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91.
辽东半岛旧石器研究可追溯至20世纪30年代, 但较大的进展则在70年代以后所取得。迄今为止, 包括以庙后山石器工业和营口金牛山人类化石为代表的旧石器早期、以海城小孤山下层石器工业为代表的旧石器中期和以海城小孤山中层石器工业、骨角制品和前阳人类化石为代表的旧石器晚期组成的辽东旧石器文化发展序列已经初步建立起来。从古生态环境和石器技术、类型学而言, 辽东半岛旧石器文化和华北同期文化存在密切的联系。  相似文献   
92.
Distribution of Exotic Plants along Roads in a Peninsular Nature Reserve   总被引:3,自引:0,他引:3  
To examine the influence of roads on the spread of invasive exotic plants, we studied six species on a peninsular nature reserve. Three species were noxious invasives that we believed to be actively spreading; one of these (goatgrass, Aegilops triuncialis) was a major problem weed that recently invaded the reserve. The other three were ubiquitous and long-established exotics. Based on the idea that roads act as corridors for the spread of weeds, we predicted that the abundances of the three noxious invasives would decline along the roads from the base to the tip of the peninsula, while the abundances of three long-established species would not. However, the only species to show a base-to-tip decline in abundance along the peninsula was a long-established species (oat grass, Avena fatua), and a field experiment showed that habitat suitability could explain this pattern. We did find that the abundance of the invasive A. triuncialis declined with increasing distances from the edges of roads, suggesting that roads act as sources of weed propagules into adjacent grasslands. Our results add support to the idea that roads act as disturbances that promote invasive species, but not to the concept that roads act as corridors for the flow of invasive propagules into new landscapes.  相似文献   
93.
94.
The Mediterranean basin is an area of high diversity and endemicity, but the age and origin of its fauna are still largely unknown. Here we use species-level phylogenies based on approximately 1300 base pairs of the genes 16S rRNA and cytochrome oxidase I to establish the relationships of 27 of the 34 endemic Iberian species of diving beetles in the family Dytiscidae, and to investigate their level of divergence. Using a molecular clock approach, 18-19 of these species were estimated to be of Pleistocene origin, with four to six of them from the Late Pleistocene ( approximately 100 000 years). A second, lower speciation frequency peak was assigned to Late Miocene or Early Pliocene. Analysis of the distributional ranges showed that endemic species placed in the tip nodes of the trees are significantly more likely to be allopatric with their sisters than endemic species at lower node levels. Allopatric sister species are also significantly younger than sympatric clades, in agreement with an allopatric mode of speciation and limited subsequent range movement. These results strongly suggest that for some taxa Iberian populations were isolated during the Pleistocene long enough to speciate, and apparently did not expand their ranges to recolonize areas north of the Pyrenees. This is in contradiction to observations from fossil beetles in areas further north, which document large range movements associated with the Pleistocene glacial cycles hypothesized to suppress population isolation and allopatric speciation.  相似文献   
95.
The Mediterranean islands have a long history of human‐mediated introductions resulting in frequent replacements of their fauna and flora. Although these histories are sometimes well documented or may be inferred from paleontological studies, the use of phylogenetic and population genetic reconstruction methods provides a complementary perspective for answering questions related to the history of insular species. In the present study, we infer the colonization history of Mallorca (Balearic Islands) by the European rabbit (Oryctolagus cuniculus) and the Iberian hare (Lepus granatensis) using sequence variation of the mitochondrial DNA control region from continental and insular specimens (total of 489 sequences). Additionally, the taxonomic identity of Mallorcan L. granatensis was confirmed using a diagnostic nuclear marker. For both Mallorcan rabbits and hares, genetic diversity was comparable to the continental populations, suggesting the introduction of multiple lineages. Two Mallorcan haplogroups were found in hares, which likely correspond to two introduction events. Rabbits from Mallorca were identified as belonging to the subspecies Oryctolagus cuniculus cuniculus, and may have been originated both from Iberian and French populations. The molecular estimates of the timing of the colonization events of the Mallorcan lagomorphs are consistent with human‐mediated introductions by early settlers on the islands. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 748–760.  相似文献   
96.
Despite some populations of European wildcat Felis silvestris in central Europe are stable or increasing, the Iberian subpopulation is in decline and is listed as 'vulnerable'. In Portugal, little is known about wildcat populations, making conservation policies extremely difficult to define. Furthermore, the secretive behaviour of these mammals, along with low population densities, make data collection complicated. Thus, it is crucial to develop efficient analytical tools to interpret existing data for this species. In this study, we determine the home-range size and environmental factors related to wildcat spatial ecology in a Mediterranean ecosystem using a combined analysis of habitat selection and maximum entropy (Maxent) modelling. Simultaneously, we test the feasibility of using radio-tracking locations to construct an ecologically meaningful distribution model. Six wildcats were captured and tracked. The average home-range size (MCP95) was 2.28 km2 for females and 13.71 km2 for one male. The Maxent model built from radio-tracking locations indicated that the abundance of the European rabbit Oryctolagus cuniculus and limited human disturbance were the most important correlates of wildcat presence. Habitat selection analysis revealed that wildcats tend to use scrubland areas significantly more than expected by chance. A mosaic of scrublands and agricultural areas, with a higher proportion of the former, benefits wildcat presence in the study area; however, species distribution is mainly constrained by availability of prey and resting sites. The Maxent model validation with camera-trapping data indicated that highly adequate model performance. This technique may prove useful for recovering small radio-tracking datasets as it provides a new alternative for handling data and maximizing the ecological information on a target population, which can then be used for conservation planning.  相似文献   
97.
The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods ( Echinogammarus sp.). There was ontogenetic variation in the diet, with small young-of-the-year (LF<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata , whereas larger fish shifted to a freshwater shrimp ( Atyaephyra desmaresti ), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.  相似文献   
98.
99.
Sequence variation of a fragment of the mitochondrial DNA encoding for the cytochrome b gene was used to reconstruct the phylogeography of the two species of bleaks occurring in Italy: the alborella Alburnus arborella in northern Italy and the vulturino Alburnus albidus in southern Italy. The study includes four populations of the alborella and 14 populations of the vulturino. A total of 57 haplotypes were identified; these could not be sorted into two reciprocally monophyletic clusters. Multiple phylogenetic methods and nested clade phylogeographical analysis consistently retrieved three well-supported clades, two of which contained both Northern and Southern Italian haplotypes. A third clade is limited to southern Italy. This clade is tentatively assigned to the vulturino. The placement in the same clade of northern and southern Italian haplotypes is explained in light of the introductions of fishes operated from northern to central and southern Italy. The origin of the vulturino dates back to the last two million years. This divergence time estimate identifies the Pleistocene confluences between adjacent river basins along the Adriatic slope of the Italian peninsula and their subsequent isolation as the cause that triggered the diversification of the genus in the area. The existence of a clade endemic to southern Italy supports the recognition of the area as a new peri-Mediterranean ichthyogeographic district, the borders of which correspond to the northern and southern edges of the vulturino range.  相似文献   
100.
Trace elements analysis, as an indicator of ancient diets, has been carried out to the human skeletal remains from the necropolis of RH5 and RH10 of Qurum (Sultanate of Oman, 3700–3200 B.C.). Soil samples from the inner part of the burials, shells, fish, turtles and herbivorous remains have been analyzed. Regarding the human bones, a first set (ribs) was related to 26 females and 41 males while a second set (femurs) was related to 22 females and 34 males. Four trace elements, among the most common indicators of diet, have been taken into consideration (barium, strontium, zinc and copper) for their stability to diagenetic effects. Manganese has been analyzed to determine the incidence of diagenesis. Data from the two sets of human bones show a narrower range of values for the femurs than for the the ribs, in agreement with a lower incidence of diagenesis in compact bones. A wider range of values from the animal samples show a higher incidence of diagenetic effects in these remains. Low levels of variability can be stressed for the soil samples. Post-mortem exchange could have more likely occurred in the outer parts of spongy bones, as manganese seems to show. The wide range of values from the ribs and, on the contrary, the narrow range from the femur indicate that an accurate choice of sample can reduce the effects of diagenesis. Regarding the alimentary habits of the groups from Qurum, the human samples (both males and females) show high rates of strontium, similar to the herbivorous. This could be associated to an aquatic diet. It is unlikely that the high levels of strontium could be linked to a high incidence of vegetables in the diet. Also archeological data seem to stress a prevalence of aquatic food in the diet. Not always do statistical analyses applied to groups with different anthropological or chronological characteristics give clear answers to the identification of ranges of values, but they have always been a valid support for the interpretation of data.  相似文献   
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