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51.
Fruit photosynthesis 总被引:12,自引:1,他引:11
Abstract. In addition to photosynthesis as in the leaf, fruit possess a system which refixes CO2 from the mitochondrial respiration of predominantly imported carbon. This pathway produces malate by the action of phosphoenolpyruvate carboxylase, PEPC, (E.C. 4.1.1.31) and appears to be regulated primarily by the cytosolic concentration of HCO3/CO2 and malate. Malate is stored in the vacuole as malic acid, constituting a major carbon pool and a potential substrate for respiration. The PEPC in apple fruit proves to be an efficient form of the enzyme with low Michaelis constants, i.e. Km = 0.09 mol m-3 PEP and 0.2 mol m–3 HCO3, and large Ki= 110 mol m-3 HCO3. In fleshy fruit, chlorophyll and chloroplasts are unevenly distributed; they resemble the C3 sun-type and arc concentrated in the perivascular tissue, with smaller chloroplasts, fewer grana per chloroplast and a larger degree of vacuolation than commonly found in a leaf of the same species. Fruit photosynthesis often compensates for respiratory CO2 loss in the light. However, due to respiration in the dark, CO2 loss is in excess of photosynthetic gain in the light, such that a continual loss of CO2 was observed in the diurnal cycle and which is maintained throughout fruit development. The rate of CO2 exchange decreases on a fresh weight or surface basis, but increases with fruit ontogeny on a per fruit basis, causing accumulation of several percent CO2 in the internal cavity. Stomata are present in the outer epidermis of those fruits examined, but with a 10-to 100-fold lesser frequency than in the abaxial epidermis of leaf of the same species. The number of Stomata is set at anthesis and remained constant, while the stomatal frequency decreases as the fruit surface expands. Stomata are as sensitive as in leaves in the early stages of fruit development, but often are transformed into lenticels during fruit ontogeny, thereby decreasing the permeability of the outer epidermis. The discrepancy between the CO2-concentrating mechanism provided by PEPC analogous to C4/CAM Photosynthesis and the kinetics of fruit PEPC, characteristic of C3/non-autotrophic tissue, suggests the definition of a new type of ‘fruit photosynthesis’ rather than its categorization within an existing type. 相似文献
52.
53.
Rachel E. Pieterse 《Plant Cell, Tissue and Organ Culture》1989,19(2):175-179
Immature embryos of apricot (Prunus armeniaca L.) cv. Royal with a PF index of 25–100 were used to regenerate plants in vitro using two methods. In the first case, callus was initiated on MS medium with 4.5 M 2, 4-D plus 0.44 M BA and regeneration of shoots from the callus occurred on MS medium with 4.4 M BA plus 1.0 M 2, 4-D. In the second case, adventitious buds were directly regenerated from the cotyledons on MS medium with 4.4 M BA plus 1.0 M 2, 4-D.Abbreviations BA
6-benzyladenine
- IBA
dole-3-butyric acid
- NAA
-naphthylacetic acid
- 2, 4-D
2, 4-dichlorophenoxyacetic acid
- PF
(embryo length/seed length) x 100 相似文献
54.
Effect of maltose on the response of potato anthers in culture 总被引:1,自引:0,他引:1
Anthers of the Solanum tuberosum genotype H3703 were cultured on medium containing equimolar concentrations of sucrose or maltose. It was found that significantly more pollen embryos became plants after culture on maltose and hence the yield of plants per 100 anthers cultured increased significantly. Mechanisms by which carbohydrate source may influence response to anther culture are discussed. 相似文献
55.
DNA replication in maize leaf protoplasts 总被引:1,自引:0,他引:1
H. Wang Adrian J. Cutler M. Saleem Larry C. Fowke 《Plant Cell, Tissue and Organ Culture》1989,18(1):33-46
Maize leaf protoplasts were investigated for their metabolic competence and capacity to synthesize DNA. When protoplasts were incubated at elevated temperatures, they exhibited a heat shock response with specific proteins being preferentially synthesized. This indicated that the protoplasts were fully metabolically functional and capable of responding to environmental stimuli. Significant DNA synthesis was observed in these protoplasts after incorporation of 3H-thymidine into chromatin by trichloroacetic acid precipitation and by incorporation of 5-bromo-2-deoxyuridine (BrdU), an analog of thymidine, detected by immunofluorescence. The immunocytochemical method revealed that about 50% of nuclei in the maize leaf protoplasts were labelled after 3 days of culture and that most of these nuclei were labelled as intensely as normal mitotic cells. Aphidicolin, an inhibitor of DNA polymerase-, decreased the percentage of labelled nuclei, demonstrating that the labelling was substantially due to replicative DNA synthesis. However, chromosome condensation was not observed. It is proposed that these protoplasts are capable of DNA synthesis, but incapable of nuclear division. Effects of media additives on the number of nuclei entering S phase in these protoplasts were also assessed by the immunocytochemical method. Inclusion of 80mM Ca2+ in the enzyme solution increased protoplast yield and also appeared beneficial to DNA synthesis. The antioxidant, n-propyl gallate, which was used to stabilize the protoplasts, delayed the onset of DNA synthesis. Arginine and spermidine produced a slight increase in DNA synthesis.Abbreviations BrdU
5-bromo-2-deoxyuridine
- DMSO
dimethyl sulfoxide
- n-PG
n-propyl gallate
- PBS
phosphate-buffered saline
Dedicated to Dr. Friedrich Constabel on the occasion of his 60th birthday 相似文献
56.
C. R. Vonk E. Davelaar S. A. Ribôt B. Shadid H. C. Van der Plas 《Plant Growth Regulation》1989,8(3):263-276
It is shown that in bulbous Iris zeatin originates from a nucleotide. This nucleotide is probably zeatin-allylic-phosphate, in which a phosphate group is attached to the isoprenoid side-chain of zeatin. The formation of zeatin-allylic-phosphate from t-zeatin and 8-[14C]-zeatin by the microsomal fractions of Iris bulb disks and Helianthus tubers was demonstrated. The responsible enzyme was partially purified. 5-AMP was found to be a phosphate group delivering substrate. Adenosine and adenine inhibited the enzyme reaction. The significance of the results is discussed in relation to cytokinin biosynthesis and the occurrence of bud blast in Iris. 相似文献
57.
Tudor H. Thomas 《Plant Growth Regulation》1989,8(3):255-261
The temperature-dependent, primary dormancy of cv. Florida 683 celery seeds in darkness was partially broken by a 30 min light exposure on the third day of incubation at 20–22°C, resulting in c 50 percent germination after 20 days. This light stimulation was negated by including different inhibitors of gibberellin biosynthesis in the incubation medium. Subsequent addition of a solution of the gibberellins A4 and A7 or of the gibberellin-active compound (1-3-chlorophthalimido)-cyclohexane carboxamide (AC94,377) overcame the inhibitory effects on germination of these GA-biosynthesis inhibitors. It is suggested that light stimulates the biosynthesis of gibberellins which are essential for dormancy-break in celery seeds and that this biosynthesis is either directly or indirectly controlled through phytochrome.Abbreviations AC94,377
1-(3-chlorophthalimido)-cyclohexane carboxamide; ancymidol, -cyclopropyl--(4-methoxyphenyl)-5-pyrimidinemethanol
- AMO1618
N,N,N-2-tetramethyl-5-(1-methyl ethyl)-4-(1-piperidinylcarbonyl)oxy-benzenaminium chloride
- BTS44584
S-2,5-dimethyl-4-pentamethylenecarbamoyloxyphenyl-SS-dimethyl sulphonium
- P
toluenesulphonate; chlormequat chloride, 2-chloroethyltrimethylammonium chloride; daminozide
- N
dimethylaminoscuccinamic acid; paclobutrazol, (2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl pentan-3-ol) 相似文献
58.
The combined effects of chlorine and ammonia on litter breakdown in outdoor experimental streams 总被引:2,自引:0,他引:2
The response of Potamogeton crispus L. breakdown to controlled doses of different levels of chlorine and chlorine + ammonia was investigated over two years in
outdoor experimental streams. In 1985, downstream riffles of 2 streams were dosed (observed in-stream concentrations) at ca.
10 μg/L Total Residual Chlorine (TRC), one stream at 64 μg/L TRC and one stream at 230 μg/L TRC. Two control streams were
not dosed and the upstream riffles of each stream served as within stream controls. In 1986, the downstream riffle of one
stream was dosed at 70 μg/L TRC and a second stream was dosed at 200 μg/L TRC. Four streams were also dosed with 2.5 mg/L
NH3-N: one stream with no chlorine, one stream with ca. 10 μg/L TRC, one with 56 μg/L TRC, and one with 150 μg/L TRC. A seventh
stream was dosed for 2 h at 2000 μg/L TRC and 2.5 mg/L ammonia and then allowed to recover (recovery stream). Each year, litter
decomposition (degree day k values) was measured during two 35 day trials (Jun–Jul and Aug–Sep). In 1985, when streams were dosed with chlorine alone,
decomposition was significantly reduced with the high (230 μg/L TRC) chlorine dose. Downstream decomposition was 27% (Jun–Jul)
and 59% (Aug–Sep) of the upstream (control) rate. No other chlorine effects were found during this period. In Jun–Jul 1986,
there was significantly lower decomposition in the downstream dosed sites of the 200 μg/L TRC alone stream, the 146 μg/L TRC
+ ammonia stream and the recovery stream; downstream decay rates were (respectively) 56%, 42% and 64% of the upstream control
sites. No other up-down pairs were different in July 1986. In Aug–Sep, all three streams with chlorine + ammonia (6, 56 and
146 μg/L TRC + 2,5 mg/L ammonia) and the 70 μg/L TRC alone stream had significantly lower decomposition rates in the downstream
dosed sites. For these streams, downstream decay rates ranged from 46% (high chlorine + ammonia) to 73% (low chlorine + ammonia)
of the upstream control rates. No other up-down pairs were different during this trial. Up and downstream sites of the stream
dosed with 2.5 mg/L ammonia alone were nearly identical for both trials (< 3% difference). These results indicate that TRC
at less than 250 μg/L can significantly reduce litter decomposition and strongly suggest that addition of ammonia to chlorinated
water can increase the toxic effect of chlorine.
currently at the Department of Fisheries and Wildlife
currently at the Department of Fisheries and Wildlife 相似文献
59.
Hiroshi Yonemitsu Koichiro Shimomura Motoyoshi Satake Shunji Mochida Masahiko Tanaka Thoru Endo Akira Kaji 《Plant cell reports》1990,9(6):307-310
Hairy roots were obtained following inoculation of the stems of Lobelia inflata L. with Agrobacterium rhizogenes strain ATCC 15834. These hairy roots contained agropine and mannopine. In addition, lobeline was detected by HPLC and confirmed by mass spectrometry. Various media were tested for the growth of hairy roots as well as for the content of lobeline in hairy roots. The growth rate of hairy roots cultured in Nitsch and Nitsch's medium was approximately one third of those cultured in other media. The lobeline content of hairy roots (18–54 g/g dry weight) cultured in these media was the same order of magnitude compared with that of roots of L. inflata (24 g/g dry weight) cultivated in pots. The hairy roots cultured in Nitsch and Nitsch's medium were morphologically different from those cultured in other media.Abbreviations MS medium
Murashige and Skoog's medium
- 1/2 MS medium
one-half strength of the standard Murashige and Skoog's medium
- B5 medium
Gamborg's B5 medium
- NN medium
Nitsch and Nitsch's medium
- FW
fresh weight
- DW
dry weight 相似文献
60.
L. Symeonidis 《Biometals》1990,3(3-4):204-207
Summary Plant yield of mycorrhizal and non-mycorrhizalFestuca rubra L. was linearly decreased with increasing zinc concentrations in nutrient solution. In all cases, non-mycorrhizal plant growth was significantly greater than that of mycorrhizal plants. Zinc and phosphorus concentrations of root and shoot of mycorrhizal plants were greater in all zinc treatments while mycorrhizal plants showed equal or lower tolerance indices to zinc than non-mycorrhizal plants. Yield depressions of mycorrhizal plants may be the result of enhanced zinc and phosphorus concentrations combined with the cost for growth and maintenance of the mycorrhizal fungi. 相似文献