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401.
ANTONY J. MUKKADA FRANK W. SCHAEFER MICHAEL W. SIMON CAROL NEU 《The Journal of eukaryotic microbiology》1974,21(2):393-397
Leishmania tropica promastigotes do not utilize glucose provided in the medium until late log phase. Rapid depletion of glucose from the medium, however, occurs during late log and stationary phases. At about the same time, the cells show maximal rates of glucose uptake as well as peak levels of phosphofructokinase and pyruvate kinase activities. The glucose analog, 2-deoxy-D-glucose inhibits glucose transport. Incorporation of this analog in the growth medium results in inhibition of growth. The hexokinase of L. tropica phosphorylates 2-deoxy-D-glucose. Pyruvate kinase is activated by fructose-1, 6-diphosphate and adenosine monophosphate. 相似文献
402.
SIMON M. TIERNEY MICHAEL P. SCHWARZ 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(3):520-530
The social organization of allodapine bees has been described in detail for most genera, although there remains a notable gap for one major lineage, the genus Allodapula . Here, we provide the first detailed study of social organization in Allodapula dichroa . Colony sizes are small and the frequency of cooperative nesting is low compared with other allodapine taxa, but there is very clear evidence for reproductive differentiation among adult nestmates. Reproductively dominant females tend to be larger than their nestmates and have much higher levels of wing wear, suggesting that they perform most foraging activities. Multi-female colonies have: (1) lower rates of complete brood absence, suggesting a substantial benefit to cooperative nesting; and (2) larger numbers of brood, suggesting that the presence of a second adult female leads to a greater reproductive output. These data suggest a major phylogenetic split in the form of social organization within the allodapines. In the genus Macrogalea (sister clade to all other allodapines), body size does not preclude young females from laying eggs, and there appears to be, at most, weak reproductive queues. However, in most other allodapines, reproductive hierarchies are prominent and younger and/or smaller females queue for reproductive opportunities, adopt permanently subordinate roles, or disperse. Interestingly, the most common forms of reproductive hierarchies in allodapines do not involve subordinates undertaking foraging roles before reproduction, but instead involve the delaying of both reproduction and foraging. This has implications for the understanding of suggested developmental ground plans in the early stages of social evolution. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 520–530. 相似文献
403.
Leakage from Fruit Cells in Water 总被引:1,自引:0,他引:1
When disks of apple tissue are placed in water, 90% of theirelectrolytes and soluble carbohydrates leak out in 23h, and cells initially intact and able to exclude Evan's Bluebecome coloured by the dye. Molar glycerol and 0.5M potassiumchloride largely protect the cells from these changes. It issuggested that apple cells burst in water, but not in hypertonicmedia. Leakage from the tissues of other soft fruits (grape,tomato, plum, banana, melon) when placed in water is as rapidand extensive as from apple; but leakage is very much slowerfrom tissues such as potato tuber, beetroot, onion bulb, lettuceleaf, and the fruits of marrow and cucumber. Leakage from applefruit tissue becomes more extensive as the apple develops towardsmaturity. 相似文献
404.
Cell distribution and surface morphology in petals, androecia and styles of Commelinaceae 总被引:1,自引:0,他引:1
ROWENA M. O. GALE SIMON J. OWENS 《Botanical journal of the Linnean Society. Linnean Society of London》1983,87(3):247-262
Cell distribution and surface morphology in petals, androecia and styles of Commelinaceae. Epidermal cell shape, distribution, surface topography and cuticular morphology in petals, androecia and styles of 10 species in the Commelinaceae are described. Petals of all species possess a basal area of elongated, straight-sided cells and an area of cells with sinuous, anticlinal walls. The degree of convolution of anticlinal wall and the length of cells varies between genera. The surface of cells in Aneilema, Commelina and Cyanotis are micropapillate. In all other genera they are low-domed. Cuticular surfaces of the three genera are smooth, while in the remainder heavily striated. The cells of stamens, staminodes, staminal hairs, and styles are variably elongated and straight-sided, their surfaces convex and cuticle striated. The degree of striation is less pronounced at the base of each organ but becomes more densely arrayed towards the apex. Petal pigments are located in upper epidermal cells in Tradescantia and Thyrsanthemum , in upper and lower epidermises in Dichorisandra and Commelina , and in both epidermises, and mesophyll of Aneilema. In most species pigmentation of androecium and style is similar to petals though often fainter at base and apex. Flavonols in the pigments give rise to spectral polmorphisms visible in longwave UV light. Epidermal adaptations for light capture in petals is compared to that in leaf structure. 相似文献
405.
406.
CATHRYN H. GREENBERG AIMEE LIVINGS TOMCHO J. DREW LANHAM THOMAS A. WALDROP JOSEPH TOMCHO ROSS J. PHILLIPS DEAN SIMON 《The Journal of wildlife management》2007,71(6):1906-1916
Abstract: We compared the effects of 3 fuel reduction techniques and a control on breeding birds during 2001-2005 using 50-m point counts. Four experimental units, each >14 ha, were contained within each of 3 replicate blocks at the Green River Game Land, Polk County, North Carolina, USA. Treatments were 1) prescribed burn, 2) mechanical understory reduction (chainsaw-felling of shrubs and small trees), 3) mechanical + burn, and 4) controls. We conducted mechanical treatments in winter 2001-2002 and prescribed burns in spring 2003. Tall shrub cover was substantially reduced in all treatments compared to controls. Tree mortality and canopy openness was highest in the mechanical + burn treatment after burning, likely due to higher fuel loading and hotter burns; tree mortality increased with time. Many bird species did not detectably decrease or increase in response to treatments. Species richness, total bird density, and some species, including indigo buntings (Passerina cyanea) and eastern bluebirds (Sialia sialis), increased in the mechanical + burn treatment after a 1-year to 2-year delay; eastern woodpewees (Contopus virens) increased immediately after treatment. Hooded warblers (Wilsonia citrina), black-and-white warblers (Mniotilta varia), and worm-eating warblers (Helmitheros vermivorus) declined temporarily in some or all treatments, likely in response to understory and (or) leaf litter depth reductions. Densities of most species affected by treatments varied with shrub cover, tree or snag density, or leaf litter depth. High snag availability, open conditions, and a higher density of flying insects in the mechanical + burn treatment likely contributed to increased bird density and species richness. In our study, fuel reduction treatments that left the canopy intact, such as low-intensity prescribed fire or mechanical understory removal, had few detectable effects on breeding birds compared to the mechanical + burn treatment. High-intensity burning with heavy tree-kill, as occurred in our mechanical + burn treatment, can be used as a management tool to increase densities of birds associated with open habitat while retaining many forest and generalist species, but may have short-term adverse effects on some species that are associated with the ground- or shrub-strata for nesting and foraging. 相似文献
407.