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51.
Justine JL 《Systematic parasitology》2007,67(3):187-209
Type-specimens of all known species of Calydiscoides Young, 1969 from lethrinids, namely C. australis Young, 1969 (type-species), C. difficilis (Yamaguti, 1953) Young, 1969, C. duplicostatus (Yamaguti, 1953) Young, 1969, C. rohdei Oliver, 1984 and C. gussevi Oliver, 1984, were re-examined; the male copulatory organs (MCO) of the type-specimens are figured for comparison. Two groups are distinguished within Calydiscoides: the 'difficilis' group, with a massive MCO (C. difficilis and C. rohdei), and the 'australis' group, with a branched MCO (C. australis, C. duplicostatus and C. gussevi). Species of Calydiscoides were found in seven species of Lethrinus (Lethrinidae) off New Caledonia, South Pacific. C. australis and C. gussevi from L. miniatus, their type-host, and C. rohdei from L. atkinsoni, its type-host, are re-described from New Caledonian specimens; all were previously known only from off eastern Australia and are new geographical records for New Caledonia. C. euzeti n. sp. is described from specimens collected from L. rubrioperculatus (type-host) and L. xanthochilus off New Caledonia. Specimens from the two hosts have slightly different measurements of the haptoral hard-parts but a similar morphology of the MCO. The new species belongs to the 'australis' group and is characterised by its MCO, which is 70-83 mum in length, elongate in shape with a characteristic anterior curved whip. 相似文献
52.
Melles DC van Leeuwen WB Snijders SV Horst-Kreft D Peeters JK Verbrugh HA van Belkum A 《Journal of microbiological methods》2007,69(2):371-375
We compared multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and amplified fragment length polymorphism (AFLP) for typing of Staphylococcus aureus and show that the methods yield similar results, although with differences in resolving power and reproducibility. Epidemiological conditions should determine which is the optimal typing method to be used. 相似文献
53.
Effects of nutritional restriction on nitrogen and carbon stable isotopes in growing seabirds 总被引:4,自引:0,他引:4
When using stable isotopes as dietary tracers it is essential to consider effects of nutritional state on isotopic fractionation.
While starvation is known to induce enrichment of 15N in body tissues, effects of moderate food restriction on isotope signatures have rarely been tested. We conducted two experiments
to investigate effects of a 50–55% reduction in food intake on δ15N and δ13C values in blood cells and whole blood of tufted puffin chicks, a species that exhibits a variety of adaptive responses to
nutritional deficits. We found that blood from puffin chicks fed ad libitum became enriched in 15N and 13C compared to food-restricted chicks. Our results show that 15N enrichment is not always associated with food deprivation and argue effects of growth on diet–tissue fractionation of nitrogen
stable isotopes (Δ15N) need to be considered in stable isotope studies. The decrease in δ13C of whole blood and blood cells in restricted birds is likely due to incorporation of carbon from 13C-depleted lipids into proteins. Effects of nutritional restriction on δ15N and δ13C values were relatively small in both experiments (δ15N: 0.77 and 0.41‰, δ13C: 0.20 and 0.25‰) compared to effects of ecological processes, indicating physiological effects do not preclude the use of
carbon and nitrogen stable isotopes in studies of seabird ecology. Nevertheless, our results demonstrate that physiological
processes affect nitrogen and carbon stable isotopes in growing birds and we caution isotope ecologists to consider these
effects to avoid drawing spurious conclusions. 相似文献
54.
Filamentous temperature-sensitive Z (FtsZ) isoforms specifically interact in the chloroplasts and in the cytosol of Physcomitrella patens 总被引:1,自引:0,他引:1
Gremillon L Kiessling J Hause B Decker EL Reski R Sarnighausen E 《The New phytologist》2007,176(2):299-310
Plant filamentous temperature-sensitive Z (FtsZ) proteins have been reported to be involved in biological processes related to plastids. However, the precise functions of distinct isoforms are still elusive. Here, the intracellular localization of the FtsZ1-1 isoform in a moss, Physcomitrella patens, was examined. Furthermore, the in vivo interaction behaviour of four distinct FtsZ isoforms was investigated. Localization studies of green fluorescent protein (GFP)-tagged FtsZ1-1 and fluorescence resonance energy transfer (FRET) analyses employing all dual combinations of four FtsZ isoforms were performed in transient protoplast transformation assays. FtsZ1-1 is localized to network structures inside the chloroplasts and exerts influence on plastid division. Interactions between FtsZ isoforms occur in distinct ordered structures in the chloroplasts as well as in the cytosol. The results expand the view of the involvement of Physcomitrella FtsZ proteins in chloroplast and cell division. It is concluded that duplication and diversification of ftsZ genes during plant evolution were the main prerequisites for the successful remodelling and integration of the prokaryotic FtsZ-dependent division mechanism into the cellular machineries of distinct complex processes in plants. 相似文献
55.
One of the main characters used in acoel taxonomy is the male copulatory organ. Despite this, ultrastructural studies of this structure are scarce. We studied the ultrastructure of the copulatory organ in eight species of acoels belonging to the taxon Childia. Members of Childia possess a well-developed conical or cylindrical stylet-like structure composed of needles. Immunogold cytochemistry of tubulin was used to determine the composition of the needles. Stylet-like structures of Childia species at the ultrastructural level are basically similar. Stylet needles show intracellular differentiations. As shown both by ultrastructural and immunocytochemical methods, the stylet needles, in all species studied, are composed of long, parallel microtubules, either tightly packed or polymerized. We report unusual polymerization of microtubules, resulting in formation of a honeycomb-like structure in cross section. Variations of ultrastructure among Childia species include numbers and arrangement of stylet needles, shape of needles, needle compactness, microtubule polymerization, direction of stylet growth, and presence/absence of different types of granules. The stylet-like structures are homologous within Childia, but are likely to prove nonhomologous with the other needle-like structures found in acoel copulatory organs. Stylets in Platyhelminthes are not homologous with stylet-like structures in acoels. 相似文献
56.
Repression of alpha-actinin SM exon splicing by assisted binding of PTB to the polypyrimidine tract 下载免费PDF全文
Polypyrimidine tract binding protein (PTB) acts as a regulatory repressor of a large number of alternatively spliced exons, often requiring multiple binding sites in order to repress splicing. In one case, cooperative binding of PTB has been shown to accompany repression. The SM exon of the alpha-actinin pre-mRNA is also repressed by PTB, leading to inclusion of the alternative upstream NM exon. The SM exon has a distant branch point located 386 nt upstream of the exon with an adjacent 26 nucleotide pyrimidine tract. Here we have analyzed PTB binding to the NM and SM exon region of the alpha-actinin pre-mRNA. We find that three regions of the intron bind PTB, including the 3' end of the polypyrimidine tract (PPT) and two additional regions between the PPT and the SM exon. The downstream PTB binding sites are essential for full repression and promote binding of PTB to the PPT with a consequent reduction in U2AF(65) binding. Our results are consistent with a repressive mechanism in which cooperative binding of PTB to the PPT competes with binding of U2AF(65), thereby specifically blocking splicing of the SM exon. 相似文献
57.
Yonas I. Tekle Olga I. Raikova Jean-Lou Justine Jan Hendelberg Ulf Jondelius 《Zoomorphology》2007,126(1):1-16
Acoel sperm characters proved useful in deciphering acoel taxonomy. The phylogenetic value of sperm characters in closely
related sub-groups or in a monophyletic taxon has not yet been assessed. We have investigated sperm ultrastructure in seven
members of the monophyletic taxon Childia sensu (Tekle et al. J Zool Sys Evol Res 43(1):72–90, 2005) and in their closest relatives, the Mecynostomidae (four taxa). All members of Childia examined show little variation in their sperm ultrastructure. The common characters of Childia taxa are: 9 + 1 axoneme structure, the presence of six distal cytoplasmic microtubules in the absence of axial or cortical
ones, long nucleus and extensive nucleus–flagella overlap. We have identified a new set of cytoplasmic microtubules lying
in the centriolar end of the sperm cell, distal microtubules. The origin and phylogenetic significance of this character is
discussed. The types and arrangement of cytoplasmic granules could be used as phylogenetic characters at a low taxonomic level.
A loose membrane amorphous core type of granule was found to be a synapomorphy for the following clade within the taxon Childia: C. crassum + C. groenlandica + C. vivipara + C. brachyposthium + C. macroposthium. Sausage shaped granules are plesiomorphic among the taxa examined. The rest of the granule characters were found to be homoplasious.
Sperm ultrastructural characters have again proven their concordance with molecular phylogeny. The only morphological synapomorphies
known for the sister taxa Childia–Mecynostomidae, in the molecular phylogeny, are characters derived from sperm ultrastructure: distal microtubules arranged
in two groups of three microtubules each and a 9 + 1 axoneme structure. The spermatozoa of Childia and Mecynostomidae show 9 + 1 axoneme configuration, seemingly similar to the 9 + ‘1’ axoneme pattern of the Platyhelminthes—Trepaxonemata.
Using electron-microscope immunocytochemistry, we have demonstrated that, unlike the central cylinder of trepaxonematans,
the central cylinder of the 9 + 1 axonemal pattern in acoels is immunoreactive to tubulin and contains a single central microtubule.
Therefore, the 9 + 1 patterns in acoels and trepaxonematans are homoplasious. 相似文献
58.
59.
Justine A. Smith Yiwei Wang Christopher C. Wilmers 《Proceedings. Biological sciences / The Royal Society》2015,282(1802)
The fear induced by predators on their prey is well known to cause behavioural adjustments by prey that can ripple through food webs. Little is known, however, about the analogous impacts of humans as perceived top predators on the foraging behaviour of carnivores. Here, we investigate the influence of human-induced fear on puma foraging behaviour using location and prey consumption data from 30 tagged individuals living along a gradient of human development. We observed strong behavioural responses by female pumas to human development, whereby their fidelity to kill sites and overall consumption time of prey declined with increasing housing density by 36 and 42%, respectively. Females responded to this decline in prey consumption time by increasing the number of deer they killed in high housing density areas by 36% over what they killed in areas with little residential development. The loss of food from declines in prey consumption time paired with increases in energetic costs associated with killing more prey may have consequences for puma populations, particularly with regard to reproductive success. In addition, greater carcass availability is likely to alter community dynamics by augmenting food resources for scavengers. In light of the extensive and growing impact of habitat modification, our study emphasizes that knowledge of the indirect effects of human activity on animal behaviour is a necessary component in understanding anthropogenic impacts on community dynamics and food web function. 相似文献
60.
Yoon S Kim J Hum J Kim H Park S Kladwang W Das R 《Bioinformatics (Oxford, England)》2011,27(13):1798-1805
MOTIVATION: Capillary electrophoresis (CE) of nucleic acids is a workhorse technology underlying high-throughput genome analysis and large-scale chemical mapping for nucleic acid structural inference. Despite the wide availability of CE-based instruments, there remain challenges in leveraging their full power for quantitative analysis of RNA and DNA structure, thermodynamics and kinetics. In particular, the slow rate and poor automation of available analysis tools have bottlenecked a new generation of studies involving hundreds of CE profiles per experiment. RESULTS: We propose a computational method called high-throughput robust analysis for capillary electrophoresis (HiTRACE) to automate the key tasks in large-scale nucleic acid CE analysis, including the profile alignment that has heretofore been a rate-limiting step in the highest throughput experiments. We illustrate the application of HiTRACE on 13 datasets representing 4 different RNAs, 3 chemical modification strategies and up to 480 single mutant variants; the largest datasets each include 87 360 bands. By applying a series of robust dynamic programming algorithms, HiTRACE outperforms prior tools in terms of alignment and fitting quality, as assessed by measures including the correlation between quantified band intensities between replicate datasets. Furthermore, while the smallest of these datasets required 7-10 h of manual intervention using prior approaches, HiTRACE quantitation of even the largest datasets herein was achieved in 3-12 min. The HiTRACE method, therefore, resolves a critical barrier to the efficient and accurate analysis of nucleic acid structure in experiments involving tens of thousands of electrophoretic bands. 相似文献