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201.
202.
Dodonov Pavel Harper Karen A. de Oliveira Xavier Rafael Silva Matos Dalva M. 《Plant Ecology》2019,220(7-8):741-756
Plant Ecology - Invasive grasses are an important threat in tropical savannas and grasslands and may be affected by natural and anthropogenic features of the environment. They may affect native... 相似文献
203.
Plant Ecology - Few studies have quantified changes in riparian and adjacent forest across landscape units. In this study, the composition and structure of riparian and adjacent forest were... 相似文献
204.
Dánae Cabrera-Toledo Jorge González-Astorga Andrew P. Vovides Alejandro Casas Ofelia Vargas-Ponce Pablo Carrillo-Reyes Janet Nolasco-Soto Ernesto Vega 《Population Ecology》2019,61(1):62-73
Ecological and microevolutionary perspectives were used to investigate signs of background extinction in two endemic species. We studied relict populations of the cycad Dioon caputoi, contrasting its population structure and neighborhood size with those of Dioon planifolium as a demographically healthier reference population. Population dynamics analysis was performed on two populations of D. caputoi through Integral Projection Models and genetic neighborhoods compared between species through 172 Inter Simple Sequence Repeat loci performed in one population of each of the two study species. The D. caputoi populations mostly comprised adult plants, while D. planifolium presented mainly juvenile individuals. Dioon caputoi showed equilibrium in population growth (i.e., λ ≈ 1), with low recruitment, and its genetic neighborhood revealed highly related individuals in a unique distance class (rij = 0.407, 33 m). A contrasting pattern was found in D. planifolium, which showed higher relatedness in the first distance class (rij = 0.543, 5 m), gradually decreasing to 20 m. The discrepancies between the two species reflect different strategies of persistence. Dioon caputoi conserves a relict dynamics with signs of a multigenerational, attritional loss of reproductive fitness, while D. planifolium does not. This study furthers our understanding of the background extinction process and the information will thus contribute to the management and conservation of this endangered species. 相似文献
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206.
Denise C.O.F. Valdetaro Thomas C. Harrington Leonardo S.S. Oliveira Lúcio M.S. Guimarães Douglas L. McNew Lucas V.A. Pimenta Rivadalve C. Gonçalves Daniel A. Schurt Acelino C. Alfenas 《Fungal biology》2019,123(2):170-182
Ceratocystis fimbriata Ellis & Halsted recently was recorded causing seed and seedling blight on Carapa guianensis Aubl. (andiroba), a tree species native to the Amazon Rainforest and prized for its valuable timber and medicinal seed oil. C. fimbriata more commonly causes wilt type diseases in woody hosts, especially on non-native host trees. However, on andiroba the disease occurs on seedlings and seeds, affecting the species regeneration. We studied 73 isolates of C. fimbriata on andiroba from three regions of the Amazon Basin to see if they represented natural or introduced populations. Analysis of ITS rDNA sequences and phylogenetic analysis of mating type genes revealed new haplotypes of C. fimbriata from the Latin American Clade that were closely related to other Brazilian populations of the fungus. In mating experiments, andiroba isolates were inter-fertile with tester strains of C. fimbriata from Brazil and elsewhere, confirming that they belong to a single biological species. Using microsatellite markers, 14 genotypes and populations with intermediate levels of genetic variability were found, suggesting that the fungus is indigenous to the Amazon Basin. Inoculation tests indicated that the andiroba isolates are host-specialized on andiroba, supporting the proposition of the special form C. fimbriata f. sp. carapa. 相似文献
207.
Andrea A. Villanueva Sofía Puvogel Pablo Lois Ernesto Muñoz-Palma Manuel Ramírez Orellana Fabiana Lubieniecki 《Cell Adhesion & Migration》2019,13(1):33-40
Neuroblastoma (NB) is the most common pediatric extracranial solid tumor. It arises during development of the sympathetic nervous system. Netrin-4 (NTN4), a laminin-related protein, has been proposed as a key factor to target NB metastasis, although there is controversy about its function. Here, we show that NTN4 is broadly expressed in tumor, stroma and blood vessels of NB patient samples. Furthermore, NTN4 was shown to act as a cell adhesion molecule required for the migration induced by Neogenin-1 (NEO1) in SK-N-SH neuroblastoma cells. Therefore, we propose that NTN4, by forming a ternary complex with Laminin γ1 (LMγ1) and NEO1, acts as an essential extracellular matrix component, which induces the migration of SK-N-SH cells. 相似文献
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209.
Leaf Decomposition in a Dry Season Irrigation Experiment in Eastern Amazonian Forest Regrowth 总被引:1,自引:0,他引:1
Steel Silva Vasconcelos Daniel Jacob Zarin Maria Beatriz Silva da Rosa Francisco de Assis Oliveira Cláudio José Reis de Carvalho 《Biotropica》2007,39(5):593-600
Leaf-litter decomposition is a major component of carbon and nutrient dynamics in tropical forest ecosystems, and moisture availability is widely considered to be a major influence on decomposition rates. Here, we report the results of a study of leaf-litter decomposition of five tree species in response to dry-season irrigation in a tropical forest regrowth stand in the Brazilian Amazon; three experiments differing in the timing of installation and duration allowed for an improved resolution of irrigation effects on decomposition. We hypothesized that decomposition rates would be faster under higher moisture availability in the wet season and during dry-season irrigation periods in the treatment plots, and that decomposition rates would be faster for species with higher quality leaves, independent of treatment. The rates of decomposition ( k ) were up to 2.4 times higher in irrigated plots than in control plots. The highest k values were shown by Annona paludosa (0.97 to 1.26/yr) while Ocotea guianensis (0.73 to 0.85/yr) had the lowest values; intermediate rates were found for Lacistema pubescens (0.91 to 1.02/yr) and Vismia guianensis (0.91 to 1.08/yr). These four tree species differed significantly in leaf-litter quality parameters (nitrogen, phosphorus, lignin, and cellulose concentrations, as well as lignin:nitrogen and carbon:nitrogen ratios), but differences in decomposition rates among tree species were not strictly correlated with leaf-litter quality. Overall, our results show that dry-season moisture deficits limit decomposition in Amazonian forest regrowth. 相似文献
210.
Nepogodiev SA Dedola S Marmuse L de Oliveira MT Field RA 《Carbohydrate research》2007,342(3-4):529-540
Rapid assembly of starch fragment analogues was achieved using 'click chemistry'. Specifically, a pentadecasaccharide and two hexadecasaccharide mimics containing two parallel maltoheptaosyl chains linked via [1,2,3]-triazoles to glucose or maltose core were synthesised using Cu(I)-catalyzed [3+2] dipolar cycloaddition of azidosaccharides and 4,6-di-O-propargylated methyl alpha-d-glucopyranoside and 6,6'- and 4',6'-di-O-propargylated p-methoxyphenyl beta-maltoside. 相似文献