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81.
82.
D. M. P. Phillips 《Cellular and molecular life sciences : CMLS》1968,24(7):668-669
Résumé La déoxyribonucléoprotéine (DNP) du thymus de veau peut lier de l'histone supplémentaire en solution physiologique. La plupart de cette protéine est très faiblement liée et s'est degagée par HCl de 3,3 mM ou moins. On suggère ainsi que l'histone supplémentaire soit combinée aux groupes carboxyl des histones originales du DNP. Néanmoins, environ 10% de la protamine, ajouté pareillement au DNP, fut liée fortement ce qui suggère qu'elle peut atteindre les groupes phosphates libres sur l'ADN. La protamine apparemment n'a pas deplacée les histones lorsqu'elle fut liée au DNP. 相似文献
83.
84.
Vaccinia virus recombinants that express cloned genes encoding antigens of unrelated infectious agents, such as hepatitis B virus and human immunodeficiency virus (HIV), provide a new approach to the development of live vaccines. Although there is evidence that genetically engineered vaccinia viruses have reduced pathogenicity a major obstacle to their use as vaccines is that severe complications can occur after vaccination, especially in immunodeficient individuals. We describe here a recombinant vaccinia virus expressing murine interleukin-2 (IL-2) and show that athymic nude mice infected with the recombinant virus resolve the virus infection rapidly whereas mice infected with control virus develop a progressive vaccinal disease. By incorporating the gene for IL-2 in live virus vaccines it may be possible to prevent the severe complications that arise in recipients with an impaired immune system. 相似文献
85.
Collins PY Patel V Joestl SS March D Insel TR Daar AS;Scientific Advisory Board the Executive Committee of the Grand Challenges on Global Mental Health Anderson W Dhansay MA Phillips A Shurin S Walport M Ewart W Savill SJ Bordin IA Costello EJ Durkin M Fairburn C Glass RI Hall W Huang Y Hyman SE Jamison K Kaaya S Kapur S Kleinman A Ogunniyi A Otero-Ojeda A Poo MM Ravindranath V Sahakian BJ Saxena S Singer PA Stein DJ 《Nature》2011,475(7354):27-30
86.
We report a population of the mussel the black sandshell ( Ligumia recta [Lamarck, 1819]) from the Carrot River in Saskatchewan, far north of the species’ known range in southern Manitoba and northwestern Ontario. Ligumia recta is reported to be declining substantially in its abundance and range, and this occurrence provides valuable information for the construction of a species status report in Canada. 相似文献
87.
88.
Invasion and the evolution of speed in toads 总被引:1,自引:0,他引:1
Cane toads (Bufo marinus) are large anurans (weighing up to 2 kg) that were introduced to Australia 70 years ago to control insect pests in sugar-cane fields. But the result has been disastrous because the toads are toxic and highly invasive. Here we show that the annual rate of progress of the toad invasion front has increased about fivefold since the toads first arrived; we find that toads with longer legs can not only move faster and are the first to arrive in new areas, but also that those at the front have longer legs than toads in older (long-established) populations. The disaster looks set to turn into an ecological nightmare because of the negative effects invasive species can have on native ecosystems; over many generations, rates of invasion will be accelerated owing to rapid adaptive change in the invader, with continual 'spatial selection' at the expanding front favouring traits that increase the toads' dispersal. 相似文献
89.
ter Steege H Pitman NC Phillips OL Chave J Sabatier D Duque A Molino JF Prévost MF Spichiger R Castellanos H von Hildebrand P Vásquez R 《Nature》2006,443(7110):444-447
The world's greatest terrestrial stores of biodiversity and carbon are found in the forests of northern South America, where large-scale biogeographic patterns and processes have recently begun to be described. Seven of the nine countries with territory in the Amazon basin and the Guiana shield have carried out large-scale forest inventories, but such massive data sets have been little exploited by tropical plant ecologists. Although forest inventories often lack the species-level identifications favoured by tropical plant ecologists, their consistency of measurement and vast spatial coverage make them ideally suited for numerical analyses at large scales, and a valuable resource to describe the still poorly understood spatial variation of biomass, diversity, community composition and forest functioning across the South American tropics. Here we show, by using the seven forest inventories complemented with trait and inventory data collected elsewhere, two dominant gradients in tree composition and function across the Amazon, one paralleling a major gradient in soil fertility and the other paralleling a gradient in dry season length. The data set also indicates that the dominance of Fabaceae in the Guiana shield is not necessarily the result of root adaptations to poor soils (nodulation or ectomycorrhizal associations) but perhaps also the result of their remarkably high seed mass there as a potential adaptation to low rates of disturbance. 相似文献
90.
Rearrangement and transcription of the beta-chain genes of the T-cell antigen receptor in different types of murine lymphocytes 总被引:2,自引:0,他引:2
M Kronenberg J Goverman R Haars M Malissen E Kraig L Phillips T Delovitch N Suciu-Foca L Hood 《Nature》1985,313(6004):647-653
Rearrangements of T-cell receptor beta-chain genes are usually found on both chromosomal homologues, occurring by both deletional and non-deletional mechanisms. Two constant-region (C beta) genes have been identified previously and at least one is transcribed in every helper or cytotoxic T cell tested, but the choice of C beta gene expression is not correlated with the specialized functions of these T lymphocytes. By contrast, four of five suppressor T-cell hybridomas examined have deleted all known joining (J beta) gene segments and C beta genes and therefore may have antigen receptors encoded by different T-cell receptor gene families. 相似文献