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F. R. Carnese A. Caratini A. Goicoechea T. A. Weimer M. H. L. P. Franco M. H. Hutz F. M. Salzano 《International Journal of Anthropology》1996,11(2-4):33-42
The whole Mapuche Indian community of Blancura Centro was covered by a demographic census, with special attention given to
variables of genetic interest. Afterwards a sample of it was investigated in relation to 22 genetic systems. The community
can be characterized as a young group, with high fertility, but moderate mortality and endogamy. The index of opportunity
for selection is relatively low (0.46). The presence of variation at the ABO and Lutheran loci suggests some non-Indian admixture,
calculated as 7% in the sample studied. Unusual findings were the absence of L*NS, low frequency (7%) of L*MS and high frequency (37%) of L*Ns. They also showed low frequencies of P*1 (28%) and DI*a (3%), but high of HP*1 (74%). Similarities, but also differences, were noted with previous results obtained in this tribe in Argentina and Chile. 相似文献
84.
M. C. Bortolini T. A. Weimer F. M. Salzano L. B. Moura M. C. B. O. Silva 《International Journal of Anthropology》1997,12(1):5-16
A total of 218 individuals living in the Brazilian cities of Porto Alegre (in the South) and Salvador (in the Northeast) were
variously studied in relation to nine erythrocyte and four plasma protein systems. The results were compared with previous
studies in some of these systems, and estimates of interethnic admixture obtained in subsamples according to morphological
appearance. As a whole, Afro-Brazilians from Salvador show 42% of non-African genes, the corresponding figure for Porto Alegre
being 59%. The Amerindian contribution to these individuals was estimated as null or negligible. Average heterozygosities
are similar to those obtained for African groups, but the gene differentiation coefficient (GST') is small. The phylogenetic
tree indicates a closer relationship of Salvador with the African subcluster, as would be expected by the admixture and istorical
data. Analyses such as this one are important for the unraveling of the complex networks responsible for the present variability
of human populations, and for the dispelling of racist concepts. 相似文献
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Distribution and population structure of the anther smut Microbotryum silenes‐acaulis parasitizing an arctic–alpine plant 下载免费PDF全文
Britta Bueker Chris Eberlein Pierre Gladieux Angela Schaefer Alodie Snirc Dominic J. Bennett Dominik Begerow Michael E. Hood Tatiana Giraud 《Molecular ecology》2016,25(3):811-824
Cold‐adapted organisms with current arctic–alpine distributions have persisted during the last glaciation in multiple ice‐free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic–alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic–alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes‐acaulis was present throughout the host's geographical range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes‐acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic–alpine distribution. 相似文献
87.
Importance of the geographic barriers to promote gene drift and avoid pre‐ and post‐Columbian gene flow in Mexican native groups: Evidence from forensic STR Loci 下载免费PDF全文
88.
Detecting and quantifying introgression in hybridized populations: simplifying assumptions yield overconfidence and uncertainty 下载免费PDF全文
Patrick Della Croce Geoffrey C. Poole Gordon Luikart 《Molecular ecology resources》2016,16(6):1287-1302
A growing threat to the conservation of many native species worldwide is genetic introgression from non‐native species. Although improved molecular genetic techniques are increasing the availability of species‐diagnostic markers for many species, efficient field sampling design and reliable data interpretation require accurate estimates of uncertainty associated with the detection of non‐native alleles and the quantification of introgression in native populations. Using fish populations as examples, we developed a simulation model of an age‐structured population that tracks the introduction and inheritance of non‐native alleles across generations by simulating stochastic mating and survival of individual fish and the resulting transmission of diagnostic markers. To simulate detection and quantification of introgression, we sampled varying combinations of n fish and m diagnostic markers to detect and quantify introgression from thousands of virtual, independent fish populations for a wide range of hybridization scenarios. Using the results of simulated sampling, we quantified the extent to which common simplifying assumptions regarding population structure and inheritance mechanisms can lead to the following: (i) overconfidence in our ability to detect non‐native alleles and (ii) unrealistically narrow confidence intervals for estimates of the proportion of non‐native alleles present. Under many circumstances, commonly used simplifying assumptions underestimate the probability of failing to detect ongoing introgression and the uncertainty associated with estimates of introgression by orders of magnitude. Such overconfidence in our ability to detect and quantify introgression can affect critical conservation and management decisions regarding native species undergoing or at risk of introgression from non‐native species. 相似文献
89.
Results of hydrochemical observations in the summer of 1983 are presented and compared to the data of previous years. Some
trends in the changing conditions of the lake over the last fifty years are characterized. Data on the chemical composition
of bottom deposits are also reported. 相似文献
90.
Júlia Graciele Vieira Geandre de Carvalho Oliveira Guimes Rodrigues Filho Rosana Maria Nascimento de Assuno Carla da Silva Meireles Daniel Alves Cerqueira Wanderly Geraldo Silva Leila Aparecida de Castro Motta 《Carbohydrate polymers》2009,78(4):779-783
In previous works, methylcellulose (MC) was prepared from sugarcane bagasse cellulose in heterogeneous medium using dimethyl sulfate (DMS) as etherification agent. MC was produced in a range of degrees of substitution (DS) from 0.70 to 1.40 and the materials showed low water solubility. In this work methylcellulose was prepared with 5 h (MC5h) of reaction with reagent substitution at each hour. MC5h showed a DS of 1.89 ± 0.04. An aqueous viscous suspension was produced with MC5h for application as viscosity enhancing admixture of cimentitious adhesive mortars. It was observed a 40.37% increase on the consistency index (CI) and a 27.70% increase on the Potential Tensile Adhesion Strength. Such characteristics show the potential of this material for the utilization in situations that require good workability, improve viscosity and adhesive properties such as for tile setting in civil engineering. 相似文献