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611.
Calmodulin interacts with MLO protein to regulate defence against mildew in barley 总被引:29,自引:0,他引:29
Kim MC Panstruga R Elliott C Müller J Devoto A Yoon HW Park HC Cho MJ Schulze-Lefert P 《Nature》2002,416(6879):447-451
In plants, defence against specific isolates of a pathogen can be triggered by the presence of a corresponding race-specific resistance gene, whereas resistance of a more broad-spectrum nature can result from recessive, presumably loss-of-regulatory-function, mutations. An example of the latter are mlo mutations in barley, which have been successful in agriculture for the control of powdery mildew fungus (Blumeria graminis f. sp. hordei; Bgh). MLO protein resides in the plasma membrane, has seven transmembrane domains, and is the prototype of a sequence-diversified family unique to plants, reminiscent of the seven-transmembrane receptors in fungi and animals. In animals, these are known as G-protein-coupled receptors and exist in three main families, lacking sequence similarity, that are thought to be an example of molecular convergence. MLO seems to function independently of heterotrimeric G proteins. We have identified a domain in MLO that mediates a Ca2+-dependent interaction with calmodulin in vitro. Loss of calmodulin binding halves the ability of MLO to negatively regulate defence against powdery mildew in vivo. We propose a sensor role for MLO in the modulation of defence reactions. 相似文献
612.
613.
Jeong PY Jung M Yim YH Kim H Park M Hong E Lee W Kim YH Kim K Paik YK 《Nature》2005,433(7025):541-545
Pheromones are cell type-specific signals used for communication between individuals of the same species. When faced with overcrowding or starvation, Caenorhabditis elegans secrete the pheromone daumone, which facilitates communication between individuals for adaptation to adverse environmental stimuli. Daumone signals C. elegans to enter the dauer stage, an enduring and non-ageing stage of the nematode life cycle with distinctive adaptive features and extended life. Because daumone is a key regulator of chemosensory processes in development and ageing, the chemical identification of daumone is important for elucidating features of the daumone-mediated signalling pathway. Here we report the isolation of natural daumone from C. elegans by large-scale purification, as well as the total chemical synthesis of daumone. We present the stereospecific chemical structure of purified daumone, a fatty acid derivative. We demonstrate that both natural and chemically synthesized daumones equally induce dauer larva formation in C. elegans (N2 strain) and certain dauer mutants, and also result in competition between food and daumone. These results should help to elucidate the daumone-mediated signalling pathway, which might in turn influence ageing and obesity research and the development of antinematodal drugs. 相似文献
614.
Lee C Hong B Choi JM Kim Y Watanabe S Ishimi Y Enomoto T Tada S Kim Y Cho Y 《Nature》2004,430(7002):913-917
To maintain chromosome stability in eukaryotic cells, replication origins must be licensed by loading mini-chromosome maintenance (MCM2-7) complexes once and only once per cell cycle. This licensing control is achieved through the activities of geminin and cyclin-dependent kinases. Geminin binds tightly to Cdt1, an essential component of the replication licensing system, and prevents the inappropriate reinitiation of replication on an already fired origin. The inhibitory effect of geminin is thought to prevent the interaction between Cdt1 and the MCM helicase. Here we describe the crystal structure of the mouse geminin-Cdt1 complex using tGeminin (residues 79-157, truncated geminin) and tCdt1 (residues 172-368, truncated Cdt1). The amino-terminal region of a coiled-coil dimer of tGeminin interacts with both N-terminal and carboxy-terminal parts of tCdt1. The primary interface relies on the steric complementarity between the tGeminin dimer and the hydrophobic face of the two short N-terminal helices of tCdt1 and, in particular, Pro 181, Ala 182, Tyr 183, Phe 186 and Leu 189. The crystal structure, in conjunction with our biochemical data, indicates that the N-terminal region of tGeminin might be required to anchor tCdt1, and the C-terminal region of tGeminin prevents access of the MCM complex to tCdt1 through steric hindrance. 相似文献
615.
Watanabe H Fujiyama A Hattori M Taylor TD Toyoda A Kuroki Y Noguchi H BenKahla A Lehrach H Sudbrak R Kube M Taenzer S Galgoczy P Platzer M Scharfe M Nordsiek G Blöcker H Hellmann I Khaitovich P Pääbo S Reinhardt R Zheng HJ Zhang XL Zhu GF Wang BF Fu G Ren SX Zhao GP Chen Z Lee YS Cheong JE Choi SH Wu KM Liu TT Hsiao KJ Tsai SF Kim CG OOta S Kitano T Kohara Y Saitou N Park HS Wang SY Yaspo ML Sakaki Y 《Nature》2004,429(6990):382-388
Human-chimpanzee comparative genome research is essential for narrowing down genetic changes involved in the acquisition of unique human features, such as highly developed cognitive functions, bipedalism or the use of complex language. Here, we report the high-quality DNA sequence of 33.3 megabases of chimpanzee chromosome 22. By comparing the whole sequence with the human counterpart, chromosome 21, we found that 1.44% of the chromosome consists of single-base substitutions in addition to nearly 68,000 insertions or deletions. These differences are sufficient to generate changes in most of the proteins. Indeed, 83% of the 231 coding sequences, including functionally important genes, show differences at the amino acid sequence level. Furthermore, we demonstrate different expansion of particular subfamilies of retrotransposons between the lineages, suggesting different impacts of retrotranspositions on human and chimpanzee evolution. The genomic changes after speciation and their biological consequences seem more complex than originally hypothesized. 相似文献
616.
Hanks S Coleman K Reid S Plaja A Firth H Fitzpatrick D Kidd A Méhes K Nash R Robin N Shannon N Tolmie J Swansbury J Irrthum A Douglas J Rahman N 《Nature genetics》2004,36(11):1159-1161
Mosaic variegated aneuploidy is a rare recessive condition characterized by growth retardation, microcephaly, childhood cancer and constitutional mosaicism for chromosomal gains and losses. In five families with mosaic variegated aneuploidy, including two with embryonal rhabdomyosarcoma, we identified truncating and missense mutations of BUB1B, which encodes BUBR1, a key protein in the mitotic spindle checkpoint. These data are the first to relate germline mutations in a spindle checkpoint gene with a human disorder and strongly support a causal link between aneuploidy and cancer development. 相似文献
617.
Double-walled carbon nanotubes are needed in a pure, highly crystalline form before features such as their electronic properties, thermal transport and mechanical behaviour can be investigated. Here we fabricate a paper-like material that consists of hexagonally packed bundles of clean, coaxial carbon nanotubes whose double walls vary little in diameter; it is prepared in high yields using chemical-vapour deposition with a conditioning catalyst and two-step purification. Our results will enable investigation of the physical properties of double-walled carbon nanotubes, which are predicted to be superior to those of both their single- and multiwalled relatives. 相似文献
618.
Kim JH Kim B Cai L Choi HJ Ohgi KA Tran C Chen C Chung CH Huber O Rose DW Sawyers CL Rosenfeld MG Baek SH 《Nature》2005,434(7035):921-926
Defining the molecular strategies that integrate diverse signalling pathways in the expression of specific gene programmes that are critical in homeostasis and disease remains a central issue in biology. This is particularly pertinent in cancer biology because downregulation of tumour metastasis suppressor genes is a common occurrence, and the underlying molecular mechanisms are not well established. Here we report that the downregulation of a metastasis suppressor gene, KAI1, in prostate cancer cells involves the inhibitory actions of beta-catenin, along with a reptin chromatin remodelling complex. This inhibitory function of beta-catenin-reptin requires both increased beta-catenin expression and recruitment of histone deacetylase activity. The coordinated actions of beta-catenin-reptin components that mediate the repressive state serve to antagonize a Tip60 coactivator complex that is required for activation; the balance of these opposing complexes controls the expression of KAI1 and metastatic potential. The molecular mechanisms underlying the antagonistic regulation of beta-catenin-reptin and the Tip60 coactivator complexes for the metastasis suppressor gene, KAI1, are likely to be prototypic of a selective downregulation strategy for many genes, including a subset of NF-kappaB target genes. 相似文献
619.
Agrobacterium-mediated transformation of herbicide resistance in creeping bentgrass and colonial bentgrass 总被引:6,自引:0,他引:6
Embryogenic calli were induced from the seeds of creeping bentgrass ( Agrostis palustris Huds. ) cv. Regent and colonial bentgrass ( Agrostis Tenuis Sibth. F1. Oxen. ) cv. Tiger. The embryogenic calli were precultured on fresh medium for 4-7 days and then co-cultivated with Agrobacterium tumefaciens, LBA4404,which contains plasmid vector-pSBGM harboring bar coding region, synthetic green fluorescent protein (sGFP) coding region and matrix attachment region (MAR) . After 3 days of co-cultivation, the calli were washed thoroughly and transferred to MS medium containing 2 mg/L of 2, 4-D, 12-15 mg/L phosphinothricin (PPT) and 250 mg/L of cefotaxime. After 2-3 months of selection, the actively growing calli of ‘Regent‘ and ‘Ti-ger‘ were transferred to MS medium with 12-15 mg/L PPT and 250 mg/L cefotaxime for regeneration. The putative transformants were maintained on MS medium with 3 mg/L PPT for long period but control died within 1 month. After establishing in greenhouse, the transformants also showed strong resistance to 0.4 % of herbi-cide Basta but control plants died within 2 weeks. Under confocal microscope, both young leaves and roots showed significant GFP expression. PCR analysis revealed the presence of a DNA fragment of GFP gene at the expected size (380 bp) in the transformants and its absence in a randomly selected control plant. 相似文献
620.