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71.
Geert Zegels Geert AA Van Raemdonck Wiebren AA Tjalma Xaveer WM Van Ostade 《Proteome science》2010,8(1):63
Cervicovaginal fluid has an important function in the homeostasis and immunity of the lower female genital tract. Analysis
of the cervicovaginal fluid proteome may therefore yield important information about the pathogenesis of numerous gynecological
pathologies. Additionally, cervicovaginal fluid has great potential as a source of biomarkers for these conditions. 相似文献
72.
Andreas WM Dress Christoph Flamm Guido Fritzsch Stefan Grünewald Matthias Kruspe Sonja J Prohaska Peter F Stadler 《Algorithms for molecular biology : AMB》2008,3(1):7
Motivation
Sequence-based methods for phylogenetic reconstruction from (nucleic acid) sequence data are notoriously plagued by two effects: homoplasies and alignment errors. Large evolutionary distances imply a large number of homoplastic sites. As most protein-coding genes show dramatic variations in substitution rates that are not uncorrelated across the sequence, this often leads to a patchwork pattern of (i) phylogenetically informative and (ii) effectively randomized regions. In highly variable regions, furthermore, alignment errors accumulate resulting in sometimes misleading signals in phylogenetic reconstruction. 相似文献73.
74.
Taxol from fungal endophytes and the issue of biodiversity 总被引:7,自引:0,他引:7
GA Strobel WM Hess E. Ford RS Sidhu X Yang 《Journal of industrial microbiology & biotechnology》1996,17(5-6):417-423
Fungi represent one of the most understudied and diverse group of organisms. Commonly, these organisms make associations with higher life forms and may proceed to biochemically mimic the host organism. An excellent example of this is the anticancer drug, taxol, which had been previously supposed to occur only in the plant genusTaxus (yew). However, taxol has been reported in a novel endophytic fungus—Taxomyces andreanae, but also has been demonstrated to occur in a number of unrelated fungal endophytes includingPestalotia, Pestalotiopsis, Fusarium, Alternaria, Pithomyces, Monochaetia and others. Thus, this report presents information on the presence of taxol among disparate fungal genera, and uses these observations as an additional argument to support efforts to study fungal endophytes and preserve their associated host plants. 相似文献
75.
Testing the covarion hypothesis of molecular evolution 总被引:14,自引:8,他引:6
The covarion hypothesis of molecular evolution states that the fixation of
mutations may alter the probability that any given position will fix the
next change. Tests of this hypothesis using the divergence of real
sequences are compromised because models of rate variation among sites
(e.g., the gamma version of the one-parameter equation) predict sequence
divergence values similar to those for the covarion process. This study
therefore focuses on the extent to which the varied and unvaried codons of
two well-diverged taxa are the same, because fewer are expected by the
covarion hypothesis than by the gamma model. The data for these tests are
the protein sequences of Cu, Zn superoxide dismutase (SOD) for mammals and
plants. Simulation analyses show that the covarion hypothesis makes better
predictions about the frequencies of varied and unhit positions in common
between these two taxa than does the gamma version of the one-parameter
model. Furthermore, the analysis of SOD tertiary structure demonstrates
that mammal and plant variabilities are distributed differently on the
protein. These results support the conclusions that the variable and
invariable codons of mammal and plant SODs are different and that the
covarion model explains the evolution of this protein better than the gamma
version of the one-parameter process. Unlike other models, the covarion
hypothesis accounts for rate fluctuations among positions over time, which
is an important parameter of molecular evolution.
相似文献
76.
The conclusion arrived at by chemical methods, that the volatile agent produced when sulphur is applied to a heated surface is gaseous sulphur, has been subjected to biological tests in which the fungi Ery-siphe graminis and Sphaerotheca Humulind the gall mite Eriophyes ribis were employed.
The fungi were found not to be sufficiently sensitive to yield satisfactory and concordant results and strong support is given to the view that actual contact of the sulphur particle with the fungus is necessary before fungicidal action can occur.
It was shown that the agent present in air passed over heated sulphur and responsible for the death of the gall mite was not removed by filtration through a heated glass-wool plug, this observation being contrary to the view that the toxic agent is produced initially in solid form.
Filtration through a cooled glass-wool plug only removed part of the volatile agent and it was shown that the gall mite is affected by the traces of sulphur volatilised at ordinary temperatures.
The results of the experiments with the gall mite were in complete accord with those obtained in the previous chemical work.
At relatively large concentrations sulphur dioxide and hydrogen sulphide are without permanent effect upon the gall mite and these gases are therefore not responsible for the acaricidal action of sulphur. 相似文献
The fungi were found not to be sufficiently sensitive to yield satisfactory and concordant results and strong support is given to the view that actual contact of the sulphur particle with the fungus is necessary before fungicidal action can occur.
It was shown that the agent present in air passed over heated sulphur and responsible for the death of the gall mite was not removed by filtration through a heated glass-wool plug, this observation being contrary to the view that the toxic agent is produced initially in solid form.
Filtration through a cooled glass-wool plug only removed part of the volatile agent and it was shown that the gall mite is affected by the traces of sulphur volatilised at ordinary temperatures.
The results of the experiments with the gall mite were in complete accord with those obtained in the previous chemical work.
At relatively large concentrations sulphur dioxide and hydrogen sulphide are without permanent effect upon the gall mite and these gases are therefore not responsible for the acaricidal action of sulphur. 相似文献
77.
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80.
Phylogenetic inference under the pure drift model 总被引:1,自引:1,他引:0
When pairwise genetic distances are used for phylogenetic reconstruction,
it is usually assumed that the genetic distance between two taxa contains
information about the time after the two taxa diverged. As a result, upon
an appropriate transformation if necessary, the distance usually can be
fitted to a linear model such that it is expressed as the sum of lengths of
all branches that connect the two taxa in a given phylogeny. This kind of
distance is referred to as "additive distance." For a phylogenetic tree
exclusively driven by random genetic drift, genetic distances related to
coancestry coefficients (theta XY) between any two taxa are more suitable.
However, these distances are fundamentally different from the additive
distance in that coancestry does not contain any information about the time
after two taxa split from a common ancestral population; instead, it
reflects the time before the two taxa diverged. In other words, the
magnitude of theta XY provides information about how long the two taxa
share the same evolutionary pathways. The fundamental difference between
the two kinds of distances has led to a different algorithm of evaluating
phylogenetic trees when theta XY and related distance measures are used.
Here we present the new algorithm using the ordinary- least-squares
approach but fitting to a different linear model. This treatment allows
genetic variation within a taxon to be included in the model. Monte Carlo
simulation for a rooted phylogeny of four taxa has verified the efficacy
and consistency of the new method. Application of the method to human
population was demonstrated.
相似文献