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排序方式: 共有73条查询结果,搜索用时 421 毫秒
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A cDNA encoding RAP74, a general initiation factor for transcription by RNA polymerase II. 总被引:15,自引:0,他引:15
A Finkelstein C F Kostrub J Li D P Chavez B Q Wang S M Fang J Greenblatt Z F Burton 《Nature》1992,355(6359):464-467
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Summary Prior melatonin administration (1 and 10 mg/kg b.wt) causes a significant reduction in apomorphine (1 mg/kg b.wt) induced rotational behaviour in both 6-hydroxydopamine and quinolinic acid lesioned rats. 相似文献
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In total darkness, melanophores of much of the integumentary pattern of Pseudopleuronectes americanus display intermediate melanosome distribution, whilst the alpha-adrenoceptor antagonist phentolamine evokes their complete dispersion. The intermediate condition is not attained in total darkness in locally decentralized melanophores. It is proposed that, in the absence of photic stimulation, spontaneous neural activity sustains a partial melanosome aggregation in this species. 相似文献
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Kempf S Srama R Horányi M Burton M Helfert S Moragas-Klostermeyer G Roy M Grün E 《Nature》2005,433(7023):289-291
High-velocity submicrometre-sized dust particles expelled from the jovian system have been identified by dust detectors on board several spacecraft. On the basis of periodicities in the dust impact rate, Jupiter's moon Io was found to be the dominant source of the streams. The grains become positively charged within the plasma environment of Jupiter's magnetosphere, and gain energy from its co-rotational electric field. Outside the magnetosphere, the dynamics of the grains are governed by the interaction with the interplanetary magnetic field that eventually forms the streams. A similar process was suggested for Saturn. Here we report the discovery by the Cassini spacecraft of bursts of high-velocity dust particles (> or = 100 km s(-1)) within approximately 70 million kilometres of Saturn. Most of the particles detected at large distances appear to originate from the outskirts of Saturn's outermost main ring. All bursts of dust impacts detected within 150 Saturn radii are characterized by impact directions markedly different from those measured between the bursts, and they clearly coincide with the spacecraft's traversals through streams of compressed solar wind. 相似文献
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Alard O Luguet A Pearson NJ Griffin WL Lorand JP Gannoun A Burton KW O'Reilly SY 《Nature》2005,436(7053):1005-1008
Abyssal peridotites are assumed to represent the mantle residue of mid-ocean-ridge basalts (MORBs). However, the osmium isotopic compositions of abyssal peridotites and MORB do not appear to be in equilibrium, raising questions about the cogenetic relationship between those two reservoirs. However, the cause of this isotopic mismatch is mainly due to a drastic filtering of the data based on the possibility of osmium contamination by sea water. Here we present a detailed study of magmatic sulphides (the main carrier of osmium) in abyssal peridotites and show that the 187Os/188Os ratio of these sulphides is of primary mantle origin and can reach radiogenic values suggesting equilibrium with MORB. Thus, the effect of sea water on the osmium systematics of abyssal peridotites has been overestimated and consequently there is no true osmium isotopic gap between MORBs and abyssal peridotites. 相似文献
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An SNP map of human chromosome 22 总被引:35,自引:0,他引:35
Mullikin JC Hunt SE Cole CG Mortimore BJ Rice CM Burton J Matthews LH Pavitt R Plumb RW Sims SK Ainscough RM Attwood J Bailey JM Barlow K Bruskiewich RM Butcher PN Carter NP Chen Y Clee CM Coggill PC Davies J Davies RM Dawson E Francis MD Joy AA Lamble RG Langford CF Macarthy J Mall V Moreland A Overton-Larty EK Ross MT Smith LC Steward CA Sulston JE Tinsley EJ Turney KJ Willey DL Wilson GD McMurray AA Dunham I Rogers J Bentley DR 《Nature》2000,407(6803):516-520
The human genome sequence will provide a reference for measuring DNA sequence variation in human populations. Sequence variants are responsible for the genetic component of individuality, including complex characteristics such as disease susceptibility and drug response. Most sequence variants are single nucleotide polymorphisms (SNPs), where two alternate bases occur at one position. Comparison of any two genomes reveals around 1 SNP per kilobase. A sufficiently dense map of SNPs would allow the detection of sequence variants responsible for particular characteristics on the basis that they are associated with a specific SNP allele. Here we have evaluated large-scale sequencing approaches to obtaining SNPs, and have constructed a map of 2,730 SNPs on human chromosome 22. Most of the SNPs are within 25 kilobases of a transcribed exon, and are valuable for association studies. We have scaled up the process, detecting over 65,000 SNPs in the genome as part of The SNP Consortium programme, which is on target to build a map of 1 SNP every 5 kilobases that is integrated with the human genome sequence and that is freely available in the public domain. 相似文献