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11.
Georg Miehe 《Plant Ecology》1988,79(1-2):21-32
The vegetation of Mt Everest is described by means of the dominant plant formations and characteristic features of biotopes. Climatic data givenin connection with weather observations show evidence that the extreme asymmetry of the altitudinal vegetation belt on the south and north slope is induced by heavy rainfall on the south slope and the desiccating effect of the Himalaya föhn in the valleys of the north slope. Biotope shift from hypsozonal distribution on the south slope to extrazonal distribution on the north slope is described, the patterns of the actual timber line are discussed in order to reconstruct the natural upper forest limit, and regressive plant successions during the last 400 years of man's impact are summarized. The dominant vegetation pattern of the alpine belt is compared with that in the European Alps. On the arid north slope alpine steppe communities occur up to 5 500 m. The highest altitudinal vegetation belt and the highest plant communities at 5 960 m are dominated by periglacial processes. The highest records of flowering plants (6 100/6 200 m) and lichens (7 400 m) are discussed in light of the present knowledge on high-altitude vegetation ecology. 相似文献
12.
David R. McConville Dennis D. Anderson Rory N. Vosé Daniel B. Wilcox 《Hydrobiologia》1986,136(1):77-83
Species composition, relative abundance, distribution and physical habitat associations of submerged aquatic macrophytes in the main channel border (MCB) habitat of Pool 5A, Upper Mississippi River (UMR) were investigated during the summers of 1980 and 1983. The submerged aquatic macrophytes in Pool .5A MCB were a small and stable component of the river ecosystem. Submerged plants occurred primarily in small, monospecific clumps. Clumps in close proximity to each other formed plant patches. Plant patches were stable in location and number between 1980 and 1983; 82.5% of the patches first observed in 1980 were present in 1983. Submerged macrophytes covered about 10–12 ha of the 201 ha MCB in Pool 5A. Submerged plants were most common in the lower two-thirds of the pool. Ten species of aquatic macrophytes occurred on rock channel-training structures and eleven occurred on non-rock substrates in the MCB. The most common submerged plants, in order of abundance, were Vallisneria americana Michx., Heteranthra dubia Jacq., Potamogeton pectinatus L., Ceratophyllum demersum L. and Potamogeton americanus C. & S. 相似文献
13.
14.
DIANE KERMACK 《Zoological Journal of the Linnean Society》1984,82(1-2):101-117
New prosauropod material from a cave filling of Upper Triassic/Lower Jurassic age in Pant-y-ffynnon Quarry, South Wales, is described. The Panl-y-ffynnon fauna also includes thecodont, coelurosaur, crocodile and lepidosaur material.
Most of the prosauropod skeleton is represented. An almost complete but disarticulated skull is preserved. The skull and whole skeleton of the prosauropod are reconstructed. Evidence from the size and relative proportions of the bones, also the state of ossification, indicates that the prosauropod remains represent juveniles.
The level of the jaw articulation combined with the form of the teeth would suggest that the Pant-y-ffynnon prosauropod was omnivorous.
The Pant-y-ffynnon prosauropod resembles closely the much less complete Durdham Down (Bristol) remains of Thecodonlosaurus antiquus Morris; the Welsh material could well be juveniles of that species. Here the Pant-y-ffynnon material is ascribed to Thecodonlosaurus sp.
The mode of deposition of the fossil material is discussed, to account for the deposit containing only juveniles of the prosauropod. 相似文献
Most of the prosauropod skeleton is represented. An almost complete but disarticulated skull is preserved. The skull and whole skeleton of the prosauropod are reconstructed. Evidence from the size and relative proportions of the bones, also the state of ossification, indicates that the prosauropod remains represent juveniles.
The level of the jaw articulation combined with the form of the teeth would suggest that the Pant-y-ffynnon prosauropod was omnivorous.
The Pant-y-ffynnon prosauropod resembles closely the much less complete Durdham Down (Bristol) remains of Thecodonlosaurus antiquus Morris; the Welsh material could well be juveniles of that species. Here the Pant-y-ffynnon material is ascribed to Thecodonlosaurus sp.
The mode of deposition of the fossil material is discussed, to account for the deposit containing only juveniles of the prosauropod. 相似文献
15.
山东莒南发现的石制品 总被引:2,自引:1,他引:1
本文报道的128件人工石制品分别采自山东莒南县的石莲子乡烟敦岭和扁山乡九顶莲花山两个地点。石制品常见类型有边刮器,端刮器和砍斫器等,另有少量的雕刻器和尖状器,内含典型细石器。就石制品的组合及工艺水平而言,其时代可能属于旧石器时代末期。 相似文献
16.
17.
Ken'ichi Saiki 《American journal of botany》1996,83(12):1630-1636
Pinus mutoi is described as a new species on the basis of a permineralized seed cone from the Upper Cretaceous of Hokkaido, Japan. The cone is at least 20 cm long and up to 6 cm in diameter, consisting of a cone axis and numerous cone-scale complexes that are arranged helically around the axis. Two winged seeds are borne on the adaxial surface of each ovuliferous scale. Each complex receives a single trace from the vascular cylinder of the cone axis. In the scale base, all the resin canals occur abaxially to the vascular strand. The spatulate bract of the fossil is unique to the specimen among the cones of both living and fossil Pinus. The central umbo, broad sclerotic cortex of cone axis, and absence of serotinous features of the fossil cone suggest affinity with the subsection Sylvestres of the section Pinus, subgenus Pinus. This is the first record of permineralized preserved Pinus cone from the Cretaceous of Eastern Eurasia. 相似文献
18.
Dr. Karl Kleemann 《Facies》1994,30(1):151-153
Summary The mytilid genusLithophaga is confirmed for the Upper Triassic. The Rhaetian specimen, boring the dead part of coral, is compared with the SenonianL. alpina, which is associated with live coral. 相似文献
19.
Dr. Arthur K. Satterley 《Facies》1994,30(1):119-149
Summary The Upper Triassic Dachsteinkalk of the Hochk?nig Massif, situated 50 km south of Salzburg in the Northern Calcareous Alps,
corresponds to a platform margin reef complex of exceptional thickness. The platform interior limestones form equally thick
sequences of the well known cyclic Lofer facies. Sedimentation in the reef complex was not so strongly controlled by low-amplitude
sea-level oscillations as was the Lofer facies. The westernmost of the 8 facies of the reef complex is an oncolite-dominated
lagoon, in which wave-resistant stromatolite mounds with a relief of a few metres were periodically developed. The transition
to the central reef area is accomplished across the back-reef facies. In the back-reef facies patch reefs and calcisponges
appear. The proportion of coarse bioclastic sediment increases rapidly over a few hundred metres before the central reef area
is encountered. The central reef area consists of relatively widely spaced small patch reefs that did not develop wave-resistant
reef framework structures. The bulk of the sediment in the central reef area is coarse bioclastic material, provided by the
dense growth of reef organisms and the wave-induced disintegration of patch reefs. Collapse of the reef margin is recorded
by the supply of large blocks of patch reef material to the upper reef slope. Additionally, coarse, loose bioclastic debris
was supplied to the upper reef slope and this was incorporated into debris flows on the reef slope and turbidites found at
the base of the slope and in the off-reef facies. Partially lithified packstones and wackestones of the lower to middle reef
slope were modified by mass movement to form breccia and rudstone sheets. The latter reach out hundreds of metres into the
off-reef facies environment. A reef profile is presented which was derived by the restoration of strike and dip information.
In conjunction with constraints imposed by sedimentary facies related to slope processes, the angle of slope in the reef margin
area ranged from 11° to 5°, forming a concave (dished downwards) slope. Water depth estimations require that the central reef
area did not develop in water of less than 10 metres depth. At the reef margin water depths were about 30 metres, at the base
of the reef slope 200 metres and deepening in the off-reef facies to 250 metres. While previous work on reef complexes from
this type of setting suggests growth in a heavily storm-dominated environment, the present author finds little evidence for
the storm generation of the fore reef breccias, although there is good evidence for storm-influenced sedimentation and reworking
in the central reef area.
Post-depositional processes were characterised by continued slope processes causing brecciation and hydraulic injection of
red internal sediments downwards into the reef slope and off-reef limestones. Hydrothermal circulation caused a number of
phases of post-depositional (diagenetic) brecciation. There appears not to have been an important period of emergence at the
Triassic/Jurassic boundary. 相似文献
20.
Largepterosaurwithamaximumwingspanofmorethan5metres.Theskullislowerandlonger,withoutmiddlecrestorsupraoccipita1crest.ThenasaIandpre-orbita1fenestraareconfluentcompletely,andoccupyaboutha1foftheskulI1ength.Thetoothlessbeakisslenderandpointed.The1ongneckiscomposedbyse-venslendercervicalvertebrae.Thenotariumconsistsofsixco-ossifiedanteriordorsalvertebrae-ThetaiIisextremlyshort.lthassixpairsof"A"shapegastralia.Theanteriorlimbsarestrong;thehumerusarethickandshort;thewing-metacarpalbonearelongert… 相似文献