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951.
Are elicitins cryptograms in plant-Oomycete communications? 总被引:13,自引:0,他引:13
Ponchet M Panabières F Milat M-L Mikes V Montillet JL Suty L Triantaphylides C Tirilly Y Blein JP 《Cellular and molecular life sciences : CMLS》1999,56(11-12):1020-1047
Stimulation of plant natural defenses is an important challenge in phytoprotection prospects. In that context, elicitins, which are small proteins secreted by Phytophthora and Pythium species, have been shown to induce a hypersensitive-like reaction in tobacco plants. Moreover, these plants become resistant to their pathogens, and thus this interaction constitutes an excellent model to investigate the signaling pathways leading to plant resistance. However, most plants are not reactive to elicitins, although they possess the functional signaling pathways involved in tobacco responses to elicitin. The understanding of factors involved in this reactivity is needed to develop agronomic applications. In this review, it is proposed that elicitins could interact with regulating cell wall proteins before they reach the plasma membrane. Consequently, the plant reactivity or nonreactivity status could result from the equilibrium reached during this interaction. The possibility of overexpressing the elicitins directly from genomic DNA in Pichia pastoris allows site-directed mutagenesis experiments and structure/function studies. The recent discovery of the sterol carrier activity of elicitins brings a new insight on their molecular activity. This constitutes a crucial property, since the formation of a sterol-elicitin complex is required to trigger the biological responses of tobacco cells and plants. Only the elicitins loaded with a sterol are able to bind to their plasmalemma receptor, which is assumed to be an allosteric calcium channel. Moreover, Phytophthora and Pythium do not synthesize the sterols required for their growth and their fructification, and elicitins may act as shuttles trapping the sterols from the host plants. Sequence analysis of elicitin genes from several Phytophthora species sheds unexpected light on the phylogenetic relationships among the genus, and suggests that the expression of elicitins is under tight regulatory control. Finally, general involvement of these lipid transfer proteins in the biology of Pythiaceae, and in plant defense responses, is discussed. A possible scheme for the coevolution between Phytophthora and tobacco plants is approached. 相似文献
952.
953.
Mutations in CUBN, encoding the intrinsic factor-vitamin B12 receptor, cubilin, cause hereditary megaloblastic anaemia 1 总被引:8,自引:0,他引:8
Aminoff M Carter JE Chadwick RB Johnson C Gräsbeck R Abdelaal MA Broch H Jenner LB Verroust PJ Moestrup SK de la Chapelle A Krahe R 《Nature genetics》1999,21(3):309-313
Megaloblastic anaemia 1 (MGA1, OMIM 261100) is a rare, autosomal recessive disorder characterized by juvenile megaloblastic anaemia, as well as neurological symptoms that may be the only manifestations. At the cellular level, MGA1 is characterized by selective intestinal vitamin B12 (B12, cobalamin) malabsorption. MGA1 occurs worldwide, but its prevalence is higher in several Middle Eastern countries and Norway, and highest in Finland (0.8/100,000). We previously mapped the MGA1 locus by linkage analysis in Finnish and Norwegian families to a 6-cM region on chromosome 10p12.1 (ref. 8). A functional candidate gene encoding the intrinsic factor (IF)-B12 receptor, cubilin, was recently cloned; the human homologue, CUBN, was mapped to the same region. We have now refined the MGA1 region by linkage disequilibrium (LD) mapping, fine-mapped CUBN and identified two independent disease-specific CUBN mutations in 17 Finnish MGA1 families. Our genetic and molecular data indicate that mutations in CUBN cause MGA1. 相似文献
954.
Mutations in ATP2A2, encoding a Ca2+ pump, cause Darier disease 总被引:16,自引:0,他引:16
Sakuntabhai A Ruiz-Perez V Carter S Jacobsen N Burge S Monk S Smith M Munro CS O'Donovan M Craddock N Kucherlapati R Rees JL Owen M Lathrop GM Monaco AP Strachan T Hovnanian A 《Nature genetics》1999,21(3):271-277
Darier disease (DD) is an autosomal-dominant skin disorder characterized by loss of adhesion between epidermal cells (acantholysis) and abnormal keratinization. Recently we constructed a 2.4-Mb, P1-derived artificial chromosome contig spanning the DD candidate region on chromosome 12q23-24.1. After screening several genes that mapped to this region, we identified mutations in the ATP2A2 gene, which encodes the sarco/endoplasmic reticulum Ca2(+)-ATPase type 2 isoform (SERCA2) and is highly expressed in keratinocytes. Thirteen mutations were identified, including frameshift deletions, in-frame deletions or insertions, splice-site mutations and non-conservative missense mutations in functional domains. Our results demonstrate that mutations in ATP2A2 cause DD and disclose a role for this pump in a Ca(2+)-signalling pathway regulating cell-to-cell adhesion and differentiation of the epidermis. 相似文献
955.
956.
L. A. García-Alonso 《Cellular and molecular life sciences : CMLS》1999,55(11):1386-1398
The peripheral sensory system of the Drosophila adult has been used for the genetic analysis of axon guidance because of its accessibility for experimental manipulation
and mutant screens. Wing, leg, antenna, or eye sensory axons are able to pathfind normally under different perturbations,
indicating that sensory axon guidance is a highly canalized process. Similarly to other model systems, sensory growth cones
seem to use multiple, simultaneous cues for guidance. In addition, sensory axons from peripheral structures seem to be capable
of using alternative substrates for pathfinding. Developmental regulation could account for the high stability of axon guidance
under experimental and natural perturbation conditions. Despite this flexibility, functional characterization of genes involved
in sensory axon guidance is being carried out in situations where there appears to be less system redundancy. 相似文献
957.
Glycine: a new anti-inflammatory immunonutrient 总被引:7,自引:0,他引:7
958.
The Pendred syndrome gene encodes a chloride-iodide transport protein 总被引:24,自引:0,他引:24
Pendred syndrome is the most common form of syndromic deafness and characterized by congenital sensorineural hearing loss and goitre. This disorder was mapped to chromosome 7 and the gene causing Pendred syndrome (PDS) was subsequently identified by positional cloning. PDS encodes a putative transmembrane protein designated pendrin. Pendrin is closely related to a family of sulfate transport proteins that includes the rat sulfate-anion transporter (encoded by Sat-1; 29% amino acid sequence identity), the human diastrophic dysplasia sulfate transporter (encoded by DTD; 32%) and the human sulfate transporter 'downregulated in adenoma' (encoded by DRA; 45%). On the basis of this homology and the presence of a slightly modified sulfate-transporter signature sequence comprising its putative second transmembrane domain, pendrin has been proposed to function as a sulfate transporter. We were unable to detect evidence of sulfate transport following the expression of pendrin in Xenopus laevis oocytes by microinjection of PDS cRNA or in Sf9 cells following infection with PDS-recombinant baculovirus. The rates of transport for iodide and chloride were significantly increased following the expression of pendrin in both cell systems. Our results demonstrate that pendrin functions as a transporter of chloride and iodide, but not sulfate, and may provide insight into thyroid physiology and the pathophysiology of Pendred syndrome. 相似文献
959.
960.
Molecular cloning and sequence analysis of myosin genes from Arabidopsis thaliana and electron microscopic observation of a myosin from characean alga have revealed that overall structure of plant unconventional
myosins is similar to that of the class V myosins. These plant unconventional myosins have two heads, a coiled-coil tail of
varied length and a globular tail piece at the end. The tail piece is probably a site for membrane interaction. Characean
myosin is of special interest because it can translocate actin filaments at a velocity several times faster than muscle myosin,
which must have evolved to support the quick movement of animals in the struggle for their lives. 相似文献