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121.
Summary Leaf disc transformation-regeneration technique was applied to the drought tolerant wild relative of cultivated tomato,Lycopersicon chilense, using a plasmid construct which contained the coding sequences of neomycin phosphotransferase (NPTII) and chloramphenicol acetyltransferase (CAT) genes. The two genotypes used, LA2747 and LA1930, showed a distinct difference in their aptitude to transformation; a higher success rate was obtained for the first genotype in every stage of the process. Shoots were formed on the regeneration medium containing 100 g/ml kanamycin through direct or indirect organogenesis. Root formation became only possible when the concentration of kanamycin was reduced to 50 g/ml. Expression of chloramphenicol acetyltransferase gene was observed in all of the kanamycin-screened plants after they matured; the activity of the gene was absent or low in some of the young plants. The presence of the CAT gene in transgenic plants was further confirmed by Southern blot analysis. Although transgenic plants grew to maturity, they did not produce fruit, owing to the self incompatibility ofL. chilense.
Abbreviations BAP
6-benzylaminopurine
- CAT
chloramphenicol acetyltransferase
- 2,4-D
2,4-dichlorophenoxyacetic acid
- IAA
indole-3-acetic acid
- LB
Luria Broth
- EDTA
ethylenediamine-tetraacetic acid 相似文献
122.
Lectin binding defines and differentiates M-cells in mouse small intestine and caecum 总被引:3,自引:0,他引:3
M-cell surface glycoconjugate expression was investigated by applying a panel of lectins to whole fixed mouse Peyer's and caecal patches. While the majority of lectins failed to identify mouse M-cells, the lectinEuonymus europaeus differentially stained the surface of M-cells in both mouse Peyer's and caecal patches, and the lectinsUlex europaeus II andBandeiraea simplicifolia I isolectin B4 identified M-cells in the Peyer's and caecal patch follicle associated epithelium, respectively. These three mouse M-cell markers failed to identify rat and rabbit Peyer's patch M-cells, although bothEuonymus europaeus andUlex europaeus II differentially stained M-cells in the periphery of rabbit caecal patch domes. These site and species related variations in M-cell surface glycoconjugate expression may reflect the local microorganism populations and will have important implications if orally delivered vaccines and drugs are to be targeted to M-cells via their surface glycoconjugates. 相似文献
123.
A family of modular type mannuronan C-5-epimerase genes controls alginate structure in Azotobacter vinelandii 总被引:3,自引:1,他引:2
Helga Ertesvåg Hilde Kristin Høidal Ingrid Kathrin Hals Anne Rian Berit Doseth Svein Valla 《Molecular microbiology》1995,16(4):719-731
The ToxR protein is a transmembrane protein that regulates the expression of several virulence factors of Vibrio cholerae. Previous analysis of fusion proteins between ToxR and alkaline phosphatase (ToxR-PhoA) suggested that ToxR was active as a dimer. In order to determine whether dimerization of the ToxR periplasmic domain was essential for activity, this domain was replaced by monomeric and dimeric protein domains. Surprisingly, PhoA (dimeric), β-lactamase (monomeric, ToxR–Bla), or the leucine zipper of GCN4 (dimeric, ToxR-GCN4-M) could substitute functionally for the ToxR periplasmic domain. ToxR-GCN4 fusion proteins, in which the ToxR trans-membrane domain was eliminated (ToxR-GCN4-C), were inactive, but an additional fusion protein that contained a heterologous membrane-spanning domain retained activity. Strains containing each of these ToxR fusion proteins were analysed for in vivo colonization properties and response to in vitro growth conditions that are known to affect expression of the ToxR regulon. Strains containing ToxR-GCN4-M and ToxR-Bla responded like wild-type strains to in vitro growth conditions. In the infant-mouse colonization model, strains containing ToxR fusion proteins were all deficient in colonization relative to strains containing wild-type ToxR, and strains containing monomeric ToxR-Bla were most severely outcompeted. These results suggest that, under in vitro conditions, ToxR does not require a dimerized periplasmic domain, but that, under in vivo conditions, the correct conformation of the ToxR periplasmic domain may be more important for function. 相似文献
124.
Lectin recognition of host-like saccharide motifs in streptococcal cell wall polysaccharides 总被引:10,自引:0,他引:10
Cisar John O.; Sandberg Ann L.; Abeygunawardana Chitrananda; Reddy G.Prabhakar; Bush C.Allen 《Glycobiology》1995,5(7):655-662
Viridans streptococci that participate in the microbial colonizationof teeth have cell wall polysaccharides composed of linear phosphodiester-linkedhexa- or heptasaccharide repeating units, each containing ahost-like disaccharide motif, either Galß1 相似文献
125.
Soft rot Erwinia bacteria in surface and underground waters in southern Scotland and in Colorado, United States 总被引:7,自引:6,他引:1
Nancy J. McCarter-Zorner G.D. Franc M.D. Harrison Janet E. Michaud C.E. Quinn I. Ann Sells D.C. Graham 《Journal of applied microbiology》1984,57(1):95-105
An anaerobic liquid enrichment method followed by plating on a selective medium revealed that the soft rot coliform bacterium Erwinia carotovora subsp. carotovora was generally present in water from drains, ditches, streams, rivers and lakes (including reservoirs) in southern Scotland and in Colorado, United States, in mountainous, upland and arable areas through the year. Many sites were remote from susceptible or diseased crops. Erwinia carotovora subsp. atroseptica was isolated much less frequently and no Erwinia bacteria were isolated from underground waters. Erwinia bacteria were also found in rain-water in Scotland, in winter snow from mountain passes in Colorado, and in sea water from the west and east coasts of Scotland and from the coasts of Oregon, California, Texas, Louisiana and Florida. The significance of the occurrence of these bacteria in water is discussed in relation to the control of blackleg and soft rot diseases of potato by production of Erwinia -free stocks. 相似文献
126.
127.
Ann L. Gnagey David L. Denlinger 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1984,154(1):91-96
Summary The last two days of embryonic development are crucial in programming pupal diapause in the flesh fly,Sarcophaga crassipalpis. Short daylength (greater than 10 1/2h of darkness) during this interval permits expression of diapause while long daylength during this brief sensitive stage eliminates the potential for diapause. Length of scotophase rather than photophase programs the diapause although three hours of light is needed to separate tandem dark periods. Early in the scotophase, photosensitivity is restricted to blue light (less than 540 nm). The scotophase can be divided into 4 phases according to the effect of light breaks on diapause expression. During Phase I (0–6 h after scotophase onset) embryos are highly sensitive to light interruption and diapause is effectively eliminated. A period of insensitivity to light, Phase II, extends from 6–hh after onset of scotophase. Light breaks at 10–11h coincide with the critical scotophase length and result in a partial reduction of diapause. In Phase IV, the scotophase reaction is complete and diapause competence is preserved even in the presence of light. Although light breaks result in elimination of diapause throughout Phase I, recovery time from a 1 h light break (length of darkness needed to counter the effect of a light break) differs dramatically depending upon when the light break is presented. Early in Phase I (0–3h) recovery from light interruption is rapid, while late in Phase I (4–6h), the effects of light are not readily reversible. The scotophase reaction thus appears to follow a step-wise progression rather than represent a simple linear response. We present a molecular model that could account for the dynamics of the scotophase reaction. 相似文献
128.
Mice of the PL/J strain exhibit a high percentage of morphologically abnormal sperm and provide a model for studying the function of abnormal sperm. The ability of such sperm to reach the site of fertilization within the female reproductive tract has been investigated. We have found a decrease in the percentage of structurally abnormal sperm within the population that reaches the oviduct. This observation suggests either that there is an active selection against abnormal sperm or that they are physiologically disadvantaged in reaching the site of fertilization. 相似文献
129.
The forms, disposition, and cytoskeletal contents of astroglia in immature mouse cerebellum were studied by immunocytochemical staining with antisera against two intermediate filament proteins, vimentin (Vim) (58,000 daltons) and glial filament protein (GF) (51,000 daltons). From embryonic (E) Day 15 to postnatal (P) Day 2, Vim is expressed in cells throughout the cerebellar anlage, including radial glia and Bergmann fibers, cells with amorphous shapes and 2–3 processes, and thick longitudinal elements oriented parallel to axons within axon tracts. GF is not expressed during the first few postnatal days, but by P7, there is a dramatic increase in GF-positive astrocyte-like cells in the putative white matter that are more densely stained and more crowded than at any other age. Between P7 and P14 all astrocytes throughout the cerebellum express both Vim and GF. From P21 on, Vim expression is progressively rarer in all astrocytes except for Bergmann fibers, and GF-positive astrocytes become less numerous. These findings raise two issues: (a) the lineage and relationships of cells expressing Vim and GF; (b) Since GF-positive cells appear as axon ingrowth ceases, axons must grow in a terrain comprised of glial cells that have a different cytoskeletal composition (vimentin), reflecting a less differentiated state, than mature astrocytes or than the GF-rich astrocytes that proliferate after injury in adult CNS. 相似文献
130.
The125I-labeled fragment C of tetanus toxin was found to bind specifically to the gangliosides GD1b, GT1b, and GQ1b when applied to thin-layer chromatograms on which a mixture of gangliosides had been resolved. As little as 2.5 pmoles of these gangliosides could be detected by this method. In addition to factors determined by the sample, namely the amount and species of gangliosides present, optimal binding of the125I-labeled fragment C also depended upon the iodination procedure used to generate the probe, the toxin concentration, and the concentration, buffer type, pH, and ionic strength of the binding solution. This new technique was shown to be a sensitive method for the detection and identification of specific gangliosides originating from extraneural or neural cells.Nomenclature: The gangliosides follow the nomenclature system of Svennerholm [Eur J Biochem (1977) 79:11–21] GM3
II3NeuAc-LacCer
- GD3
II3(NeuAc)2-LacCer
- GM1
II3NeuAc-GgOse4Cer
- GD1a
IV3NeuAc, II3NeuAc-GgOse4Cer
- GD1b
II3(NeuAc)2-GgOse4Cer
- GT1b
IV3NeuAc, II3(NeuAc)2-GgOse4Cer
- GQ1b
IV3(Neu-Ac)2, II3(NeuAc)2-GgOse4Cer
- GP1b
IV3(NeuAc)3, II3(NeuAc)2-GgOse4Cer 相似文献