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461.
卧龙自然保护区亚高山暗针叶林树种更新研究 总被引:3,自引:0,他引:3
在卧龙亚高山暗针叶林中选取有代表性的18个林窗斑块以及对照的林下样方进行群落学调查,记录乔木树种和灌木树种的相关数量特征。按照树种在林窗内外的重要值差异结合树种本身生态学特性将群落中出现的乔木层树种划分为先锋组和耐荫组两类生态种组。林窗内外乔木树种的组成明显不同,两类生态种组树种幼苗在林窗与林下环境中的更新表现出差别,这与树种本身的生态学特性以及所处林窗的环境有关,同时亚高山暗针叶林中灌木层优势种小径竹的生长对树种更新方式也产生一定的影响。 相似文献
462.
Liepelt S Sperisen C Deguilloux MF Petit RJ Kissling R Spencer M de Beaulieu JL Taberlet P Gielly L Ziegenhagen B 《Annals of botany》2006,98(5):1107-1111
BACKGROUND: The reconstruction of biological processes and human activities during the last glacial cycle relies mainly on data from biological remains. Highly abundant tissues, such as wood, are candidates for a genetic analysis of past populations. While well-authenticated DNA has now been recovered from various fossil remains, the final 'proof' is still missing for wood, despite some promising studies. SCOPE: The goal of this study was to determine if ancient wood can be analysed routinely in studies of archaeology and palaeogenetics. An experiment was designed which included blind testing, independent replicates, extensive contamination controls and rigorous statistical tests. Ten samples of ancient wood from major European forest tree genera were analysed with plastid DNA markers. CONCLUSIONS: Authentic DNA was retrieved from wood samples up to 1,000 years of age. A new tool for real-time vegetation history and archaeology is ready to use. 相似文献
463.
Simone Hofstetter Willy Tinner Verushka Valsecchi Gabriele Carraro Marco Conedera 《Vegetation History and Archaeobotany》2006,15(2):87-98
Fundamental uncertainties exist in the study region about the former lowland vegetation at local scales. All existing palaeoecological
results are derived from sediments of medium- to large-sized sites (8–5000 ha), which are thought to record mainly regional
vegetation in their pollen content. Therefore the very small mire at Balladrum (0.05 ha) was analysed for pollen, plant-macrofossils,
and charcoal and the results compared with those of previous studies in the same region. Common regional signals were detected,
but also new insights for the tree species Pinus cembra (L.), Abies alba (Mill.) and Castanea sativa (Mill.). Our palaeobotanical data reveal the local dominance of the timberline species P. cembra during the Lateglacial (16500–14250 cal b.p.) at low-altitudes. For A. alba an early presence in the area is suggested by pollen data, corroborating previous high-altitudinal studies indicating the
presence of glacial refugia in the region. Occasional findings of C. sativa pollen throughout the Holocene may indicate the local but very rare presence of this species in the Insubrian Southern Alps,
in contrast to the conventional opinion that C. sativa was introduced during the Roman Period. Altogether the results confirm the need of multiproxy palaeobotanical records from
basins of variable size to assess the past composition of vegetation more accurately.
Communicated by F. Bittmann 相似文献
464.
Rafat Podlaski 《植被学杂志》2008,19(2):173-182
Question: The mosaic‐cycle concept of forest dynamics dominates in Central Europe. According to this concept intermediate‐scale disturbances only accelerate the forest break‐up under existing cycles of forest development. Is such an approach correct, or should new developmental cycles be elaborated for intermediate‐scale disturbances? Location: Near‐natural Abies alba ‐ Fagus sylvatica forests in the ?wiétokrzyski National Park in Central Poland. In these forests intermediate‐scale disturbances occurred between 1970 and 1990. Methods: Data were collected twice in areas surrounding 212 permanent sample points (in 1994 and 2004). Two increment cores were taken from 259 sample Abies trees. The effect of intermediate‐scale disturbances on radial increment of Abies was assessed. Probabilities of stand transition during a 10‐year period between individual stages and phases of development of the mixed forest were calculated. The development stages and phases were arranged into hypothetical succession series of successive changes. Results: In 1994 70 stands and in 2004, 47 stands representing stages and phases containing the older generation formed by trees > 100–150 years were found. Also, in 1994 142 and in 2004, 165 stands representing stages and phases containing the younger generations only, formed by trees < 100‐150 years, were recorded. Stages and phases containing only younger generations do not occur in the existing forest development cycle which does not consider the influence of intermediate‐scale disturbances separately. Two developmental cycles, which take into account the presence of the older generation and the younger generations only (under conditions of the occurrence of intermediate‐scale disturbances), are proposed. Conclusion: The mosaic‐cycle concept of forest dynamics can be used to analyse the dynamics of Central European near‐natural mixed‐species forests, but new developmental cycles should be elaborated for intermediate‐scale disturbances. 相似文献
465.
In subalpine forests near the forest limit on Mt. Fuji in central Japan, slush avalanches occasionally destroy forest-floor
vegetation through an influx of volcanic gravel from bare upper sites. The vegetation structure of Larix kaempferi–Abies veitchii forests near and distant from avalanche paths was investigated to determine the effects of forest-floor disturbance on successional
processes. The Larix population in a forest near an avalanche path, where there had been signs of forest-floor disturbance
by avalanches, had a discontinuous age structure with three age groups, indicating that Larix seedlings established under the Larix canopy after the forest-floor disturbance. In contrast, the Larix population in a forest distant from avalanche paths, where there had been no forest-floor disturbance, had a continuous age
structure, with no plants younger than the 90-year-old trees, indicating that this population had established on bare ground
over a long period. These data suggest that the primary requirement for the regeneration of L. kaempferi on the forest floor is a mineral substrate. Conversely, A. veitchii had a continuous age structure in both forests. However, forest-floor disturbances by avalanche(s) may exclude A. veitchii from the forest because A. veitchii is very sensitive to scoria deposition. In conclusion, forest-floor disturbance by avalanche(s) provides L. kaempferi with an opportunity to establish on the forest floor, resulting in the maintenance of Larix forests alongside avalanche paths in the upper subalpine area on Mt. Fuji. 相似文献
466.
Petrussa E Bertolini A Krajnáková J Casolo V Macrì F Vianello A 《Plant cell reports》2008,27(1):137-146
A valuable method to isolate and purify mitochondria from embryonal masses of two coniferous species (Picea abies [L.] Karst. and Abies cephalonica Loud.) is described. Crude mitochondria from both species were shown to be intact, oxygen consuming (with malate plus glutammate,
succinate and NADH as substrates) and well coupled (respiratory control ratio ca. 4). The oxidation of the substrates was
only partially KCN-insensitive (alternative oxidase) in some cases. However, these fractions were contaminated by membranes
(e.g. plasmalemma, tonoplast, Golgi and endoplasmic reticulum). After purification by a discontinuous Percoll gradient (18,
23, 40%, v/v), three mitochondrial populations were separated. The 0/18 interface fraction was composed mainly of broken and
uncoupled mitochondria, while the other two (18/23 and 23/40 interface fractions) contained intact and coupled mitochondria,
but only 23/40 interface fraction revealed to be better purified starting from both coniferous embryonal masses. In the latter
purified fraction, the presence of a cyclosporin A-sensitive KATP+ channel was demonstrated. These findings were discussed in the light of the potential use of these mitochondrial fractions
in bioenergetic studies, or in the involvement of these organelles to stress response in conifers. 相似文献
467.
468.
Aims We investigated the treeline dynamics of two environmentally contrasting areas in the Nepalese Himalaya to address the following questions: (i) Does the timing of establishment of the current treeline differ between the two study areas, and can area-specific treeline developments be identified? (ii) Do recruitment patterns and height growth indicate recent climate-driven treeline advance, following the general prediction for the central Himalayan region, in the two study areas?Methods A dry-climate treeline dominated by Pinus wallichiana and a mesic-climate treeline with Abies spectabilis were selected for study. In each area, we sampled the size and age structure of the study species along three elevational transects (20-m wide) from the forest line to the tree species line crossing the treeline. We also sampled treeline trees from within and outside transects to reconstruct past treeline establishment dynamics.Important findings Despite differences in moisture regimes, tree species and recent climate trends, our two study areas showed very similar treeline dynamics over the past six decades. In both areas, the recruitment of treeline trees indicates stationary treelines over the past six decades with the current treelines being dominated by trees that were established around 1990. The mesic area has experienced an overall climatic warming trend, and the stationary Abies treeline is hypothesized to be regulated by non-climatic factors, notably grazing. The dry area has not experienced warming but increased climatic variability and some very cool summers in the recent decades may explain the stationary to weakly receding Pinus treeline, which appears more climatically controlled with decreased recruitment over the past decades and decreased growth towards higher elevations. In both areas, there is a potential for treeline advance, depending on future land use and climate change. Our results highlight the importance of conducting treeline ecotone analyses for several sites or areas, and considering both climatic and non-climatic drivers of the treeline dynamics within each of these areas, for understanding regional treeline dynamics. 相似文献
469.
Abstract. The growth and survival of coniferous trees (particularly Abies sachalinensis) and broad-leaved trees (particularly Quercus crispula) were followed over a 15-yr period in a 15.5-ha area in a northern mixed forest in Japan, and the coexistence of the two groups was simulated by a density-dependent projection matrix model. The density-dependent model assumes that the density effect of mother trees due to one-sided competition for light on smaller-sized tree regulates the demographic functions. The mother tree densities of conifers and broad-leaved trees have stronger negative effects on the recruitment and survival of seedlings of their own group than of the other group. These results support the idea of reciprocal replacement for conifer and broad-leaved trees. Simulations using the density-dependent model showed that the two groups will co-exist within a particular range of recruitment rates. However, the density of both groups did not affect the growth rate of any tree, and equilibrium DBH-distributions from density-dependent matrices were quite different from present distributions both for conifers and broad-leaved trees. On the other hand, equilibrium DBH-distributions of conifer and broad-leaved trees from density-independent matrices were quite distinct from each other, reflecting different survivorship curves of the two dominants. These results suggest that density-dependent processes are not so important for shaping population structures in this northern mixed forest. 相似文献
470.
Jens?I.?FindEmail author Julia?A.?Charity Lynette?J.?Grace Michel?M.?M.?H.?Kristensen Peter?Krogstrup Christian?Walter 《In vitro cellular & developmental biology. Plant》2005,41(6):725-730
Summary Stable genetic transformation of embryogenic cultures of Abies nordmanniana (Nordmann fir or Caucasian fir) was achieved using the Biolistic? transformation technology, followed by regeneration of transgenic plants. Selection of the transgenic tissue was based on
the antibiotic resistance induced by the neomycin phosphotransferase II gene (npt II), in combination with the antibiotic geneticin. Six transclones were recovered from a total of 215 bombardments. Expression
of the β-glucuronidase gene (uidA) was confirmed by histochemical analysis, and expression of npt II was verified by quantification of NPTII protein by enzyme linked immunosorbent assay (ELISA). Both genes were still expressed
in the embryogenic tissue after 5 yr of in vitro culture and in mature somatic embryos and plants produced from these cultures. The integration of npt II was confirmed by Southern hybridization in embryogenic tissue after 5 yr of culture. After 5 yr of growth, uidA was still expressed in needles from the transformed trees. 相似文献