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101.
LOVE DALÉN EVA FUGLEI PÁLL HERSTEINSSON CHRISTIAN M. O. KAPEL JAMES D. ROTH GUSTAF SAMELIUS MAGNUS TANNERFELDT ANDERS ANGERBJÖRN 《Biological journal of the Linnean Society. Linnean Society of London》2005,84(1):79-89
The circumpolar arctic fox Alopex lagopus thrives in cold climates and has a high migration rate involving long-distance movements. Thus, it differs from many temperate taxa that were subjected to cyclical restriction in glacial refugia during the Ice Ages. We investigated population history and genetic structure through mitochondrial control region variation in 191 arctic foxes from throughout the arctic. Several haplotypes had a Holarctic distribution and no phylogeographical structure was found. Furthermore, there was no difference in haplotype diversity between populations inhabiting previously glaciated and unglaciated regions. This suggests current gene flow among the studied populations, with the exception of those in Iceland, which is surrounded by year-round open water. Arctic foxes have often been separated into two ecotypes: 'lemming' and 'coastal'. An analysis of molecular variance suggested particularly high gene flow among populations of the 'lemming' ecotype. This could be explained by their higher migration rate and reduced fitness in migrants between ecotypes. A mismatch analysis indicated a sudden expansion in population size around 118 000 BP, which coincides with the last interglacial. We propose that glacial cycles affected the arctic fox in a way opposite to their effect on temperate species, with interglacials leading to short-term isolation in northern refugia. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 79–89. 相似文献
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Gustavo?Camps-VallsEmail author Alistair?M?Chalk Antonio?J?Serrano-López José?D?Martín-Guerrero Erik?LL?Sonnhammer 《BMC bioinformatics》2004,5(1):135
Background
This paper presents the use of Support Vector Machines (SVMs) for prediction and analysis of antisense oligonucleotide (AO) efficacy. The collected database comprises 315 AO molecules including 68 features each, inducing a problem well-suited to SVMs. The task of feature selection is crucial given the presence of noisy or redundant features, and the well-known problem of the curse of dimensionality. We propose a two-stage strategy to develop an optimal model: (1) feature selection using correlation analysis, mutual information, and SVM-based recursive feature elimination (SVM-RFE), and (2) AO prediction using standard and profiled SVM formulations. A profiled SVM gives different weights to different parts of the training data to focus the training on the most important regions. 相似文献103.
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Recombinant adenovirus is one of the primary vectors for human gene therapy. However, the aggregation of unstable virus has
been a recurring problem during the production of purified virus for human therapeutics. To facilitate the development of
a robust manufacturing process for recombinant adenovirus vectors, a convenient and reliable size distribution analytical
assay is necessary and we demonstrate here that disc centrifuge sedimentation is applicable to this purpose. Using the disc
centrifuge system and the line start method, the assay can provide particle size distribution of adenovirus samples within
30 min. The assay can detect virus concentrations down to 0.01% (w/v) or 3 × 1011 particles per ml. The apparent hydrodynamic diameter of recombinant adenovirus was determined to be about 0.063 μm. Furthermore,
the disc centrifuge analysis was able to detect adenovirus dimers, trimers, and tetramers, consistent with a rigid sphere
approximation for adenovirus, as well as a large aggregate of 0.35 μm. The appearance of viral aggregates is confirmed by
increased light scattering based on A320/A260 ratios. The technique could be useful for monitoring the kinetics of aggregation for adenovirus and other DNA and RNA viruses
in the submicron region. Therefore, this novel assay provides a critical tool for purification development of viral vectors
for meeting therapeutic and research needs.
Received 18 September 1997/ Accepted in revised form 15 May 1998 相似文献
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Astorga and Williams1 have demonstrated that leucocytes from some patients with rheumatoid arthritis (RA) have an impaired one-way mixed leucocyte reaction2 (MLR) when stimulated with leucocytes from other such patients. No definite explanation of this phenomenon is given. We have investigated other diseases in which auto-immune aetiology is suspected to see whether similar phenomena are associated with them. Here we report our investigations of multiple sclerosis (MS). 相似文献
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