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111.
Fluid balance is a major physiological problem for hematophagous ticks. To maintain osmotic balance they must conserve water for prolonged periods while seeking a mammalian host, and they must eliminate a very large volume of excess fluid taken in during a relatively short period of feeding. This is accomplished in part by modification of the salivary gland during 7–10 days of feeding to secrete a copious saliva which is pumped into the bovine host. This function has previously been attributed to certain interstitial epithelial cells of the type III acinus which differentiate in the course of feeding into cells reminiscent of those of the avian salt gland. The ultrastructural changes in the type III acinus during the blood-meal were studied. In addition to the differentiation of the interstitial cells, this paper describes a remarkable sequence of changes in external form and internal organization of the e-cells. This results in their transformation from typical protein-secreting glandular cells to transport cells having myriad basolateral processes interdigitating with those of the ablumenal interstitial cells to form a basal labyrinth comparable to that of other fluid-transporting epithelia. The findings are discussed in relation to various postulated mechanisms for fluid and electrolyte transport. 相似文献
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Quantitation of iptakalim in human plasma by high-performance liquid chromatography-tandem mass spectrometry 总被引:1,自引:0,他引:1
Teng G Wang Y Tang Y Wang R Fang Y Fawcett JP Gu J 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,859(2):256-260
This paper describes a rapid and sensitive analytical method for the quantitation of iptakalim, a novel antihypertensive drug, in human plasma. The method is based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) using sildenafil as internal standard. Sample preparation involved liquid-liquid extraction with dichloromethane-diethyl ether (2:3, v/v) in a basic environment. Chromatography was carried out on an amino column with a mobile phase consisting of acetonitrile-water (55:45, v/v, water containing 0.5% formic acid). Detection employed electrospray ionization (ESI) tandem mass spectrometry in the multiple-reaction-monitoring (MRM) mode. The assay was linear in the concentration range of 0.5-100 ng/ml with a lower limit of quantitation (LLOQ) of 0.5 ng/ml. Intra- and inter-day precision (R.S.D.) were <4.5% and <12.0%, respectively and the accuracy (R.E.) was in the range +/-5%. The method was successfully applied to a single oral dose pharmacokinetic study in human volunteers. 相似文献
115.
van Dijk RE Székely T Komdeur J Pogány A Fawcett TW Weissing FJ 《Proceedings. Biological sciences / The Royal Society》2012,279(1735):1927-1936
Eurasian penduline tits (Remiz pendulinus) have an unusually diverse breeding system consisting of frequent male and female polygamy, and uniparental care by the male or the female. Intriguingly, 30 to 40 per cent of all nests are deserted by both parents. To understand the evolution of this diverse breeding system and frequent clutch desertion, we use 6 years of field data to derive fitness expectations for males and females depending on whether or not they care for their offspring. The resulting payoff matrix corresponds to an asymmetric Snowdrift Game with two alternative evolutionarily stable strategies (ESSs): female-only and male-only care. This, however, does not explain the polymorphism in care strategies and frequent biparental desertion, because theory predicts that one of the two ESSs should have spread to fixation. Using a bootstrapping approach, we demonstrate that taking account of individual variation in payoffs explains the patterns of care better than a model based on the average population payoff matrix. In particular, a model incorporating differences in male attractiveness closely predicts the observed frequencies of male and female desertion. Our work highlights the need for a new generation of individual-based evolutionary game-theoretic models. 相似文献
116.
Cook BD Baker AM Page TJ Grant SC Fawcett JH Hurwood DA Hughes JM 《Molecular ecology》2006,15(4):1083-1093
The widespread distribution of the freshwater shrimp Paratya australiensis in eastern Australia suggests that populations of this species have been connected in the past. Amphidromy is ancestral in these shrimps, although many extant populations are known to be restricted to freshwater habitats. In this study, we used a fragment of the cytochrome c oxidase I mitochondrial DNA (mtDNA) gene to examine diversity within P. australiensis and to assess the relative importance of amphidromy in its evolutionary history. We hypothesized that if transitions from an amphidromous to a freshwater life history were important, then we would find a number of divergent lineages restricted to single or groups of nearby drainages. Alternatively, if amphidromy was maintained within the species historically, we expected to find lineages distributed over many drainages. We assumed that the only way for divergence to occur within amphidromous lineages was if dispersal was limited to between nearby estuaries, which, during arid periods in the earth's history, became isolated from one another. We found nine highly divergent mtDNA lineages, estimated to have diverged from one another in the late Miocene/early Pliocene, when the climate was more arid than at present. Despite this, the geographic distribution of lineages and haplotypes within lineages did not support the notion of a stepping-stone model of dispersal between estuaries. We conclude that the extensive divergence has most likely arisen through a number of independent amphidromy-freshwater life history transitions, rather than via historical isolation of amphidromy populations. We also found evidence for extensive movement between coastal and inland drainages, supporting the notion that secondary contact between lineages may have occurred as a result of drainage rearrangements. Finally, our data indicate that P. australiensis is likely a complex of cryptic species, some of which are widely distributed, and others geographically restricted. 相似文献
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Dan Zhang Yingwu Wang Jiangbin Han Weisong Yu Lili Deng J. Paul Fawcett Zeyuan Liu Jingkai Gu 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2009,877(5-6):581-585
This paper describes a rapid and sensitive method for the quantitation of 20(S)-protopanaxadiol (PPD) in human plasma based on high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS). The analyte and internal standard (I.S.), ginsenoside Rh2, were extracted from plasma by liquid–liquid extraction and separated on a Zorbax extend C18 analytical column using methanol–acetonitrile-10 mM ammonium acetate (47.5:47.5:5, v/v/v) as mobile phase. Detection was by tandem mass spectrometry using electrospray ionization in the positive ion mode and multiple reaction monitoring (MRM). The assay was linear over the concentration range 0.1–100.0 ng/ml with a limit of detection of 0.05 ng/ml. The method was successfully applied to a clinical pharmacokinetic study in healthy volunteers after a single oral administration of a PPD 25 mg capsule. 相似文献
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Y. Qiao C. Harvard C. Tyson X. Liu C. Fawcett P. Pavlidis J. J. A. Holden M. E. S. Lewis E. Rajcan-Separovic 《Human genetics》2010,128(2):179-194
Array CGH enables the detection of pathogenic copy number variants (CNVs) in 5–15% of individuals with intellectual disability
(ID), making it a promising tool for uncovering ID candidate genes. However, most CNVs encompass multiple genes, making it
difficult to identify key disease gene(s) underlying ID etiology. Using array CGH we identified 47 previously unreported unique
CNVs in 45/255 probands. We prioritized ID candidate genes using five bioinformatic gene prioritization web tools. Gene priority
lists were created by comparing integral genes from each CNV from our ID cohort with sets of training genes specific either
to ID or randomly selected. Our findings suggest that different training sets alter gene prioritization only moderately; however,
only the ID gene training set resulted in significant enrichment of genes with nervous system function (19%) in prioritized
versus non-prioritized genes from the same de novo CNVs (7%, p < 0.05). This enrichment further increased to 31% when the five web tools were used in concert and included genes within
mitogen-activated protein kinase (MAPK) and neuroactive ligand-receptor interaction pathways. Gene prioritization web tools
enrich for genes with relevant function in ID and more readily facilitate the selection of ID candidate genes for functional
studies, particularly for large CNVs. 相似文献