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171.
S T Weintraub W B Stavinoha R L Pike W W Morgan A T Modak S H Koslow L Blank 《Life sciences》1975,17(9):1423-1427
Norepinephrine, dopamine and serotonin concentrations were measured in mouse whole brain. Animals were killed either by decapitation or by exposure to 250 msec microwave irradiation which produces irreversible inactivation of brain enzymes. The biogenic amines were determined by mass fragmentometry, fluorometry and by a combination of high performance liquid chromatography and an electrochemical detector. No differences were found in the levels of these neurochemicals between the two methods of animal sacrifice. Therefore, rapid inactivation of brain enzymes is not necessary prior to analysis for catecholamines and serotonin in mouse whole brain. 相似文献
172.
Simone L. Sandiford Yuemei Dong Andrew Pike Benjamin J. Blumberg Ana C. Bahia George Dimopoulos 《PLoS pathogens》2015,11(2)
Actin is a highly versatile, abundant, and conserved protein, with functions in a variety of intracellular processes. Here, we describe a novel role for insect cytoplasmic actin as an extracellular pathogen recognition factor that mediates antibacterial defense. Insect actins are secreted from cells upon immune challenge through an exosome-independent pathway. Anopheles gambiae actin interacts with the extracellular MD2-like immune factor AgMDL1, and binds to the surfaces of bacteria, mediating their phagocytosis and direct killing. Globular and filamentous actins display distinct functions as extracellular immune factors, and mosquito actin is a Plasmodium infection antagonist. 相似文献
173.
Nest-site selection involves tradeoffs between the risk of predation (on females and/or nests) and nest-site quality (microenvironment),
and consequently suitable nesting sites are often in limited supply. Interactions with “classical” predators (e.g., those
not competing for shared resources) can strongly influence nest-site selection, but whether intraguild predation also influences
this behavior is unknown. We tested whether risk of predation from an intraguild predator [the diurnal scincid lizard Eutropis (Mabuya) longicaudata] influences nest-site selection by its prey (the nocturnal gecko Gekko hokouensis) on Orchid Island, Taiwan. These two species putatively compete for shared resources, including invertebrate prey and nesting
microhabitat, but the larger E. longicaudata also predates G. hokouensis (but not its hard-shelled eggs). Both species nested within a concrete wall containing a series of drainage holes that have
either one (“closed-in”) or two openings (“open”). In allopatry, E. longicaudata preferred to nest within holes that were plugged by debris (thereby protecting eggs from water intrusion), whereas G. hokouensis selected holes that were open at both ends (facilitating escape from predators). When we experimentally excluded E. longicaudata from its preferred nesting area, G. hokouensis not only nested in higher abundances, but also modified its nest-site selection, such that communal nesting was more prevalent
and both open and closed-in holes were used equally. Egg viability was unaffected by the choice of hole type, but was reduced
slightly (by 7%) in the predator exclusion area (presumably due to higher local incubation temperatures). Our field experiment
demonstrates that intraguild predators can directly influence the nest density of prey by altering maternal nest-site selection
behavior, even when the predator and prey are active at different times of day and the eggs are not at risk of predation. 相似文献
174.
Farkas S Nagy K Palkovits M Kovács GG Jia Z Donohue S Pike V Halldin C Máthé D Harkany T Gulyás B Csiba L 《Neurochemistry international》2012,60(3):286-291
The cannabinoid type-1 receptor (CB1R) is one of the most abundant members of the G protein-coupled receptor family in the central nervous system. Once activated by their cognate ligands, endocannabinoids, CB1Rs generally limit the timing of neurotransmitter release at many cortical synapses. Prior studies have indicated the involvement of CB1R in neurodegeneration and in various neuronal insults, with an emphasis on their neuroprotective role. In the present study we used a novel selective CB1R radioligand to investigate regional variations in CB1R ligand binding as a factor of progressive Braak tau pathology in the frontal cortex of Alzheimer’s disease (AD) patients. The frontal cortex was chosen for this study due to the high density of CB1Rs and their well-characterized involvement in the progression of AD. Post-mortem prefrontal cortex samples from AD patients from Braak stages I to VI and controls were subjected to CB1R autoradiography with [125I]SD-7015 as radioligand. Regional concentration of [125I]SD-7015, corresponding to, and thereby representing, regional CB1R densities, were expressed in fM/g_tissue. The results show that CB1R density inversely correlates with Braak tau pathology with the following tendency: controls 1R radioligand [125I]SD7015 in human brains, allowing the detection of fine modalities of receptor expression and radioligand binding during the progression of AD. 相似文献
175.
Pike LJ 《Biochemical Society transactions》2012,40(1):15-19
Scatchard analyses of the binding of EGF (epidermal growth factor) to its receptor (EGFR) yield concave up Scatchard plots, indicative of some type of heterogenity in ligand-binding affinity. This was typically interpreted as being due to the presence of two independent binding sites: one of high affinity representing ≤10% of the receptor population, and one of low affinity making up the bulk of the receptors. However, the concept of two independent binding sites is difficult to reconcile with the X-ray structures of the dimerized EGFR that show symmetrical binding of the two ligands. A new approach to the analysis of 125I-EGF-binding data combined with the structure of the singly-occupied Drosophila EGFR have now shown that this heterogeneity is due to the presence of negative co-operativity in the EGFR. Concerns that negative co-operativity precludes ligand-induced dimerization of the EGFR confuse the concepts of linkage and co-operativity. Linkage refers to the effect of ligand on the assembly of dimers, whereas co-operativity refers to the effect of ligand binding to one subunit on ligand binding to the other subunit within a preassembled dimer. Binding of EGF to its receptor is positively linked with dimer assembly, but shows negative co-operativity within the dimer. 相似文献
176.
Thomas W. Pike 《Journal of Insect Behavior》2012,25(3):277-286
Chromaticity diagrams for tri- and tetrachromatic animals (with three and four cone classes in their retina, respectively,
contributing to colour perception) are widely used in studies of animal colour vision. These diagrams not only allow the graphical
representation of perceived colours, but the coordinates of colours plotted within these diagrams can be used to extract colour
metrics, such as hue and chroma, or can be used directly in statistical analyses, and therefore aid our understanding of vision-mediated
behaviour. However, many invertebrate species have more than four cone classes in their retina, and may therefore have pentachromatic
or hexachromatic (or greater) vision. This paper describes an extension to the triangular and tetrahedral chromaticity diagrams
commonly used for tri- and tetrachromats, respectively, that allows colour coordinates (and hence colour metrics) to be calculated
for animals with more than four cone classes. Because the resulting chromaticity diagrams have more than three dimensions,
meaningful ways to visualise the spatial position of plotted colours are discussed. 相似文献
177.
178.
During the last deglaciation calving bay reentrants formed over several deep inner shelf basins around Antarctica as the ice sheets retreated. Marine diatoms flourished in spring and summer within the bays, providing exceptionally high silica flux rates to the basins on an annual basis. As a result, several hundred years of the late deglaciation are archived in many of these deep basins as continuously laminated diatom-rich marine sediments. The laminae are excellently preserved and offer a unique opportunity to study deglacial processes over the Antarctic shelf at very high resolution (subseasonal to seasonal at best). Annual palaeoenvironments from these sediments have been recently reconstructed. However, finer sedimentary detail is also apparent by the preservation of sublaminae of single diatom species, which represent discrete productivity events (blooms). In this paper, we focus on Thalassiosira tumida (Janisch) Hasle sublaminae preserved in the 5 m thick deglacial laminated sequence of NBP01-01 Jumbo Piston Core (JPC) 43B from Iceberg Alley ( 67°S, 63°E) on the Mac.Robertson Shelf, East Antarctic Margin. These T. tumida sublaminae are distinctive, occur several times throughout the deglacial sequence and are always preserved within summer laminae. Importantly they carry ecological and paleoceanographic information for deglacial Iceberg Alley and possibly the entire East Antarctic Margin. We describe and illustrate the T. tumida sublaminae using scanning electron microscope backscattered electron imagery of highly polished thin sections and secondary electron imagery of sublamina fracture surfaces. T. tumida sublaminae range in thickness from 0.57 to 21.07 mm (mean = 5.12; σ = 4.49) and are defined as discrete sedimentary intervals within a summer lamination where T. tumida is the dominant diatom species (abundance > 50%; but frequently > 80%) or is very abundant (abundance 40% to 49%). Based on the stratigraphic position of these sublaminae in the annual/seasonal succession and on published morphological, ecological and distributional data of living specimens in culture and in the field, we surmise an open-water, late summer bloom for T. tumida in deglacial Iceberg Alley, at sea-surface temperatures of 0 to − 1.69 °C, under low or fading light levels just prior to significant sea-ice formation. We suggest that the sublaminae formed by a combination of episodic T. tumida blooms (surface concentration), followed by rapid deposition (high flux) and optimal frustule preservation on the sea floor. Increased sublaminae frequency upcore suggests a lengthening of the summer season, while their complete cessation 43 years prior to the end of lamination deposition in outer Iceberg Alley (JPC43B) may be due to a coastward population shift. 相似文献
179.
Sandal N Petersen TR Murray J Umehara Y Karas B Yano K Kumagai H Yoshikawa M Saito K Hayashi M Murakami Y Wang X Hakoyama T Imaizumi-Anraku H Sato S Kato T Chen W Hossain MS Shibata S Wang TL Yokota K Larsen K Kanamori N Madsen E Radutoiu S Madsen LH Radu TG Krusell L Ooki Y Banba M Betti M Rispail N Skøt L Tuck E Perry J Yoshida S Vickers K Pike J Mulder L Charpentier M Müller J Ohtomo R Kojima T Ando S Marquez AJ Gresshoff PM Harada K Webb J Hata S Suganuma N Kouchi H Kawasaki S Tabata S 《Molecular plant-microbe interactions : MPMI》2006,19(1):80-91
Development of molecular tools for the analysis of the plant genetic contribution to rhizobial and mycorrhizal symbiosis has provided major advances in our understanding of plant-microbe interactions, and several key symbiotic genes have been identified and characterized. In order to increase the efficiency of genetic analysis in the model legume Lotus japonicus, we present here a selection of improved genetic tools. The two genetic linkage maps previously developed from an interspecific cross between L. japonicus Gifu and L. filicaulis, and an intraspecific cross between the two ecotypes L. japonicus Gifu and L. japonicus MG-20, were aligned through a set of anchor markers. Regions of linkage groups, where genetic resolution is obtained preferentially using one or the other parental combination, are highlighted. Additional genetic resolution and stabilized mapping populations were obtained in recombinant inbred lines derived by a single seed descent from the two populations. For faster mapping of new loci, a selection of reliable markers spread over the chromosome arms provides a common framework for more efficient identification of new alleles and new symbiotic loci among uncharacterized mutant lines. Combining resources from the Lotus community, map positions of a large collection of symbiotic loci are provided together with alleles and closely linked molecular markers. Altogether, this establishes a common genetic resource for Lotus spp. A web-based version will enable this resource to be curated and updated regularly. 相似文献
180.
Meyer MB Watanuki M Kim S Shevde NK Pike JW 《Molecular endocrinology (Baltimore, Md.)》2006,20(6):1447-1461