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71.
Juliana R Martins Francis MF Nunes Alexandre S Cristino Zilá LP Simões Márcia MG Bitondi 《BMC molecular biology》2010,11(1):23
Background
Hexamerins are hemocyanin-derived proteins that have lost the ability to bind copper ions and transport oxygen; instead, they became storage proteins. The current study aimed to broaden our knowledge on the hexamerin genes found in the honey bee genome by exploring their structural characteristics, expression profiles, evolution, and functions in the life cycle of workers, drones and queens. 相似文献72.
73.
Approximately 100 strains derived from natural populations of Drosophila
melanogaster were tested for the presence or absence of P- element
sequences by using two molecular probes derived from internal regions of a
full-sized P element. Strains that had been collected from several
continents at varying times during the past 60 years were examined. The
oldest available strains, representing most major geographical regions of
the world, exhibited no detectable hybridization to the P-element probes.
In contrast, all recently collected natural populations that were tested
carried P-element sequences. The earliest appearance of P elements occurred
in collections made during the 1950s and early 1960s in the Americas and
during the late 1960s on other continents. The youngest strains that were
completely devoid of P elements originated in populations sampled during
the mid-1960s in America, but as late as 1974 in populations from the USSR.
There are differences in the patterns of hybridization to the two P-element
probes between populations from different geographical regions. These
differences are consistent with the varying P-M phenotypic properties of
these populations. Taken together with the results of phenotypic tests
reported in earlier studies, the available evidence is consistent with the
hypothesis of a worldwide P-element invasion of D. melanogaster during the
past 30 years and suggests that the putative invasion of the Americas
possibly preceded by approximately a decade that in Europe, Africa, and the
rest of the world.
相似文献
74.
Life history traits of the mango mealybug,Rastrococcus invadens Williams, were compared between two neighboring mango trees (Mangifera indica L.), one of which was heavily infested and the other slightly infested. On the infested tree, mealybug survival was high
because of good feeding conditions and low escape. The pre-reproductive period of mealybugs on the heavily infested tree was
shorter and total offspring production higher than that of mealybugs on the uninfested tree. This significantly affected the
intrinsic rate of natural increase and explained the observed differences in population densities among the trees. The results
obtained from an additional experiment using juvenile clones from the same two mango varieties, in which environmental factors
were uniform, demonstrated the importance of plant genotype on mealybug size and survival. 相似文献
75.
Host stage selection and sex allocation by Gyranusoidea tebygi Noyes (Hym,, Encyrtidae) were studied in choice and no-choice experiments in the laboratory. The parasitoid reproduced on first, second, and third instars of the mango mealybug, Rastrococcus invadens Williams (Hem., Pseudococcidae), and it avoided hosts that were already parasitized. Host feeding was occasionally observed. Sex ratios of the offspring produced by individual wasps were highly biased in favor of females, whereas the sex ratio of groups of wasps foraging under crowded conditions varied from male biased in smaller hosts to female biased in larger hosts. Females had longer developmental times than males, developed faster in larger mealybugs than in smaller ones, and were always larger than males emerging from the same host instar. Their size increased with the instar of the host at oviposition. About 90% of all ovipositions in second and third instar nymphs resulted from an attack with multiple stings, starting with a sting in the head of the host for the most part. The function of these head stings is either to assess quality of the host or to subdue hosts prior to oviposition. Encounter rates, number of attacks, and number of stings during one attack increased, while ovipositions decreased with host instar. Time investment per oviposition and time spent preening increased with increasing host age because older hosts defended themselves more vigorously than younger ones. Thus, while fitness of the parasitoid increased with host size, fitness returns per time decreased. The implications of this host selection behavior for the biological control of the mango mealybug are discussed. 相似文献
76.
Life table data for Rastrococcus invadens and its introduced natural enemy Gyranusoidea tebygi were obtained in the field and in the laboratory. The mealybug population's potential rate of increase ranged from 0.066/day to 0.078/day. The potential for increase of the parasitoid was double that of its host. Seasonal fluctuations in abundance of R. invadens were followed from 1988 to 1992 on mango trees in southern Benin. The population density of R. invadens decreased during the rainy seasons and peaked during the dry seasons. Mealybug field sex ratios were extremely variable, and the impact of such variability on the mealybug's potential rate of increase was analyzed. The populations of the exotic encyrtid G. tebygi, introduced into Benin in 1988 for control of the pest, were synchronized with the host populations. The spatial patterns of parasitism distribution in relation to the host population density were either independent or directly density-dependent, both at the tree level and for larger zones. However, reducing the scale of analysis resulted in different types of relationships. The impact of predators was a minor factor in the population dynamics of the mealybug. Four of the six species of hyper-parasitoids attacking mealybugs parasitized by G. tebygi developed high populations. In the two orchards studied, mealybug populations eventually collapsed and disappeared. This fact is discussed as being an indication that the biological control of the mango mealybug by G. tebygi was achieved by non-equilibrium local dynamics, and should be evaluated in a meta-population perspective. 相似文献
77.
Mitochondrial control-region sequences in two shorebird species, the turnstone and the dunlin, and their utility in population genetic studies 总被引:12,自引:0,他引:12
We determined the mitochondrial control-region sequences of five turnstones
(Arenaria interpres) and three dunlins (Calidris alpina). Comparisons
revealed that the central part (part II) is conserved relative to much more
variable parts at the beginning (part I) and the end (part III). This
pattern of sequence conservation is also found in the control regions of
other vertebrates. The average sequence divergence between turnstone and
dunlin was 21.8% for part I, 7.5% for part II, and 29.5% for part III.
Within-species sequence divergence over the entire control region was much
lower, at 0.9% for turnstones and 2.0% for dunlins. In both shorebird
species, part III contains a repetitive sequence composed only of A and C
nucleotides, which has not been found in the control regions of other
birds. A survey of the part I sequences of 25 turnstones and 25 dunlins
sampled around the world revealed that these species have very different
population genetic structures. Dunlins are not only much more
differentiated in their sequences but also have a strongly subdivided
population genetic structure. Pleistocene vicariant events combined with
strong natal philopatry and high mutation rates of the sequences are likely
responsible for this population genetic subdivision. Conversely, part I
sequences of turnstones are weakly differentiated and are geographically
unstructured. We argue that this is not the result of global gene flow but
that, instead turnstones have recently expanded from a refugial population
that was bottlenecked.
相似文献
78.
Estimating the patterns of connectivity in marine taxa with planktonic dispersive stages is a challenging but crucial task because of its conservation implications. The red gorgonian Paramuricea clavata is a habitat forming species, characterized by short larval dispersal and high reproductive output, but low recruitment. In the recent past, the species was impacted by mass mortality events caused by increased water temperatures in summer. In the present study, we used 9 microsatellites to investigate the genetic structure and connectivity in the highly threatened populations from the Ligurian Sea (NW Mediterranean). No evidence for a recent bottleneck neither decreased genetic diversity in sites impacted by mass mortality events were found. Significant IBD pattern and high global FST confirmed low larval dispersal capability in the red gorgonian. The maximum dispersal distance was estimated at 20–60 km. Larval exchange between sites separated by hundreds of meters and between different depths was detected at each site, supporting the hypothesis that deeper subpopulations unaffected by surface warming peaks may provide larvae for shallower ones, enabling recovery after climatically induced mortality events. 相似文献
79.
Sara Monteiro Alexandra Carreira Regina Freitas Ana Margarida Pinheiro Ricardo Boavida Ferreira 《PloS one》2015,10(4)
There are literally hundreds of polypeptides described in the literature which exhibit fungicide activity. Tens of them have had attempted protection by patent applications but none, as far as we are aware, have found application under real agricultural conditions. The reasons behind may be multiple where the sensitivity to the Sun UV radiation can come in first place. Here we describe a multifunctional glyco-oligomer with 210 kDa which is mainly composed by a 20 kDa polypeptide termed Blad that has been previously shown to be a stable intermediary product of β-conglutin catabolism. This oligomer accumulates exclusively in the cotyledons of Lupinus species, between days 4 and 12 after the onset of germination. Blad-oligomer reveals a plethora of biochemical properties, like lectin and catalytic activities, which are not unusual per si, but are remarkable when found to coexist in the same protein molecule. With this vast range of chemical characteristics, antifungal activity arises almost as a natural consequence. The biological significance and potential technological applications of Blad-oligomer as a plant fungicide to agriculture, its uniqueness stems from being of polypeptidic in nature, and with efficacies which are either equal or greater than the top fungicides currently in the market are addressed. 相似文献
80.
Johanna H Kattenberg Eleanor A Ochodo Kimberly R Boer Henk DFH Schallig Petra F Mens Mariska MG Leeflang 《Malaria journal》2011,10(1):1-18