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41.
This article documents the impact of site conditions and farming practices on the occurrence of rare and endangered weeds on arable land in the Czech Republic. A survey was conducted between 2006 and 2008 in winter cereals, spring cereals and wide‐row crops. The relationship between the occurrence of plants and explanatory factors was analysed using a multivariate analysis to calculate species frequencies in different types of farming, crops and altitudes. In total, 290 relevés were recorded, with a total number of 172 weed species. Nineteen weeds, classified as rare and endangered species according to the national Czech list, were identified in 106 relevés. The highest effect on the occurrence of rare and endangered weed species was observed for altitude. Almost half of the recorded endangered and rare species belonged to the thermophilous weed vegetation typical for cereals on basic soils. A higher occurrence of endangered species has been confirmed for organic farming, where the sum of frequencies was 4.5 times higher than in conventional farming. Field size was not included in our analyses, but could be a factor affecting weed assemblages. The highest frequency of rare species was recorded in spring cereals, followed by winter cereals and wide‐row crops. Higher numbers were identified within fields with higher weed coverage. Lower farming intensity and diversified farming systems at higher altitudes provided better conditions for the occurrence of rare species than intensively farmed lowlands. 相似文献
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Long term data to estimate population trends among species are generally lacking. However, Natural History Collections (NHCs) can provide such information, but may suffer from biases due to varying sampling effort. To analyze population trends and range-abundance dynamics of Swedish longhorn beetles (Coleoptera: Cerambycidae), we used collections of 108 species stretching over 100 years. We controlled for varying sampling effort by using the total number of database records as a reference for non-red-listed species. Because the general frequency of red-listed species increased over time, a separate estimate of sampling effort was used for that group. We observed large interspecific variation in population changes, from declines of 60% to several hundred percent increases. Most species showed stable or increasing ranges, whereas few seemed to decline in range. Among increasing species, rare species seemed to expand their range more than common species did, but this pattern was not observed in declining species. Historically, rare species did not seem to be at larger risk of local extinction, and population declines were mostly due to lower population density and not loss of sub-populations. We also evaluated the species’ declines under IUCN red-list criterion A, and four currently not red-listed species meet the suggested threshold for Near Threatened (NT). The results also suggested that species’ declines may be overlooked if estimated only from changes in species range. 相似文献
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Inttxiducti()nWaterbeetlesoftenrefert()apalpic()n1ia,co11stitutcaratllerlargegroupofcolcopter:l,distrit,utedi11allparts()ftIleworld.TI1eyshowagrcatlnorpl1ologicaIdivcrsityal1datremel1tIousrangeil1size.Traditiollalwaterquality11lol1it()ri11gco11sists()fdippi11gwatersampIesoutofstreallls,carryil1gtllesesaIl1plcsbacktolaboratory,andtl1ensul)jecth1gtlle11lt<)aseriesofcllemicalallalyses'ByIookingattI1eco11ce11tratio11sofvariouspolIuta11ts,scie11[istsl1oPC[()makeprc(Iictiol1saboutl1owda11gerous… 相似文献
46.
Thirty-five species of Cleridae and Thanerocleridae are recorded from Israel, 15 for the first time. General and local distribution,
phenology, prey insect and their host plants are listed. 相似文献
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本文记述了甘肃省草地主要害虫91种,其中直翅目63种,同翅目16种,膜翅目2种,缨翅目5种,双翅目4种,蜱蟥目1种。 相似文献
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An attempt is made toward the application of IUCN criteria and Red List Categories to agricultural and horticultural plants (excluding ornamentals). The main sources for this study were Mansfeld’s Encyclopedia (2001) and the IUCN Red List of threatened plants (2001). About 200 threatened cultivated plants are considered and presented in the respective lists, among them completely extinct crop plants such as Anacyclus officinarum and Bromus mango. The information available about neglected and underutilized crop plants still lags behind that about wild plants, especially at the species level, and more studies are required. On the other hand studies of major crops at the infraspecific level, are very advanced and can serve as models for investigating the wild ones. 相似文献
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Efficiency in biomonitoring studies is essential to maximize return (i.e. useful data) for investment (e.g. time, training, personnel). Here, we test several options for reducing data resolution when streamlining monitoring protocols, and use the results as a framework to discuss the costs and benefits of decreasing information when sampling intertidal assemblages. Specifically, we ask; (1) Is it necessary to collect species abundance data, or is species presence-absence information sufficient to differentiate sites? (2) Is it necessary to sample organismal abundance at the species-level or is coarser (higher taxon or functional group) resolution sufficient to resolve patterns of difference in intertidal community structure? and (3) How general are these patterns across different oceanic regions? We answer these questions using data from Northeast Atlantic, Northwest Atlantic, Northeast Pacific, and Southwest Pacific intertidal monitoring studies. Results show that compared to species-level sampling, genus-level sampling requires knowledge of 25% fewer taxa, but results in only a 5% difference in the ability to discern between-sample similarities. Likewise, family-level sampling involves 50% fewer taxa, and is accompanied by only an 8% difference in between-sample similarities. Species lists and functional groups were variable in performance, working well for some regions, and poorly for others. These findings will assist in the selection of monitoring protocols with the potential for increased geographic scope and temporal frequency of sampling, resulting in longer time series of data collection, and a reduction in the required taxonomic skills for individuals involved in scientifically useful biomonitoring programs. 相似文献