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排序方式: 共有175条查询结果,搜索用时 31 毫秒
171.
PATRICK K. DEVERS DEAN F. STAUFFER GARY W. NORMAN DAVE E. STEFFEN DARROCH M. WHITAKER JEFFREY D. SOLE TOM J. ALLEN STEVE L. BITTNER DAVID A. BUEHLER JOHN W. EDWARDS DANIEL E. FIGERT SCOTT T. FRIEDHOFF WILLIAM W. GIULIANO CRAIG A. HARPER WILLIAM K. IGO ROY L. KIRKPATRICK MICHAEL H. SEAMSTER HARRY A. SPIKER Jr. DAVID A. SWANSON BRIAN C. TEFFT 《野生动植物专论》2007,168(1):1-36
172.
173.
SUMMARY. 1. The immature stages of the craneflies Lipsothrix nigrilinea and L. fenderi are spent in galleries within decayed red alder ( Atntts rtibra ), in low order streams of the Pacific Northwest. L. fenderi also occurs in some coniferous wood and wood in semi-terrestrial sites at stream margins. Larvae of both species feed on the wood and are important degraders of this material.
2. The immature stages are briefly described and behaviour of the two species is compared.
3. L. nigrilinea has a predominantly biennial life cycle. It emerges from April to August in response to receding water level. The absence of this cue results in an extension of the life span to 3 or more years. The non-deterministic life cycle results in high variability of juvenile and adult weights.
4. L. fenderi is basically a biennial species, with a more synchronized autumn emergence. A portion of the population may emerge after 1 year if oviposition occurs early enough to allow autumnal growth of larvae or if growth is relatively rapid.
5. The extended life cycle of Lipsothrix spp. and the broad emergence of L. nigrilinea are concluded to be adaptations to a habitat/resource which is relatively stable and allows long-term association. 相似文献
2. The immature stages are briefly described and behaviour of the two species is compared.
3. L. nigrilinea has a predominantly biennial life cycle. It emerges from April to August in response to receding water level. The absence of this cue results in an extension of the life span to 3 or more years. The non-deterministic life cycle results in high variability of juvenile and adult weights.
4. L. fenderi is basically a biennial species, with a more synchronized autumn emergence. A portion of the population may emerge after 1 year if oviposition occurs early enough to allow autumnal growth of larvae or if growth is relatively rapid.
5. The extended life cycle of Lipsothrix spp. and the broad emergence of L. nigrilinea are concluded to be adaptations to a habitat/resource which is relatively stable and allows long-term association. 相似文献
174.
Transitions in cuticular composition across a hybrid zone: historical accident or environmental adaptation? 总被引:2,自引:0,他引:2
STUART H. BUCKLEY TOM TREGENZA ROGER K. BUTLIN 《Biological journal of the Linnean Society. Linnean Society of London》2003,78(2):193-201
Two subspecies of the grasshopper Chorthippus parallelus form a hybrid zone in the Pyrenees. Transitions across the zone, including changes in mating signals and reproductive isolation have been intensively studied. Cuticular pheromones have been identified as likely mate recognition signals. Since the major role of the cuticle is in waterproofing, environmental adaptation of cuticular composition has the interesting potential to generate assortative mating as an incidental by-product. We describe the pattern of variation in cuticular hydrocarbon blend in four transects through the hybrid zone. We find no evidence for a previously observed displaced cline in one blend component. There were differences between subspecies but these varied among transects and were small compared with variation between transects. We examined environmental variation within one transect and found a correlation between vegetation and cuticular composition, suggesting that environment influences the constitution of the cuticle, and hence natural selection may interact with mating signals in this species. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 193−201. 相似文献
175.
Comparisons were undertaken to investigate cost‐effective methods of implementing the enzyme‐linked immunosorbent assay (ELISA) for sporozoite determination in anophelines when large numbers require processing. Comparisons between ELISA plate reader and visual assessments were performed with Anopheles funestus and Anopheles gambiae s.l. (Diptera: Culicidae), as were comparisons between whole‐body mosquito samples, heads and thoraces, and abdomens alone. Rates obtained from pools of five or 10 mosquitoes were compared with those for individual mosquitoes, as were rates obtained using different sampling methods. A total of 41 792 An. funestus and 9431 An. gambiae s.l. collected in light traps, and 22 323 An. funestus and 6860 An. gambiae s.l. from exit collections were analysed. Visual assessments gave results similar to those of machine readings. Sporozoite rates were similar in both species, as were rates by collection method. The use of whole mosquitoes increased estimates of infection rate by 0.6%. Pool size did not affect infection rates of An. gambiae s.l., but rates were higher among individually tested An. funestus than among those tested in pools. For large‐scale surveys, the use of whole mosquitoes in pools of 10 mosquitoes, with correction for overestimation, and the noting of results according to a simple three‐stage visual assessment of positivity is the most cost‐effective approach and is sufficient to obtain reliable data for comparative purposes. 相似文献