana Gaertn.), and that has homologies to certain plant trypsin inhibitors. mRNA for this probable amylase/protease inhibitor (PAPI) is expressed primarily in aleurone tissue during late development of the grain, as compared to that for the amylase/subtilisin inhibitor, which is expressed in endosperm during the peak of storage-protein synthesis. PAPI mRNA is present at high levels in aleurone tissue of desiccated, mature grain, and in incubated aleurone layers prepared from rehydrated mature seeds. Its expression in those layers is not affected by either abscisic acid or gibberellic acid, hormones that, respectively, increase and decrease the abundance of mRNA for the amylase/subtilisin inhibitor. PAPI mRNA is almost as abundant in gibberellic acid-treated aleurone layers as that for -amylase, and PAPI protein is synthesized in that tissue at levels that are comparable to -amylase. PAPI protein is secreted from aleurone layers into the incubation medium.Abbreviations ABA
abscisic acid
- ASI
barley amylase/subtilisin inhibitor
- bp
nucleotide base pairs
- Da
dalton
- dpa
days post anthesis
- GA3
gibberellic acid
- PAPI
probable amylase/protease inhibitor
- poly(A)RNA
polyadenylated RNA
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis 相似文献
997.
Are sucrosyl-oligosaccharides synthesized in mesophyll protoplasts of mature leaves of Cucumis melo?
Biosynthesis of sucrosyl-oligosaccharides (raffinose, stachyose) was traced in source leaves of Cucumis melo after 14C-photoassimilation. The main carbon compound exported was 14C-labeled stachyose. No oligosaccharide synthesis was detected in young, importing leaves. Mesophyll protoplasts, isolated from mature leaves which had previously photosynthesized 14CO2, did not contain 14C-oligosaccharides but contained [14C]-sucrose and 14C-hexoses. Isolated minor-vein-enriched fractions from the same leaves, however, showed nearly 30% of the 14C of the neutral fraction to be in oligosaccharides. Isolated, viable mesophyll protoplasts incubated with NaH14CO3 also failed to incorporate radioactivity into oligosaccharides, although sucrose and galactinol synthesis was unimpaired. Galactinolsynthase activity in leaf extracts and in mesophyll protoplasts was 16.8 mol·h-1·mg-1 protein and 13.8 mol·h-1·mg-1 protein, respectively. Galactosyltransferase (EC 2.4.1.67), which synthesizes stachyose from raffinose and galactinol, had an activity of 50 nmol·h-1·mg-1 protein in leaf extracts and was also present in the minor-vein-enriched fraction, but could not be detected in mesophyll protoplast lysates. The results indicate that mesophyll cells may not be the site of stachyose synthesis although precursor compounds like sucrose and galactinol are synthesized there.Abbreviation HPLC
high-performance liquid chromatography 相似文献
998.
M. V. Gusev T. G. Korzhenevskaya L. V. Pyvovarova O. I. Baulina R. G. Butenko 《Planta》1986,167(1):1-8
Tobacco (Nicotiana tabacum L.) shoots associated with the nitrogen-fixing cyanobacterium Anabaena variabilis Kütz. (ATCC 29413) were regenerated in mixed cultures of tobacco callus and the cyanobacterium. The cyanobacteria were localized inside the tissues as well as on the surface of regenerated shoots, formed heterocysts, and were capable of acetylene reduction. 相似文献
999.
C. E. Deane-Drummond 《Planta》1986,169(1):8-15
[14C]Methylamine influx intoPisum sativum L. cv. Feltham First seedlings showed Michaelis-Menten-type kinetics with apparentV
max=49.2 mol·g-1 FW·h-1 and apparentK
m=0.51 mM. The competitive interactions between ammonium and methylamine were most obvious when biphasic kinetics were assumed with saturation of the first phase at 0.05 mM. The inhibitor constant for ammonium (K
i)=0.027 mM. When [14C]methylamine was used in trace amounts with ammonium added as substrate, the influx of tracer showed Michaelis-Menten-type kinetics with apparentV
max=3.46 mol·g-1 FW·h-1 and apparentK
m=0.15 mM. The initial rate of net ammonium uptake corresponded with that found when [14C]methylamine was used to trace ammonium influx. The latter was also stimulated by high pHo and inhibited by nitrate. Ammonium pretreatment±methionine sulphoximine or glutamine pretreatment of the seedlings inhibited subsequent [14C]methylamine influx, while methylamine or asparagine pretreatment stimulated [14C]methylamine influx. There was also a stimulatory effect of prior inoculation withRhizobium. The results are discussed in terms of current models for the regulation of ammonium uptake in plants. 相似文献
1000.
C. L. Díaz P. C. van Spronsen R. Bakhuizen G. J. J. Logman E. J. J. Lugtenberg J. W. Kijne 《Planta》1986,168(3):350-359
The lectin on the surface of 4- and 5-dold pea roots was located by the use of indirect immunofluorescence. Specific antibodies raised in rabbits against pea seed isolectin 2, which crossreact with root lectins, were used as primary immunoglobulins and were visualized with fluorescein- or tetramethylrhodamine-isothiocyanate-labeled goat antirabbit immunoglobulin G. Lectin was observed on the tips of newly formed, growing root hairs and on epidermal cells located just below the young hairs. On both types of cells, lectin was concentrated in dense small patches rather than uniformly distributed. Lectin-positive young hairs were grouped opposite the (proto)xylematic poles. Older but still-elongating root hairs presented only traces of lectin or none at all. A similar pattern of distribution was found in different pea cultivars, as well as in a supernodulating and a non-nodulating pea mutant. Growth in a nitrate concentration which inhibits nodulation did not affect lectin distribution on the surface of pea roots of this age. We tested whether or not the root zones where lectin was observed were susceptible to infection by Rhizobium leguminosarum. When low inoculum doses (consisting of less than 106 bacteria·ml-1) were placed next to lectin-positive epidermal cells and on newly formed root hairs, nodules on the primary roots were formed in 73% and 90% of the plants, respectively. Only a few plants showed primary root nodulation when the inoculum was placed on the root zone where lectin was scarce or absent. These results show that lectin is present at those sites on the pea root that are susceptible to infection by the bacterial symbiont.Abbreviations FITC
fluorescein isothiocyanate
- TRIC
tetramethylrhodamine isothiocyanate 相似文献