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1.
Five (or so) challenges for species distribution modelling   总被引:24,自引:3,他引:21  
Species distribution modelling is central to both fundamental and applied research in biogeography. Despite widespread use of models, there are still important conceptual ambiguities as well as biotic and algorithmic uncertainties that need to be investigated in order to increase confidence in model results. We identify and discuss five areas of enquiry that are of high importance for species distribution modelling: (1) clarification of the niche concept; (2) improved designs for sampling data for building models; (3) improved parameterization; (4) improved model selection and predictor contribution; and (5) improved model evaluation. The challenges discussed in this essay do not preclude the need for developments of other areas of research in this field. However, they are critical for allowing the science of species distribution modelling to move forward.  相似文献
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云南西部中-晚泥盆世硅质岩相地层及其放射虫动物群   总被引:12,自引:3,他引:9  
本文论述的中晚泥盆世放射虫产于滇西阿里、回库、南雅、里拉、太尔市、晒经坡和长育村等地的硅质岩中,包括15属18种10相似种8未定种,其中有3新种。共发现3个泥盆纪放射虫动物群,它们是Eoalbaillella lilaensis动物群(D2);Helenifore laticlavium动物群(D^1 3);Holoeciscus foremanae动物群(D^23)。文章讨论了3个问题①Eoal  相似文献
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内蒙古草原繁殖鸟类群聚组成之比较   总被引:9,自引:2,他引:7       下载免费PDF全文
颜重威  邢莲莲  杨贵生 《生态学报》2000,20(6):992-1001
利用 5月份温带草原鸟类繁殖期 ,在荒漠草原、草原、湿地、沙地和山地等植被 ,选取 1 1个面积 1 0 0 hm2 ( 50 0 m×2 0 0 0 m)同样大小的样区 ,由 3人各隔 1 50 m作平行的穿越线调查 ,并记录所见鸟类的种类与数量。同时 ,也在每一样区任取面积 1 m2 之植被样方 ,记载样方内植物的种类、垂直高度、覆盖度和植物鲜重。调查结果显示草原繁殖鸟类的种类不多 ,在无树的荒漠草原植被是 4~ 6种 ,草原植被在 5~ 8种之间 ,湿地植被 1 5种 ;在有树的沙地植被是 9~ 1 2种 ,山地植被 6种。鸟种多样性和丰富度指数不大 ,由大而小依序是沙地植被、湿地植被、山地植被、草原植被、荒漠草原植被 ;密度也不高 ,由大而小依序是无树草原的湿地植被、草原植被、荒漠草原植被 ,而后是有树草原的沙地植被、山地植被。鸟类食性分布方面 ,荒漠草原和草原植被以食杂性鸟类为优势 ;湿地植被以食虫性鸟类为多 ;沙地植被以食杂与食肉性鸟类为胜 ;山地植被以食虫和食杂性鸟类较多 ,并增加一些食肉性鸟类。  相似文献
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Rapid anthropogenic climate change is already affecting species distributions and ecosystem functioning worldwide. We applied niche-based models to analyse the impact of climate change on tree species and functional diversity in Europe. Present-day climate was used to predict the distributions of 122 tree species from different functional types (FT). We then explored projections of future distributions under one climate scenario for 2080, considering two alternative dispersal assumptions: no dispersal and unlimited dispersal. The species-rich broadleaved deciduous group appeared to play a key role in the future of different European regions. Temperate areas were projected to lose both species richness and functional diversity due to the loss of broadleaved deciduous trees. These were projected to migrate to boreal forests, thereby increasing their species richness and functional diversity. Atlantic areas provided an intermediate case, with a predicted reduction in the numbers of species and occasional predicted gains in functional diversity. This resulted from a loss in species within the broadleaved deciduous FT, but overall maintenance of the group. Our results illustrate the fact that both species-specific predictions and functional patterns should be examined separately in order to assess the impacts of climate change on biodiversity and gain insights into future ecosystem functioning.  相似文献
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Ensemble forecasting of species distributions   总被引:5,自引:0,他引:5  
Concern over implications of climate change for biodiversity has led to the use of bioclimatic models to forecast the range shifts of species under future climate-change scenarios. Recent studies have demonstrated that projections by alternative models can be so variable as to compromise their usefulness for guiding policy decisions. Here, we advocate the use of multiple models within an ensemble forecasting framework and describe alternative approaches to the analysis of bioclimatic ensembles, including bounding box, consensus and probabilistic techniques. We argue that, although improved accuracy can be delivered through the traditional tasks of trying to build better models with improved data, more robust forecasts can also be achieved if ensemble forecasts are produced and analysed appropriately.  相似文献
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Composition and distributional patterns in arctic rotifers   总被引:4,自引:4,他引:0  
Based on collections of rotifers from 212 localities in arctic North America, the patterns of distribution and composition are evaluated. An attempt is made to discern the dominant components of the rotifer community in arctic habitats. One hundred and sixty five species of rotifers are reported, three of which represent new records for North America. With increasing latitude and decreasing summer temperatures, a decline in species richness and change in species composition is observed. Some rotifers that previously were not adequately described are redescribed and illustrated. The significance of the dispersal capacity of rotifers in the arctic is discussed.  相似文献
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Species delimitation in the Hwamei Garrulax canorus   总被引:4,自引:1,他引:3  
Due to the male's elaborate songs, the Hwamei Garrulax canorus is the most popular caged bird in the global Chinese community. Three allopatric Hwamei subspecies have been described: G. c. canorus in central and southern China and northern Indochina, G. c. owstoni from Hainan and G. c. taewanus from Taiwan. We sequenced the entire mitochondrial cytochrome b gene to reconstruct the molecular intraspecific phylogeny of the Hwamei. Molecular phylogenetic trees indicated that individuals of the three subspecies formed three monophyletic clades with high bootstrap support (> 95%). The basal clade was G. c. taewanus . According to a conventional molecular clock (2% divergence per million years), G. c. taewanus split from the other Hwamei taxa around 1.5 million years ago, and G. c. owstoni diverged from G. c. canorus around 0.6 million years ago. Considering the periodic connection between the Asian mainland and nearby continental islands during the glacial periods, habitat vicariance may have played a more important role than geographical vicariance in facilitating the differentiation of these taxa. Molecular diagnosability, population integrity, and concordance between the population ranges and the topology of the phylogenetic tree suggested that the Hwamei should be delimited into at least two full species: G. canorus and G. taewanus . Our work represents one of the first attempts to re-evaluate the intraspecific systematics for an eastern Asian bird species using molecular data.  相似文献
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