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581.
Genome divergence in two Prochlorococcus ecotypes reflects oceanic niche differentiation 总被引:1,自引:0,他引:1
Rocap G Larimer FW Lamerdin J Malfatti S Chain P Ahlgren NA Arellano A Coleman M Hauser L Hess WR Johnson ZI Land M Lindell D Post AF Regala W Shah M Shaw SL Steglich C Sullivan MB Ting CS Tolonen A Webb EA Zinser ER Chisholm SW 《Nature》2003,424(6952):1042-1047
The marine unicellular cyanobacterium Prochlorococcus is the smallest-known oxygen-evolving autotroph. It numerically dominates the phytoplankton in the tropical and subtropical oceans, and is responsible for a significant fraction of global photosynthesis. Here we compare the genomes of two Prochlorococcus strains that span the largest evolutionary distance within the Prochlorococcus lineage and that have different minimum, maximum and optimal light intensities for growth. The high-light-adapted ecotype has the smallest genome (1,657,990 base pairs, 1,716 genes) of any known oxygenic phototroph, whereas the genome of its low-light-adapted counterpart is significantly larger, at 2,410,873 base pairs (2,275 genes). The comparative architectures of these two strains reveal dynamic genomes that are constantly changing in response to myriad selection pressures. Although the two strains have 1,350 genes in common, a significant number are not shared, and these have been differentially retained from the common ancestor, or acquired through duplication or lateral transfer. Some of these genes have obvious roles in determining the relative fitness of the ecotypes in response to key environmental variables, and hence in regulating their distribution and abundance in the oceans. 相似文献
582.
Surprisingly few birds have penises, but among those that do, the Argentine lake duck (Oxyura vittata) tops the bill - the penis of this small stifftail duck from South America is shaped like a corkscrew and, at almost half a metre long, is the largest of any bird measured so far. Factors responsible for the evolution of this remarkable organ could include runaway selection, whereby drakes with longer penises gain dominance and copulate with more females, or preference by females for drakes with longer and more decorated penises. 相似文献
583.
A consensus amino-acid sequence repeat in Torpedo and mammalian Ca2+-dependent membrane-binding proteins 总被引:23,自引:0,他引:23
A group of calcium-binding proteins which bind to biomembranes has recently been identified in widely different cells and tissues (refs 1-7, reviewed in ref. 8). Three of these proteins (p70, p36 and p32.5) cross-react with antiserum to calelectrin, a Ca2+-binding protein (relative molecular mass 34,000 (34K] from the ray Torpedo marmorata, giving rise to their designation as calelectrin-related proteins. We now report that calelectrin, p36 and p32.5 contain a 17-amino-acid consensus sequence which is conserved and present in multiple copies. We suggest that this sequence may be common to other members of this new group of Ca2+-binding proteins and may underlie their unusual mode of combination with biomembranes. 相似文献
584.
SIV adaptation to human cells 总被引:44,自引:0,他引:44
V M Hirsch P Edmondson M Murphey-Corb B Arbeille P R Johnson J I Mullins 《Nature》1989,341(6243):573-574
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C. Djerassi B. Gilbert J. N. Shoolery L. F. Johnson K. Biemann 《Cellular and molecular life sciences : CMLS》1961,17(4):162-163
Zusammenfassung Die Struktur desAspidosperma-Alkaloids Pyrifolidin (I) wird durch Protonresonanz und durch Vergleich mit Aspidospermin und Aspidocarpin bewiesen. Dieses Alkaloid ist in seiner absoluten Konfiguration ein Antipode des Aspidospermins.
Paper XXV,C. Djerassi, A. A. P. G. Archer, T. George, B. Gilbert, J. N. Shoolery, andL. F. Johnson, Exper.16, 532 (1960).
Acknowledgement. Financial support has been provided by grant H-5048 of the National Heart Institute, National Institutes of Health (U.S. Public Health Service), and by the Conselho Nacional de Pesquisas (Brazil). The postdoctorate research fellowship ofB. Gilbert in Rio de Janeiro was financed from a grant of the Rockefeller Foundation in support of a collaborative research program between Stanford University and the Instituto de Quimica Agricola, Rio de Janeiro (Brazil). 相似文献
Paper XXV,C. Djerassi, A. A. P. G. Archer, T. George, B. Gilbert, J. N. Shoolery, andL. F. Johnson, Exper.16, 532 (1960).
Acknowledgement. Financial support has been provided by grant H-5048 of the National Heart Institute, National Institutes of Health (U.S. Public Health Service), and by the Conselho Nacional de Pesquisas (Brazil). The postdoctorate research fellowship ofB. Gilbert in Rio de Janeiro was financed from a grant of the Rockefeller Foundation in support of a collaborative research program between Stanford University and the Instituto de Quimica Agricola, Rio de Janeiro (Brazil). 相似文献
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Do economic advances spring directly from fundamental scientific discoveries? The early history of the transistor suggests that the situation is not nearly so simple as this. 相似文献