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991.
Daisuke Igarashi Yoshihiro Izumi Yuko Dokiya Kazuhiko Totsuka Eiichiro Fukusaki Chieko Ohsumi 《Planta》2009,229(3):633-644
The metabolism of vegetative organs in plants changes during the development of the reproductive organs. The regulation of
this metabolism is important in the control of crop productivity. However, the complexity of the regulatory systems makes
it difficult to elucidate their mechanisms. To examine these mechanisms, we constructed model experiments using Arabidopsis
to analyze metabolic and gene expression changes during leaf-stage progression and after removal of the reproductive organs.
Leaf gene expression levels and content of major amino acids, both of which decreased during leaf-stage progression, increased
after removal of the reproductive organs. In particular, the levels of expression of cytokinin biosynthesis genes and cytokinin-responsive
genes and the cytokinin content increased after removal of the reproductive organs. Analysis of plants with knockout of a
cytokinin-biosynthetic gene (AtIPT3) and a cytokinin receptor gene (AHK3) indicated that glutamate dehydrogenase genes (GDH3) were regulated by cytokinin signaling. These data suggest that cytokinins regulate communication between reproductive and
vegetative organs, and that GDH3 is one target of the cytokinin-mediated regulation of nitrogen metabolism.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
992.
Phytochemical investigation of the whole plants of Agave utahensis Engelm. (Agavaceae) has resulted in the isolation of 15 steroidal saponins (1-15), including five spirostanol saponins (1-5) and three furostanol saponins (11-13). Structures of compounds 1-5 and 11-13 were determined by spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HL-60 human promyelocytic leukemia cells. 相似文献
993.
Chemical studies on the constituents of Eranthis cilicica led to isolation of ten chromone derivatives, two of which were previously known. Comprehensive spectroscopic analysis, including extensive 1D and 2D NMR data, and the results of enzymatic hydrolysis allowed the chemical structures of the compounds to be assigned as 8,11-dihydro-5-hydroxy-2,9-dihydroxymethyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 5,7-dihydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 5,7-dihydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 9-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-8,11-dihydro-5,9-dihydroxy-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 8,11-dihydro-5,9-dihydroxy-9-hydroxymethyl-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, and 7-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-4-hydroxy-5H-furo[3,2-g][1]benzopyran-5-one, respectively. The isolated compounds were evaluated for their antioxidant activity. 相似文献
994.
DNA polymerase δ (Pol δ) is one of the main replicative DNA polymerases in human cells and therefore is a critical determinant of the overall accuracy of DNA synthesis. Here we document the fidelity of a human Pol δ holoenzyme and systematically score the types of mutations that the enzyme generates in a forward mutation assay. We find that human Pol δ is highly accurate, catalyzing less than one nucleotide mis-insertion per 220,000 nucleotides polymerized. Inactivation of proofreading or mutation of a conserved active site residue significantly elevates the frequency of incorporation errors, demonstrating the contribution of both the base selection and proofreading domains to the overall accuracy of synthesis by Pol δ. The highly selective nature of the polymerase active site is also indicated by the stalling of Pol δ upon encountering multiple types of DNA lesions. However, DNA damage is not an absolute block to Pol δ progression. We propose that partial lesion bypass by Pol δ represents a balance between stalling to allow for repair of mutagenic lesions by specialized repair proteins and bypass of damage to allow for successful completion of DNA synthesis by Pol δ in the presence of weakly blocking DNA adducts. 相似文献
995.
Yoshihiro Kino Chika Washizu Yoko Oma Hayato Onishi Yuriko Nezu Noboru Sasagawa Nobuyuki Nukina Shoichi Ishiura 《Nucleic acids research》2009,37(19):6477-6490
The expression and function of the skeletal muscle chloride channel CLCN1/ClC-1 is regulated by alternative splicing. Inclusion of the CLCN1 exon 7A is aberrantly elevated in myotonic dystrophy (DM), a genetic disorder caused by the expansion of a CTG or CCTG repeat. Increased exon 7A inclusion leads to a reduction in CLCN1 function, which can be causative of myotonia. Two RNA-binding protein families—muscleblind-like (MBNL) and CUG-BP and ETR-3-like factor (CELF) proteins—are thought to mediate the splicing misregulation in DM. Here, we have identified multiple factors that regulate the alternative splicing of a mouse Clcn1 minigene. The inclusion of exon 7A was repressed by MBNL proteins while promoted by an expanded CUG repeat or CELF4, but not by CUG-BP. Mutation analyses suggested that exon 7A and its flanking region mediate the effect of MBNL1, whereas another distinct region in intron 6 mediates that of CELF4. An exonic splicing enhancer essential for the inclusion of exon 7A was identified at the 5′ end of this exon, which might be inhibited by MBNL1. Collectively, these results provide a mechanistic model for the regulation of Clcn1 splicing, and reveal novel regulatory properties of MBNL and CELF proteins. 相似文献
996.
Yoshifumi Yamawaki Yoshihiro Toh 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(3):253-264
Responses to visual stimuli of some neurons that descend the nerve cord from the brain were recorded extracellularly in the
mantis Tenodera aridifolia. Most of the recorded neurons showed their largest responses to looming stimuli that simulated a black circle approaching
towards the mantis. The neurons showed a transient excitatory response to a gradually darkening or receding circle. The neurons
showed sustained excitation to the linearly expanding stimuli, but the spike frequency decreased rapidly. The responses of
the neurons were affected by both the diameter and the speed of looming stimuli. Faster or smaller looming stimuli elicited
a higher peak frequency. These responses were observed in both recordings from the connective between suboesophageal and prothoracic
ganglia and the connective between prothoracic and mesothoracic ganglia. There was a one-to-one correspondence of spike firing
between these two recordings with a fixed delay. The neurons had the receptive field on ipsilateral side to its axon at the
cervical connective. These results suggest that there is a looming-sensitive descending neuron, with an axon projecting over
prothoracic ganglion, in the mantis nervous system. 相似文献
997.
998.
The voltage-dependent anion channel (VDAC) is a major outer mitochondrial membrane protein. It is well documented that VDAC
plays an important role in apoptosis, a kind of programmed cell death, in mammalian systems. However, little is known about
the role of the plant counterpart during the process of plant-specific cell death such as pathogen-induced hypersensitive
response. To address this issue, we isolated three VDAC full-length cDNAs (NtVDAC1–3) from Nicotiana tabacum. The deduced products, NtVDACs, share 78–85% identity and retain the conserved eukaryotic mitochondrial porin signature distal
to their C-terminal regions. Mitochondrial localization of three NtVDACs in plant cells was confirmed via a green fluorescent
protein fusion method. Then, we addressed the main issue concerning pathogenesis relation. The N. benthamiana orthologues of NtVDACs were upregulated by challenge with the non-host pathogen Pseudomonas cichorii, but not after challenge with the virulent pathogen P. syringae pv. tabaci. Both the pharmaceutical inhibition of VDAC and silencing of NbVDACs genes compromised the non-host resistance against P. cichorii, suggesting the involvement of VDACs in defense against non-host pathogen. Involvement of NbVDACs in Bax-mediated cell death
was also verified using a similar approach.
The nucleotide sequence reported in this paper has been submitted to DDBJ under the following accession numbers: NtVDAC1 (AB286176), NtVDAC2 (AB286177), and NtVDAC3 (AB286178).
An erratum to this article can be found at 相似文献
999.
1000.
Attachment of an NMR-invisible solubility enhancement tag using a sortase-mediated protein ligation method 总被引:1,自引:1,他引:0
Yoshihiro Kobashigawa Hiroyuki Kumeta Kenji Ogura Fuyuhiko Inagaki 《Journal of biomolecular NMR》2009,43(3):145-150
Sample solubility is essential for structural studies of proteins by solution NMR. Attachment of a solubility enhancement
tag, such as GB1, MBP and thioredoxin, to a target protein has been used for this purpose. However, signal overlap of the
tag with the target protein often made the spectral analysis difficult. Here we report a sortase-mediated protein ligation
method to eliminate NMR signals arising from the tag by preparing the isotopically labeled target protein attached with the
non-labeled GB1 tag at the C-terminus.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献